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Hopkins Baja Design / Build Thread

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jeiB View Drop Down
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Topic: Hopkins Baja Design / Build Thread
    Posted: 2010-Jan-25 at 7:05pm
good work Thumbs Up. How much does it weight? 
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Post Options Post Options   Quote johnpate01 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-25 at 8:38pm

Its looking good, guys.  Keep it up.

There were some comments about the front bracing location in our thread too, but it seems that both ways have passed tech.  Check the rules and decide for yourself, though.

-John
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-25 at 9:03pm
Originally posted by jeiB

good work Thumbs Up. How much does it weight? 
Thanks jeiB!
 
Just took it off the scales, we've added a couple of extra tubes but the final weight is 34903 g (76.947 lbs)
 
a bit heavy for sure, but this is one crazy stiff chassis.
 
---------
 
Thanks John, I think both will pass fine as well. 
 
Cheers,
Adam
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-25 at 10:25pm
We are close to finishing our frame as well. I might weight it tmrw. According to the CAD, it should be almost 85lbs FULLY tabbed, tmrw im hoping for 70 thought. I ll post back with the result

Edited by jeiB - 2010-Jan-25 at 10:26pm
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-29 at 11:51am
actually weights 68lbs Thumbs Up
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Post Options Post Options   Quote asims Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-29 at 1:45pm
Originally posted by jeiB

We are close to finishing our frame as well. I might weight it tmrw. According to the CAD, it should be almost 85lbs FULLY tabbed, tmrw im hoping for 70 thought. I ll post back with the result
...
actually weights 68lbs


How'd you lose 17 pounds from CAD?  Did you have the wrong material thickness somewhere, or wrong material properties?

We usually end up a pound or two over what the model says from welds and tabs and such.
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-29 at 2:03pm
well its 68 lbs without the tabs but all of the tubes, so there still tabs to be added, so i will be approaching 85lbs soon.
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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-30 at 12:33am
Wow....ours weighs in at a little over 100lbs according to Solidworks Censored
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Post Options Post Options   Quote blue2kss Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-30 at 3:22am
^^^ ouch
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Post Options Post Options   Quote asims Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-30 at 3:37pm
What size tubing are you using?
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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-30 at 4:10pm
1.25" .065 wall for the main members and then 1" .065 wall for the supporting members....I know we should have used .035 for the 1"
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-30 at 6:05pm
we use 1" 0.049 for the bracing members. I think 0.035 might be too hard for our welder..
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Post Options Post Options   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-01 at 9:10am
Don't let your welder's capabilities stop you from using .035".  Make them practice on some .035" and go for it.  It's not really any harder than .049" or .065" provided you have a good grasp on heat control.  Making a really nice notch helps a lot for .035" as well.
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Post Options Post Options   Quote tp Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-02 at 2:17pm
0.035 is easy once you get the hang of it (especially if you are TIG welding). If you are going to try to put bends in, think about using a mandrel. 
Also, squirrels.

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Post Options Post Options   Quote MTomasko2011 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-03 at 8:44pm
We've never tried bending .035, but welding is cake.  The only time it can get tricky is if someone does a crappy job notching and theres a huge gap, but that can be said about any size.  Id be hesitant to try it with MIG, but if your welder is capable of welding an entire frame with TIG, id almost guarantee he can weld .035 with a little practice
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-03 at 9:55pm
To be honest, we have huge turnover in our team. Our "official" welder is a lab technician (he has access to the better machine) and i have a new recruit that started tig this year. For our team, using 0.049 is more of a facilities constraint because we have access to a tig welder were we cant really control the current. Anyway, I dont think going to 0.035 is worth is because it requires so much more care/time to notch and fit.

Sorry to Jhu for hijaking ur thread. U should post more pics!!!  Embarrassed
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Post Options Post Options   Quote CobraCommander Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-04 at 7:06am
Our team has made use of .035 and the best advice is get your welder some practice working with such a thin material. Set the machine up right and your guy should be able to keep from making it look like swiss cheese. The other important thing is knowing when you're able to get away with patching that tiny little hole and when you're going to have to start over because your making a huge turd-pile weld... It happens, but the more your welder gets experience the less often you'll be in that situation.
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-27 at 10:55pm
Hey guys,

Some more progress from Baltimore City's largest car maker.....

