Hello guys

I have recently converted my ´73 coupe from automatic to manual.
To do so I have purchased kit from American Powertrain with Tremec T56 - 6 speed. I have put new transmission high in the tunnel as much as I could but still it is pointing down making my drive shaft angle too big. (Not to forget I had to modify trasmission cross member as well by letting transmission to sink down about 2 inch to be able to fit it in tunnel at all)
I did not measure current angle but it could be around 10 degrees or more. Of course I have vibrations while driving....
What would be a good way to deal with this problem?

Can I lower engine a bit down? I have new 2 piece motor mounts (CORVETTE Energy Suspension Motor Mounts/Motor Mount Inserts 3-1114R) with thick metal inserts. Can I take inserts out and just leave urethane mounts? Will my holes align?

I can still go up with transmission I might have 3/4 Inch tunnel clearance so far - so maybe I could take 1/2 inch.

Is there a way to lower differential? How much till I hit the frame? What is the best way to do it? Insert metal piece in between the diff. cross member and some shims in between bushings + larger nut?
I hope i will not have to cut the frame!!

Please help I would like to know all my options before I proceed

 

I ran into the same issue with my LSx, Richmond 6 speed swap.
I had the engine 3 degrees down, diveshaft was flat at 0 degrees, and the diff was 0 degress. The original vette setup was almost flat, 0 degrees on all.
I couldnt drop the engine any lower, but was able to shim the trans mount up as high as possible.
The front of the differential is mounted to a "tongue" that bolts the the frame with a rubber isolator between. I cut the thickness of the rubber isolator down to move the pinion angle up. I've also seen other people redrill the "tongue" mount to increase the diff pinion angle.
I was able to get within 1/2 degree of the engine and diff matching, probably better than factory, no vibrations.

 

Thanks for the feedback. It is good somebody had the same issue and managed to solve it. Especially your note about differential "tongue".
I have taken inserts out today from the engine mounts - it took me about 5 hours thanks to my headers :-)
Anyway I have managed to lower engine block by 1/2 inch, pretty good result. I hope to raise my transmission in couple of days also by 1/2 inch.

 

OCB,
my Van Steel delrin bushing does not sit flush against the saddle. Does yours? If so, any ideas to issue? Should I call Van Steel? Thanks.

 

You could try posting here: https://www.corvetteforum.com/forums/c3-tech-performance/4811572-engine-transmission-and-differential-pinion-angles.html



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