How to connect LS driveshaft to Getrag Differential
 

So I just finished replacing my Getrag differential in my LS2 swap car. I bought this car as is and did not have the pleasure of building it. When I removed the driveshaft, I noticed the large rubber circular spacer between the driveshaft and differential with 6 holes in it. I would assume this is there to absorb vibration and shock to the drive system.

As it is now, the flange on the Getrag is a triangle, and the driveshaft flange is circular (FM stage 3 driveline kit). There are only 3 bolts that go through the driveshaft, through the rubber spacer, and attach to the ears of the triangle Getrag flange. This leaves 3 holes on the rubber spacer unused.

I noticed when I pulled the Getrag from a Cadillac STS, the design of that rubber spacer was used differently. In the Caddy, 3 holes of the black spacer were attached to the Getrag, and the remaining 3 holes were attached to the driveshaft. Meaning the driveshaft was not directly attached to the Getrag, but used the black spacer as the connection. This seemed like it would really take the shock off the differential under hard acceleration. I tried doing this on the Miata, but the circular driveshaft flange would not allow it.

How are others making this connection on their LS cars with the Getrag diff? Any thoughts?

Mine uses a AL adapter with the drive shaft and diff in different bolt holes.

http://i448.photobucket.com/albums/q...ps4aw56nhx.jpg

Looks like you ditched the rubber dampener all together. Here is a pic of what I'm talking about
Attachment 6331

You can see the black piece is attached to the diff, and holes are available to attach the drive shaft (which was also shaped liked a triangle). I guess Cadillac really wanted a smooth ride! When I tried to do the same attachment with a round driveshaft flange, the head of the bolts attaching the dampener to the diff prevented a smooth mating surface. I just ran a longer bolt through diff, dampener, and driveshaft. Seems to work well.

I was just wondering if there was a different solution - apparently there is.

That rubber piece should adsorb some shock load. Better for drive line longevity but a wear part.

From what I recall, V8R stopped using the rubber piece/adapter right before I started my swap (late 2011). Here's what mine looks like. No rubber gizmo.

https://www.v8miata.net/attachment.p...ine=1432745147

I have replaced a lot of those rubber couplers back in my Merkur Scorpio wrenching days. I would suggest that you go a different route.

I primarily work on German cars and those flex discs are usually found on them. I have seen them fail but only due to severe negligence. But if v8r stopped using them they must have some pretty solid reasoning behind it.

I have the V8R Stage 3 Driveline kit that was purchased in 2012. It was assembled by a shop using the rubber dampener. I wonder if the driveshaft has enough length to slide out of the tranny and make a direct connection. Looks like it is currently slid all the way into the tranny. If not, where can I get one of those aluminum spacers?

VR8 or FM would be my first calls...

Seems like you're having all the same questions that I had when installing mine.

This thread should answer your questions. Both V8R and FM address the question.

CTS Diff Question - MX-5 Miata Forum

That is fantastic info. Do you by chance have the measurements they quoted as being the new design and able to direct connect the round driveshaft flange to the triangle diff flange? This would save me from bothering them again. Thanks.

I don't remember the number on that. I think I was just measuring it as I spoke with V8R on the phone.

I'd measure mine, but I'm out of town for the weekend.