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Preferred CVT

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    Posted: Jun/17/2009 at 12:28pm
As far as I know there are four different CVTs primarily used by teams:

1) Polaris P90
2) CVTech
3) Gaged Engineering
4) Comet

We have used the polaris set up for the past three years and have never been satisfied with it.  I'm thinking of moving to the new CVTech or something from Gaged.  Just wondering what other teams are running and what their thoughts were.


Edit: added comet to the list.


Edited by mu - Jun/17/2009 at 1:49pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/17/2009 at 1:13pm
Comet makes a couple models that several teams run.  We run one of their 700's I believe.  I'm not the drivetrain guy, but I know it's a Comet, and a lot better than the Polaris was on our car.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JHrdy724 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/17/2009 at 1:18pm
never used a p90.
the team used to run a comet(from my understanding it ran hot, lacked tunability, and didn't quite get the desired ratio).
Ran the CVTech for several years(older model was reliable and nice, newer model suffers from reliability issues, haven't used the newest)
Just switched to the gaged this year (takes hours upon hours upon hours to get tuned right, had threads holding a ramp on tear out, runs hot)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mu Quote  Post ReplyReply Direct Link To This Post Posted: Jun/17/2009 at 1:48pm
Forgot about the comet CVTs.  That's what our team used to use before moving to polaris.  Unfortunately it was before my time so I don't know how well it worked.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnpate01 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/17/2009 at 8:50pm

We used a Comet 700 series and had mixed results out of it.  It was very reliable, though.  I don't think we could kill it if we tried.  

I agree with the Auburn guy, we couldn't get the ratio quite right.  We had to settle with "close enough."

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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/18/2009 at 4:02pm
Gaged is nice, but really expensive and difficult to tune properly.
CVTech is cheap and fairly easy to use/tune etc, but can be unreliable.
Comet is old news.
Never heard anything about a polaris, but oregon state uses it so it cant be that bad.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote EAD Motorsports Quote  Post ReplyReply Direct Link To This Post Posted: Jun/18/2009 at 4:06pm
I was working carnage crew during endurance once and noticed several teams who could no longer get up hills had the low-end Comet CVT. Not the 700 series. This was 2-3 years ago. Not sure if they're even sold anymore.
 
Anybody know the price points (assuming you aren't getting a break) for various CVTs?
Honestly, a CVT faq (ratios, wt, general design, cost) would be nice. Anybody up for it? Wink


Edited by EAD Motorsports - Jun/18/2009 at 4:09pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote OctoberSky Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2009 at 1:42am
yes please...though I doubt anyone really wants to put up their spring and weight combos...We've used Polaris for at least the past 4 years and never had any trouble with tuning or reliability other than breaking them when they hit our old "steel band" cvt covers. they're about the heaviest cvt's you can get, but as stated Oregon State seems to like them, so they're worth something
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2009 at 9:37am
We've used Comet for 4 years now and will not be using them again.  They get HOT and they do it QUICK.  I notice a slow down after just one lap at Wisconsin.  The only good thing is that you really can't break them.  We have never done any maintenance and it still "works"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2009 at 10:58am
Originally posted by CLReedy21 CLReedy21 wrote:

Gaged is nice, but really expensive and difficult to tune properly.
CVTech is cheap and fairly easy to use/tune etc, but can be unreliable.
Comet is old news.
Never heard anything about a polaris, but oregon state uses it so it cant be that bad.


We finished 2nd overall in dynamic events on an "old news" Comet.  Ours isn't exactly stock either though so...  Our car was more set up for top speed than acceleration but even still we took 13th(in accel) and out ran a couple of the schools running Gaged CVTs.

From what I've seen and heard, Comet is hard to beat for reliability/simplicity.  As far as I know, we have never had a failure, of any kind, out of our Comets.

Gaged is supposedly really hard to tune, extremely light weight, and extremely expensive, though they seem to be reliable.

One of our old cars runs a Polaris and we could never get it to run right with it but obviously Oregon State has it figured out.  It's pretty big and heavy but seems to be relatively reliable.

Another one of our older cars runs a CVTech from a year or two ago.  It seems to run fine though we don't have the hours on it to say anything about durability.  From the sounds of it, the newer ones aren't nearly what the older ones were as far as reliability goes.  The CVTech does look pretty easy to adjust though.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2009 at 2:01pm
You know what I mean Dillon :)  To call your setup a comet is like calling a pro-stock drag car a mustang :P

We ran the gaged this year with alot of success.  They are very tunable, but you can get it wrong alot before getting it right.  We changed our final ratio for the midwest race and ended up not needing it and hurting our accel score.  If you go gaged you have to machine on the unit and make your own weights.  You also have to get custom primary springs.  They will end up costing right around $1000 for one setup, but you get what you pay for.  We finished 3rd, 2nd, and 14th in accel and paired a 3rd in pull with the 3rd accel.  I can pretty much guarantee we'll show up with one again next year.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2009 at 2:51pm
Our biggest reasons for not trying the Gaged were cost and all the horror stories about tuning.

