Rear alignment diagnosis please (RACE RESULTS ADDED)

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ngyoung
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Re: Rear alignment diagnosis please

Post by ngyoung »

I believe with Stan's method you want to set the car the same as you would stage on a track. Regardless of how you start, the goal is to get it to roll the same path with either rear wheel weight biased.

If you have steer set on your DFW I dont think the reverse roll works anymore since the car is turning into the opposite wheel.
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birddog
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Re: Rear alignment diagnosis please

Post by birddog »

davet wrote:I closed up the rear wheel gap and I'm now running .57 oz on DFW and 3" of steer. No wobbles and pretty quiet down my homemade track. I increased the steer to 5" and she was much louder, still no wobble. Dropped steer down to 2"and she seemed quiet too.
I ran into this with my adult division car this year. My scout seated his own axles (which I thought were awfully tight) and I seated mine a bit less tight. My sons cars didn't have a wobble, but mine did. I tightened up the gap on my rear wheels and the wobble disappeared. Adding more steer wasn't helping get rid of the wobble, but tightening up the gap did it.

I think I'm running about a 0.010 inch gap, which seems pretty tight, but its working.

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pwrd by tungsten
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Re: Rear alignment diagnosis please

Post by pwrd by tungsten »

davet wrote:The stock axles have a bend so small I couldn't see it. I twisted them to get wheels to the heads forward and back. Goes dead straight both directions. I closed up the rear wheel gap and I'm now running .57 oz on DFW and 3" of steer. No wobbles and pretty quiet down my homemade track. I increased the steer to 5" and she was much louder, still no wobble. Dropped steer down to 2"and she seemed quiet too.

When I adjust steer I set my DFW against my line and the rear on that side 1/16" away from the line. Do I do the same with your method above Stan? If running in reverse do adjust it also the wheels are line up or set the side of the body parallel to the line?

Race is in 10 days so there's no going back now.
Perhaps 2.5 to 2.75" over 4 feet? Somewhere in that range seems correct to me.
W Racing!!!!
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LightninBoy
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Re: Rear alignment diagnosis please

Post by LightninBoy »

Speedster wrote:LB, the scouts are going to Love this. Thank You.
No problem. Let me know how it works for you. I've been successful with it and used it while helping several families. I initially used it to check drilled holes with straight axles but I've also used it to align bent rear axles when helping other families. When aligning bent axles, I moved that weight to the extreme left or right to get an idea of what an individual wheel was trying to do. Probably not as effective as the cantilever approach of Stan's, but it seemed to work.

Anyways, if I hear that others are having success with it, I'll be a bit more aggressive about sharing it.
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davet
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Re: Rear alignment diagnosis please

Post by davet »

I'm still having trouble with this car. It looks like the inside rear edge of one rear wheel is scuffing as it has more wear than the other side. I'm not sure how it could be scuffing the track when it goes to the head in both directions.
I found that my straight DFW hole must have slight toe in as with a straight axle it sucks into the body going forward no matter how I spin it. Goes to the head in reverse. I got the wobble out last with more DFW weight and by giving the rear wheels a touch of toe-out. Not sure if that's good or not

I think LB's aligning method may get a try tonight. Race is tomorrow so it'll be an all-nighter. Pulled last years car off the shelf and it will lead this car by 1/2 a car-length just on our kitchen table roll. I wish we could just re-skin it and kill-em'.
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davet
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Re: Rear alignment diagnosis please

Post by davet »

LB, will it also veer off course if not aligned? If I get the rears to heads in both directions over the same distance I'm good?
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davet
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Re: Rear alignment diagnosis please

Post by davet »

our track and car:
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Stan Pope
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Re: Rear alignment diagnosis please

Post by Stan Pope »

Beautiful car and test setup!

LB test setup tells you if rear holes are true or not. That is good to know! But it is less informative if they are not true... it doesn't tell you what you need to do to make it right. And it doesn't tell you about how true the actual axles are or allow you to verify alignment after racing without removing the DFW.

I think you can answer some of the remaining questions by repeating the roll test, in particular the reverse roll, with added bias weight on the rear, making first one, then the other, rear wheel dominant.

I would still prefer to be able to check alignment without modifying any of the settings.
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davet
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by davet »

THANK YOU LIGHNINBOY!!!. LB spoke with me over the phone for over 20 minutes yesterday explaining his test, what to look for and possible fixes for our wobble. All 2.95's and a single 2.96 today. 2nd Place in Pack to a guy who hit a 2.91 and is the annual winner within our Pack. Only one other guy out of 68 cars to go under 3.00 and he did that in 2 heats. We loaded all weight to the rear and got 2 test runs. I was certain we would have a wobble but it was smooth with 4" steer.

I used LB's method which worked beautifully even though I don't know enough to use it to it's full potential. i still had some wobble at 0345 hrs this morning. I was certain the rear alignment was correct and went to bed wondering what to do since race was today. I banked on one of 2 things being the problem, 1) Not perfectly square drill press table when grooving the BSA axles or 2) My track was throwing me off however, last years car was silent and straight on this track right off the shelf.

My boy polished 2 new axles this morning but this time we didn't groove them. They were dead straight axles. I installed them, ran LB's test and it was perfect (with my limited knowledge) first time. Ran it on our track and had major wobble unless DFW was up in .68 oz range. Steer didn't make any difference.

Now I thought maybe track issues. We loaded all our tuning weight to the rear axle and centered then headed to the race knowing we had 2 test runs. I kept steer at 4" since that would be hard to adjust without our kitchen table. We were certain we would have to move weight forward after test runs but it was silent and fast.

On the way, no kidding, we said a prayer that all of the cars would reach their full potential (no crashes or parts falling off). After our test runs both rear axles had slid out almost to the point of coming out because we did final glue job when we left for the race. Fortunately they were marked.

He also got the "Best Car That's Not A Car" award.
Last edited by davet on Sat Jan 24, 2015 11:07 pm, edited 2 times in total.
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Stan Pope
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by Stan Pope »

Way to go, Team!!! :thumbup:
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davet
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by davet »

Thanks for your help Stan.
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Scrollsawer
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by Scrollsawer »

Great Job! Congratulations! :clap: :bigups:

Love the aircraft carrier car.

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davet
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by davet »

Scrollsawer wrote:Great Job! Congratulations! :clap: :bigups:

Love the aircraft carrier car.

Scrollsawer
Thanks. The pic here doesn't do the colors justice. I was talking to another dad today who explained how he cut the tip of his finger off last in the saw trying to cut his boy's car. He said it bled all over and he still can't feel anything in that tip. I thought of ur story right away. My point is this...your future still looks good for car building Scrollsawer.
Last edited by davet on Sat Jan 24, 2015 10:39 pm, edited 1 time in total.
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davet
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by davet »

3 nights little sleep was worth it when my boy said, "Thanks Dad for helping me build a fast car." So I say that back to you all here, "Thanks for helping us build another fast car!" All the info needed to make a fast car is here but u have to read everything, ask questions and trial and error in order to understand what u guys are talking about.

Also, we were faster this year than last even though last yrs car, right off my boy's bedroom wall with no lube added, was faster on our inclined kitchen table than this yrs car.
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LightninBoy
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Re: Rear alignment diagnosis please (RACE RESULTS ADDED)

Post by LightninBoy »

davet wrote:THANK YOU LIGHNINBOY!!!.
Happy to help anyone who is passionate and working hard at this. Nice work! And love the track setup.
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