i have noticed lately that when i rev the car up to past 4,000 rpms the motors starts to give off this vibration, the motor seems to vibrate more when i am actually driving and then gun it. but it also does the same thing if I am just reving it. Feels like something is off balance. I was thinking maybe the harmonic balancer, what do you guys think?? its a 87 lx but had a motor swap with a 1990 gt, so also maybe bad motor mounts? thanks a lot

 

Check your balancer out. If there is stuff sticking out, that might be it.

 

You could have something coming loose, as well. The tranny input shaft and/or pilot bushing can also be at fault.

 

thanks guys, so its nothin realy serious you think? definately not the crankshaft out of balance or something???

 

I dunno how harsh this vibration is, but if i rev mine up to 4k i feel a slight vibration which is normal to me. If it's something harsh..well it could be numerous things. Say your timing if off, or you have a plug/wire that ate the dust..you'd be running on 7 cylinders, you'd have an ok idle butas the rpm rises it would vibrate like mad. If it's ok reving at a stop, but when you drive it vibrates..could be tires, brakes, driveshaft universal play or even out of balance..list goes on and on. My advise is if your not sure and this vibration is harsh..get it checked out by a certified technician, may cost some cash now for the inspection..but end up saving you a chunk down the line.

 

Input shaft to the tranny or a bad pilot bearing is something to worry about, as is a bad balancer. In short, any vibrations above 4k are going to be something to worry about.

 

i cant say they are very harsh, but i will definately try to get that checked out, anyway thanks for the input, it really doesnt seem like something really out of the ordinary, i mean i though maybe it was a 5.0 thing or something. its not like the whole car really shakes, and yes my timing might be off, i noticed a slight misfire a while ago, idles ok now but you can definately tell that its missing sometimes.

 

driveshaft...or you might wanna check, to see if your driveshaft is loose..or needs rebalancing ....my 97 gt was doing the same thing...and the reason it was vibrating was because of a loose driveshaft.

 

Bad motor mounts? I would probably go with the D-shaft thought.

 

its not the driveshaft tho, b/c it the i get almost the same vibrations when i just rev the engine in nuetral or with the clutch disengaged. So im guessing its either a bad motor mount or the harmonic balancer. I just cant tell which one