There is no doubt it's expensive, and everyone I have talked to says it's a bitch to tune, but you can't argue with the results that people are getting when they get them tuned right.

Our Comet is cheap since the modifications have been done in house.  As far as weights and springs go, we still have some room for improvement.


Edited by dillon_b12 - Jun/20/2009 at 2:51pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote paasch Quote  Post ReplyReply Direct Link To This Post Posted: Jun/22/2009 at 6:50pm
We used a Comet up through 2003, then switched to Polaris.  I would recommend a Comet for new teams, you just call QDS and they'll send you a CVT that works pretty well on the Briggs out of the box.   The Comet design limits the tuning options though.

We switched to Polaris to get more tuning ability.  There are a bunch of factory helix ramp options available for the secondary.  The primary weight profile can be re-machined to provide different shift-out characteristics.  Plus springs and preload adjustment.  They are reliable, as long as you don't get them too hot or try an Aaen roller secondary kit.  :^)  Downside is they're heavy, and put a hurt to your cost report.

We tested a CVTech in 08, but couldn't get it to match the performance of the Polaris.  I admit we were comparing a CVT we had lots of experience tuning verses one we didn't.  Got to like the small hit to your cost report though.

I've been looking at the Gaged website for 3 years now, thinking that might be interesting to try.  The caged secondary helix solves the problem we had with the Aaen roller kit in the Polaris, where the rollers would loose contact with the helix when the car is in the air, then slam down hard when you land.  The roller on ramp setup in the primary looks very customizable.  I suppose Gaged realizes that if he could put out a quality product designed specifically for BajaSAE he could sell a bunch.

While you can do decent CVT tuning with a stopwatch, really getting it right requires a data acquisition system with at least two channels, one for primary (engine) rpm and one for secondary rpm or groundspeed.  And call Aaen Performance and get a copy of their CVT tuning book.  Make it required reading for all the newbies.  Wink
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Jun/22/2009 at 9:31pm
Good to know, except data aq. is not in all of our budgets.....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Waffles Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2009 at 12:12pm
You peaked my interest, I know it's off topic, but this place called DATAQ has some good ones for $800...  a few cheap voltage regulators and a battery ($50-$90)...  alot of sensors you can get samples for, for free...  I think you might could do it for $1000, and you would only buy it once...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mu Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2009 at 2:53pm
Try speaking with National Instruments.  They are usually very helpful when it comes to student projects.

I'm currently trying to get an engine and CVT dyno up and running.  I'll let you guys know how it turns out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote paasch Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2009 at 3:59pm
Also try talking to your faculty and Department Chair.  I know budgets are tough right now, but there may be some Departmental or University funding for lab equipment.  If you can tie this in with formal design of experiments, you may be able to get the instrumentation you need.  I know that there are small USB data acq systems for a couple $100.  As waffles suggests, call the sensor companies and ask for donated samples.

You'll have a faster car, and you will do better in Design.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zehlerdj Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2009 at 9:44pm
Anyone using the new CVTechs. We had reliability issues with the newer casting of the old style and looking into the new ones along with other options. I thought I heard more reliability issues with the new ones as well, just wondering if anyone experienced the same?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thompm1 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/25/2009 at 3:54am
I like the Gaged and Auburn will be running it again next year.  I suggest tunning the Gaged in a race ready form(cover and backing plate).  They also get really hot(seen upwards of150+F), but you have to remeber that they were designed to be run with absolutly no guards/sheilding and for a period of about 8 sec.  Like Chris said you will need to have custom springs and weights for it as well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote OctoberSky Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2009 at 1:09am

"We switched to Polaris to get more tuning ability.  There are a bunch of factory helix ramp options available for the secondary.  The primary weight profile can be re-machined to provide different shift-out characteristics.  Plus springs and preload adjustment.  They are reliable, as long as you don't get them too hot or try an Aaen roller secondary kit.  :^)  Downside is they're heavy, and put a hurt to your cost report."


good to know, I was just thinking of buying the roller kit...did it break the thing or just start causing strange shifting?  I was also looking into the teflon coated ramps, but I have to see if they have the same angles we normally run...I image they would not be as problematic as the roller system.


