Tire/ Wheel selection |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Using a normal nut when you need a tapered one would be inviting disaster. Your wheel would never be concentric. One option if you need tapered lock nuts is to make tapered washers and the use a normal lock nut. Wouldn't be too hard to drill out a tapered nut and cut it down to turn it into a tapered washer. |
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-Tom
Oregon State BajaSAE Team Captain |
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Wheels: I'm guessing its because of price but I'm a bit surprised we were the only Baja team that seemed to us Keizer Wheels. They are heavily used in SAE Formula. If you can find a Douglas rim in the size you need, they're cheaper. But for a little more $ Keizer will make a rim in any bolt pattern, diameter, width, back spacing you want. You can get absolutely zero scrub radius with custom back spacing! Don't know what the current pricing is like but a custom rim with dent rings and mud cover cost about $120 back in the day.
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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With the demands of todays racers, you can get a Douglas wheel in almost any backspacing that you can dream of. Not only that, but personally I don't know how much I'm going to trust a road wheels with what we do. I've seen our Formula team break wheels. Judging by how many wheels I've destroyed, Baja just demands something stronger. If you have a properly designed suspension, you can get a zero scrub radius with whatever wheel you choose. Like maybe something off the shelf. EDIT- didn't realize that Keizer makes quad wheels too. Thought it was just sprint car and road wheels.
Edited by tp - Mar/14/2011 at 3:45pm |
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-Tom
Oregon State BajaSAE Team Captain |
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ErikHardy
Baja Godfather Joined: Apr/12/2010 Location: Hood, Flint, MI Status: Offline Points: 939 |
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Along the lines of what tp said, would there be enough material to put the lugnut in the lathe and put a small taper on the end of it. |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Most tapered lugs are 37 degrees (I believe). You would need a pretty massive lock nut to put that sort of taper on it.
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-Tom
Oregon State BajaSAE Team Captain |
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Douglas wheels are almost all spaced 3" in from the outside. Keizer will make you one spaced 0". That means your custom A-arms can be 3" longer, better angle on the ball joints, more travel, what ever you want to design, etc. Keizer makes nice spun metal race quad wheels. Never damaged one with a anti-dent ring. |
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ErikHardy
Baja Godfather Joined: Apr/12/2010 Location: Hood, Flint, MI Status: Offline Points: 939 |
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I misread what he was talking about, I thought he had a flat lugnut and just needed a tapered end, my mistake.
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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You can backspace Douglas wheels 1, 2, 3, 4, 4.5 or 5 inches. The problems is if you got too much one way or the other you end up putting lots of stress on your wheel bearings.
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-Tom
Oregon State BajaSAE Team Captain |
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dillon_b12
Baja Godfather Joined: Nov/15/2008 Status: Offline Points: 781 |
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Douglas wheels can be had in 4+1 as well as the standard 3+2 offset. I e-mailed Keizer near the end of '08 for some pricing so I'm not sure how current this is:
Current pricing for Douglas wheels: 10x5 Wheel 3+2 Offset 4/156 Bolt Pattern (This is a Yamaha Raptor wheel.) Blue Label(.125): $58.00 Black Label(.160): $68.00 Red Label(.190): $77.00
Edited by dillon_b12 - Mar/14/2011 at 6:26pm |
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Greenreed1936
Bolt Sorter Joined: Aug/31/2009 Location: Rapid City Status: Offline Points: 24 |
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We have run Keizer wheels for the last 5 or so years and just now had one destroy itself at Michigan Tech's Winter Comp.
They hold up to the abuse quite well. A little spendy but perform very well. |
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SDSMT BAJA SAE
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SDTech
Milling Master Joined: May/13/2009 Location: Rapid City, SD Status: Offline Points: 68 |
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To be fair, that wasn't really the fault of the wheel... |
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SDSMT Baja SAE
Car #'s 4 & 6 - Oregon Car # 14 - Wisconsin #4 & #79 - Western Washington 2010-2011 SDSM&T Team Lead |
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Greenreed1936
Bolt Sorter Joined: Aug/31/2009 Location: Rapid City Status: Offline Points: 24 |
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Well thats true. You were driving |
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SDSMT BAJA SAE
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Where do you get your Douglas wheels from? I'll need to buy some soon. I need this:
4/4 10X6 1.0 + 5.0 0.190 (red label?)
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CLReedy21
Baja Godfather Joined: Nov/30/2008 Location: Marysville, OH Status: Offline Points: 736 |
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You're probably gonna find that one under the "call" section.
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-Chris Reedy
TTU Alumni Fourwheeler Drawer "Quick with the hammer, slow with the brain." |
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Just in case any one is interested.
They cost $140.
