Bump Steer Kit

[AirCooledExcellence]

Hi All,

I'm considering fitting a bump steer kit to my car. It's been lowered and it looks like the rack needs to come up about half an inch before it's at the same height as the turbo tie rods.

My question to you guys is; will fitting the kit make much of a difference to my steering? At present my steering seems to be very sensitive to every bump or dip in the road.

Cheers,

Tim.
____________
1983 SC Targa

[BER]

Tim,

The answer to your question is a function of how much you lowered your front end and how thick the bump steer washer is.

I dropped my front end ('84 911) to 24.5" (floor to top of wheel arch). This produced bump steer. I installed the Weltmeister Bump Steer Kit (approx. 1/2" thick spacer) and that eliminated all bump steer.

Hope this helps.

Regards, Bruce

[Jdub]

Bruce:

So if the car was lowered on the front end to 25" or higher is the bump steer kit not required?

Reason I ask is that I will be performing a suspension rebuild and will pull the steering rack for a relube. Seems a good time to put in a bump steer kit, but I do not intend to lower my car to Euro spec but instead something between US and Euro. This would *seem* to mean I do not need the kit but it is one of those "As long as I'm in there" things.

Would putting a bump steer kit in a car that doesn't need it be good insurance should I or a future owner decide to slam the car? Would it hurt if it is not needed?

Thanks much in advance,
John

[surflvr911sc]

I just lowered my car in the past week and I installed the WM bump steer kit (10mm spacers) at the same time. The front sits at 25 1/4" after corner balancing and the steering feels great. I did not drive it before the kit was installed so I do not know if there would have been a bump steer problem if I hadn't but it was really easy and everything feels good. I have stock tie rods and plan on installing turbos so if should only get better. If it feels sensitive and jerky on bumps now, I think you should do it.

[BER]

John,

First, I do not profess to be a Porsche suspension expert. The purpose of the bump steer washers are to raise the steering rack in order to re-level the steering geometery.

At 25", you are "on the cusp" so to speak. I know some guys that have set their ride height to 25" and claim they do not have bump steer (no bump steer washers installed). I have heard other 911 owners say they installed a Bump Steer washer at a 25" ride height. Remember, height (measured floor to top of wheel well) is also a function of wheel/tire diameters.

You say you will be lowering your car to between US and Euro height. I would think you will not need the washers installed.

I would suggest that you do your suspension work and lower the car to the desired height. Then drive it and see if you encounter bump steer. If you do, then install the washers. They are not a big job; I installed the washers on my '84 911 in under an hour.

Regards, Bruce

[jwill911]

I have to be honest, I'm not sure my `87 Carrera has the bump steer washers installed. From the amount of bump steer I experience I'd say no. My car is ~25" to front fender lip. If they aren't there I'd like to install them to see the difference.

Question: Does installing the washers affect the alignment? I would think repositioning the steering rack any at all would either move the toe one way or the other.

TIA for any clarification,
John
`87 Carrera Coupe

[island911]

yep, it will toe it in. not much though, sine of small angles is ~zero. (and there is where engineers and mathemations part company)
edit: You may want to re-align, though. As the suspension moves, the angle can become large, having started from a less than optimal position.

[Vipergrün]

I am trying to figure out the geometry of this stuff in my head w/o looking at the car. Is it any coincidence that the bump-steer kit uses a 10mm spacer to raise the rack and there is a 10mm spacer we are suppose to remove from the top of the strut when lowering the cars? I guess I am wondering if removing the spacer on top of the strut has the same effect as adding the spacer under the rack. Or does removing that spacer make the problem worse? Just thinking out loud...

-Brad
80SC

[pbs911]

I Is it any coincidence that the bump-steer kit uses a 10mm spacer to raise the rack and there is a 10mm spacer we are suppose to remove from the top of the strut when lowering the cars?

I belive the shock spacer is to keep the shock working through an optimum range of movement. When you lower the car, and not remove the spacer the shock will bottom out.

I just plunked down what seems to be $$ on the drop link bump steer kit. The only feedback I have been able to get on this second means of bump steer is from Jack O. Hopefully I will have something to add in the next week when it is installed and my bump steer eliminated to the fullest extent.

I did notice that the 935 (?) tie rod as depicted in BA's Handbook had the same drop link style of tie rod specifically to tun bump steer. So I feel comfident that the idea works. How well only time will tell.

[Ove]

I believe the strut spacers exist only to maintain the suspention geometry (shock travel) after the front end of the car is raised to meet US bumper height regulations. As far as I know the spacers were not installed on any Euro-spec. 911.
I like to think of them as part of a factory lift-kit


If you are lowering from factory US height to factory Euro height, you will not need steering rack spacers.

I lowered my car a month ago, 2" down to 24,5" and really noticed the difference in bump steer. (Some of) this could be due to lack of alignment after I lowered it. I just got the steering rack spacers today, and turbo tie rods are on their way. Then I will get the suspension aligned to make sure everything is right.
I was considering the drop link bump steer kit, but it looks like few people use it (because of the price(?)). Sounds like a good way of addressing the problem though, please let us know how it works for you, Paul.

[KTL]

Anybody have any interference problems when installing the spacers? When I reinstalled my rack and put the spacers in place, the body of the steering rack presses quite firmly against the fuel lines . I did not like the idea of this so I decided against installing the spacers. Probably doesn't matter as the consensus says I don't need them. My height is at 25 1/4 in., floor to fender opening meas'd at wheel center with 16in. 205/55 tires.

Thanks,