URGENT: Rear Wheel Alignment Issue - Please Help!

[ScoJo]

This is the first time that we have encountered this problem.

We align our rear wheels by putting only those in and just running down a test board. We've done this for the last few years, but this time, no matter how much adjustment we try to make (rear wheels are bent axles at 2.5 degrees using rail rider tool), the car drifts dramatically to the left (which would be away from the rail!).

I put in the DFW, adjusted the axles in the rear for what I believe is zero toe, and confirmed that when rolling forward and rearward that the nails do stay out on the axle heads.

But why can I not get it to stop drifting strongly to the left with just the rear wheels? This seems like a speed killer.

[ScoJo]

The axle groove in the rear (which we must use) seems to be square with the block. The odd thing is that the straightest I can seem to make it go with just the rear wheels requires adjusting toe to what I believe would be steering toward the LEFT. I cannot figure this one out. And our race is in three days.

In past years we've always gotten the car to go straight with just the rear wheels with very little adjustment from the 12 o'clock position.

[ScoJo]

Very little if anything has been changed in the way we shape and weight the car.

[ScoJo]

I should also note that we swapped the rear wheels back and forth and nothing corrects the bad rear wheel steer that we get.

[Stan Pope]

http://www.stanpope.net/bentaxlealign.htm

email me if you have questions.

[davet]

Our problem was the DFW hole was not exactly perfect with zero toe so it was steering when had a straight axle installed. I used this method from Lighninboy to confirm our rears were correct. Very easy. There is a thumbtack stuck into the bottom of the car centered between the front axles. Doublestick tape on the thumbtack head and stick it down onto the square or any thing you can make work. I made a "L" shape from a few paint stir sticks.
http://vid1289.photobucket.com/albums/b ... 9zkf7c.mp4

[ScoJo]

Stan,

That was a great video, and you certainly are much more thorough than I have ever been with my kids!

Unfortunately, we have a race on Saturday and I don't have the time to construct these awesome bias weights, and I do not have as elaborate of a test board. We've been using the method of just installing the two rear wheels and seeing if the car moves straight down the board. In the past, this has worked pretty well, with usually only a small adjustment from 12 o'clock needed for one wheel to get the car to track straight. This year, however, regardless of the adjustments made (as well as swapping the two rear wheels), the car steers strongly away from the direction of the rail.

Do you think there is hope to correct this with just the axles, or do you think that this is a symptom of the car body? The latter is unfixable in the time we have left. I could prepare new nails in the coming days, but making a new body is out of the question, unfortunately.

This is our last year, and I'd hate for it to end in a flop.

[ScoJo]

davet,

Unfortunately our steer issue occurs without the front wheels installed.

[sporty]

You are going to have to try different axles with a slightly different bend to try and correct. The hard part with slots. Already using bent axles. Is in solving the issue. The car might not have the sake rear height on the rears. Tilt.

Are the two rear wheels the same o.d. and same bore size ?
Sporty

[ScoJo]

They are. The insides of the hubs were cleaned with a 0.098 chucking reamer and the outsides were turned.

[ScoJo]

I've been bending with the RR tool to 2.5, but in the last two years I have shimmed with a business card strip because without it I can hardly see any bend. Any tips for bending new axles?

[sporty]

I went to using the new derby work axle bender. And really like it.

Other then what you are doing with the older design. That's what I use to do. Might have to not use the wax paper.

U reamed your own bores ?. Hmmm. I don't think I'd try that. Maybe you will share how you did it sometime.

Sporty

[Speedster]

Max-V, Pro Axle Bender, #5198, $79.95. You can bend the axle to any degree you desire.
Here's something you can try quickly. Don't ream the bores. They are all very close to .096. I have 3 raw wheels that are less than .002 out of round. Yes, many are .005 or worse. If you don't have a concentricity gage, simply guess at it. Put 2 wheels on an Axle Made in China, or better yet, a Max-V 4094 axle. If you have the axle guide by all means use it. If you're buying basic wheels where nothing has been done to them except make them round, I like Derby Evolutions. I'm not a salesman for Steve but I like his wheels, even though he charges me sales tax. See what happens when you use LightninBoy's thumb tack technique.
Who turned the outside of your wheels? If you don't mind, after your race, mail them to me. I'd like to turn them on my gage. I'll be happy to pay the return postage and include 2 raw wheels with less than .002 runout. Anyone know what the number of the closest drill bit is to a .098 bore?

[Stan Pope]

A yardstick taped to a flat board and 1 or 2 oz weight taped to the car can also do the job. Just need to WEIGH the rear wheels individually to assure that you have accomplished the necessary dominance.

[Stan Pope]

Anyone know what the number of the closest drill bit is to a .098 bore?

#40 is 0.098" Close enough?