"And call Aaen Performance and get a copy of their CVT tuning book.  Make it required reading for all the newbies."


agreed.  the book is amazing, but you definitely gotta be into baja to get through all 70 whatever pages...dunno if the newbies could handle it. ; ) 


"While you can do decent CVT tuning with a stopwatch, really getting it right requires a data acquisition system with at least two channels, one for primary (engine) rpm and one for secondary rpm or groundspeed."


on the line of data acq's for teams that don't have one already, I think AIM has given us a nice discount in the past, and their system isn't too expensive (mychron4), and if you order it right you can take care of lap timing, rpms, ground speed (assuming the wheels aren't spinning too much), temperature, whatever toots your flute.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote paasch Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2009 at 11:48am
Originally posted by OctoberSky OctoberSky wrote:

good to know, I was just thinking of buying the roller kit...did it break the thing or just start causing strange shifting?  I was also looking into the teflon coated ramps, but I have to see if they have the same angles we normally run...I image they would not be as problematic as the roller system.


We ran an Aaen roller secondary kit during the 2004 West competition.  We had a decent amount of testing on it before hand, but probably not a full endurance.  It was fine during  the first day dynamic, but by the end of endurance the rollers were all broken, and the CVT was barely shifting.  I'm amazed we finished.  Ever since we've been trying to get the 4th axis working on our Fadal to machine our own caged helix.

I second the AiM Sports Mychron4 recommendation.  Our experience with their stuff has been very good.  Looks like a team could get going on data acq for $500.  Money spend on data acquisition will do a team way more good than spending it on the 3 or 4 way adjustable remote reservoir shocks I see on so many cars.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thompm1 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/29/2009 at 1:56pm
You can get a discount from AIM for being an SAE team and the system will only cost you around $350.  I also suggest investing in photo gates, they are worth the investment.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote paasch Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2009 at 11:48am
Originally posted by thompm1 thompm1 wrote:

You can get a discount from AIM for being an SAE team and the system will only cost you around $350.  I also suggest investing in photo gates, they are worth the investment.

I agree with Michael 100%, a good set of gates will give you times to 0.001 seconds, very handy for resolving small differences in your CVT and gearing setups.  More importantly, they also remove all the measurement variability in human timing, so you are measuring the effects of actual changes and not timekeeper reaction times.  We've had good luck with systems from Race America:  http://www.raceamerica.com/  That was our Timer T4 elapsed time system on the hillclimb at Washougal in May.  The 2004 & 2006 Oregon organizers used our autocross system for maneuverability.  We also have an Axware ET system, purchased when we couldn't find our Race America ET system (it was lost then found somewhere in the SAE shop, must keep organized!).  The Axware system uses the Race America photo detectors.

I would not recommend the wireless barrel racer system that SDSMT used at the SD competition in 2007.  Those guys had nothing but trouble with those gates.

As with the data acquisition, these systems cost some money up front but they will benefit a team for years.  We bought our systems in 2002, one of our Baja guys wrote a a grant proposal to the OSU alumni foundation, and they gave us the funding.  Most universities have technology or instrumentation upgrade funds available if a team can make the "engineering education" case through a well written proposal.  Partnering with the Formula team helps make a stronger case.


Edited by paasch - Jul/01/2009 at 12:23pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeremyB Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2009 at 2:56pm
Tongue
Originally posted by paasch paasch wrote:

 We've had good luck with systems from Race America:  http://www.raceamerica.com/  That was our Timer T4 elapsed time system on the hillclimb at Washougal in May.  The 2004 & 2006 Oregon organizers used our autocross system for maneuverability.  We also have an Axware ET system, purchased when we couldn't find our Race America ET system (it was lost then found somewhere in the SAE shop, must keep organized!).  The Axware system uses the Race America photo detectors.
How much do those systems cost?
Quote
I would not recommend the wireless barrel racer system that SDSMT used at the SD competition in 2007.  Those guys had nothing but trouble with those gates.
 
Not sure what SDSMT had. BajaSAE Auburn 2009 used FarmTek's Drag/Sprint timing system, which is the same as a wirless barrel racing sytem, but with another set of eyes for seperate start/stop gates. It worked flawlessly. $1000.
 
 
Regarding datalogging (which should probably have its own thread). --------------
The MyChron 4 is a nice piece for limited logging. If you want one temp input, a speed and rpm input (enough for CVT tuning) and a sweet display - it is a winner. If you want to go further and put linear pots on the shocks, a rotary pot on the steering, load cells on the shocks, use multiple thermocouples, hook up a MAP sensor to the engine, or whatever else you can dream up, the MyChron isn't going to help. A flexible logger + some a bit of circuit building is the way to go. Like a DL-710. More expensive and more difficult to build, but you will learn orders of magnitude more than if you had purchased a MyChron.
The flip side is I would have chosen the MyChron 4 when I was in Baja just because we didn't have enough resources to build/integrate such a logger. [We had a DL90 when I did Baja]. Now? I would buy a logger or build my own from scratch.


