Cavilry

Hey all!

After 8 years, I am finally back in an SN95! I have a 1994 GT with a 5 speed that I just bought as a "budget" car. Luckily I don't currently depend on it for transportation, but I do need it to be my daily driver sooner rather than later.

My main issue is that there is an EXTREME vibration under acceleration at certain RPMs. I do not believe it is engine related because in Neutral I can rev it all I want without getting the vibration.

While accelerating from about 2K-2.5K RPM and then again from 3.5k on up, the car shakes pretty violently. No discernible noise (slight exhaust rattle). I can only liken it to sitting on a poorly loaded washer. haha.

I checked the driveshaft and can't feel any slop, but it was a bit difficult to tell. Any ideas?

Oh, and just because I know all forums love pictures:

NSteinseifer

I just had the same issue in my car I just bought. First thing I checked was the harmonic balancer, mine was shot. The key thing that fixed mine was a bad throw out bearing. At idle listen for a knocking sound from the bell housing, if you do hear one push down the clutch and see if it goes away.

mattdel

Could be the balancer, but in my experience, load based vibrations are caused by misfires. Namely, the secondary coil windings are no longer within spec and can't keep up. Don't assume it isn't engine related. Like you said, it's load based. Free revving an engine in neutral creates no load, therefore doesn't replicate the problem.

dawson1112

So its only under load ? Not speed related or it dont do it while coasting? It probly is a engine miss under load. I would have to agree. If it feels like a off balance washer under load its probly missing on a cyl under load.
Run some koer tests and do the cyl balance test.
http://sbftech.com/index.php?topic=2471.0

Cavilry

Thanks so much for the feedback all.

I guess is should amend my statement. It happens both while accelerating and while decelerating, but only if I double clutch while down shifting and rev the engine up pretty high.

mattdel

Well thats a horse of a different color. Check driveline mounts.

Cavilry

Thanks very much. I am thinking I will swap that out since it is relatively cheap and easy. Any feedback as to a good OEM supplier? I would prefer not to get one any stiffer as I have had plenty of problems with stiff mounts and vibration.

mattdel

No sense spending money on an undiagnosed problem. Check 'em all first, it could be something else. Engine has 2 mounts, tranny has 1.