Vibration - could it be T5 tranny?
 

We've got a vibration in our 88GT 5-speed. Only vibrates when it's in gear at higher rpms. Recently started acting up, could it be the original T5 starting to munch out? Any ideas on what we can check to find the vib?

Here's a list of what we've installed in the car:

Drive Train:
King Cobra clutch - brand new
Pro-5 shifter
machined fly wheel
aluminium drive shaft
3.73s
Eaton Posi
31-spline axles

Engine:
ZEX 100shot gas
under drive pullies
MAC longtube headers
stewart high-flow water pump
Fluidyne radiator
140amp alt
X303 cam(recent install)
Typooon intake(recent install)

On my T-5, it was caused by the driveshaft pinion flange bolts backing off just a bit. Check those. I see you already have the aluminum driveshaft cause the stock one is a big suspect.

Check the harmonic balancer if it also vibrates in neutral.

In general, when any transmission/gear related item is "going" then you will hear shrieks and whines. I love it! When my T-5 went, the input shaft retainer broke and the car sounded like it was in reverse through all gears and it built to a loud hiss. People thought I had a turbo!

crazypete, that's funny about people thinking you had a turbo. :D

Mustang_289, once again looking at the harmonic balance, what kind do you have on there. I would check that first as that would be my biggest (most important) concern. Make sure the rubber is in good condition and it spins true.

When you say "vibration in gear at higher rpms" what exactly do you mean? Do you mean something like "in 4rth at 5000 rpm"? When you say "vibration" do you mean like Major vibration or more than you expected would be there? Do you mean it's vibrating througout the whole car or just a vibration you're feeling through tthe shifter? I just like to mention and search the easy and perhaps overlooked (but obvious) things first. For example, you will feel more vibration with the race short throw shifter than the stock due to the lack of all the rubber bushings and sound deadeners that are in the stock shifters. A little to moderate vibration in the shifter at say, yellow line rpms isn't abnormal in many cases. Also, as mentioned b4 you already have a new Al drive shaft (and new rear diff??).

BTW, how are you liking the Typhoon intake???

lol, crazy pete, my clustershaft broke some teeth in my old t-5, everyone thought i had a blower :) i drove it around a long time like that.

Man, make sure all your bellhousing bolts and fasteners are tight, i cant stress that enough.
also like mentioned, the harmonic balancer and u-joints need to be checked.

reply
 

the harmonic balancer is a ford oe replacement. it is about 4 or 5 months old. when i put it on it was working fine no vibrations or anything. the car only vibrates in gear. if i put it in neutral and rev there is no vibration. so it is something from the flywheel back. i know that for sure. the transmission does not whine or anything like that. vibration is bad 2k rpms and up.