Edited by JeremyB - Jul/01/2009 at 3:14pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote McGiver Quote  Post ReplyReply Direct Link To This Post Posted: Jul/10/2009 at 12:13pm

We melted a comet in alabama. At the starting line they pushed me back at the starting line, for grid, 5ft with my engine off which shifted the secondary all the way in and made my belt tight as hell. There was a smoke cloud of belt from the belt frying on the starting line in some pictures. It melted all the bushings in the primary #%##^%#$@$. Something to watch out for. But i was still fast off the line mabe it was the liquid bushings.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Unproductive Quote  Post ReplyReply Direct Link To This Post Posted: Jul/11/2009 at 4:04am
We ran a Gaged clutch this year at wisconsin and were pretty happy with the performance. It wasn't optimal but due to the time issues we had(built the car in 6 weeks and ran it for the first time at comp) we were running a baseline setup that bill @ gaged suggested.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mu Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2009 at 1:32pm
Originally posted by Unproductive Unproductive wrote:

We ran a Gaged clutch this year at wisconsin and were pretty happy with the performance. It wasn't optimal but due to the time issues we had(built the car in 6 weeks and ran it for the first time at comp) we were running a baseline setup that bill @ gaged suggested.


It seems like people are pretty happy with the gaged CVT minus the tuning involved.

I want to use one for the next car but I can't get a hold of Bill.  Everytime I call he's always busy and he hasn't returned one of my calls yet.  Maybe he just doesn't like me...
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Hello all,

My name is Rob Woods and I am the coach for the MCC Mini Baja team. I was one of the founding members from way back when. I have been involved with 4 mini baja cars and I designed a formula car when at University at Buffalo. This last car MCC used and the formula car I designed in Buffalo used Gaged Engineering CVT's for one simple reason. It is future of CVT needs in SAE events.

The formula car we built used a briggs and stratton v-twin coupled to a gaged cvt and it finished 18th although everything on it was extremely untuned and untested. I first made contact with Bill at Gaged to let him know what I wanted to do and he was very supportive. Through working with him he upgraded his rollerized secondary with a caged helix that has eliminated Jr Drag lockup issues and also the dreaded overrunning torque slap that the baja comp has dealt to lesser designs. One of the largest benefits to getting a gaged cvt is you have direct access to Bill who incredible knowledgeable and just a damn nice human being. His cvts aren't exactly tailored to mini baja but that has changed drastically in the last couple years.  This year he has made some items such as helix's that are suited for our low power comp and there is more coming this year since the interest in his products are growing tremendously. Terps rocking out a first place in accel for Alabama and Wisconsin this year should be an indication of what is up. That and Greg Ramsey from Terps dug into the clutch and really got the sucker working good. Greg Ramsey also a standup guy as well. Thanks alot of the help at comp Greg. Our sleep deprived mind required you to repeat things a couple times until it sunk in so thanks for being patient.

So I keep hearing the "good but it is hard to setup" argument. This is not true. What is true is that mini baja for a long time has been a rather un-technically challenging series that has really upped its game in the last 4 years that I was away from it. The days of just buying something, strapping it on to your car and just running it are over. Multi adjustable dampers, cvts, traction controls, etc are here now. These systems REQUIRE tuning to get functioning correctly. If you intend on buying things out of the box like the old way of doing things, you will be left behind in those respective areas.

The only challenge for a gaged cvt is getting enough weight on the fulcrum arms in order to get them to engage low enough which really isn't hard. Nothing machined tungsten doesnt solve real quick. Gaged has a bunch of different springs. ramps, helix's, etc for you to choose from. In order to optimize it you are going to need a datalogger and a chassis dyno would make live very easy. Bill reccomends using a Mychron 4 660 unit since he sells them. Here is where the magic starts which the extra money you spend on his stuff. You can send him datalog outputs and he will let you know exactly what is going on with your clutch. He understands the "black art" of his own equipment and can help you sort it out. It is in his best interest to make his equipment run awesome and he does so. This inbedded customer service is priceless.

I spoke with him three weeks ago and he is getting slammed with Jr Drag setups and race support so if you are having issues getting a hold of him then that would be why. Be patient and he will get back to you. I would suggest you send him an email instead for the time being. He is planning some major modifications to the unit that will benefit all of his customers. Some of which will directly help us such as new compound belts that hold up longer than the super sticky stuff he sell now for the jr drag community. In the mean time I would be more than happy to answer question regarding the setup and provide you guys with dimensions and rough solid models (SW 2008) so you can start playing with setups in your 3D space. I also told Bill he needs to come up with QDS/Comet style datasheets to provide to SAE teams so help in this matter. Also now that more teams are succesfully using his gear he/we have a baseline setup for people to run with. Be patient for the time being and know that his equipment is superior to all in terms of size, weight and potential. You will have to pay to play so dont bother him with nickel and dime efforts for sponsorship and free stuff.

