Back Wheels Alignment with Bent Axles

[DuckOfAllTrades]

I know this is a question that may have already been answered in this forum, but I can't seem to find the exact solution I'm looking for.

And of course the easy solution is DON'T bend the back axles, use a jig or buy a pre-drilled body with them already canted. But I don't own a jig and have no means to drill them, and a drilled body is usually not an option. I'm stuck with BSA blocks/slots. I can leave them straight, but when I DO bend them, my question is:

What is the best way to align the back wheels with bent axles? I have no trouble with the front, but think this is where I struggle most. I don't know any way to check them besides by eye. When one of my cars is slow and has bent back axles, it's ALWAYS this problem. I can turn one axle and guess, then turn the other and guess...but this leaves a lot of room for error and can take a long time and a lot of tinkering. Between the back wheels and the front, I'm puzzled about which to adjust to get the best results. I just end up guessing on both back axles until the car seems faster and I'm sure it won't ride the rail, but this is inexact and there has to be a better way, right?

Thanks in advance. This is the ONE thing I feel I can do better and really put together a fast car!

 

[Wolfram Racing]

I rarely use bent rear axles...but here's my opinion for what it's worth. Slow roll the car forward and watch if the rear wheels migrate away from the body. You want the to slowly migrate, not slam quickly. You also want to do it several times to make sure it happens consistently. Beyond that, track tuning.

 

[DuckOfAllTrades]

I rarely use bent rear axles...but here's my opinion for what it's worth. Slow roll the car forward and watch if the rear wheels migrate away from the body. You want the to slowly migrate, not slam quickly. You also want to do it several times to make sure it happens consistently. Beyond that, track tuning.

Yeah, I'm going to make a few test cars without bent axles and see what happens. I just assumed they were to be bent.

I've been holding the car up to a light and looking at the gap between the wheels and the body. Then I turn the axle until it appears even on both sides. This is no exact, I'm sure. I'm worried if they aren't perfect, they will be pointed a different direction on each side and fighting with the car to go different ways.

 

[TRE]

I know this is a question that may have already been answered in this forum, but I can't seem to find the exact solution I'm looking for.

And of course the easy solution is DON'T bend the back axles, use a jig or buy a pre-drilled body with them already canted. But I don't own a jig and have no means to drill them, and a drilled body is usually not an option. I'm stuck with BSA blocks/slots. I can leave them straight, but when I DO bend them, my question is:

What is the best way to align the back wheels with bent axles? I have no trouble with the front, but think this is where I struggle most. I don't know any way to check them besides by eye. When one of my cars is slow and has bent back axles, it's ALWAYS this problem. I can turn one axle and guess, then turn the other and guess...but this leaves a lot of room for error and can take a long time and a lot of tinkering. Between the back wheels and the front, I'm puzzled about which to adjust to get the best results. I just end up guessing on both back axles until the car seems faster and I'm sure it won't ride the rail, but this is inexact and there has to be a better way, right?

Thanks in advance. This is the ONE thing I feel I can do better and really put together a fast car!

the best way is to not bend your rear axles..if you have a test track and want to waste a day tuning then you can try to bend them

 

["The Fonze"]

I know this is a question that may have already been answered in this forum, but I can't seem to find the exact solution I'm looking for.

Are you sure about that?

 

[Thinkin'Bout Racin]

I know this is a question that may have already been answered in this forum, but I can't seem to find the exact solution I'm looking for.

And of course the easy solution is DON'T bend the back axles, use a jig or buy a pre-drilled body with them already canted. But I don't own a jig and have no means to drill them, and a drilled body is usually not an option. I'm stuck with BSA blocks/slots. I can leave them straight, but when I DO bend them, my question is:

What is the best way to align the back wheels with bent axles? I have no trouble with the front, but think this is where I struggle most. I don't know any way to check them besides by eye. When one of my cars is slow and has bent back axles, it's ALWAYS this problem. I can turn one axle and guess, then turn the other and guess...but this leaves a lot of room for error and can take a long time and a lot of tinkering. Between the back wheels and the front, I'm puzzled about which to adjust to get the best results. I just end up guessing on both back axles until the car seems faster and I'm sure it won't ride the rail, but this is inexact and there has to be a better way, right?

Thanks in advance. This is the ONE thing I feel I can do better and really put together a fast car!

Look up lighting boys video on speed square testing of your alignment. While it is not a perfect answer, if you decide you want/need to bend axles, this is the best solution I have found. Build yourself a simple speed square testing station and be sure to test the car both forward and backward. You can get it really close, but anytime you take off a wheel, you will need to go thru this same set up again. Marking the axles will save some time, but you can't get them exact again without testing again. Also, make sure to have the car at the same attitude that it will be running at with the DFW installed. Otherwise, you will be setting the rear to have a toe-in or a toe-out condition.

At some point a good drill jig is worth it's weight in gold!!

 

["The Fonze"]

Hey TBR when are we gonna see you back on the track?

 

[HurriCrane Racing]

With bent axles, k-house grooves are a must. I would slow roll the car both forwards and backwards. I'm looking for both wheels to migrate out, in both directions. For me, the faster the better.

