Bump Steer at Euro settings

[84toy]

My car is at Euro height settings. Looking under the car at the tie rods, they are not even close to being level. I have some turbo tie rod kits to install and will make a set of bump steer spacers to fix it. It does bump steer a lot. I've read here that the Euro settings are the "correct" height and does not require a bump steer kit, so I am curious if others have the same problem. It has stock wheels and tires.

[Chris79SC]

Euro ride height & 17" rims meant bump steer kit for me.

I have a '79SC and even with the rack spacers I'm still not too happy. I'm contemplating using the Weltmeister deluxe bump steer solution which I think is a modified rack.

From what I've learned "euro" isn't always the same as euro. Many US 911s are lowered to "euro" ridehight while actually being lower than a true euro 911. At least that's my impression from reading this board. Maybe your's is like that?

When I lowered my euro Carrera to something like Club Sport ride hight I needed a bump steer kit. Added Weltmeister spacers and voila, no bump steer

[Paul Franssen]

Er...thought this might be the right time ti ask: what exactly is "bump steer"??? thanks....!

Paul

When stock the tie rods are level. As you lower the car they are no longer level. This causes "bump steer" which can be felt through the steering wheel. To me it felt as if the front wheels tried to follow every little irregularity in the road surface.

I don't know exactly how to describe it You can feel it in the steering wheel.

[Silveresrty911S]

...and when you hit a bump the steering wheel trys to turn on it's own, kinda jerking it in one direction or the other from where your trying to steer it!
Is Euro ride height considered 25" rear and 25-1/2" front?

[Formerly Steve Wilkinson]

If "Euro ride height" means you have to be real careful not to hit the towhooks, I suspect it's lower than true Euro. At least that's the case with my '83 SC, which has 16" wheels and is lowered to what I "thought" was Euro height. Considerable bump steer, especially felt with a small Momo wheel, and I just ordered Pelican's steering-rack spacers.

To elaborate on what my friend Mikkel posted, if you don't dare let go of the steering wheel, you have bump steer.

Stephan

[ChrisBennet]

My car is (er was) lowered to something like 24.75 front, 24.25 rear (with tall 17" tires) and I didn't have a problem with bump steer. I bought rack spacers years ago but I never needed them. I wonder if you guys have your cars lowered much lower than that. Do you have short sidewall tires i.e. 40 series on 15" wheels?
-Chris

[ted]

Bump steer is the change in toe-in or out that occurs when the front suspension is either compressed or extended 1 inch either side of ride height.

If you can minimize the toe change during this range of travel your car will handle more predictably.

Saturday we found my car had 1 mm toe out at 1 inch below ride height and 2 mm at 1 inch above ride height. With some adjustments that was reduced from 1 mm toe change to .25 mm toe change through the 2 inches of travel.

When you disconnect your front torsion bar to mock up your suspension travel you may loose your corner balance. After you have reduced the bump steer you will need to recheck your front alignment.

My 911 has modified spindles, my bump steer solution would not apply to most cars.

[Zeke]

Think of 'bump steer' as a change in the direction of each front wheel due to suspension travel as stated above. If you are in a high speed corner and the car is moving up and down due to the road surface, you are getting steering movement that you are not doing with the wheel. If you are working the wheel sort of like steering the handlebars on a bike to keep balance, you don't need upredictable movement.

Can you imagine that bike where you are able to only generally guide the bike instead of precise control of the handlebars? Like a loose handle bar. That would be similar the bump steer phenominum.

[dickster]

here's a quote:

" Driving a car that has the correct bump steer curve makes the difference between a nice steering car and an excellent steering car; one that is predictable and controllable under hard braking as well as through bumpy turns. "

"Don't confuse steering wheel feedback with bump steer. Feedback is just that, the front wheels creating variable forces that the driver feels through the steering wheel - bump steer is a change in toe angles (settings) due to wheel travel."

i have also read that bump steer can make the car feel "darty".

[thabaer]

My stock '79 w/ factory 16s (7f,8r) was lowered in Germany by the PO, feels fantastic at all speeds. I run 205s up front with no problems even on warped pavement, you CAN feel the steering settle and shift when the surface changes the right(wrong?) way but it isn't radical enough to throw you.

[Wil Ferch]

You may want to try ( instead of rack spacers)...the ERP bump steer kit. Kinda spendy ( $350 or so)...but the ends of the steering arms ( closest to the ball joint) are raised/lowered to get the most neutral bump steer effect. Although pricey...it's truly the right way to go when you think about it. Rack spacers can't be more than about 12 or 13 mm thick. As long as you don't lower more than 12mm, you'd be OK with rack spacers. But... most of us would like to get lower than that, and if you want better steering control under these conditions, it's the ERP kit.
--- Wil Ferch

[Chuck Moreland]

Correctly set at Euro height, the car should have very little bump steer.

But what is Euro height? The oft quoted 25.5 front wheel arch, 25 rear wheel arch is not accurate. Those measures are dependent upon tire diameter and variations in body work that might run 1/2 inch or so. This is a blunt instrument that is suitable only for crude adjustment.

To properly set ride height, you need to follow factory procedures - eg. Measure the difference between tbar center and wheel center.

[Wil Ferch]

Chuck is correct...but I've found errors in the workshop manual that were never edited to correct these errors. As I recall, especially for the rear suspension...I could never get the A , B and C dimensions to make any logical sense......
---Wil Ferch