Rear Wheel Alignment Help Needed

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acswain
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Rear Wheel Alignment Help Needed

Post by acswain »

I am having problems aligning my rear wheels to run on the axle heads. They are canted 2.5 degrees using the rr tool. During alignment test the rear wheels drift toward the body when rolled foward, and drift toward the axle head when rolled backwards. I thought that this indicated a toe-in problem and rotated the axles in the slots to correct. It appears that no mater how I adjusted the toe-in and toe-out by rotating the axles, the wheels continually drift towards the body when rolled foward and toward the axle heads when rolled backward. Any advice? (I am using the pre-existing axle slot)
john4840
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Re: Rear Wheel Alignment Help Needed

Post by john4840 »

Sounds like one of the axles are crooked. Make sure all the axles are straight. I had this problem and I had to shim the axle to make it straight.

John
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sporty
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Re: Rear Wheel Alignment Help Needed

Post by sporty »

When rules require you to use the slots. it just does not come easy. Its work. You might have a bad piece of wood.

And , if the slots are not bad enough, trying to use bent axles for cant, is even harder to do.

I have, used strait axles in the slots and angled them with cant, using dimes. pennies, ect and used a light coat of oil on spare axles. got my cant and check they were not toeing in or out and glued them in, sat a weight on top and let it dry.

naturally, no wheels were on. I then took my needle nose pliers, turned them and carefully removed them. and then installed my wheels and prepped, (good axles) and seemed to work for me, when dealing with cant for rears.


I did the same thing for the front, just opposite cant and raised up the front of the block, until I got the desired cant and ect, glued in, turned and twisted out those axles and inserted my canted RR axle.

I use to fill the wholes with 20 min epoxty, some rules, said they needed to be able to see the axles. so i used clear glue to fill the wholes.

but drilling out, was a melty, sticky, axle whole mess.


I prefer a 4 foot longe, 4 inch wide smooth board, raised a few inches up, no front wheels on, a piece of 3m clear tape and maybe a slight rub of graphite on the tape under the front end of the car. and see if the car will go strait down the board.

I do not like the push back and forth a few inchs, methos, for confirming toe in or out issues.

it the rears cant run strait 4 feet down the board. the will be pretty slow down the track and even worse, once the graphite wears out quicker, due to the added friction there.

Sporty
Rukkian
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Re: Rear Wheel Alignment Help Needed

Post by Rukkian »

I know sporty gave some great info (as always), but it would be good to get some more info - are you using the slots, or drilled holes? If you did drill the holes, how did you do it (drill press, derby worx tool, etc).

Also, did you straighten the axels first before bending them?
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sporty
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Re: Rear Wheel Alignment Help Needed

Post by sporty »

Rukkian wrote:I know sporty gave some great info (as always), but it would be good to get some more info - are you using the slots, or drilled holes? If you did drill the holes, how did you do it (drill press, derby worx tool, etc).

Also, did you straighten the axels first before bending them?

I used the pro body jig to drill wholes into the slots. When I tried filling them with a clear glue that hardened well.

I did not use the axle straitner tool to straiten the axles. I had better luck putting them into my drill press and if they wobbled. i did not use them or if the head looked off center from the shaft of the axle.


Yes I always use a drill press, when drilling.


And i have just used the slots, if the rules called for it and I was not allowed to fill the axle slots up.

But sometimes the slots were tight enough, drilling the axle whole, helped me have a better aligned rear axle slots and front. I could usually tell, where the axle should be at in the slot.
acswain
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Re: Rear Wheel Alignment Help Needed

Post by acswain »

I used the pre-existing slots, and did straighten the axles before bending. I thought that it may be possible the pre-existing slot was not exactly perpendicular to the body (I did check before build) but, wouldn't that just cause toe-in on just one side and toe-out in the other?

Another thought I had was that the rr tool is not canting the axle as much as it should. Since my son polished the axles this year he may have taken more off than in previous years hence reducing the diameter of the polished side of the axle. Could this reduced diameter on the polished side of the axle reduce the cant from the rr tool? Still I am not sure if this would cause my excessive toe-in problem..but maybe a combination of both the above?
john4840
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Re: Rear Wheel Alignment Help Needed

Post by john4840 »

acswain wrote:I used the pre-existing slots, and did straighten the axles before bending. I thought that it may be possible the pre-existing slot was not exactly perpendicular to the body (I did check before build) but, wouldn't that just cause toe-in on just one side and toe-out in the other?
Usually when this happen the slot is not perpendicular to the body or the axle is in the slot crooked, it could cause the wheels to always migrate towards body when car rolls forward. Do have other axles to try? I know how frustrating it can be to try figure out the problem.

John
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Stan Pope
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Re: Rear Wheel Alignment Help Needed

Post by Stan Pope »

acswain wrote:... it may be possible the pre-existing slot was not exactly perpendicular to the body (I did check before build) but, wouldn't that just cause toe-in on just one side and toe-out in the other?
Yes

The symptom you describe is definitely a "toe error" situation. Consider temporarily replacing the wheels and axles with straight axles (or #44 drill bits) and using a try square along a true side of the car. Compare blade of square to straights of axles/bits. Then replace with original bent axles (but no wheels) and look at the range of toe angles you can accomplish by twisting the axles.
Stan
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rpcarpe
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Re: Rear Wheel Alignment Help Needed

Post by rpcarpe »

Welcome to the madness of tuning your car!
I suffered the same malady (rear wheels out while going forward, in while rolling backward) BEFORE finding Derby Talk.
Now this gets prevented by drilling canted rear axle holes, no problems this year using The Block.

Stan, John and Sporty seemed to have diagnosed it just like I would.
Good luck, measure twice, bend once.
My wife started a new support group... Widows of the Pinewood Derby.
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