Rear alignment diagnosis please (RACE RESULTS ADDED)

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pwrd by tungsten
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by pwrd by tungsten »

Congrats!

Remember:

1) Drill rears first and roll down plank to check alignment. If not perfect discard and start over before proceeding further.
2) Weight on DFW for a given wheelbase is determined by COM. For excellent prep and alignment 5/8 - 3/4 " is a sweet spot.
3) Wiggle at the very end of the race can mean a win. Strange enough. Tune the car so that it runs straight across the finish line (least amount of steer) and then adjust stir more and less (using a steering table) to see where speed is max. they do not always match.
W Racing!!!!
davidwilkie
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Re: Rear alignment diagnosis please

Post by davidwilkie »

Stan Pope wrote:
davet wrote:If you were aligning "my way", you would decide up front how much DFW-side rear wheel clearance you want, e.g. 1/16" off rail, and align to that point. Probably takes two cycles to get there: make opposite side rear wheel dominant and adjust it to get DFW side rear to track 1/16" off rail; make DFW side rear wheel dominant and adjust it to track 1//16" off rail; make oppoisite side rear wheel dominant and adjust it, if needed, to get DFW side rear to track 1/16" off rail, ... Stop when no adjustment needed after changing sides!.
How does one make one rear side "dominant"? Put weight on that side?

Also, presume need bent rear axles to tune or it's just throw out and redrill?
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Vitamin K
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Re: Rear alignment diagnosis please

Post by Vitamin K »

davidwilkie wrote:
Stan Pope wrote:
How does one make one rear side "dominant"? Put weight on that side?

Also, presume need bent rear axles to tune or it's just throw out and redrill?
The method's here: http://stanpope.net/bentaxlealign.htm You might just watch the 5 minute application video and then watch the *ahem* full lecture if you're interested in the technique.

Your axles need some degree of bend to use this method. So if you have drilled cant, you can put a tiny bit of bend (like, half a degree) in your rears so that twisting them will change the orientation.
davidwilkie
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by davidwilkie »

Thanks! My boys are drilling their bodies this weekend. We are still debating straight drills versus canted. Our bending tool only offers 1.5 and 2.5 degree bends so it seems drill and live with (or re-drill) or bend and play with. Coin toss might be needed.
Last edited by davidwilkie on Tue Jan 27, 2015 7:32 am, edited 1 time in total.
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Vitamin K
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by Vitamin K »

I didn't use a bending tool for our bent axles this year. I bent the axles with the pointy end half clamped between a pair of pliers and the nail head half braced on a piece of scrap wood. Then I used Stan's chart (http://stanpope.net/pwaxlebend.htm) to check the angles and apply more bend as needed.

I had pretty good success, though I did overbend one pair of axles, which I put on my 2 year old's car. It still ran well, but I think it would have done better with more conservative rears. I theoretically could have tried to bend them back the other way, but I didn't want to do too much to any one axle.
davidwilkie wrote:Thanks! My boys are drilling their bodies this weekend. We are still debating straight drills versus canted. Our bending tool only offers 1.5 and 2.5 degree bends so it seems drill and live with (or redri) or bend and play with. Coin toss might be needed.
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pwrd by tungsten
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by pwrd by tungsten »

davidwilkie wrote:Thanks! My boys are drilling their bodies this weekend. We are still debating straight drills versus canted. Our bending tool only offers 1.5 and 2.5 degree bends so it seems drill and live with (or re-drill) or bend and play with. Coin toss might be needed.
I would prep two wheels and axles that will never be raced (consider them spares).

Drill rears 2.5 degrees cant. Drill fronts as well. Install only the rear wheels. Roll down a board and see if it tracks straight. If it does not start over again with a new block. Once you get a working rear setup then go from there. This is in my opinion the fastest car design. Given that the axles you prep for the race may not be perfect you may need to turn them a bit to tune and or try more axles until you get straight ones. But I vote for leaving the axles unbent.

Never place an un-prepped axle in a wheel bore you plan to race.
W Racing!!!!
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