Here's the car on wheels. 

Steering --- Done
Rear suspension --- Done
Front suspension --- Done
Pedals( brake and gas) --- Done

Not done
Drivetrain
Rear brakes
Tie Rods







Later,
Adam

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Post Options Post Options   Quote Moreau Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-28 at 2:09am

Decided to finally register so I could stop being a lurker and contribute to this forum.  I'm one of the more involved members on the Hopkins Baja team and just wanted to answer a few questions (some of which no one asked... probably).  For curiosity's sake, I'm the guy with the goatee in the pics.

There was some mention of the forward bracing being rather far away from point C.  I agree that it looks funny (and could have been moved further up the bend... slightly), but there's a strange technicality in the rules about how the FBM up and the RH overhead are defined.  Based on the wording of the rules, the forward bracing by definition connects to the FBM up (and point C is defined to be on the RHO...). 
 
The much better reason, however, is rule 31.2.8, which stipulates that no part of the triangle formed by the foward bracing (between the SIM and FBM up) may have a member with a bend greater than 30 degrees.  The angle between the FBM and RHO is required, by rule 31.2.7, to be greater than 45 degrees.  We interpreted this rule as requiring the FAB to be significantly beyond the start of bend on the RHO (which is also point C) so that the bracing triangle does not contain a significantly bent member.  It is impossible to legally connect point C to the SIM and have everything else on the frame be legal to the rules, hence the "close as possible" phrasing of 31.2.8.1 when describing front bracing attachment location.
 
We could have moved the front bracing attachment further up the bend, but hesitated for a few reasons.  First, we were using .035" thick 1" tubing for the member (which was being welded to 1.25", .065" thick) and we don't have any way of notching a tube end to accurately match the curve of the bend.  Invariably, we would have had to make several attempts to get the curve right and evenly on both sides (and we would probably have run out of .035 tube), and the gap left would have made for a hideous weld.  Notching to the flat (ish) start of the bend was much easier to do accurately and evenly on both sides, and was less of a welding challenge.  Secondly, we thought the rules had enough wiggle room to allow for this.
 
Also, our frame could lose some weight.  We had thought that .065" was the cut off for good bendability for some reason, but now that we know .049" works as well we'll be incorporating a lot of it next year.  For all of the triangulation and most of the straight bars, we starting using .035" 1" tube this year.  I do about half of the welding on the car, and I love this stuff.  No, I don't like welding it, but it really is amazing stuff if you can keep it away from impacts and out of buckling.  Our frame is not yet excellent, but it is much much better and much lighter than anything we made in the past.  We tested the torsional rigidity of the 2010 chassis against the 2009 chassis (plus body panels still attached), and found it to be 71% stiffer AND approximately 30-40 lbs lighter (with all of the Frankenstein modifications made to that thing, no one knows what it weighs but it's a boat anchor).
 
Seriously: to those who don't yet do it, incorporate .035" tubing.  Welding it is either easy or hard as hell.  If the gap is really small, it's cake and looks very pretty.  If it has a large gap (and by God did we have some large gaps...  1/4" in a few places...), then it is incredibly tricky with failure rewarded by tube vaporization.  The issue we ran into was fitting triangulating members to a node that already had some other members welded to it.  We had to grind off one edge of the notch to fit the tube in, and then prayed for the best when welding it.  So watch out for that and plan ahead when assembling Wink.
 
One last thing: Anyone have recommendations for body panel fastening?  We, as a team, are COMPLETELY PARANOID about putting tabs on the car that only hold body panels.  They're a pain in the ass to make, hard as hell to get in the right spot (and angle and hole position...), and welding them securely creates a hell of a lot of welding work in funny places, usually where torches don't reach.  So we considered Dzus clips... but they look like premade tabs with even more finicky fasteners.  We have, for now, decided on riveting certain panels to the frame tubes directly, using sealing rivets, because it's super light, easy work, and really strong.  The down side being, every time we remove and replace one, a jingle gets added to the frame that will never come out.  This is fine for the firewall, and possibly the floor panel, but side panels?  Meh...  and if we make composite panels (unlikely, but we have some members really interested in doing it) the rivets won't play nice with them (cracking, etc).
 
