RR Front wheel Camber help!!!

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tmack
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RR Front wheel Camber help!!!

Post by tmack » Thu Jan 12, 2012 3:49 pm

My son and I are first time PWD builders. We had our pack workshop last week and came in 2nd for most wins/hour with our standard car with nothing special except polished axles/wheels-no camber. The father/son team that came in 1st had a 3 wheel RR..we were hooked to make one as well! So we bent the axles (2.5 rear/1.5 front). Negative camber on rears--wheels riding on the axle heads both directions...all good in the back! For the DFW, started out with neg camber--wheel riding on axle head...adjusted for 2"/4ft drift. All looked good.

But then I read a Derby Talk blog stating positive camber is the way to go for the DFW. So being the compulsive person I am..I decided to spin the DFW axle to 6 o'clock postion for positive camber, set back up for 2"/4ft drift. Now when I test on my homade center rail at slow speed. The DFW now rides on the car body continuously. I thought I read that the rail would push the wheel off the car body towards the axle head once wheel/rail contact was made? This is not what I am seeing. Can anyone tell me if this is normal, is my alignment off, or should I revert back to neg camber DFW? Still thinking [junk] camber is better just because the DFW isn't squeezed between the rail and axle head any more but not sure. Please help...1 week till the race!!
Thanks



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FatSebastian
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Re: RR Front wheel Camber help!!!

Post by FatSebastian » Thu Jan 12, 2012 3:57 pm

:welcome: tmack!
tmack wrote:Can anyone tell me if this is normal...?
This is normal. The hub tends to maintain body contact (prepare the body and hub accordingly).



tmack
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Re: RR Front wheel Camber help!!!

Post by tmack » Fri Jan 13, 2012 8:38 am

Thanks FS!



chief33
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Re: RR Front wheel Camber help!!!

Post by chief33 » Fri Jan 13, 2012 11:48 am

So you want to start with the axle bent down?

Thanks



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5kidsracing
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Re: RR Front wheel Camber help!!!

Post by 5kidsracing » Fri Jan 13, 2012 12:18 pm

chief33 wrote:So you want to start with the axle bent down?

Thanks
Correct, the front steer wheel will have positive cant and the axle is bent down.


For my "Pinewood Story" go to: http://5kidsracing.webs.com/index.htm

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Re: RR Front wheel Camber help!!!

Post by EdZep » Fri Jan 13, 2012 5:32 pm

tmack wrote:So we bent the axles (2.5 rear/1.5 front).
Hi Friends, just a little on our experience with front axles:

One year, making two cars, one for older son ("OS") and one for younger son ("YS"). Similar design (flat wedge), weight, COM, etc. between the two. We put 2.5 degree bend on OS's DFW, then inadvertently put only 1.5 on YS's car. OS beat YS, and after the race we ran them on test track multiple times trying to figure out why one was superior to the other. Only after pulling and examining axles did we realize we must have used wrong end of the RR tool on YS car. So in our experience, 2.5 deg on DFW is better.

Further, we have found that the best orientation of the front axle is to rotate the bottom somewhere in the neighborhood of about 45 degrees forward. If we can test, we start here then adjust a little bit in each direction to see if we can tweak up a bit.

Also, we ran tests with rear axles bent at 1.5 and could not get a better result than compared to non-bent rears, so we save ourselves the work of bending the rears.

FWIW, the OS car mentioned above took first place in district that year, his last year as a Cub. Using what we'd learned (along with about a million other factoids gleaned from this board, thanks to everyone btw), YS took first in district the next year!

Hope this helps!

/jeff



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Re: RR Front wheel Camber help!!!

Post by ScoJo » Sat Jan 14, 2012 5:03 pm

Thanks for the info. We're thinking about increasing from 1.5 to 2.5 on our DFW due to the edge question I asked on my other thread. Perhaps if we do this, it will help since we like to square that edge in order to square it with the hub. Thoughts?



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Re: RR Front wheel Camber help!!!

