T 5 Vibration

The driveshaft gains RPMs in direct correlation to road speed. If it is your driveshaft, the problem should get worse as you speed up until it reaches a spot where the vibrations start to cancel themselves out. They don't truly cancel out, but they are occurring so fast that it seems to get smooth.

Did you get the driveshaft shortened? Was it re-balanced? Could have been welded wrong. Is the T5 used? Abused?

If one of the bearings in the T5 is shot, when you "unload" the trans by letting off the gas, this would reduce the vibrations.

I wish I had an answer, but it is tough to diagnose reading about it.

I'm in the middle of a T-5 conversion myself and was just reading this week about the use of centering dowels in the flywheel for positioning the pressure plate. I found quite a few posts where people that didn't use the dowels ended up having vibration issues. Some posted back that installing the dowels solved the problem. Of course, I think this only applies to the newer 10.5" clutch and flywheels. I don't think the older 10" ones used the centering dowels, they just used the bolts to position the pressure plate on the flywheel.

I will be running the later 10.5" clutch and flywheel with my conversion. The flywheel didn't have the centering dowels when I got it. I just ordered a kit from Jegs that has the dowels and new pressure plate bolts for about $19 shipped. I figure it's a cheap investment to eliminate one opportunity for vibration. For whatever reason, it seems like I read a lot about people having vibration issues after a T-5 conversion in older mustangs.

Other possible issues:
Transmission mount
driveshaft yoke is worn
Too much driveshaft freeplay (3/4 to 1 inch is ideal)
Have read someone had an issue with the shifter resting on the opening in the tunnel
pinion angle
flywheel/clutch alignment

Ken 72 said:

Thanks for the feed back, the T5 is a used trans so I do not know of the insides I was able to use the drive shaft from the FMX, changed the yolk but did not re-balance drive shaft. I do have the 1" freeplay. The flywheel was 50oz change to 28 oz not sure if pinion angle is correct. How would I know if the trans mount is bad?

Click to expand...

Hi,
First, I have to ask, why no balancing of the driveshaft? This would be a no brainer. If there is any significant compliancy in the mount, change it.
Again, start by having the driveshaft balanced.
Happy Motoring!

If you didn't replace the rear bushing in the T5, you should. Pretty cheap and I think it can be done with the trans in the car. I believe it requires a "special" tool that costs more than the price of having it done. It should be noted that standard "best practice" for any used T5 swap is:
1>Replace (or have replaced) rear tail bushing & seal. A sloppy rear bushing can allow just enough "wiggle" on the slip yoke to cause what you describe.
2>Check that the front bearing retainer (the part that the throw out bearing rides on) is steel and not grooved or worn. If aluminum, it should be replaced with steel to avoid binding and/or uneven clutch feel/operation.
HTH,
Gene