C4 to T5 swap guys... how far did you shorten your driveshaft?

[SadbutTrue]

I am using the swap yoke from NPD... I've been running the driveshaft at the same length it ws with the old C4 for about a year now. No real problems, but the T5's rear main seal is leaking like a sieve. Not sure if thats necessarily because of the driveshaft being too long, but I figure while I'm fixing that is a good opportunity to get my driveshaft shortened (I have a mild vibration in the drivetrain somewhere and figure having the driveshaft at the proper length might help that too).

So yeah... how far do I need to shorten it?

 

[daddy oth]

i shorten my stock d/s with stock t-5 yoke by 1 in.

 

[BarnStang]

Found this:
http://www.thrashdriveshaft.com/measure_sheets1.htm
You can know for sure what length to have it shortened to.

 

[STSFCTN67]

we have very similar setups. I shortened mine by 1 inch and also put a few flat washers beteen the mount and the tranny to get rid of the vibration.

 

[iskwezm]

didnt shorten mine

 

[6t9 stang]

didnt have to shorten mine either

 

[SadbutTrue]

we have very similar setups. I shortened mine by 1 inch and also put a few flat washers beteen the mount and the tranny to get rid of the vibration.

I heard something about using shims/washers/something to get rid of the vibration. I have a minor vibration and I think thats the cause... what exactly is that process again? Are there other methods (i thought i heard something about addressing it on the other end of the driveshaft... ie somehow inserting shims on the rear axle side)?

I've been going about a year without any major issues due to the length, but wonder if my rear main seal leakage might have anything to do with the driveshaft being slightly too long.

 

[CraigMBA]

Didn't shorten mine.

 

[SadbutTrue]

Could the driveshaft length have anything to do with my rear main seal leaking? Im not sure, i would think the driveshaft being too long would have a bigger effect than just leakage, but thats just me and my gut is often wrong.

And can anyone elaborate on the use of shims/washers to eliminate the driveline angle vibration with T5s?

 

[STSFCTN67]

When I first drove the car after the swap there was a really bad vibrartion at low speeds especially when I was slowing down getting off the highway. I brought it back to the muffler shop to see if there was a vibration from their installation. On the lift the mechanic started hitting different spots under the car with a rubber hammer and listening for a certain sound. Anyway he said there is something wrong with the tranny mount. We pushed up on it and there was movement even though it was tightened all the way. I went home and put two washers between the c4 mount and the new crossmember. That solved the problem. You should shorten the driveshaft you need a little suspension play.