Trans vibration??

[Lash]

My car has a pretty bad vibration at around 65+ mph....but only when it's in 5th gear (you can feel the shifter handle buzz) When it's in 4th @ 65+ it's non-existant. Also...when it's vibrating/buzzing in 5th....it goes away when you let off the gas.

What could cause theis problem?

 

[ninety15.0]

My brother has the exact same problem right now as well. Im leaning towards the driveshaft not being balanced very well. He has a steeda tri ax and 3.55's. i see you have 4.10's do you have the stock shifter...stock driveshaft?

 

[HISSIN50]

The DS should be spinning at the same speed whether in 4th or 5th (if absolute speed is the same).

 

[ninety15.0]

The DS should be spinning at the same speed whether in 4th or 5th (if absolute speed is the same).

Thats a good point and i knew i should have said something about that...and of course you caught it. However...i have a theory. When you are in 4th at 65+ with 4.10's you have to be pressing the gas pretty considerably to maintain speed (3400 rpms??)....at least considerably more than you would in 5th. That given, the additional load may be changing that vibration. at 65 in 5th there is practically no load on the motor...vibration would be more prevalent!? when he lets of the gas completely it goes away...maybe because you have the reverse scenario as when there is a load on the drivetrain in the forward direction. thats my theory anyway?

 

[Lash]

The DS should be spinning at the same speed whether in 4th or 5th (if absolute speed is the same).

Exactly. That's what I was thinking. If it was the DS....you'd think it would happen in 4th and 5th (possibly not at the same speed though). 4th is smooth as butter all the way through..... 5th is smooth til 65.


The DS is stock. I did notice that it does have a fair amount of rust on it. I wonder if that would play a part????
Shifter was stock...recently replaced with a short throw....but the problem is still there.... no changed at all.

 

[speedytang]

Sounds like the 5th gear carriar bearings is worn and causing the problem.

 

[Lash]

Sounds like the 5th gear carriar bearings is worn and causing the problem.

Ahh...that would make sense.

 

[trbkrb]

Mine vibrated and had the same on/off throttle symptoms quite a bit when over 55 MPH in 4th and 5th. I did replace the driveshaft with an aluminum one and it is better, but it still vibrates over 75 or so. I know my tranny probably needs a rebuild (over 200,000 miles on it) so I do agree that it is probably the bearings in the tranny. I plan to get it rebuilt soon.

Good luck on it!

 

[speedytang]

I have a T-5 apart now that started that vibration and finally could not get it in 5th gear. The 5th gear bearings are so bad that it moves on the shaft a good 1/2" up and down.

 

[Mr. Rustypwnz]

hey how much is it to rebuild a t5?

Thanks josh

 

[Lash]

I though 5th gear didnt have bearings?

I though that a dig drive gear spins even with the countershaft and the small driven gear rides on the output shaft, both on splines.

 

[87Mustang351]

i would say its either ur tranny mount or the bushing in the tail end of your transmission (Y)