Respectfully,

Rob Woods

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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/12/2009 at 11:52pm
Originally posted by rjwoods77 rjwoods77 wrote:

Hello all,

My name is Rob Woods and I am the coach for the MCC Mini Baja team. I was one of the founding members from way back when. I have been involved with 4 mini baja cars and I designed a formula car when at University at Buffalo. This last car MCC used and the formula car I designed in Buffalo used Gaged Engineering CVT's for one simple reason. It is future of CVT needs in SAE events.

The formula car we built used a briggs and stratton v-twin coupled to a gaged cvt and it finished 18th although everything on it was extremely untuned and untested. I first made contact with Bill at Gaged to let him know what I wanted to do and he was very supportive. Through working with him he upgraded his rollerized secondary with a caged helix that has eliminated Jr Drag lockup issues and also the dreaded overrunning torque slap that the baja comp has dealt to lesser designs. One of the largest benefits to getting a gaged cvt is you have direct access to Bill who incredible knowledgeable and just a damn nice human being. His cvts aren't exactly tailored to mini baja but that has changed drastically in the last couple years.  This year he has made some items such as helix's that are suited for our low power comp and there is more coming this year since the interest in his products are growing tremendously. Terps rocking out a first place in accel for Alabama and Wisconsin this year should be an indication of what is up. That and Greg Ramsey from Terps dug into the clutch and really got the sucker working good. Greg Ramsey also a standup guy as well. Thanks alot of the help at comp Greg. Our sleep deprived mind required you to repeat things a couple times until it sunk in so thanks for being patient.

So I keep hearing the "good but it is hard to setup" argument. This is not true. What is true is that mini baja for a long time has been a rather un-technically challenging series that has really upped its game in the last 4 years that I was away from it. The days of just buying something, strapping it on to your car and just running it are over. Multi adjustable dampers, cvts, traction controls, etc are here now. These systems REQUIRE tuning to get functioning correctly. If you intend on buying things out of the box like the old way of doing things, you will be left behind in those respective areas.

The only challenge for a gaged cvt is getting enough weight on the fulcrum arms in order to get them to engage low enough which really isn't hard. Nothing machined tungsten doesnt solve real quick. Gaged has a bunch of different springs. ramps, helix's, etc for you to choose from. In order to optimize it you are going to need a datalogger and a chassis dyno would make live very easy. Bill reccomends using a Mychron 4 660 unit since he sells them. Here is where the magic starts which the extra money you spend on his stuff. You can send him datalog outputs and he will let you know exactly what is going on with your clutch. He understands the "black art" of his own equipment and can help you sort it out. It is in his best interest to make his equipment run awesome and he does so. This inbedded customer service is priceless.

I spoke with him three weeks ago and he is getting slammed with Jr Drag setups and race support so if you are having issues getting a hold of him then that would be why. Be patient and he will get back to you. I would suggest you send him an email instead for the time being. He is planning some major modifications to the unit that will benefit all of his customers. Some of which will directly help us such as new compound belts that hold up longer than the super sticky stuff he sell now for the jr drag community. In the mean time I would be more than happy to answer question regarding the setup and provide you guys with dimensions and rough solid models (SW 2008) so you can start playing with setups in your 3D space. I also told Bill he needs to come up with QDS/Comet style datasheets to provide to SAE teams so help in this matter. Also now that more teams are succesfully using his gear he/we have a baseline setup for people to run with. Be patient for the time being and know that his equipment is superior to all in terms of size, weight and potential. You will have to pay to play so dont bother him with nickel and dime efforts for sponsorship and free stuff.

Respectfully,

Rob Woods

585-615-8474


Rob you are correct that this is the CVT of the future, but at the same time it is a significantly more complex unit than others available.  I've been through a season of testing and tuning that started with this unit that started in August and the solution I came up with was maybe not optimal, but considering the drastic redesign of our car and the limited personnel we had I call it a success.  The low angle helixes were something we had custom made at the last minute before Auburn and it really made a difference for us in overall driveability and made the package really usable for the car.  This year's goal is to go further down that path and look at multi-angle helixes made in house.  Another thing that we did, something that I didn't see anyone else using this year, was the 8" secondary which gave us a bit of a low end advantage on some of the other Gaged cars.  As for catering to Baja Bill now stocks the 8" secondaries thanks to us, and you can thank Justin af UF for the 7075 primary pulleys that resist the wear on the inside of the pulley a little better and withstand the heat more.  Last time I spoke with him he was putting together a package specifically for Baja. 

