High speed vibration

[Traitor5150]

Well the title gives it away. Ever since I got my car when i get above 90 mph and let off the gas my shifter vibrates alot it vibrates alot when I aacclerate also. But there are some speeds where it is if fine below 80 it's fine and arounds 95 its ok but anywhere under or below its real bad. It has always done it even with stock clutch. I did redo the clutch 6 months ago and had no effect. Im thinking driveshaft... where do i get it balenced??? or possibly harmonic balencer has 120K on it

 

[wytstang]

The balancer is easy to check just look at the if it has rubber hanging out of the back it's shot. Also I would look at U joints on the driveshaft if it has alot of play there gone. You mentioned doing the clutch you may have forgotting to mark it before it was removed so you may want to rotate it and see oif the cures the vibration.

 

[Rootus]

Output shaft.

 

[95strokerPSU]

Output shaft.

Farther explaination please.

 

[Rootus]

Farther explaination please.

Bent output shaft. I had exactly the problem Traitor5150 describes -- at 115 mph (the highest I ever took it before fixing it) the shifter was vibrating so badly the knob was just a blur. Pulled the T-5 and found that the output shaft was bent.

Of course, there are no guarantees... so I'd swap driveshafts first to be sure. But with a vibration coming directly through the shifter, it's either going to be a seriously bad driveshaft or the output shaft.

Dave

 

[94-302-vert]

Traitor- my car is doing kinda the same thing. between 78 and 85 mph if I featehr the gas (up to maybe 1/4 or so throttle) it will do it. More or less gas and it goes away. Also only after things have warmed up (won't do it in the first few minutes if I jump right on the highway from a cold start)...

I already did the alum driveshaft and that made huge differences after my gear swap. I know my gears were not doen right initially and I think that is where my noise/vibration are coming from as the gears are continuing to break in.

I decided to jut let it ride for a few k more miles to see if it gets better or worse... it is hard to tell day to day but i think it is gettign better.

Since you are saying it follows speed not engine RPM it is not your balancer that is the problem. My balancer was bad so I had changed it out and it didn't help me at all.

I agree to get the alum d/s and see where that leaves you. What else has been done to the car?

 

[rude_life]

How did you fix a bent output shaft?

 

[Traitor5150]

Well I rebuilt my tranny about 6k ago. I did it myself 3rd gear used to grind It was the syncro dogs so i replaced them and all of my bearing syncros and pretty mutch all the small parts. Tranny is fine now but as far as i remeber it always vibrated. I have HCI an all the bolt on bs. I guess to find out if my output shaft is bent im gona have to pull the tranny I might just wait untill I get a tko or t56 to do that since I plan to do a vorteched 383 stroker.