Post by FatSebastian » Sat Jan 14, 2012 5:23 pm

EdZep wrote:So in our experience, 2.5 deg on DFW is better.
Some have found even more is better!
ScoJo wrote:We're thinking about increasing from 1.5 to 2.5 on our DFW due to the edge question I asked on my other thread. Perhaps if we do this, it will help since we like to square that edge in order to square it with the hub. Thoughts?
To avoid making information hard to locate, it may be best to direct thoughts back onto that thread (where Sporty already noted that it would likely help "allot of cant").



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Re: RR Front wheel Camber help!!!

Post by Jeff Piazza » Fri Jan 20, 2012 1:08 pm

EdZep wrote:OS beat YS, and after the race we ran them on test track multiple times trying to figure out why one was superior to the other.
If you don't mind my asking: by roughly how great a margin did Older Son beat Younger Son? Are we talking about 1/8" difference, or half a car length?

Was victory determined by a single heat, or several?

So many variables are at work in a single derby heat, I'd like to hear a little more about the conditions from which you derived your conclusion.

/JEP



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Re: RR Front wheel Camber help!!!

Post by tmack » Tue Jan 24, 2012 7:03 am

Just wanted to give an update on how our first time RR performed at the pack race this past weekend. We won every individual heat (4) and had an 5th fastest average so we qualified for districts. We had one really slow time that raised our average time, not sure what happened there...think they should drop slowest time before calculating the average :x . The pack track was really short , shaped like hockey stick, our car seemed to maintain its speed better on the straight away than other cars so I hope the district track is longer (40+ feet).

Anyway, special thanks to thanks to John484(at pack workshop) and Sporty(emails) for all the advice!
On to districts...
John4840....Tommy can't wait to see RJ's "good" car! :bigups:



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Re: RR Front wheel Camber help!!!

Post by john4840 » Tue Jan 24, 2012 9:22 am

tmack wrote:Just wanted to give an update on how our first time RR performed at the pack race this past weekend. We won every individual heat (4) and had an 5th fastest average so we qualified for districts. We had one really slow time that raised our average time, not sure what happened there...think they should drop slowest time before calculating the average :x . The pack track was really short , shaped like hockey stick, our car seemed to maintain its speed better on the straight away than other cars so I hope the district track is longer (40+ feet).

Anyway, special thanks to thanks to John484(at pack workshop) and Sporty(emails) for all the advice!
On to districts...
John4840....Tommy can't wait to see RJ's "good" car! :bigups:
You are welcome. Congrats to your son :clap:. Sounds like your pack has a best track and that is the same type of track that is used at the Bushy Run District race. The track at the district race is long and since you are RR you should have an advantage over most of the cars. By the way that is how they run the district race 4 runs on each lane of the track and the times are added up. Good luck to your son and we will see you Saturday.

John



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Re: RR Front wheel Camber help!!!

Post by EdZep » Fri Jan 27, 2012 2:20 pm

Jeff Piazza wrote:
EdZep wrote:OS beat YS, and after the race we ran them on test track multiple times trying to figure out why one was superior to the other.
If you don't mind my asking: by roughly how great a margin did Older Son beat Younger Son? Are we talking about 1/8" difference, or half a car length?

Was victory determined by a single heat, or several?

So many variables are at work in a single derby heat, I'd like to hear a little more about the conditions from which you derived your conclusion.

/JEP
Hey Jeff, hope this reply isn't too late for you!

In our pack race, we score based on the sum of times of four heats. The total time of car in 1st place ("older son") on 40' track was 12.442 seconds, car 2 ("younger son") was 12.601, and the car in third place was 12.710.

So that gives us an average difference of about 0.04 seconds per heat.

I believe, based on memory and a little math, that's somewhere between one-half and one full car length. Overall, sufficiently significant I would say.
john4840 wrote: The pack track was really short , shaped like hockey stick, our car seemed to maintain its speed better on the straight away than other cars so I hope the district track is longer (40+ feet).
My belief is that in general whatever helps you win on a short track will help you on a long track, at least if there are no other significant differences in conditions. Our district track is two sections (16') longer than our pack track so we go less aggressive on the COM (1.2" or thereabouts) to help with stability. Can't say for certain if that specific factor alone helps us, since we can't test and compare two otherwise identical cars on that track.

Good luck to everyone!

/jeff



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