Can bad engine mounts cause this type of vibration?

Whisper · Post by **Whisper** » December 7th, 2007, 10:53 pm

I've been kind of meaning to troubleshoot this for a while now, but anyway...

Ever since the swap, I've experienced vibration during moderate to heavy acceleration. I can mostly feel it through the steering wheel, but it makes the whole car vibrate, because I can hear the mirrors and trim rattle as it happens. It's also somewhat noticeable when just coasting in gear, but not as much. It does not happen at all when coasting in neutral, so that possibly rules out alignment, wheel bearings, wheel and tire balance. The vibration frequency doesn't seem to be dependant on speed that I'm driving at, and feels like it's dependent on engine RPM instead - it gets more frequent as the RPM increases, and it's the same in all gears.

I do not think it's the axle shafts/CVs, because I've gone through several (for other reasons), and I think the vibration would increase with speed, as the axle spun faster and faster, which doesn't seem to be the case.

Engine mounts were filled during the swap, but not replaced. They're not new, and I suspect them. I can't think of what else it could be.

Could it be transmission related, because that was replaced as well, with a different used one?

Thanks.

hgallegos915 · Post by **hgallegos915** » December 8th, 2007, 1:36 pm

Have the rotors checked. Could be the bearings. Sometimes its just luck how it happens. After my swap my both front bearings went out a week after a nother. Then recently after boost my rear breake rotors warped and was causing vibratios. Did you put all the bolts in the right shaft behind the engine? Loose motor mount? mad motore mounts? usually if its a mount the vivration is only suring acceleration and not constant speed.

Audessy · Post by **Audessy** » December 9th, 2007, 12:17 pm

Bad mounts will cause "shaking" not vibrating. You'll experience this when you drop the clutch too harsh. The block will shake back and forth against the inertia of the car. In horrible cases like my friend with his probe GT you'll hear a CLANK on a clutch drop because his engine is only supported by the far right and far left mounts. Both the lowers are disintegrated. I was going to say alignment but alignment isn't rpm affected as much as speed.

I just thought about this now. Could it be your flywheel maybe? Bad clutch job? There's not many ways of checking this. If you got the time or cash get that tranny back out of there and have that flywheel looked at. Why not get a fidanza

Whisper · Post by **Whisper** » December 9th, 2007, 3:41 pm

Well, I guess you could say it's shaking, it's between that and vibration. Feels maybe like constant wheel hop from 2500 rpm to maybe 4500 rpm that gets more and more rapid until it's so fast it just smoothes out. Which does seem like engine-related vibration.

I don't dump the clutch, but actually there is a bit of a "clank" when I release the clutch after shifting gears.

I have a spare tranny, that I'm planning to get rebuilt, but that's later. Not sure how bad clutch or flywheel could cause something like this. Suppose the flywheel was so unbalanced that it shaked the whole car - in that case it would just disintegrate.

Audessy · Post by **Audessy** » December 10th, 2007, 1:45 am

If you need to find out how bad your mounts are then get a friend with one of his cars with a similar setup. Grab onto that intake manifold and pull and push on each car. Compare and contrast. I'm sure there's a fancier way of doing it. But if your unfamiliar with bad mounts and are what I call a "backyard mechanic" it should point you in the right direction.

The probe I was talking about I could move the front valve cover down about 2 inches. I weigh 150 lbs by the way so it didn't take much.

I'm guessing you did the ZE swap right? Corksport engine mounts probably would've been a smart idea. I wish I did.

I know what you're talking about. I get it only when I don't give it enough throttle before letting the clutch out.

If you're getting that clank noise then I'd be careful. That could missing/old bushings on the cross brace. In a rare case it could be the intake manifold ramming into the bulkhead.

Whisper · Post by **Whisper** » December 10th, 2007, 9:22 pm

Aight, thanks. I'll check it out.

lakersfan1 · Post by **lakersfan1** » December 12th, 2007, 8:54 pm

Bad mounts cause shaking at idle, not at speed.

Audessy · Post by **Audessy** » December 13th, 2007, 12:29 am

Aye, but switching between gears can make it stumble. Especially if a mount is completely broken.

Whisper · Post by **Whisper** » December 25th, 2007, 5:16 pm

Ok, what about transmission mounts?