There is quite a bit of knowledge about the Gaged units on this forum with Maryland, UCF, MCC, Auburn, and TTU using the clutches at this time.  If you have any questions or want some direction feel free to ask.  I won't give away our exact setup (it probably wouldn't apply to a different car as well anyways) but I can save you alot of time in narrowing down your search for a usable system.
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Bill is making 26 and 28 degree helix's now. He told me about the 8" and I think we will be running it next year. I hope he does the harder compound deal. He really needs to consolidate and make a SAE form for it. I am sure that in the next couple years there will be a big rush to get into his stuff.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mu Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2009 at 1:12am
Thanks for the response, Rob.  I figured he was probably pretty busy.  I'll try shooting him an email.

The more I hear about gaged the more I like.  It seems like Bill is dedicated to creating a CVT tailored to the needs of Baja competition.  Hopefully I can get my hands on one fairly soon so I can start playing with it.

Any specs, dimensions, models, etc that you can give me for the gaged CVT would be greatly appreciated.  Again, thanks for the help.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2009 at 3:59am
I had, I think, the first batch of low angle helixes done in 26, 28, and 30.  They make a big difference.

As far as what to order I would say the Dominator GX-7 with the 5.75" primary (in 7075) and the 8" secondary.  Get 26, 28, and 30 degree helixes.  I had more success with the 9-18 ramps in the primary, but that's something we're looking at doing custom this year.  Get it either way but I think that the barrel lock is a PITA and doesn't do much for you.  I've got an old Impact unit from 2004 and it doesn't have it and it works fine.  Run the dual cog belt if you have a fairly short C-C on the shafts, if not a comet 40 series belt will work but be less efficient.

As far as ordering it get it in soon, this is their busy season.  Last year it took me nearly 3 months to get my clutch.  I did have some custom requests that took some extra machine time, but this is just a busy time of year.  I know Jake, Bill's son is knowledgible but sometimes he can be hard to keep in touch with or really get on the ball.  I've had the most success dealing directly with Bill on my orders including some last minute overnight to the hotel belt shipments :)


Edited by CLReedy21 - Jul/13/2009 at 4:10am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2009 at 1:40pm
What kind of shift ratios were you getting out of that setup? It sounds like you had our setup but deeper on the low range side. We are in the process of fixing a couple things from the comp and getting the Mychron 4 660 mounted up on the car. Once we do we can get some logs and see where we were. We had a 7075 5.5" primary and a 7.5" secondary. Used the 26 degree helix, 9-18 ramps, clear primary spring, blue secondary spring set to the 5 hole from the left and ran 80 gram a piece tungsten weights with a longer bolt to hold them. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2009 at 4:15pm
For the low range I think it was around 3.8-9:1 (don't quote me, I'm estimating), but I know I was seeing overdrive of about .83:1 on the top end.  I ran a custom (not stock Gaged) primary spring and an older black secondary spring from my old Impact unit.  The preload hole sounds about right, but I used significantly more weight than you, as in the ballpark of double.  From what I gathered talking to Maryland they are running around the same weight as us.  We ended up running a higher weight setup due to the increased belt pressure it gave us for pulling and off the line punch.
 
As for times we ran consistent 5.62x at all 3 competitions with a 120# driver in a 380lb car.  We top out at a touch over 35mph.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2009 at 4:48pm
I meant to say two 80 gram weights so 160grams and whatever the difference in the weight of the stock bolt and the one I put in which is maybe 5 grams. Terps hit a 5.2x and they said the car weighed 330lbs. There is a lot in the CVT in terms of experimenting to do and that is the benefit of it all. We plan on solid modeling the whole thing and doing a dynamic assesment of the what is actually going on in terms of all the forces much like Aaen points out in his book and see if there are any relationships with the weight/spring/ramp combo versus the power curve of the engine. Terps commented about doing this and that is probably why they have done so well with there. Works for them so it would be something to look into for sure.


Edited by rjwoods77 - Jul/13/2009 at 4:57pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/13/2009 at 5:43pm
That sounds better.  Their car is lighter than ours and they definently have some more tuning time.  I kinda had to put my CVT work on hold once we got a good solid setup since I was needed elsewhere.  Once the race gets going we're pretty even and race side by side or bumper to bumper :), but right off the line and on short events they have a little advantage.
 
