Silkeepjs

Hello everyone..im new this forum. I have a 94 5.0 i just got. I'm scared to drive it because of REALLY BAD vibrations. its minor when i start the car, but whenever i accelerate its as if im rollin on Octagonal wheels. im thinking its my driveshaft + U-Joints, but how would i verify once i have it off? also with it being at start up as well, im kinda thinking it could be something else, possibly tranny mount. idk, any ideas or advice will help!

dawson1112

So the car does this while setting still at idle ? In neutral ? If it does this while sitting still its not in the drive line , more something on the engine . Does the car Idle smooth other than the vibration? A really bad miss can feel like a vibration .
Idle the car and watch the harmonic balancer . They are known to go bad . Usually will wobble back and forth. While in neutral sitting still rev it up to 2000 rpm and back down make note of weather the vibration gets worse or if its even still there.
There is a chance you have more than one problem also , but lets stick to narrowing down at idle for now.

Js88lx

Yup what he said! I just had a bad H/B and it too shaked my car.

https://mustangforums.com/forum/5-0l...k-knock-2.html

Silkeepjs

thats what i was thinking as well, tomorrow ima check out the harmonic balancer a lil more in detail...all i did was take a glance at everything to give me some possibilities....i dont think i'll notice the same vibration at idle because my cams, but at initial startup, and any time i pass 1200 RPM its BAD! and gets worse. tho i drove it this way, and its only when im on the throttle! in all gears including reverse.

Silkeepjs

of all things...i've never messed with a harmonic balancer before, and quite frankly im not to knowledgeable on em, im gonna read up on it, and hopefully have a better idea as to what im dealing with, also i'll record a video of it tomorrow and share a link to it, that way you guys can see and hear what im dealing with. thanks!

Pony 5.0

Put it in neutral, then rev it. If it vibrates look at the H/B or the motor mounts. If it vibrates only when you drive, could be u-joints, your wheels may have lost their balance, tie rods (inner or outer), your tranny mount, or your rear control arms (upper or lower). I have had all of these go bad on me at one time or another.

1991 Mustang GT

Is there a difference when at idle compared to when moving. If not, then its prolly not drivetrain and as everyone is saying check your harmonic balencer (spelling). I'm 27, I got my '91 when I was prolly 20 and had almost zero knowledge and changed my Harmonic, so don't sweat it if thats what you have to do. Continuing on the initial thought, it could be motor mounts.

But back to the beginning, we need to know if at idle and in motion... if there is a different. Just using common sense tho, if you have a bad vibration at idle... it is NOT drivetrain

caaraa

Put it in neutral, then rev it.

Silkeepjs

It was my HB! i swapped it out last night. it was 2 peices LMAO! the outer was detached from the inner, it all makes sense in my head now. Took me less than an hour to be completely done! thanks for your help everyone =)

Js88lx

Yup.., had that feeling! Always is the best feeling after you find the prob and fix it at the same time!!