Do I need a bump steer kit?
 

I've got my front suspension components out of the car, and a turbo tie rod kit on the way. Concerning bump steer, I see from searching past posts that it's recommended to install the kit if you're going lower than Euro ride height. So, what if I'm right at Euro height - should I install it anyway? Will there be any negative effects of installing it when I don't really need it?

I tend to want to install this kit because it's very cheap, and now's the time to do it with the whole front end laying on the garage floor. Let me know what you think.

Always a good idea....I actually anticipated a need and the previous owner had done it....

The kit is sitting in my tool box. I'm pretty sure I'll use it....

I lowered my SC to approximately Euro ride height. (not sure exactly what the setting is, my mechanic did the final adjustment). He told me not to put on the bump steer kit (he said there is a lot of misinformation on the internet), so I didn't. I don't notice any problem.

Bump steer is good if you are LOW and have excess response in the steering from mionor bumps in the road....not for everyone....

Maybe, maybe not noticeable. When lowered outside of factory specs, the tie rod angles, relative to the vehicle height, can cause excessive toe-in/out changes as the vehicle height changes during suspension compression/expansion. This results in abnormal handling characteristics, especially when cornering at speed.

The $10 kits are basic stabs at reestablishing the same geometry when at factory height. Since the cost is minimal, I suggest doing it. Don't forget to first loosen, then retighten the steering shaft u-joint connection so there's no binding when adding spacers (raising) to the steering rack.

For serious attempts to minimize bump steer (e.g. track car), one needs a dial indicator, a work plan and new tie rod/modified strut hardware. There are various ways to accomplish this. Fred Puhns, "How to Make Your Car Handle" is one reference source for the work plan. ERP, ER, Smart Products and other Porsche-specific sources can provide the hardware, many via Pelican's catalog.

Hope this helps,
Sherwood

Seems to me ,that we are assuming that there will only be two positions for the rack height---no spacers per original. Or the kit size spacers[whatever that is]
for any ride hight lower than standard.
Surely there would be an optimum spacer thickness for each ride height?
Wouldnt be hard to try some spacers of various thicknesses,as trial and error?
[Flames expected ,as usual]

That's why the ERP kit was developed. You can fine tue the steering arm geometry w/ these kits. Good for use w/ stock/altered rack height and stock/altered spinle height

Bob,
Whichever compensating hardware is used, the method to confirm/measure typically uses a dial indicator or equivalent to track toe change while the suspension rises and falls relative to the static ride height. One method attaches a flat plate in place of the wheel as a measuring surface for the indicator and removing the torsion bar so the suspension can be easily moved throughout its travel. It's a mandatory procedure for a well-prepped track car. For a street car, the usual hardware choices get you in the ballpark.

Sherwood

simple test = parallelism check

see BV's comments last week w/ diagram

Dave,

I've had my 1983 911SC lowered to European height (25" at the wheeel arch) for 25 years, have tracked almost every track in the east, most of the best in the Midwest, and Willow Springs, Laguna Seca, Las Vegas, etc, in the West and have NEVER felt a need for the bump steer "fix". My car does not wander when it hits a bump, and I don't know what all the fuss is about.

I'd be willing to bet that no European car delivered in Europe has such a spacer either.

But if you have the spacers and bolts, and want to use them, there's no harm done. You just won't feel any difference in daily driving, and none on the track.

Why make it more complicated than it is?

that brings us to the problem of what is european height. It is not measured at the fenders by the factory. It is measured by subtracting the wheel center height and the torsion bar center height.

You are correct that at RoW height no bump steer kit is needed, but there are many of us that run lower than that. The thing that you want to aim for is horizontal steering arms at static loaded height. IF the steering arms are angled up or down it leads to excess toe change w/ suspension travel(aka bump steer). Will you feel it? that depends on a lot of other things, one is if you run a lot of toe anyway(most street alignment does) then a little more or less will not have a big impact on you, but if your alignment spec is at or near zero, as on many tracked cars then the impact is magified.

Bill, as usual, is correct. My "European height" (to go with my European birth?), yields the steering arms being almost perfectly level. Thus, I guess I've never thought I had a problem.

So Dave, try the empirical approach. Install the stock tie rods. Drive the car for a while, and then install the Turbo tie rods. And drive the car for a while. And note if there's any difference. Your car, your ride height, your car weight, your suspension components all differ from other people's (remember, our cars were mostly hand-built back in the day before Dr. Wiedekind). My car's left side is slightly different than the right side, but I've compnesated by corner and weight balancing, and other little tricks for the track.

Experimentation is the life-blood of the scientist.

How else are you going to spend your weekends, but with a Porsche, and a great cigar after you've done the work, and sit back to admire your handicraft.

That reminds me...I forgot to order the cigars.

Thanks for the advice guys. I haven't bought the kit yet, and it's easy enough to install later without taking anything else apart. So I think I'll put the car back together and assess the tie rod angle after settling on a final ride height.

I used the adjustable bump steer kit from elephant racing. It made a huge difference in the ride. I'm at about euro height on my Targa. Before the kit the steering enjoyed every groove on the road after the kit it feels almost like stock height. Not a cheap kit but well worth the dollars.

I put a bump steer kit on my 1974 Porsche 914 and i get this nasty clicking noise when i turn. I heard some people say it will go away but doesn't seem right. Any ideas?

rderow, post a pic taken from directly in front of the car at the same ht. as the suspension that shows the arms & tie rods

Does the clicking sound coincide with tire rotation or steering wheel rotation?

S

Good call, Sherwood

My car is lowered and I have the bump steer spacers on the steering rack. Thinking I had a bump steer problem, I installed one of the sophisticated kits. As I changed something else in the process, I spent a month trying to chase down the horrible handling that resulted. Pulling the bump steer kit (not the spacers) fixed everything. I'd say don't waste your time or money. Unless your car is a dedicated track machine lowered way more than the couple of inches most of us do, a few hundred dollars for a bump steer kit will get you the worst handling car you've ever had! If you do a search here or on the racing thread, I don't remember which, you can read my pathetic story from beginning to end.

I don't see a need for a bump steer kit. If you get terrible kickback, its probably because you're running out of jounce travel - the common 25" fender height "euro height" doesn't leave all that much jounce travel - and the best solution to that is to raise the car up a bit or to stiffen your tbars, or better yet, raise your spindles.

OTOH, if you can fit the spacers (I actually cannot - my rack goes up 6mm max for whatever reason), they aren't going to harm anything either.