Stuck on alignment w/ railraider

[trappist]

Last night I finished my wife's car and my car. We rail ride with the left front wheel dominate so it steers right into the rail. We use the rail rider tool from Derby Worx. All our cars are 3 wheelers

On those two cars, I got really lucky and the rear wheels pretty much had perfect alignment - the wheels stayed on the axle heads going forwards and backwards. Only made small adjustments to get the right amount of steer to the right.

Then my son and I worked on his car. No matter what we do, the rear wheels will not move to the axle heads when rolling backwards. only when rolling forward. Since the car isn't going to race backward, should I really concern myself with this?

The biggest problem is no matter what we did, the car will not steer right. It will either go perfectly straight or steer left.

Do I need to put more bend in the axle? When we bend the axle, I don't really see a noticeable bend in it. Should I be? I've done it so that I can totally see the bend before, but when I've done that it left marks on the polished portion and the wheels developed a chatter that wasn't there before.

Any advice is appreciated.

[Murph]

Hi Trappist,
Interesting post. One thing that stood out was that your rear wheels stayed on the axle heads when moving forward. You should be in good shape.

With respect to getting the car to steer towards the center rail, put a tad more bend on the front DOM axle. Not too much or it will be hard to get the right drift (towards the center rail).
Give it a try and report back.

Thanks!
Murph

[trappist]

Thanks Murph.

I've seen where the wheels move to the outside only going forwards several times before in the past. They move in going backwards. In years past I've either managed to get it or just had to give up and live with it only working going forward. The cars I had to give up on didn't seem as fast, but I doubt that was the only factor, but who knows? I've always used 2.5 bend on the rears like the RR tool says.

I did end up putting more bend on the front axle and tried again. I made sure it was a solid 1.5 deg. No dice.

Then I tried a different axle thinking maybe something was wrong with it. No change, same bend in it.
So I went and added more bend to the original. No change. Only madness.

So I went and changed it to 2.5 deg bend. I could definitely see the bend. *Still* no change. About to pull my hair out. Boy getting very restless.

Then I added a single layer of masking tape to the RR tool and hammered again. FINALLY the car turned right. We tuned a bit and got the drift we wanted, about 3-4 inches over 4 & 1/2 ft, which has worked pretty well for us before.

Rear wheels look and sound good when the kid spins them with his finger.

Front wheel now makes a little bit of noise it didn't before. Not really bad chatter like I've had before, but I know 2 things: It isn't good and it happens when I apply bend to axles using the RR tool. I only slightly hear it when the car is rolling on the tuning board, not when spun with the finger.

We wanted to use minimal bend on axles this time, and it worked out on my wife's car and my car, but not the boy's car.

Should we really be able to see the bend in the axle or should it be pretty much un-noticeable?

[Murph]

"Noise" is not good. Here are a couple of areas to look at.

Make sure you did not pick up any debris on the wheel thread contact surfaces. Run you finger around the wheel where there is contact with the track.

Make sure your front DOM Wheel's inner hub is properly polished.

"Ever so slightly sand" the outer thread surface of the front DOM Wheel if it is suspect.

Thanks!
Murph

[*5 J's*]

To me it sounds like the axle hole for the DFW may not be drilled squarely. For example - if it was drilled such that it "leaned" back 1.5 degrees, and then you bent an axle at 1.5 degrees - the best you could do is steer straight. At a 2.5 degree bend the most you could get is 1 degree of steer - but that would be if you had none of the 2.5 degrees used for a positive cant.

We have had this issue in the past. If you have already sanded 1/16 or 1/8 off the DFW side of the car - it would be really hard to check. When we are done drilling and before we remove any material from the DFW side we insert a pin gauge (or you could use your drill bit) into the hole and use a small square to verify the axle holes are near perfectly perpendicular to the body.

As for the noise you picked up - yea, I would look at the things Murph suggested.