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


Founding Member
May 1, 2002
Granada Hills, California
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?
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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.
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?
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:shrug:. 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.