Vibration

[adictionbass]

alright guys, i have a little problem. i bought a 94 ex coupe probably a little bit over a month ago, and on the test drives i could tell the wheels definitely needed to be balanced. I say o well, its going to be my weekend/race car and bought it anyway. Took it into my work, balanced the wheels and everything seemed fine. However, under hard acceleration, the whole car vibrates. I can be cruising at 80, 90, or even 100 mph and the car is smooth, stable, and doesnt pull side to side at all. The only time it shakes/vibrates is when im at more then ~85% throttle.
All the suspension and bushings check out ok, tell me what you think.

[imported_mntdewred]

choking the engine by not getting enough fuel??? just throwing out ideas, not really sure...

[imported_SasSi]

Have you checked the motor mounts? If they haven't been replaced by now, chances are they are dry-rotted & need to be. If they're aftermarket & polyurethane then that may also cause the vibration b/c it keeps your motor from moving & instead causes the car to shake.

Also, there might be a flat spot on the tire(s) which will DEFINITELY cause your car to vibrate. Sometimes you can still balance them, but you will feel it when you drive. Check the sidewalls for bumps. It could possibly be a broken belt in the tire.

Just some thoughts... good luck!

[dubcac]

Could be the tires themselves are out of round. Could be bad alignment. Could be a bad axle. Has the car been in any accidents?

[adictionbass]

carfax said no accidents (doesnt relly mean much) and the guy i bought it from said no accidents (doesnt really mean much either). tires are good, they're BFGs with only about 8000 miles on them. If it was an alignment, axle, or the tires, i dont think the car would ride perfectly smooth and straight at 100mph.. Its weird, it only does it during Hard acceleration (well, as hard as a stock ex can accelerate). i havent checked the mounts yet, but i really want to get this figured out before i drop 350-400 ponies in her in a couple weeks. thanks for the ideas, im going to go check the mounts

[adictionbass]

alright, mounts seemed fine. the only one that didint appear in excellent condition was the upper tranny mount. The outter coating as im going to call it was pealing off, kind of like sunburn, but the under layer appeared to be in good condition. right now im trying to figure out if this is something i should figure out, or if i should just say screw it, im ripping it all out in a couple weeks for the swap. i just dont want to get the new motor and everything in, and not be able to drive it

[imported_team_adrenaline]

Sounds to me like an Inner CV Joint is failing, the inners will cause these same symptoms, the only way to check them is to jack both front tires up and run it through the gears and see if there is a visual vibration unfer hard accel. There most likely will be, watch the axles spin and make sure they are spinning true, if not that's the bad one. Also just because the boot is still in one peice doesn't always mean the joint itself is still in good shape. If this isn't it let me know and I have some more suggestions.

[adictionbass]

awesome, just the kind of advice i was looking for. Ill take it into work this week and put her on a lift. If this is the problem, im just going to let it go since im ripping it all out to put that beast sitting in my garage in
thanks guys

[cynosurecivic]

now that i read this, my car kinda does that sometimes