Bad vibration at high speed?

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Apr 14, 2007 | 02:00 AM

TheSecretFormula

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From: S. Florida

Bad vibration at high speed?

Since I got my Formula it has had a vibration at high speed. Once you get up past 85-90mph the whole car starts to shake. I got the wheels balanced and still had the same thing. Thought it might be a bad axle or carrier bearing. Rebuilt the whole rear down to new differential and axle shafts. Same thing. Thought I had a couple of bent rims. Changed the wheels and tires. Same thing. Any thoughts. Shocks, wheel bearing, tranny or motor mounts? It's weird because the car is solid as a rock until you get over 85 or so. It also feels like the engine might be breaking up and causing it sometimes. Maybe a bad harmonic balancer or something? It has new plugs, wires, fuel filter, air filter, etc. Any thoughs would be appreciated. Thanks.

Last edited by TheSecretFormula; Apr 14, 2007 at 02:28 AM.

Apr 14, 2007 | 04:17 AM

EDS01SS

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From: Hampton Virginia

Are you using a Polyurethane transmission mount? if so they have been known to cause bad vibrations. Also check your u-joints and your complete driveshaft for dings and missing weights.

Apr 14, 2007 | 04:45 AM

SpaZMaN

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From: Chi-Town

it should be something drivetrain related, i'd check your driveshaft, maby go get it tested.

Apr 14, 2007 | 05:54 AM

GEARHED

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As mentioned, check the poly mounts and shaft. If you have an older converter it may also (along with the ds) be going out and can cause a strange vibration, didn't check your mod list. Can you describe about where it seems to come from? (under the shifter, right front, directly under the hood, passenger seats)

Apr 14, 2007 | 11:50 AM

TheSecretFormula

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The driveshaft looks fine visually. Actually it looks brand new which could be the problem in itself if it was not balanced correctly. It has no dents, dings and the weights are there. The U joints seem okay as well. The car has the stock tranny mount and is an M6 so no convertor to worry about.

Apr 14, 2007 | 04:13 PM

Switchblade

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From: Windsor, Ont

You might want to double check your pinion angle. It should be at -2 or -3 degrees.

Apr 14, 2007 | 04:22 PM

anniversary30

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It was on the old lt1 cars but there was a recall on the driveshafts years ago. I only mention it cause my 96 ws6 formula had the same problem at 85 to 90. the whole dash would start to shake.