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Old 08-18-2009, 10:21 AM   #1
ra1337
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Default Loose Steering after 4wheel alignment on highway

Ok here's a some background info: Slapped on the Prodrive springs to replace the OEM ones. Rotated the tires (RE960AS PP) and one of the tires from the back had a radial pull so had to replace that one along with the other one in front. So the two front tires are brand new and the rear ones are a year old. Went to the alignment shop (Harold's frame shop in Novi) and here are my suspension settings:

Camber: LF,RF,LR,RR: -1 1/8, -1, -1, -7/8
Toe: 0 toe all around
Caster: 5 1/2 4 1/2

Talked with the mechanic and he said the above are in degrees..... although I am not sure since I see fractions and that usually means inches but anyways....

Here's the deal: The car is fine on street roads or anything below 70mph. As soon as I get on the freeway, the car seems to have loose steering feeling to it. It wasn't there before this new alignment spec, and I don't know the old one (might have been OEM) cause I bought the car 3 months ago. Is it because of not having any Toe? or is it something else? I was going to say steering rack bushings but it was fine before, very stable and taut. I have some theories but I am no expert so needed some insight. Thanks in advance.
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Old 08-18-2009, 10:29 AM   #2
Scooby921
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What exactly do you mean by loose? Is it dead/vague or is it suddenly following all the grooves in the road? Following grooves is a property of adding negative camber.


You free this evening? Come to the Novi meet and we'll go for a drive and try to figure it out.
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Old 08-18-2009, 10:33 AM   #3
ra1337
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Ok cool thank you! I will come to the meet today and we can figure this out. It's hard to describe this loose that I am talking about haha. It is as though I can move the steering wheel a degree or two and the car doesn't respond. It might be the dead/vague you mention but it's fine if I move it a tad above the couple degrees I mentioned. It's a pretty scary feeling for me on the freeway going 80mph because it doesn't feel as planted as before...
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Old 08-18-2009, 11:28 AM   #4
Scooby921
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Just thinking out loud...(or on keys)...

Changing the alignment wouldn't automatically make the rack bushings go bad. But they could have been bad before and the new alignment has made it more prominent. I think its more likely the tires you changed. While they are the same thing, they are now new/full tread depth. The added depth of the tread blocks means the tire will flex more under a given input before you notice a response...similar to the difference between a summer tire with a stiff sidewall and a winter tire with a soft sidewall. It could also be something as minor as air pressure. If you've increased or lowered the tire pressures you will change the contact patch with the ground and that affects grip, slip angle, and steering response.
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Old 08-18-2009, 11:55 AM   #5
ra1337
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Quote:
Originally Posted by Scooby921 View Post
Just thinking out loud...(or on keys)...

Changing the alignment wouldn't automatically make the rack bushings go bad. But they could have been bad before and the new alignment has made it more prominent. I think its more likely the tires you changed. While they are the same thing, they are now new/full tread depth. The added depth of the tread blocks means the tire will flex more under a given input before you notice a response...similar to the difference between a summer tire with a stiff sidewall and a winter tire with a soft sidewall. It could also be something as minor as air pressure. If you've increased or lowered the tire pressures you will change the contact patch with the ground and that affects grip, slip angle, and steering response.
Yea I'm thinking it's the tires too because the front two are brand new and the rear ones are older. Would the difference in tread be enough for the front to lift a little under higher speeds? The tire pressure is about 32 all around when I checked this morning when they were cold. Either way we will figure it out I'm sure at Gatsby's today. What time will you be getting there?

Last edited by Scooby921; 08-18-2009 at 12:09 PM. Reason: stupid edit button is in the way of my quote button
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Old 08-18-2009, 12:09 PM   #6
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Originally Posted by ra1337 View Post
Yea I'm thinking it's the tires too because the front two are brand new and the rear ones are older. Would the difference in tread be enough for the front to lift a little under higher speeds? The tire pressure is about 32 all around when I checked this morning when they were cold. Either way we will figure it out I'm sure at Gatsby's today. What time will you be getting there?
Tread wouldn't make it lift, but the air pressure would make it feel a little soft. I should be there by 5:30...I work all of 2 miles away.
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