Rack and Pinion placement

Edited: 8/2/2008 2:11:05 AM by JDugan4859

Basically building a frame up truck, and have a question on the placement of the rack and pinion. I have it set up so that if you drew a line from toe rod mount to tie rod mount, the R&P would fall in that line. Doing this I only get about 1/164" of an inch of toe in/out when traveling the suspension (doing this all in CAD).

The problem is that I need to move the R&P forward in order to clear the motor and the bag. I can't grasp my veable 2d mind around what is going to happen pushing it forward. I looks like I need to move it forward 9-1/2" to clear everything, but can do some redesign if need be. Trying to build this right the first time.

Also, I do have everything set so that the angle of the tie rod meets up with instant center of the upper and lower arm, thats how I get the 1/164" toe.

wow 9.5" from being straight? thats a pretty big jump, id try to move some other things around to try to get it straighter. i think the biggest problem may be the fact that when you turn the wheel, the tires may come over and hit the tie rods very early, but you basically dont want them hitting the tie rods at all.

What is your reason for having to move it up 9.5"? What is it that you have to clear and can you move some of those things around? If you have pics that might help. I'm doing my r&p install on my frame build right now so maybe with more info I can help.

Edited: 8/2/2008 3:57:52 PM by JDugan4859

We are going to run an RE8 up front, so I have an 8" bag. I would have to move it forward already to clear the bag, and have o move it even futher forward to clear the bracket that is going to hold the control arms. The straight line is coming right off the spindle mount, the angled line is where it will need to be.

Quickpost this image to Myspace, Digg, Facebook, and others!

note that on the tie rods, the part that swivels, (excuse me for not knowing the proper term) needs to be in a line drawn from the upper control arm bushing to the lower arm bushings looking from the front.

if the swiveling parts of the rack are wider or narrower than the lines mentioned above, your toe will change as you go up or down.

the rack can only be mounted within a certain area to keep proper steering throughout your travel. moving the rack that far forward can cause alot of clearance issues when turned. you would bind before lock and/or have tire contact issues before lock as well.

what are you basing the suspension on? some known setup or measurements or are you going from sratch?

Jon, can you give the vehicle info and possibly pics of it? I understand your CAD drawing but sometimes need to see the actual thing. Do you have the arms and spindle mounted that you can take a pic of?

Edited: 8/2/2008 4:47:20 PM by JDugan4859

Edited: 8/2/2008 4:45:39 PM by JDugan4859

Started by looking at the 03ish Full Size Chevys, things have been tweaked to improve camber and fit the frame width.

If I am doing things right, the wheel will hit the frame before it hits the tierod, but I could be wrong. We are doing all the design work before we start on this.

Some of this I am doing from home, and when I was going over my notes I thought the tierod mount was 3-1/2" forward of the spindle mount, called the shop to double check that, and it turns out it is 5-3/4" forward, so I will only need to move the R&P forward 5-1/2", looking more like this.

Quickpost this image to Myspace, Digg, Facebook, and others!

Could I build a tab that would move my mount location forward off the spindle, I would only need to go forward about 3-3/4" to clear everything that way.

Originally posted by BankruptRam



Jon, can you give the vehicle info and possibly pics of it? I understand your CAD drawing but sometimes need to see the actual thing. Do you have the arms and spindle mounted that you can take a pic of?



This is on a 2002 F150, with a manderal bent frame. No pictures yet, we are doing all the layout before we start cutting. We are a couple weeks away from making anything anyways as we ordered uniballs from BL and they are 3 weeks out, so we have time to move things, and we have to send the arms off to be cut since we can't cut 1/2" and want it more accurate than the plasmacam can do.

yes, running larger wheels you can get away with that. Id like to see some of the drawings. I have a "how to design hotrod suspension" book by Boyd Coddington I use for refrence.

Jon I think I know you.

Originally posted by stumbledin

Jon I think I know you.

Where you from? O use to be in DO, ran the Dallas chapter for several years. Hang out alot in NW Arkansas, and know alot of guys out in MS, Keef and all them.

sent u an IM