Vibration in the rear...is it my U joints?

Roush21 · Jan 29, 2004

I got a vibration in the rear of my car it only ever occurs when im going like 60-65mph and let off the throttle then it vibrates from the rear of the car. Then if i give it gas the vibration goes away.... I was told it was my U joints....anyone agree or have a different opinion? The car is a 98 cobra w/ 4.10 gears the gears have been in for about 5,000 miles with no problems b4 so i dont think its the gears....what do you think?

rblcollee · Jan 29, 2004

look at the bolts that connect the drivshaft to the rear and make shure those are tight. I had i problem like this

luther1228 · Jan 29, 2004

do you drag race alot? does the 98 have irs?

COramprat · Jan 29, 2004

The u-joint vibration I had was determined by rpm's. It started out in 4th and 5th gears but eventually happened in all gears. I would get a very deep 'moan' around 2300-2500rpms. You can check the u-joints by getting under the car to see if there is any play in the driveshaft. If the shaft wiggles around on the u-joints then you probably have a bad one. The key word is a deep sounding vibration...almost like the hum of a sub woofer.

GinoGT · Jan 29, 2004

I noticed a kind of rear end and transmission (or my shifter) vibration the other day, would kinda like to know what it is. It happened at around 135mph, was still happening at 145mph.

MustangLife · Jan 30, 2004

Usually geared cars have those kinda vibrations on the freeway. Ford realized these cars have that kinda vibration in stock form. Thats why they have the "dog-bone" back there. Its the weight thing infront of the differential. Aluminum Driveshafts usually fix this problem. Unless it is really really bad. Also It could be driveshaft alignment. When you lower your car it tends to do this. The angle of the driveshaft gets out of wack.

Hope this helps you.

Josh

Roush21 · Jan 30, 2004

coramprat said:
The u-joint vibration I had was determined by rpm's. It started out in 4th and 5th gears but eventually happened in all gears. I would get a very deep 'moan' around 2300-2500rpms. You can check the u-joints by getting under the car to see if there is any play in the driveshaft. If the shaft wiggles around on the u-joints then you probably have a bad one. The key word is a deep sounding vibration...almost like the hum of a sub woofer.

Yes it does sound like a deep hum, like a subwoofer kinda. It does happen in 4th and 5th gears cuz thats when I am normally doing the 60-65mph and when I let of the throttle you can hear it and actually feel it also. Then when i give it gas again it completely goes away. Anybody else have this or have an opinion??? I do not have IRS to answer one of the questions posted by another user and someone else asked do I drag race alot??? Whats alot? I would say I drag race whenever giving the oppurtunity and always when there is money involved. I would say I am a moderate drag/street racer but if I am not racing my car is 100% babied. Thanks for the great info and advice so far....can I get a little more b4 I go and pay the shop to put new U joints in my car (hopefully thats what it is and I dont waste money) lol Thanks all

Vibration in the rear...is it my U joints?

Roush21

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rblcollee

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luther1228

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COramprat

...I can take it. I think.

GinoGT

MustangLife

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Roush21

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Vibration in the rear...is it my U joints?

Roush21

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COramprat

...I can take it. I think.

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