Edited by Akron 1998 to 2004 - Mar/18/2011 at 12:20pm |
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ballast
Bolt Sorter Joined: Sep/30/2012 Status: Offline Points: 28 |
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anyone who has used carlisle at489 2*ply tires please share your experience . I personally think that 2ply is more prone to punctures or cuts. But my doubt is that will it get punctured even under normal conditions or only under harsh conditions. Any information will be appreciated. thankyou.
Edited by ballast - Sep/30/2012 at 4:23am |
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jacking with the screw
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Soccerdan7
Organizer Joined: Sep/22/2010 Location: CA Status: Offline Points: 780 |
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We have used them for our rears for our last 3 competitions and the only flat we had was due to a massive impact that also dented our trailing link, bent the lower camber link pretty bad and sheared the driveshaft...
They are a great lightweight rear tire.
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Danny
Cornell (fall'07 - spring'12) Former Captain / MEng / that guy with all the carbon 10 races, 7 top ten's, 2 overall wins |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Does anyone knows what are the typical values of the rolling resistance,and static friction coefficient of the mini Baja tire running on the tared track/road?
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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I do not exactly know the typical values for rolling resistance of a Baja tyre but however, based on my experience, they must be in the range of 10N - 150N. Please keep in mind that rolling resistance is a function of the vertical force, inflation pressure and forward speed of the tyre and hence I have expressed it as a range.
You can experimentally determine your tyre's static friction coefficient by using a simple spring balance. This value would be realistic and it would also have more validity during your design evaluation and car's dynamic analysis.
Edited by sujandinesh - Jul/18/2018 at 3:58am |
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Hi
I am working on the Mini Baja from South Africa. The total weight of the mini Baja including the weight of the baja is 310Kg. My aim is to archive the maximum velocity between the range of 50km/h-60km/h.But I only managed to archive 44km/h by calculations. My question is, when I calculate the resistance forces, should I consider both Static friction and Rolling resistance friction? In my calculation I considered them both and I found that, the static friction has a very huge negative impact towards achieving my goal. Now I am not sure if I should take the static friction into account. |
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RLM
Baja Godfather Joined: Nov/15/2012 Location: Hamilton, ON Status: Offline Points: 1258 |
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The static friction of what?
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McMaster Baja Racing (09-Dec 2015)
Team Captain 2012-2015 Suspension Lead 2015-2016 All spoonfeed PM requests will be billed at $10 USD per reply, payable via paypal. |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Static friction between the Baja Tires and the surface or road. Remember the rolling friction occurs between the tires and the surface also.
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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There is no such thing as a rolling resistance friction. It is either expressed as a moment or a force (not preferred). The rolling resistance moment maybe one of the reasons for your decreased speed range but however I would only investigate this after going through other losses such as the transmission, air drag etc. I do not understand what you mean by the next highlighted statement.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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This is definitely not one of the reasons why you have a decreased speed range. I do not understand how you would use this and calculate the resistance forces. Friction is paramount for grip without which you would have 100% slip condition i.e. the tyre with a certain angular velocity but with no forward speed. My suggestion would be to reinvestigate the losses in your transmission.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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I hear u but my question is, which friction must I use in my calculations between static friction resistance and rolling friction resistance?
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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Are these calculations to determine the resistance to your car? Then neither.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Yes. For example: F_static = u*N, where (u=0.4) static friction coefficient and (N=310kg*9.81) normal force. Therefore F_static = 0.4*310*9.81 = 3041.1N. And F_rolling = u*N, where (u=0.02) rolling resistance coefficient and (N=310kg*9.81) normal force. Therefore F_rolling = 0.02*310*9.81 = 60.822N.
Remember there is also an air drag resistance force that I have to add on these two forces. My question again, do I add Air drag resistance force with rolling resistance force or Air drag resistance force with static friction resistance force or I have to add all three resistance forces in order to get the total resistance force for an accelerating Baja from rest on a flat level track?? |
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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Now I get what you want to ask.
To be honest, whether to consider the static or rolling friction coefficient is a pretty basic concept, I would suggest you rethink this and try to imagine the car as a brick or a brick with wheels. Coming to the second part, the air drag is an additional resistance the car faces, so it is a separate effect. The last part, regarding the rolling resistance, I think needs some clarification. The rolling resistance is purely a resistance offered by the viscoelastic nature of the tyre rubber to a freely rolling tyre. This is coming solely from your tyre and hence is also a separate effect.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Thank you for your explanations but you still have not answered my question.
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Thank you
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RLM
Baja Godfather Joined: Nov/15/2012 Location: Hamilton, ON Status: Offline Points: 1258 |
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This statement was where I was trying to steer the conversation, Just didn't think it would need to be this spelled out.
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McMaster Baja Racing (09-Dec 2015)
Team Captain 2012-2015 Suspension Lead 2015-2016 All spoonfeed PM requests will be billed at $10 USD per reply, payable via paypal. |
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