As far as Aaen's goes the last time I read it he said that trying to dynamically model a clutch was a frustratingly complex if not impossible task and that your time would be much better spent doing field tests of weight/spring/ramp combos.  For that reason I havn't delved into the theory much, I just run more tests until I get the results I want.  Now an excel spreadsheet of times for various adjustments is a fantastic aid that I recommend bigtime.  Look for trends to the optimum settings for each part, rinse, repeat.  Don't forget that the car has to be driveable and pull and stop and so forth.  We had some awesome setups initally that would kill the engine if you brake checked it...no good for a race situation.  I would periodically take our car out to the test track we have and run a couple laps to see, somewhat subjectively, if I was making the car better or worse.
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You will also need to make sure you truly "balance" your CVT.  It is very easy to tune a CVT to accel, but you want to make sure that you are not sacrificing your ability to maneuver because the unit does not down shift properly and you bog in the turns.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2009 at 8:53am
Originally posted by paasch paasch wrote:


While you can do decent CVT tuning with a stopwatch, really getting it right requires a data acquisition system with at least two channels, one for primary (engine) rpm and one for secondary rpm or groundspeed.  And call Aaen Performance and get a copy of their CVT tuning book.  Make it required reading for all the newbies.  Wink
 
Hope this adds to the general knowledge of CVT tuning in Baja....
 


Edited by jhu42 - Jul/24/2009 at 1:51pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote charles ulaval Quote  Post ReplyReply Direct Link To This Post Posted: Jul/14/2009 at 10:37am
We use the new CVTech like Sherbrooke and ETS and it's working pretty well. I guess the 3 of us were in the top 10-12 fastest cars... The ratio is nice, not too hard to adjust, lighter than the previous one. The only scary thing is the 3/4" shaft for the driven pulley.
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Hey everybody,

Just got off the phone with Bill at Gaged Engineering. I had a pretty good conversation about SAE design events and what is needed out of Gaged equipment in order to get a package put together for teams to use so that the concerns that have been put out there aren't there anymore.  They have some neat upgrades/improvements coming down the pike and they are very interested pushing into this market. I am hoping that before the summer is out they will have something put together for us as series. I would suggest that you continue to contact them by email and put a header in the title box the references your college and the mini baja so he recognizes who is contacting him. Example: "Monroe Community College Mini Baja Information Request"

Respectfully,

Rob Woods


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gismo Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 12:12am
Originally posted by rjwoods77 rjwoods77 wrote:

What kind of shift ratios were you getting out of that setup? It sounds like you had our setup but deeper on the low range side. We are in the process of fixing a couple things from the comp and getting the Mychron 4 660 mounted up on the car. Once we do we can get some logs and see where we were. We had a 7075 5.5" primary and a 7.5" secondary. Used the 26 degree helix, 9-18 ramps, clear primary spring, blue secondary spring set to the 5 hole from the left and ran 80 gram a piece tungsten weights with a longer bolt to hold them. 


So USF will be tinkering with a CVT this year, Gaged. I have some questions and hope you guys can help me (us) out. From what I've read I think I have a good grasp of how the springs and weights affect performance, and how to begin tuning a CVT. What I want to know is what exactly is 7075 referring to? The material? Also, how do you choose how large or small your primary and secondary are. Why 5.5" and why 7.5" as opposed to say 5" and 8". Also, these dimensions, they are for diameter I am assuming, or are they for like belt travel for instance? I think I understand what the helix angles do, the less angle, the more force on the secondary? This is for back shifting? And as for ramps... What does the nomenclature 9-18 indicating? I really don't know anything about the ramps yet. Answers to these questions is appreciated. If you could include pics of the ramps/weights that are on the Gaged CVTs that would be helpful as well.

About your weights, were they custom made or are there different sets of weights you were able to get from Gaged? Are there any parts of your CVT that you didn't obtain from Gaged?

Also on the Gaged website they advertised that their CVTs are splined to the crank shaft.  As far as I know you aren't allowed to spline the crankshaft of the Briggs. And for my last question, can anyone tell me at what RPM the Briggs puts out peak power?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Unproductive Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 12:42am
7075 is the aluminum alloy it's made from.

We CNC'd the weights out of tungsten, they're very simple. They just have to fit inside the I.D. of the primary and have the correct weight, no special shapes or anything. They could have been cut on a hand lathe but we didn't have the time to possibly mess up one of our pieces of tungsten stock.

Our CVT is keyed, he has both. I hate keyways.


If you haven't already, read the book(pdf) posted above. It's got some good info for you.


Edited by Unproductive - Jul/15/2009 at 12:44am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 12:49am
First off you don't want a gaged, you want to run a direct drive...

Second, wwhich one of you losers is this?

7075 Aluminum primary pulleys.

We chose the 5.75" diameter primary for the desirable overdrive it gives and the 8" diameter for its low end torque.  You can also get a second set of 7" pulleys to change the overall gear ratio a bit between races.

The lower the helix ratio the more it will slow down the secondary shift out and faster it will return it to low ratio (backshifting).