 

[Jimmy & his 2 Kids]

So I only share this for if you find yourself with axles that are bent and worrying about alignment. Before I found league racing and learned... I actually drilled the rears canted by hand and eye balled it. Of course this I will NEVER do again. But I got a good cant and they migrated out well. But I could tell they had bad toe. With ONLY the rear wheels installed and let the car roll down a smooth surface (tuning board now of course) and watched what it did. Without the front wheels on there affecting how it rolled and and on a good smooth surface bad alignment was easy to see...
The car would consistently react to the toe and go one way or the other. Added K grooves and slight bends to the axles and just turned the axles a smidge at a time until the car rolled on rears only straight. Then prayed to God they still migrated outward! But it worked, the car rolled well and we killed the field at the AGP.
But again this was only because I didn’t know any bettter.
But in short... k grooves and tuning mildly bent rears until the body with just rear wheels on it consistently rolled straight. Because if they are toed badly it will show and can be tuned out.
Lightnin Boys video showing a triangle with a pin on it would accomplish same thing as rolling it on a slope with only rear wheels installed.
Again... good drill, straight rear axles... none of these shenanigans should be nec other than K grooves for fine tuning for more speed since not many axles are perfectly straight anyways.

 

[bracketracer]

While nobody (myself included) on here would recommend running bent rear axles, there's another web site where they advocate such things. I thought the videos for this process were on youtube but I can't find them any more. These are the only pages I could find but the video links didn't work for me-
http://stanpope.net/camalignweight.htm or http://www.stanpope.net/camalign.php?rail=right

The TL,DL version is that you bias the weight on each rear wheel one at a time and tune until the thing rolls straight then add your bent front axle and tune for drift. Downside is that you have to repeat the procedure every time you remove a wheel so it might be ok for a scout car but for a league car it's a PITA. I did try it once on a league entry just to see how effective it was. I got to within .002 of my best car on straight axles so it's pretty close but the straight axle car is waaaaay easier to reprep.

 

[Thinkin'Bout Racin]

Hey TBR when are we gonna see you back on the track?

This is off topic, but I didn't want to ignore you. I have been real busy helping the Cubs and siblings. I have also been volunteering at school for the Lego Robotics club. My son's school (middle school) did real well this season. They had a 7th grade team that won the advanced long term challenge. This was against teams including senior high school students. They also had a team the was second in both the long term and the short term challenges. This was against only middle school kids. In all about 400 kids and 40+ teams competed. It is amazing how much the physics carries over to building robots! It is really fun to watch the kids "get it" both in Robotics and in PWD. When they start to finish my sentence for me ......I know they understand.

So all of that to say I am not sure when I will be racing again, but I do have one completely new car and another rebuild that are getting close of my own.

 

[derby freak]

Not running bent axles is definitely the easiest route but I do know one guy that used to run bent rears and if he's still active on any of the forums he would be a good one to talk to about it and that is a guy named ZZ racing

 

["The Fonze"]

This is off topic, but I didn't want to ignore you. I have been real busy helping the Cubs and siblings. I have also been volunteering at school for the Lego Robotics club. My son's school (middle school) did real well this season. They had a 7th grade team that won the advanced long term challenge. This was against teams including senior high school students. They also had a team the was second in both the long term and the short term challenges. This was against only middle school kids. In all about 400 kids and 40+ teams competed. It is amazing how much the physics carries over to building robots! It is really fun to watch the kids "get it" both in Robotics and in PWD. When they start to finish my sentence for me ......I know they understand.

So all of that to say I am not sure when I will be racing again, but I do have one completely new car and another rebuild that are getting close of my own.

With all of your PWD knowledge you should be able to put a car together in a few short hours. Everybody deserves me time. Don’t forget to take it.

 

[Thinkin'Bout Racin]

With all of your PWD knowledge you should be able to put a car together in a few short hours. Everybody deserves me time. Don’t forget to take it.

Thanks for the kind words and vote of confidence. I really do like help teaching the kids!

I am still painting my cars ...I need to move to vinyl....I know. The two cars that are close have been curing for about 8 weeks. But they do look really nice. Wheels are done. I just need to do axles and assembly. I have also been working on our track and am nearly done with that. Time will tell if they are worthy of shipping or not.

 

[DerbyDad4Hire]

Get a tuning board with a method of setting the car up the same every time. Put your bent axle in the front and 2 straight axles in the rear. Tune it to where you want it to steer. Once you get the steer set replace a rear straight axle with a bent one. Turn it til it hits the same spot you had it tuned to. Do the same thing with the other rear. It won't be perfect but at least you will eliminate as much of the rear steer as you can.

 

[DuckOfAllTrades]

Get a tuning board with a method of setting the car up the same every time. Put your bent axle in the front and 2 straight axles in the rear. Tune it to where you want it to steer. Once you get the steer set replace a rear straight axle with a bent one. Turn it til it hits the same spot you had it tuned to. Do the same thing with the other rear. It won't be perfect but at least you will eliminate as much of the rear steer as you can.

WOW! That never occurred to me! Perfect, thanks.