Coleroad

The problem being discussed here is bump steer. The suspension geometry for the sc430 has to much bump steer. In this case it is caused by to much angle of the tie rods in relation to the plane of the lower ball joints. This causes toe out the toe in going over a bump. This is what you feel in the steering wheel, the tires changing directions.changeing to poly or solid bushings hold the suspension in place better. It is though not getting rid of the bump steer. It is reducing other movements caused by the bump steer. An adjustable outer tie.rod kit is the only way available to reduce bump steer. The kit uses shims to change the angle of the tie rod. When lowering the car bump steer is increased on the sc430 unless steps are taken to reduce it. For you 4x4 people, lifting the truck cause this problem too. If you have ever driven one that was lifted, and the steering geometry wasn't addressed. You have see an extreme example of this already. So much so you can get what has been called the death wobble.

Coleroad

This is the type of outer tie rod I'm referring to.
http://www.stage3motorsports.com/***..._kit_1_med.jpg

Coleroad

A video explaining bump steer for those that are more visual.

Poqman

No, but the rack does not have the movement the other bushings do. That may explain why it hasn't squeaked and I did not grease mine.

Poqman

Good input. It has a name

riknchar

Yep, that seems to describe my problem perfectly. Never knew there was an actual term for it, though. My car only has 45K miles on it, and the front suspension seems super clean and not worn, but I definitely have the wiggle you describe when I hit bumps.

So did the SC front suspension change between 2002 and the later (post 2006) models? I really never had that sensation in my 2006 or 2009 SC, but I have felt the same thing in other used 2002's I've test driven.

I do think the easiest and cheapest starting point is to put new Daizen Steering Rack bushings in. That may do enough to make me satisfied with the ride. Good to hear that others haven't heard any squeaks from their Poly Steering Rack bushings...

I'll let everyone know how much improvement I get with the new bushings. Thanks!

Coleroad

I have poly bushes in my BMW. I don't have squeaks from them either. Grease and clean parts i haven't had a problem been four years now.

Coleroad

I have poly rear subframe and differential bushes. Veverything up front except the tension strut (aka caster control arm on the sc). That one is a aluminum monoball bush.

When reading reviews keep in mind a poly bush is not a given hardness. Poly bushes vary in hardness. A durometer is used to tell you how hard it is. So when comparing, compare apples to apples. A rubber bush can be just as hard as some poly bushes are. The ones in my BMW are 75 or 90 on the durometer, depending on which ones we are talking about. It's important to note what the rating is.

Coleroad

I don't see anywhere on figs or dazian's site where they give the durometer a rating. Who knows how close they are to each other. If they read this it would be nice to know. That maybe the difference in price or may not be, between the two.

JakeinCali

I just bought a 2004 SC430 with 18,000 miles on it. One of the issues that I am trying to get sorted is there is a lot of bump steer. What is the best solution for this?

I have heard of replacing steering rack bushings and adjustable outer tie rod. Is there a preference on the steering rack bushings, OEM or a particular brand/type? Is there a recommendation on tie rods? Do I need to replace both inner and outer?

Also, I have run flat tires on there. Could these abominations be affecting it?

riknchar

I never did overcome the bump-steer issue on my 2002, and ended up trading it in on a super-low mileage 2006 4 years ago. My 2006 now has 23k miles, and rides completely smoothly, with no wobble or bump-steer from the front end. I really don't know what caused it on my 2002, but it was very aggravating and ultimately made me want to upgrade to the 2006 model.

GmanSC

I have 07SC with run-flats and I don’t have bump-steer. Wonder that would be the flaw on the pre 06 models?