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Re: slight vibration at above 55 Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 13 Dec 2000 11:37:19
In Reply to: slight vibration at above 55, laura, Tue, 12 Dec 2000 22:05:59 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Quasi makes good points. Hold a constant road speed in fourth, then shift into fifth. If your road speed is the same, but the vibration increases, I would suspect an engine mount issue. If the vibration varies with road speed, I'd suspect tires.
It's been my experience that worn engine mounts show up as excessive movement while shifting, and usually don't increase vibration at cruise. It is possible that you've got some resonance, that in a certain engine speed range there is a resonance in the engine mounts that pass more vibration. You tend to cruise at a constant engine speed on the highway in 5th, and other noises are minimal. Driving around, the engine varies in speed, and makes more noise accelerating, so you might not notice a vibration as much. It could be mounts, but I doubt it.
When you shift into 5th, the engine revs drop and in general, there is less thrashing about than in 4th. Is it possible that you just notice the vibration more in 5th because less is going on? I'm getting back to tires. I've had cases where there was a vibration only at high speed that came from the tires. One obvious possibility is a slightly unbalanced wheel. Look at your rims for a clean spot- like where a weight *used* to be. Since many shops put weights on the inside rim, that could be a bit tough. Maybe spring for getting the tires rebalanced. There is another problem I've run into that causes high speed vibration - an out-of-round tire. Not egg-shaped, but with a slight high or low spot. The tire still balances fine, but that little up and down shows up at speed. The way to check for that is to jack up the car just enough for the tire to be off the ground, and spin it. If the tire to ground gap changes at one spot, you've found your culprit.
Put your hand on the shifter? Do you feel vibration in it? Try swapping tires from front to back and see if the problem changes.
Basically, if the vibration tracks road speed, suspect tires, and if it tracks engine speed, suspect a resonance in the engine mounts. This doesn't cover 100% of the possiblities, but it cover the most probable ones.
Good luck!
, Wed, 13 Dec 2000 11:37:19 <-- Viewing This Message
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