Bump steer

[fredswain]

It has been so long since I've had a short front arm RC10 that I can't remember how to get rid of bump steer on it. For all I know I had it as a kid but didn't know it was bad. I am rebuilding the car I had as a kid and want it to be as good as it can be within the limitations of the parts I had back then but I'd prefer no bump steer. I have the 15* caster blocks on the front with inline steering. I've tried the Losi aluminum bell cranks and the A&L steering. It still has it. What is the solution that gets rid of it? Is it something custom made? Was there a solution?

[fredswain]

Wow I found a question that can't be answered here. I didn't think there was one!

[scr8p]

It can be adjusted by raising or lowering the steering tie rods on the bellcrank and/or knuckle.

[Coelacanth]

I took care of bump steer issues with a buddy's AYK Buffalo and my Barney Optima that has a highly customized front end. The following links may be helpful; not to mention scr8p pretty much identified what you need to specifically look at.

http://www.rc10talk.com/viewtopic.php?f=40&t=24393&start=12

http://www.rc10talk.com/viewtopic.php?f=30&t=21530&start=108

[fredswain]

I've tried playing with the end heights. That's the first thing that I tried. No luck. The wheels start out straight and then as the suspension compresses the wheels will ultimately turn inwards but instead of it being uniform as the wheel goes up, they toe outwards in the middle of the range and then back in sharply at each extreme. I've tried raising the inside, raising the outside, lowering the outside, different bell crank styles, etc. I'm at a loss for a solution but I do have a couple of far fetched ideas to play with yet.

Oops, I just noticed that I didn't mention that this is with the wide front end graphite chassis. I would think that whatever would work on the standard nose would work on the wide provided that I widened the spacing between the bell cranks to match but playing around on a standard nose I still can't get rid of it.

[Coelacanth]

Wow I found a question that can't be answered here. I didn't think there was one!

Actually, you could've just searched for "bump steer" and you would've hit on my links and many others.

[Coelacanth]

Upload a few pics showing your tie rods & steering geometry, that might help people provide some suggestions.

[Jay Dub]

If memory serves, the bellcranks weren't widened as the suspension mounts were, correct? If this is the case, you will only ever have a compromise, because of the length descrepency between the tie rods for steering (they got longer right), and the length of the arms (they stayed short right). You will have the "toe iin/toe out" effect perminentally. -Jeff

[fredswain]

No they weren't widened. I thought they should be. Tonight I installed the A&L bell cranks which is done like the JRX2 bell cranks. The advantage to them in this scenario is that I can make a new cross bar that is wider to match. I used a scrap piece of carbon fiber to do just that tonight and it works out very well. My new problem is that the camber link ends on the shock tower and steering link ends now hit each other. I am using Dubro heavy duty rod ends which are larger than the ball cups. I need to get some button head screws and run them through the link end before the tower so I get some room back. I need to do the same on the bell crank. I am going to make another cross bar that moves the mounting point rearward 1/8" to allow it to completely clear. This should take care of all of my issues. This is probably a part of why my car never handled well as a kid!

[Coelacanth]

My buddy with the Buffalo I linked to above told me, "I need to put on rear wheels & tires or tires with big spikes on the front, because it can't steer for crap!" It wasn't until I was rebuilding it that I discovered the awful toe-out bump steer.

[fredswain]

All I remember is that I had to drive point and shoot with that old car and tire selection was very critical. When I got the JRX2 I was much faster around the track. I couldn't understand why other people had RC10's that were so much easier to drive. I never had good luck with that car. It will be interesting to drive another one just like it again but with the steering fixed and the car tuned based on what I know now. It will still have it's deficiencies of course but I'd at least like to know what it's potential was.