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Discussion Starter #1
Between 65-80 theres a small noticable vibration in the ride but doesnt overly affect the ride quality... but once I hit around 85, the whole car shakes. Not violently, but enough to know somethings not right and is quite irritating. The weird thing is, if I play with the RPMs alittle bit, it will completely smooth itself out and ride beautifully for a few seconds, and then work itself back into a nice little shake. The steering wheel goes nuts and I can feel it through my drivers seat too. I have a stock drive shaft, tranny and engine for the most part. Only upgrades I have are springs and shocks (and rims, which have been balanced). Any ideas? :confused:
 

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Could also be worn IRS mounts.
 

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When was the last time you had your tires rotated and balanced? That might have something to do with it. Its either that, or possibly your driveshaft balance is off.
 

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Discussion Starter #8
Smoothes out gradually when I let off the gas, then smoothes out more when I decel under 80MPH. Plus Im not sure if its related, but when I go over bumps, something (in the suspension) sounds like its moving (clunks). But when I check all the nuts and bolts, everythings tight. I cannot tell if the shaking is coming from the front or the rear of the car though. Tires should be balanced, but I can probably get them done again.
 

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Gen,

Sounds like you got a bad bushing in the suspension. Do you ever feel one of the front tires dragging when you back up with the wheel turned tight to lock and coming of a "hump"? Then I'd have your strut rod bushings checked. If they need replacing, go with the urethane bushings.
 

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Discussion Starter #10
PCD said:
Gen,

Sounds like you got a bad bushing in the suspension. Do you ever feel one of the front tires dragging when you back up with the wheel turned tight to lock and coming of a "hump"? Then I'd have your strut rod bushings checked. If they need replacing, go with the urethane bushings.
Never really had a situation like that. And all the strut stuff was replaced when I did my Tokico's... so... guess Ill have to crawl under there and see if I can see any torn bushings.
 

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You may or may not know this already, but a "strut rod bushing" isn't exactly associated with the shocks or struts. The "strut rod" is a brace that goes from the lower control arm to the subframe in the front of the car. The bushings on that rod are what PCD referred to.

It sounds more to me like a drivetrain or wheel imbalance than a suspension issue.
 

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Here is another possibility...

Depending on what kind of rims you have they may need hubcentric rings for the MN12 application.. Check with the manufacturer and then check to see if they are there ... if you are supposed to have them and don't have them, get them and put them in.

Hubcentricity: A wheel that is mounted on a vehicle, should be hubcentric, to assure proper fit, and hence will eliminate such issues as vibration, shimmy, and erratic tracking! A hubcentric fitment, is one where the interior of the backside of the wheel - referred to as "centerbore"-is an exact fit to the "hub"-that protrudes from the mounting surface of the wheel. The relevant issue here is that the WEIGHT BEARING of the wheel on the car is done on the HUB when it is "mated" to the wheel! This has to be an exact fit.

Just a thought...
 

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Discussion Starter #14
well, Ive had my cobra rims for over a year and this problem is maybe 2 months old... so Im confident my rims arent causing it, unless the tires are imbalanced.
 

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If the shake is felt in the steering wheel, then most likely the origin is in the front end.

Start with the simplest and easiest solutions, then work your way up the money tree.

1. Proper lug nut torque
2. wheel balance.
3. damaged tire (broken band)
4. Concentricity of wheel to hub (index high to low)
5. Concentricity of tire to wheel (index high to low)
6. concentricity of hub itself.

If you have a locking lug nut, try removing it and put a stock one on.

Crawl under the car and check things out. Take a pry bar and check for play in the front end.

Look at: Strut rod bushings at the lower control arm


The Shop manual has some detailed information on troubleshooting vibration isses.

If it were me, I would get the front wheels re-balanced and go from there.
 
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