Vibration past 90mph and other trans issues

[GTCobra407]

Hey yall,

My 94 gt picked up a vibration that start at 85 mph no matter what gear. It sounds like a revolution and feel like it's coming from the driveline.

Also it grinds into first regularly. I have to shift to 2nd then 1st to avoid the grinding. Could this be thr synchro?

I want to avoid paying 5000 for a tkx swap if it's something that can be a quick fix or issue with my clutch.

Specs on my mustang: 331 stroker, Holley sniper, 3.55, aluminum driveshaft. Mcleod street pro 10.5 inch and billet flywheel 28oz balance

 

[Daryl]

2nd paragraph: sounds Ike a synchro. I learned very quickly when I got my TKX 5-speed that I have to shift to 1st gear first before throwing it into reverse.

The vibration @ 85mph regardless of gear issue, I’m just spit-balling but could be a few things: harmonic balancer? driveshaft tweaked or out of balance? Worn @ the pinion? (it’s too early and I’m brain-farting but I’m thinking of the point where the driveshaft sets in the upright bearing at the point where the driveshaft meets the front of the rear gear melon; maybe the Universal Joint? I need coffee!) Flywheel out of balance?

Are the rear gear oil and transmission oil @ proper levels? And not needing changing? Start with the simplest fixes first before you convince yourself that you need a new transmission. I’m sure others will be of a bit more help but these are just ideas for you to consider. Good luck and keep us posted!

P.S.- consider posting same in the Driveline Tech forum. May as well, to get more eyeballs on it.

 

[07GtS197]

With the vibration being speed dependent, it’s most likely either the driveshaft or wheels and tires.

Do you have a firewall adjuster? Most likely the first gear grind issue is the clutch out of adjustment.

 

[95opal]

I would suspect the same as above.
The aluminum driveshafts tend to rub on the brake bracket. May have scored it up unevenly. Does the symptom occur when the cats in neutral and you bring up the revs or just while the clutch is engaged? Just want to eliminate a slipped balancer.
The stock t5 is probably on borrowed time with a 331 anyway.

 

[GTCobra407]

The clutch does chatter on idle sometimes. And I do not have a firewall adjuster.

prior to the new modifications the car drove smooth as butter. After the install the grinding started with the trans.

On idle when I rev it no vibrations either its smooth. The balancer is a solid trick flow and not a rubber one. Everything had the proper weights put in. Prior to being set in the car.

 

[Musturd]

The old t5 will live until it doesn’t . Bunch of us have the tkx in here now with great results . These cars are 30 years old now the factory t5’s weren’t all that great behind stock power levels. Hopefully you can get some more life out of it . I’ve had my tkx for 3 years at well over 500whp with zero complaints .

 

[GTCobra407]

The old t5 will live until it doesn’t . Bunch of us have the tkx in here now with great results . These cars are 30 years old now the factory t5’s weren’t all that great behind stock power levels. Hopefully you can get some more life out of it . I’ve had my tkx for 3 years at well over 500whp with zero complaints .

Looking like this going to be the way it's going to go

 

[joemomma]

Late to the party here, but check your trans mount. Could be worn. My car had a similar vibration at the top of 4th and I had a new mount ordered but sold the car before I got around to replacing it.