MerCruiser TRS tailstock Coupler
 

Well it seems the only part that seems to evade me in my diesel swap TR set up is a coupler that goes from the BW output shaft to the TRS upper drive yolk. It would sit inside the back bearing of the tailstock. Does anyone have any or know where I could get one? They are NLA from merc, and I can’t find any for sale. Part number is 55758A2.

I know we have some good previously used pieces on the shelf.

I added them to our store if you want one.

https://www.mercruiserparts.com/57758a2-coupling-assy

Thank you I’m ordering one right now. By chance do you know if all 72c BW will bolt up to that tail stock? I know it’s suppose to be the green tag 1018 72c 1:1. On the other hand there are a number of BW 72c that are 1:1. From my understanding they are all the same bolt pattern up front right? For that matter so are all BW 71 and 72’s?

Any of the Velvet drives with a ratio other than 1:1 consist of 2 pieces, the front hydraulic section and then a reduction section or V drive. So all the hydraulic sections are 1:1 and the ratio is in the reduction or V drive. And yes the mounting to the flywheel housing is the same on all of them.

The actual model for a 72 series that directly fits a TRS (or any of the Mercury tailstocks) is a 1018-014. There are a couple of others that can be made to work but the -014 is the one you want.

For the sake of preserving knowledge, could you explain the process of “making” other 1:1 BW trannys work? As you said the green tag 72c is the drop in replacement. What about the 1:1 71c or the other 72c 1:1’s? What is the process of making those work? Do Different output shaft sizes create problems or are they all the same output? any knowledge you could share would be great.

It's more than just the green tag. You are looking for a specific model. Best to find one of those to keep things simple.

71 series (1017's) are about an inch shorter front to back. And would be marginal for a diesel.

As far as making some of the other models work it will be plugging some oil holes and possibly providing an oil pickup depending on the model.