Cascade Crew

blue89 · Posted: Fri Apr 25, 2008 1:28 pm Post subject: Spindle arm modifications

Tell me what you guys think of this. i'm basically thinking of cutting the steering arm of my spindle shorter and then using a heim joint and yoke setup.

Midwest Control

I have a pic hereThird gen picture found on this thread.

This will decrease my steering ratio making for quicker turns as well as modify my alignment on turn in. Does anyone have a reason why this will fall apart? I'm thinking that the heim joint won't like the side loads. The heim will be screwed lengthwise into the existing arm:

1) Shortening the arm and decreasing ratio
2) Since the arm is bowed inboard, this will move the tie rod pickup point outboard, affecting the ackermann.

Quasi-Traction · Posted: Fri Apr 25, 2008 2:06 pm Post subject:

heh.

I just got done reading the TGO post about changing over to a Rack and Pinion and saw the little sketch you did.

blue89 · Posted: Fri Apr 25, 2008 2:25 pm Post subject:

I'm pretty crafty with my MSPaint drawings....

What do you think, am I crazy? i think it will work. The yoke will prevent the heim joint from screwing out but I'm worried about the side load. Hopefully the 5/8" will take a bit before it bends.

Quasi-Traction · Posted: Fri Apr 25, 2008 4:34 pm Post subject:

is your goal to increase the turning radius, or to shorten the length you have to turn the wheel, lock to lock? or both?

I'm really not sure there's enough material on the spindle after shortening it to make it work. Would you weld a stud with threads to it and thread the yoke into it?

Sorry for being a little slow here. It just seems to me if something like this was achievable and holds or works successfully, it would have been done by now.

but I like your thinking... Wink

91RSVert · Posted: Fri Apr 25, 2008 5:46 pm Post subject:

What are you refuring to as "side load" on the heim?

If its what I think. That is how the spohn torque arm is designed on the front main point. And trust me, the past week I have put it thru hell Twisted Evil

Dewey316 · Posted: Fri Apr 25, 2008 6:37 pm Post subject:

the one thing I would worry about, is getting enough motion range out of the heim-joint, the side loading is not a **huge** since it really isn't a side load, you are just putting the mounting end in sheer, you aren't actualy side loading the joint.

I would be more interested to find out what it is you are trying to change. Really the steering setup isn't that bad on our cars, the bump-steer and ackerman, are pretty darn good for a stock car like ours.

--John

blue89 · Posted: Fri Apr 25, 2008 8:26 pm Post subject:

Sheer load was what i was considering the side load. I did a model in Solidworks that shows that the front end tows in on turn. I'd really like it to either not toe at all or toe out just a tad. Reason being is that I drive the car sideways enough that it would be nice to have less slip on the front tires. And the way that its setup it clearly has anti-ackerman. I'm going to set my castor at zero and try to do some measurements. That and fix the bump steer.

Dewey316 · Posted: Fri Apr 25, 2008 8:52 pm Post subject:

I wouldn't set your caster at 0*, that would be misserable to drive.

Is your only goal here, more ackerman effect?

Xophertony · Posted: Sat Apr 26, 2008 8:08 am Post subject:

iansane · Posted: Sat Apr 26, 2008 8:53 am Post subject:

Pulled from the thread on tg.o

blue89 · Posted: Mon Apr 28, 2008 7:54 am Post subject:

I talked to crazyhawaiian a while ago. He was the first person i've met that drifted an fbody regularly.

You can't really read it but I'll summarize for you. For the turning radius of our cars of 12 feet (24 foot diameter), the front wheels will have to be at 29* and 22*, with the latter being the outside wheel. And this does not account for tire slip angles. So adding another 4* or so and you'll get 33/22* (11* toe out) split of ackermann just to make the car turn at its best at full lock.

I then modeled the front end in solidworks and a static ride height and measured the angles. With the inside tire set at 33* (57.80) the outside is 32.08* (57.92) That is a toe-in of 1* at full lock. That is 0.42" of toe-in. I think that is a bit much and I'd like to change it. I've never heard of anyone doing it so i figured I'd try it out and see what happens.

I understand that it is a safety feature because it will introduce natural understeer in a panic situation. I for one do not like understeer one bit. So the idea here is to move the tie-rod pickup point on the steering arm to a location more to the outside of the car. Since the current spot is really close to the tire it will be hard to just move it in. The other alternative is to shorten the arm. Since the arm bends in, shortening it will also move the pickup point further out.

Does this help out at all?

blue89 · Posted: Mon Apr 28, 2008 8:06 am Post subject:

I just did some more measurements and the tie-rod will have to moved to 1.22" outside of the king pin at a 5" steering arm for perfect ackermann. I probably won't get that, but we'll see. Having unequal length pitman to steering arm lengths will probably exaggerate the antiackermann effect enough that it will null my attemps to correct it.

Dewey316 · Posted: Mon Apr 28, 2008 8:10 am Post subject:

Are you accounting for body roll in your calculations? Under body roll, the outside tire toes out, and the inside tire toes in (in theory, less than the outside tires toe out), that is part the the geometry set up in our cars.

Making the tie rod longer, makes your roll induced ackerman less, if you you really want to increase ackerman in the way the car actualy moves, you would actualy want to shorted the tie-rod.

--John

blue89 · Posted: Mon Apr 28, 2008 8:59 am Post subject:

Steering changes on body roll would be bump steer? If the tie rod was any different in length than the king pin to k-member length then you will get body roll induced steering changes. I would then think that if the lengths were the same and parrallel to each other then you would have no changes. Isn't that the basis of bump steer corrections?

The way that I use the car I have minimum body roll at full lock. It will have to be examined when I get the desired goals to see what the side effects will be.

blue89 · Posted: Mon Apr 28, 2008 11:59 am Post subject:

I just found that I can get 2* of toe out if I make a custom center link that is 3" shorter overall. So I might make one of those and see. It would be way safer than cutting the spindles. It will make the outside arm swing forward oddly if run past the steering stops. Also the pitman/idle arms will be pointed towards each other a little.

91RSVert · Posted: Mon Apr 28, 2008 6:28 pm Post subject:

So you take the 3" out between the two sets of tierods?

Try measuring one off your old school s10 and see what it is. they are narrower then camaros and have extreamly similar steering.

blue89 · Posted: Mon Apr 28, 2008 8:53 pm Post subject:

ya, a shorter center link will change alot weither for the good or bad. Might be fun. I think the s10's have a shorter pitman/idler arms too. If you can take a look for me that would be great.

91RSVert · Posted: Tue Apr 29, 2008 4:02 am Post subject:

blue89 · Posted: Tue Apr 29, 2008 7:30 am Post subject:

Thats okay, I know where I can find one. i would imagine it would be shorter because the frame on the s10 should be narrower. I thought the arms were shorter though. Does anyone know if the steering box has internal stops?

blue89 · Posted: Wed May 07, 2008 11:23 am Post subject:

I found a guy here at work with an s10. Turns out that the S10 center link is 19" (camaro 23") and is 9" between tie rod's (camaro 15"). So this will give me a little more ackermann than i was minimally hoping for (good thing!). All I need are tie rods that are a little longer. No biggie, i'll buy some longer solid tie rod sleeves and I should be set! I just hope all the tapered bolts are the same thickness.