This is topic Foxbody VIBRATION!!! in forum Tech Talk at Northern California Ford Owners  .


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Posted by GR8WHITE281 (Member # 10372) on :
 
Just picked up a '90 Gt and it vibrates really bad at high revs. On take off if I accelerate through the rpms on 1st and 2nd everything is fine until I ht 3rd over 3k rpms, then it shakes really bad at the shifter. When I'm on the freeway and I'm in 5th going about 60 mph I give the gas a little tap and I can feel likea clunk , but only when I give the gas pedal a tap. On the freeway sometimes the vibration is really bad and sometimes it dies down a little. I'm going to be checking the car today. I know it's somewhere In the drivetrain because only the transmission vibrates.

I will check u joints, driveshaft, rear wheels, and if everything checks out I might remove the tranny and check the flywheel.

Another note is the guy that had it before me drove the car over a sidewalk, messed up the rear quarter panels a little and the car is lowered , don't know if this can help but I feel like he might of bent something .

Ill keep the thread updated but any help and tips would be appreciated.
 
Posted by El komander (Member # 10751) on :
 
Check your driveshaft bolts! Bet there loose
 
Posted by Tom Renzo (Member # 13165) on :
 
Shaft bolts or not seated properly on the flange. Also the U JOINTS. Good luck!!
 
Posted by Stangn5oh (Member # 10875) on :
 
Your on the right track....
For me i had the same problem on my 89 gt, i waited to long to fix it.
Rear yoke broke
Seal on tail of tranny started leaking
Transmission mount wore
Then it caused my motor mounts to shake loose and strip.

So check all the above because it was a domino effect for me.

i replaced the tranny mounts and it was good for a few days then started again, it caused my motormounts to fail within a few days.

I got the threads retapped on motor,bought a fms driveshaft w/ yokes, new polyurethane motor and tranny mounts, replaced the seal on tail of tranny and all was good

[ 2013-10-12, 03:32 PM: Message edited by: Stangn5oh ]
 
Posted by IH8WNTR (Member # 13212) on :
 
I had a similar issue not too long ago. I changed out my driveshaft to an aluminum one and now its all good. Runs smoother than ever.
 
Posted by dean-93 (Member # 9401) on :
 
ive got a similar issue right know im trying to figure out
 
Posted by GR8WHITE281 (Member # 10372) on :
 
Driveshaft bolts are tight, u joints look good theres no play. Transmission shifts smooth only pops out of 5th because of the vibration, no grinds.

I did notice something though. Sounds to me like a bad axle. I heard a loud rattling coming from the rear differential. When driving straight i turn to the left and noise gets louder, turn to the right and noise goes away. I thought at first something in the hatch was rattling but its coming from the rear end. There was quite a bit of play in the rear end.

So i feel maybe the passenger side axle is bad and its causing the vibration
 
Posted by GR8WHITE281 (Member # 10372) on :
 
How could i check if the axle is bad before tearing Apart the rear end?
 
Posted by red5o (Member # 12651) on :
 
I have that same problem and I am assuming it my pilot bearing
 
Posted by LXjames (Member # 10791) on :
 
Your right axle is bent. When you turn right you put pressure on the left and the right is relieved causing no noise. I would say I got some axles for you but my boy already took my 7.5
 
Posted by GR8WHITE281 (Member # 10372) on :
 
I am going to replace the rear end and change the driveshaft and ill go from there and see what happens. Ill update after I swap the parts in. Thanks cafords.
 
Posted by 50Reasons (Member # 6452) on :
 
I'd put the rear end on jack stands and put the car in 1st gear and let the wheels roll freely to see if the axel wobbles the rear wheel if so bent axel
 
Posted by Duncan Motors (Member # 7045) on :
 
do what 50 reasons said. check before replace.
 
Posted by GR8WHITE281 (Member # 10372) on :
 
quote:
Originally posted by Duncan Motors:
do what 50 reasons said. check before replace.
Will do. Should there be any play if I move the axle in towards the differential, I would put the e brake on and check for play
 
Posted by GR8WHITE281 (Member # 10372) on :
 
quote:
Originally posted by 50Reasons:
I'd put the rear end on jack stands and put the car in 1st gear and let the wheels roll freely to see if the axel wobbles the rear wheel if so bent axel
Did this and didnt see the wheel wobble.

However while in the air the it would make a clunking noise in the differential. It would go away and then do it again. I can hear it from under the car and from the driver seat. Sounds like loose driveshaft but I already checked all 4 bolts and they are tight
 
Posted by triple b (Member # 8763) on :
 
its your u joints they are bad or your drive shaft is out of balance. replace both. There should be play in the axle shaft. pushing in and pulling out is the difference between the slot in the shaft and c-clip. putting the car on jacks and rolling it wont show a bent axle unless its very bad. have someone drive it and you get on the freeway in another car to see if the wheel is bouncing up and down on the suspected side. Axel dont go bad they break, become bent or strip their teeth.

[ 2013-10-23, 04:50 PM: Message edited by: triple b ]
 
Posted by GR8WHITE281 (Member # 10372) on :
 
quote:
Originally posted by triple b:
its your u joints they are bad or your drive shaft is out of balance. replace both. There should be play in the axle shaft. pushing in and pulling out is the difference between the slot in the shaft and c-clip. putting the car on jacks and rolling it wont show a bent axle unless its very bad. have someone drive it and you get on the freeway in another car to see if the wheel is bouncing up and down on the suspected side. Axel dont go bad they break, become bent or strip their teeth.
I feel the axle splines are stripped or something. That's what it sounds like when I drive it.

I will try swapping one of my friends driveshaft with mine and see what it does. Thanks
 
Posted by triple b (Member # 8763) on :
 
If they were stripped your car would not move or only one wheel would have power making the car pull on one side
 
Posted by 86 T TOPS (Member # 8855) on :
 
My 95 had the sme problem took it to a Mufler shop to put in my tail pipes and checked my ds when it was lifted and sure enough there was one bolt missing and another about to fall off they charged me 10 bucks for a bolt and tightned the rest and the vibration is gone !!
 




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