bump steer

74914 · 11-08-2002, 05:19 AM

Read some posts recently about front end lowering. I'm aware of the bump steer that can come with lowering, and the spacers offered to compensate. Question (multi-part): is the amount that one lowers the car the same as the amount of compensation needed, ie. lower 1/2", space 1/2". It seems that the spacers comes in one size. Does this compensate for a wide range of lowering, or only minimum lowering. Could it be that one needs double spacing on a car that's had alot of lowering? In general, how much can one lower the front before you run into bump steer again after already using spacers.
Thanks
Ed

Jeroen · 11-08-2002, 06:50 AM

You can't keep raising the steeringrack infinatly. You'll run out of space because the chassis is in the way.
So these spacers are close to the max you can move it up.

There are other solutions, but these are not as simple or cheap...

Not simple: You can bend the knuckles on the strut, to compensate bumpsteer.
This is mostly done when the spindle is raised (like RSR struts)

Not cheap: SmartRacing has developed special tie-rod ends that function as a spacer between the strut-knuckle and the tie-rod
IIRC these are adjustable

HTH,

Jeroen

bludden · bludden's Garage

Last weekend, while I was swearing-err working on my brakes, I decided to put in these spacers. But after getting the original bolts off and putting the spacers in place, I found that I could not get the bolts to start, due to either the changed angle of the rack or perhaps bacause the bottom threads are not good anymore??

Anyways, I put it back together and everything worked. So at least I didn't break a functioning piece!

Anyone else have problems getting the bolts to start after using these spacers?

Zeke · 11-08-2002, 09:20 AM

You should have gotten longer bolts as part of the kit. Be very carefull starting those bolts, they cross thread real easy.

bludden · bludden's Garage

The bolts with the kit were black, but they were the same size as the ones currently on the car. I was thinking the same thing myself though...wierd.

Brad Roberts · 11-08-2002, 08:53 PM

Ed,

You have figured out what many 914 racers before you have figured out. The kit you buy for bumpsteer is only good for a certain ride height of the car.

The proper way to adjust bump is to use a bump gauge and to use "shims" until the bump is correct. The ones sold get it close, but its never completely correct. We can spend 3-4 hours setting bump correctly (bounce car and take measurement, add or remove shims under rack as needed) We now use the SmartCamber method and adjust bump at the strut (much easier than unbolting the rack every time until you get the proper shims in place)

B