A 9-18 ramp has a 9" radius and an angle of 18 degrees if I remember correctly.

Our weights are custom made tungsten, we ordered it from McMaster in bars..  Our primary springs are also a 3rd party piece.

The Gaged units are available with a standard 1" Tecumseh/Briggs post for the primary.

Peak power is in the 33-3400 neighborhood if I remember right and peak torque is down at 26-2700.  Somebody back me up or tell me I'm wrong, but those are the numbers that stick out in my mind.
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Before I answer your questions I need to pick my Jaw up off of the floor.

First - 7075 (Aluminum)  is referring to the material of the sheaves only.

Second - all unit sizes are diameters, The difference between the sizes will help to determine your ratios.  With a larger secondary unit it will allow for a ratio that extends a little further to the low end(greater reduction).

Third- Belts,  currently Gaged makes belts in a variety of widths,cogs,and compounds and 4 c-c distances, the greatest of which is currently 9.25 in.

fourth- All the weights for Baja have to be custom, Gaged only manufactures very low weights.  We have to compensate for our lack of RPM and have larger weights.  You may also have to machine cutouts in the hat to make room for your weights.

Fifth- Springs, you will need to order your own springs, I suggest http://www.centuryspring.com/.  I suggest getting a few ranging from 15 lbs/in up to about 55 lbs/in(primary springs).

Sixth- splining, Gaged the PTO with a 1 in. bore and 1/4 keyway

Seventh - I know that peak torque out put is usually between 2200-2400 rpm's which at max is about 14 lbs-ft.  I will have to double check that 


Edited by thompm1 - Jul/15/2009 at 4:02pm
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Ok, so I found that max tourque is anywhere between 2200-2800(14.226-14.265) and max Hp@3600(in the range of about 9.2-9.8 but most likely the lower end of that scale)
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Hello Gismo,

You must be one of the FNG's on the team this year. Dustin told me your team had a fresh crew coming in. Let me set you down the path that will keep you and your team busy for a bit. I am stating these next steps/facts because cvt packaging is a world different than gearbox packaging. I sent the models to Dustin so you should have them to play with in Solidworks.

1: Assemble the primary cvt onto you engine model.
2: Constrain the axis of the secondary clutch parallel to the axis of the primary clutch.
3: Constrain the distance from the secondary axis and the priamry axis to 9" (max gaged c-to-c)
4:Now start moving the engine and secondary clutch around the car to see where it will fit. You will need some sort of final chain/gear reduction after the clutch that will range somewhere between 7:1 and 10:1 that is typically done in a couple stages. This will have a large effect on where you put your secondary clutch axis.  If you are running a IRS then you have to be aware that the secondary clutch diameter has to clear the halfshafts. If you are running a swingarm then just copy what we did assuming you want the lowest possible cg which you should. Or pack the engine against the firewall, run the cvt straight up, shaft across the top, first chain drive to the swingarm pivot, second chain drive to the final drive axle. I say pass it over the top so you have the cvt on one side and the chain drive on the other. Helps big time with maintainance. Once you have your setup packaged you can start worrying about the internal setup. Many differnt ways to skin the cat but that is the biggest bitch about cvt's is packaging. Get past this part, read the Aaen book, and then ask the next set of questions.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 1:49pm
What are everyone's thoughts on running a CVT to a 5 speed gear box? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 2:05pm
I always thought of the cvt and the multi speed gearbox (more than hi-lo) as two different ways to skin a cat.  It can be done (probably very heavily) but why would anyone need that much variability in selecting gears?  I'm not sure it would have any desireable effect, seems to me that you'd have to be on the stick shifting all the time.
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Nexteer Automotive
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Milling Master
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Joined: Jul/11/2009
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Unproductive Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 4:14pm
If you used the gearbox as a normal gearbox(shifted constantly) the cvt would defeat the whole purpose. When you upshift, the cvt would backshift to keep rpm constant and therefore gear ratio constant at that instant.

If you were to use it as a range selector, it would work, but why would you need 5 ranges.
-Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/15/2009 at 11:24pm
Originally posted by Rob71zilla Rob71zilla wrote:

What are everyone's thoughts on running a CVT to a 5 speed gear box? 


Ohio State's 2005 car had that exact setup.  Comet CVT running to a re-packaged ATV 5-speed, then a chain drive to an open diff. It got 1st place in powertrain at Wisconsin that year. 5th in design at RIT. And I hear it was quite fast. 5th gear in that flats was north of 40mph.

That said, whenever I drove it, the shifter was stuck in 3rd, so who knows. However, the backshifting issue when you change gears certainly is an issue, and is why we haven't done it again, that and we don't use chains anymore, either.
-Joe
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