I'm very interested right now in sealing rivnuts.  Watertight, threaded so panels can be removed easily, lightweight, and relatively easy to install (vs welding in tabs).  They can be installed blind, and supposedly are okay on tubes with small radii, but I dunno...  thoughts on this?
 
(As you might have noticed, I'm prone to Wall O' Texting)


Edited by Moreau - 2010-Feb-28 at 2:10am
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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-28 at 2:37am
We used Dzus tabs for all of our body work after they outlawed Velcro (probably because of us). Dzus tabs are fantastic when you get them lined up properly. Unfortunately, doing that can be a bitch. The best way we found was to weld the tabs to the frame, and then mark the panels where the holes should be. This still doesn't always work nicely, especially on panels that go around a bend. But for straight panels, they are pretty easy.

But when you get them right, it's just a few quick turns of a screwdriver to pull any panel off the car. This is super handy.
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Post Options Post Options   Quote racers.baja Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Feb-28 at 12:31pm
We have mounted panels both ways, rivets and tabs.  It is much more time consuming to mount the tabs but once they are on they make things much easier.  Take a look at aa-manufacturing, we bought some laser cut body tabs from them for around 35 cents each and they are nice (1/4" hole...085" thick) .  We usually try to make everything ourselves but its hard to pass up buying tabs for ten bucks or spending hours making them when you could be working on other critical parts. Since we already have alot of time in the fiberglass panels we opted for laser cut tabs to speed things along.  We welded the nuts on the inside of the tabs so we only have to mess with the bolt when removing panel, which makes removal with a drill extremely quick.    
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-01 at 1:41am
Wow!!!  More stuff!!!

So we got the car on wheels like I said before and finished the tie rods today and were able to take it out and push it around.  Really happy the way the front suspension turned out.  These Fox Float Evols are pretty incredible,  The are really really responsive ( unlike float's of old ) and look great.  Also I'm particularly proud of our almost elimination of bump steer ( see video)  I used the biggest rack I could find,  Desert Karts 14" rack  http://www.desertkarts.com/item80862.ctlg , not bad on price either $98.00

Anyways, here's the video,  hope to be testing off road this weekend. 






later,




Edited by jhu42 - 2010-Mar-01 at 1:44am
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Post Options Post Options   Quote EAD Motorsports Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-01 at 11:47am

Originally posted by Moreau

There was some mention of the forward bracing being rather far away from point C.  I agree that it looks funny (and could have been moved further up the bend... slightly), but there's a strange technicality in the rules about how the FBM up and the RH overhead are defined.  Based on the wording of the rules, the forward bracing by definition connects to the FBM up (and point C is defined to be on the RHO...). 

 

I believe the intent of the rule is to attach as near as possible to point C, even if you attach to the RHO, but the wording essentially relegates you to putting the either at the start of the bend near point C (which is part of the FBMup) or after the bend - assuming you don't want to put a node in a bend. A query to the rules committee would clarify the issue.

 

Originally posted by Moreau

The much better reason, however, is rule 31.2.8, which stipulates that no part of the triangle formed by the forward bracing (between the SIM and FBM up) may have a member with a bend greater than 30 degrees. 

 

31.2.8 says "the bend shall not exceed 30 degrees (see figure)."  The 30 degree figure only regards the FAB, not its interaction with what it attaches to. Your FAB has a 0 degree bend and can't have a bend unless it is 30" or shorter.

 

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Post Options Post Options   Quote Moreau Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-01 at 5:46pm
Originally posted by EAD Motorsports

31.2.8 says "the bend shall not exceed 30 degrees (see figure)."  The 30 degree figure only regards the FAB, not its interaction with what it attaches to. Your FAB has a 0 degree bend and can't have a bend unless it is 30" or shorter.

 
Yeah, this is where the rules need to be clarified. 
 
Originally posted by 31.2.8

The roll hoop shall be braced in the front and/or rear.  The hoop must be braced on both left and right sides.  From a side view, the bracing must be triangulated, with the maximum length of any member not to exceed 101.6 cm (40 inches) between attachment points. From a side view, the angles of the triangulation must be no less than 20 degrees. A bent tube cannot exceed 81.3 cm (32 inches) in total length and the bend shall not exceed 30 degrees (see figure).
 
