? for Chuck (bump steer kit)

[armandodiaz]

Chuck:
I just finished installing the new bump steer kit. I'm just wondering if this is as low as it goes, or am I missing something. I have all the spacers on the bottom of the knuckle. The front fender lower lip is @ 23.25in. I did remove the rack spacers but I thinking of putting them back in.



It's hard to tell from the picture, but the rack is sitting lower than the outer tie rod.

[Chuck Moreland]

Hi Armando

Unless you have raised spindles, with a wheel arch height of 23.25 (very low) the rack will be lower than the rod end.

The goal is not to make the tie rod horizontal (common misconception).

The quick-and-dirty objective is to make the tie rod and control arm parrallel. Your control arms angle up, so too should your tie rods.

A more precise height adjust can be made by measuring the bump steer.

[Chuck Moreland]

As an aside, if you are not running raised spindles, I would recommend against such a low ride height. You have very little suspension travel and hitting the bump stops is likely, causing unpredictable spring rates and handling.

The severe angle on the control arm messes up the geometry, lowering your roll-center causing more body roll in turns, and reducing camber gain.

[armandodiaz]

Originally posted by Chuck Moreland

The goal is not to make the tie rod horizontal (common misconception).

The quick-and-dirty objective is to make the tie rod and control arm parrallel. Your control arms angle up, so too should your tie rods.

Your right, I thought the tie rods had to be horizontal. I'll double check and compare tie rod to A-Arm. For now, I'm just trying to get it close as I will be taking it to get corner balanced once in a few months.

Thanks for the help

[armandodiaz]

I didn't think it was too low. As I understand it, ROW height is 24" frt and 24.5"rear.
I have 23.25" frt and 23.75" rear. Here's a pic:

[Jeff Alton]

The ROW height is more like 25/25.5 so your numbers are a little low....

I run my car (aggressive track setup) at about 24.75R and 25F. However I have seen pics of lots of cars that are waaaaay lower...
My 935 style suff has raised inner pick up points as well and I do run with raised spindles.

Jeff

[Chuck Moreland]

Measuring wheel arch height is not accurate because tire diameters vary (with tire type, size and wear), affecting measured height. Also there is variation in the body work.

More accurate is to measure the angle on the control arms/spring plates:



Better way is to measure the difference between torsion bar center and wheel center. Bentley calls out front difference at 108mm (hub higher than tbar), rear difference at 16mm (hub lower than tbar). I believe these are US ride heights, euro is about an inch lower.

The front should measure about 1/2 inch higher at the arch than the rear (neglecting body and tire variations as above). This yields a 1% rake.

Generally accetped ROW spec is 25.5 front, 25 rear. In reality this is lower than the factory shipped the ROW cars.

So unless you have very small diameter tires (doesn't look like it), 23.25 is very low.

[armandodiaz]

I used the fender lip as a starting point then measured from the ground to the lower part of the torsion bar cap (3") and used the same measurement for the other side. Like I said I'm just trying to get it close until I can take it in for a corner balance.

I'm going to start by leveling one of my control arms, measure, then match the other side. Then add 1" to the rear. This should get me close, without getting me into trouble.

[armandodiaz]

Final #s
After reading a few other post, I went with 24.5" frt and 24" rear. For whatever reason I thought the rear was supposed to be higher. Don't ask me why, I guess I had a brain fart.
Everything looks pretty level now. I can't raise the spindles, that will throw me in another class. I'm sure the corner balance will tweek it a little more.

Thanks all.

[Brother]

Damn. I just went and measured my ride heights. 25.25" up front and 23.5" in the back.

How much adjustment do you get out of the adjustable springplates, or am I looking at reindexing torsion bars here?

[armandodiaz]

I've never worked with the factory spring plates, but as I understand it, they're adjustable if you wish to raise the car not lower it. If the rear is at 23.5 then I think someone already reindexed them.