I interpret this as applying to all of the members that form the triangle as seen from the side.  It is ambiguous as the rule uses plural for the tubes without specifying exactly which.  My take is that if they explicitly mention triangulation and set bend angle maximums (applying to an unknown number of members of said triangulation) then the FAB should form a triangle and not a quadrilateral with whatever it attaches to.  This is purely guesswork, but my intuition is that a perfect triangle of bracing removed from point C is ultimately more protective to the driver than a quadrilateral brace attached to point C were both types crushed to failure in an upside-down forward impact situation.  Although the unreinforced bend to the RHO would probably crumple first with triangular bracing...
 
Mmmm... we should definitely ask for clarification...
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-05 at 2:22am

Testing Saturday.....

 
Hope we make it
 
 Question
 
Later,
Adam
 
 
 
 
 
 
Adam Baumgartner
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-08 at 12:20pm
Well....

We did not exactly make our goal of testing Saturday, but with little to no sleep on most of the teams part we were able to get the vehicle finished and out testing Sunday.  Below are some really good pictures of testing. 

A couple of notes

The tire on the left of the car is backwards, we did not have enough time to get in mounted properly, came in from Rocky Mountain ATV that way.

We have our UMBC inspired nose art, which is good for +2 hp
http://www.umbc.edu/sae/pictures_index.html

With no CVT tuning, stock CV TECH w/ 12.56:1 Reduction, our 150 ft acceleration time is ~ 6.0 sec

Car weight is about 425 lbs, but we have more stuff to add so this will change.

Comments welcome :D 

Later guys,
Adam































































Edited by jhu42 - 2010-Mar-08 at 12:24pm
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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-08 at 1:40pm
Looks like you guys had some fun.  How did everything go? Any failures or dissapointments during the day? 
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Post Options Post Options   Quote Kenneth Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 8:48am
Nice job getting the car going guys, but I think you meant "Michigan-inspired nose art"...



We thought we were being so original...

Also, do you guys pay somebody to change your tires? If so, you may want to look into some manual tire mounting methods. We've been using one of these things from Harbor Freight for years with great success.



We change tires at competition all the time with it (sometimes asking for shampoo from a nearby hotel front desk for bead lube). We also don't use that silly dangly bead breaker thing on the bottom. We have a bead breaker that looks more like this:


Changing your own tires can be a tremendous cost and time savings if you go through tires like we do. We now have a fancy tire machine, but still bring the manual stuff to competitions.
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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 10:09am
bead locks Smile
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Post Options Post Options   Quote tp Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 11:34am
There is no reason with ATV tires that you shouldn't be able to get them on with tires spoons and soap. If you can't, then you probably shouldn't be changing tires.
Also, squirrels.

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Post Options Post Options   Quote BamaBoy Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 11:41am
Originally posted by tp

There is no reason with ATV tires that you shouldn't be able to get them on with tires spoons and soap. If you can't, then you probably shouldn't be changing tires.


X2

ATV tires are a snap to mount and dismount.  Sounds like you just need more practice.
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 12:04pm
Hi Kenneth,
 
Apologies Apologies!!!!!!!
 
Sorry I forgot about you guys :) 
 
We have our tires changed by the Auto shop on campus that services the Shuttles 
 
Thanks for the tip,
 
Actually it was sort of neat to test with one backwards, there is much more grip when they are mounted correctly, Duh!! but good to see it in practice
 
I do like the nose art but unlike you guys we probably dont have the balls to do it at competition. :)
 
Later,
Adam
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 12:10pm
Originally posted by Rob71zilla

Looks like you guys had some fun.  How did everything go? Any failures or disappointments during the day? 
Hi Rob,
 
We did have some fun, it was really nice to have the car testing so early :)  Everything went really well, it is a very maneuverable car for us.  We had hypothesized that making the front shocks softer, much much softer would add to the turning of the car and were correct.  The drivetrain tests did not have any CVT tuning, only stock so those times can only get better.  We did a skidpad and that took a look at steady state handling, but it was hard to get steady state tricycling.  The only incident we had was a a chain pop off of the 1st reduction.  This was caused by a slightly misaligned input shaft, and slight being ~0.5 mm.  The 35 pitch chain is very small and small misalignments which are normally fine for 420 chain really seem to matter.  It was about closing time anyways and with out the necessary tools to fix it we just headed home. 
 
Great DAY!!!! Made staying up all night ~ 3 nights totally worth it LOL
 
Adam


Edited by jhu42 - 2010-Mar-13 at 12:26am
Adam Baumgartner
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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 12:12pm
Originally posted by jhu42

I do like the nose art but unlike you guys we probably dont have the balls to do it at competition. :)


Personally, I was a fan of the car that had the pin-up girl nose art Thumbs Up I don't remember who it was, but I think they were at Auburn.

Edit: Illinois was rocking a pin-up girl at Wisconsin, but my caption says "More pin-up nose art" so there was another one out there.


Edited by adrive7 - 2010-Mar-09 at 12:16pm
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Post Options Post Options   Quote msctgb Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 1:51pm


That was us (Missouri S&T) at Auburn.
We also had the general on the other side.

Yeah yeah, they're big pictures.
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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 2:37pm
Originally posted by jhu42

Originally posted by Rob71zilla

Looks like you guys had some fun.  How did everything go? Any failures or dissapointments during the day? 
Hi Rob,
 
We did have some fun, it was really nice to have the car testing so early :)  Everything went really well, it is a very manuverible car for us.  We had hypothesized that making the front shocks softer, much much softer would add to the turning of the car and were correct.  The drivetrain tests did not have any CVT tuning, only stock so those times can only get better.  We did a skidpad and that took a look at steady state handeling, but it was hard to get steady state tricycling.  The only incident we had was a a chain pop off of the 1st reduction.  This was caused by a slightly misaligned input shaft, and slight being ~0.5 mm.  The 35 pitch chain is very small and small misalignments which are normally fine for 420 chain really seem to matter.  It was about closing time anyways and with out the necessary tools to fix it we just headed home. 
 
Great DAY!!!! Made staying up all night ~ 3 nights totally worth it LOL
 
Adam
 
#35 chain huh?  We used that at RIT '07 and it was border line strong enough.  The biggest problem was that it stretched a lot and stretched fast.  If we landed at WOT the chain snapped no questions asked.  The last 2 years we ended up using 35-2 chain with much better success. 
Good luck, hope everything holds together for you
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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 2:52pm
Yeah, #35 chain sketches me out. I used it on my little 5hp street kart, and it would jump a lot even on that. Is it possible for you to bump up to 420?
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 3:07pm
Hmm I see what your saying.
 
Its a hybrid chain box.  Reduction 1 is 35 pitch chain, Reduction 2 is 420 chain.
 
The chain is Regina Chain, so its high quality. 
 
Here are the 35 chain stats
 
 
115 HHKart  Average tensile strength = 2248 lbs
 
and the 420 stats
 
 
124 RX3  Average Tensile Strength = 4271 lbs
 
Based on what I've seen so far in testing, no problems here.  The key is that the 35 chain is on the 1st reduction, not on the second, needed to go to 420 for that one.
 
Adam
 
 
Adam Baumgartner
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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 3:18pm
It's not so much strength in my mind as it is jumping the sprockets. But if you get some solid test time in and it doesn't cause issues, go for it. I know part of my problem on my kart was alignment.
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Post Options Post Options   Quote exbaja Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 6:36pm
With thin rims tire irons are an issue, they can collapse a rim with stiffer tires.  

Tire machines are key to sanity in my opinion.  
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Post Options Post Options   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 6:43pm
The real key to 35 series chains is three rows and 1 reduction :P

It's just down to making the two sprockets small and large enough then :)

Ditto on the alignment by the way.  I'm sure you have it under control, but it just makes me feel better inside to say it.

Looks good man, you guys are way ahead of us this year.
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Post Options Post Options   Quote tp Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-09 at 6:55pm
Originally posted by exbaja

With thin rims tire irons are an issue, they can collapse a rim with stiffer tires.  

Tire machines are key to sanity in my opinion.  


How thin are we talking? I've mounted plenty of tires on .125 aluminum wheels w/o any problem.
Also, squirrels.

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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-10 at 12:04pm
Originally posted by jhu42

Hmm I see what your saying.
 
Its a hybrid chain box.  Reduction 1 is 35 pitch chain, Reduction 2 is 420 chain.
 
The chain is Regina Chain, so its high quality. 
 
Here are the 35 chain stats
 
 
115 HHKart  Average tensile strength = 2248 lbs
 
and the 420 stats
 
 
124 RX3  Average Tensile Strength = 4271 lbs
 
Based on what I've seen so far in testing, no problems here.  The key is that the 35 chain is on the 1st reduction, not on the second, needed to go to 420 for that one.
 
Adam
 
 
We used #35 for bot reductions which is probably why we had the issues that we had.  Using 420 like you are is definitely a smart decision. 
Robbie
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-12 at 10:16am
Video from testing



No comments on the driver, i'm not very good, took most of the corners too wide.  It was very fun however :D


Edited by jhu42 - 2010-Mar-12 at 10:17am
Adam Baumgartner
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Post Options Post Options   Quote asims Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-12 at 9:17pm
Looks pretty good.  If you did any high speed runs, just remember that your going to lose about 5-10 mph when you put in the firewall LOL
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-13 at 12:31am
Just finished the frame completely with all the tabs getting ready for powdercoating on Monday.  Frame weighs exactly 94.7 lbs with all the tabs on it (kill switches, battery mount, 5th point harness tabs, etc).  This is +~ 20 lbs from where we were before.  Which makes sense looking at it.  I'm interested in seeing how much the powdercoat adds.  I will update you when I get those numbers.

Later,
Adam
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Post Options Post Options   Quote frinesi2 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-15 at 6:26am
Looking good, guys. I'm interested in seeing how much weight powdercoating adds as well.

And that steering wheel . . . I recognize it . . .
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Post Options Post Options   Quote Rambo Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-15 at 10:42am
Looking good! Thumbs Up

I noticed the rock rings on your wheels. That's something we're looking into for this year. Our rims only last about one competition before they're toast. How much weight do those add? Have you had any issues with smashed rims since you've added them?

Nice graphics too, by the way. I've always thought it would be sweet to have a sort of WWII fighter theme. Unfortunately, it doesn't really work well with orange and black...
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-15 at 11:28am
Originally posted by Rambo

Looking good! Thumbs Up

I noticed the rock rings on your wheels. That's something we're looking into for this year. Our rims only last about one competition before they're toast. How much weight do those add? Have you had any issues with smashed rims since you've added them?

Nice graphics too, by the way. I've always thought it would be sweet to have a sort of WWII fighter theme. Unfortunately, it doesn't really work well with orange and black...


Hi Rambo,

The rims are the ITP Baja series rims. 



http://www.itptires.com/sportatv/t9_baja.html

For having a "rock rim" inner part, they are really light Big smile

The reason for this is because the inner disk is not welded to the rim, the outer part of the rim is rolled around it, constraining it from moving.  Its a really cool design.  However, the only downside is they cost $100 each.  We've never really had serious problems from rims getting torn up, but we've also taken it easy to avoid rims going bad on us.  With these rims they give you a lot more confidence to go over obstacles faster.  Also we increased our front tire size from 21" to 22" to add to our durability.  And went with the Holeshot XC, apparently the most puncture resistant tire on the market ;)


http://www.itptires.com/sportatv/holeshot_xc.html



We did not have any flats in Auburn, but saw lots of other teams with them.






Who needs your own WWII fighter theme, you guys have your own plane :)







Later,
Adam






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Post Options Post Options   Quote Rambo Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Mar-15 at 3:36pm
Originally posted by jhu42



Who needs your own WWII fighter theme, you guys have your own plane :)







Later,
Adam


True, but while that paint job looks great on a plane with jet engines and wingtips, our car lacks those features (for now, anyway). Wink

Thanks for the info on those wheels, too. We are trying to cut down our cost report this year, so we might look into some "in-house" alternatives, but other than cost, those wheels look great! Last year, we ran Carlisle 489 A/T tires on Douglas Wheels. They're pretty cheap, and the tires are great, but we'd like to try to improve our wheels.

As far as I know, we've gotten lucky and avoided flats at competition as well, but the amount of abuse those wheels suffer makes me nervous. I'll try to get some pics up of some of the carnage, if I can find any.

Nice work, anyway!

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