Velvet drive “expert” needed

[Rowglide]

I have an older (some might say obsolete) velvet drive CR2 10-13 (006) transmission and though it works great and does not leak, I feel I should freshen it up while the engine is out for a rebuild.

My main question revolves around the pinion shaft but. I have read of them coming loose and that people have used castellated nuts with cotter pins to prevent this problem.
Is this a reasonable cure? Is there any special knowledge needed to perform this task ie. torque on nut before drilling shaft...
Also... does anybody know if the nut for both the pinion and output shafts are listed as 4775Q in the manual. I cannot find this part anywhere. Is it the same / superseded as the 4775L or is there another part #? 1000-149-034 is used on later model 71c 72c trans. New nuts should be used.

Thanks
Jim

[Lepke]

To use a castle nut you need a hole thru the shaft - is one there now? If not it may be difficult to drill. The shaft is probably forged or hardened. Locktite would probably do the job. If the manual doesn't have torque spec's, look up the nut size in a standard torque table.
Change the seals while it's easy.

[Rowglide]

Thanks,
The shaft has not yet been pierced. I hate drilling hardened steel especially small bores, one broken bit can destroy a perfect day. This is a known problem on CR2 transmissions, but it seems most issues occured before the internet. Very little to read on the matter. Seems the nylock type nut had a habit of breaking free on the left hand rotation versions of this transmission. Contacted Velvet Drive... said "It's obsolete...sorry, best of luck".
Definitely new seals, and a new damper plate...
Cheers
Jim

[DeepFrz]

I'm not sure of your exact requirement but check out Nord Lock. They may solve your problem.

[oleman]

I am not familiar with that tranny but I have never had an issue with the one-use deformed nut locking nuts. The nylocks are also one use only in most applications and most failures are due to the tech re using an old locking nut for either type. Most gear boxes whether marine or automotive have the same main shaft lock-nut issues. I have seen some nuts tack-welded in heavy trucks in a make-do situation.
Determine the diameter, thread pitch and rotation of the threads and get a flange locking nut from McMaster and torque it to service manual specs or spec for the diameter.
Attempting to drill the shaft without having it securely clamped in a vice and using a drill press will be problematic! and most likely not required.
I would not depend on lock-tight except as extra security with a NEW nut.
Good luck with your project.
ADDING A DISCLAIMER: Lock nuts on a stainless shaft and nut have a tendency to gall the threads, making it practically impossible to get the nut off with out cutting. Always use nyloc and lock-tight on stainless.

[Cheechako]

I would definitely not use nyloks there. I put them on and engine coupling when repainting the coupling etc. It had been trouble free for years with normal hi grade nuts and lock washers. I thought I was smart putting nyloks on, within a few hours of motoring they had come loose, one completely off, and the whole thing was rattling around down there at sea, which I had to crawl in there and redo it again.
"If it aint broke dont fix it"

[Locquatious]

Originally Posted by Cheechako

"If it aint broke dont fix it"

Said the man by the side of the road.

If the engine isn't worn out, don't bother changing the oil.

[Maka]

I have a velvet drive transmission. They are reliable and dependable.
They are small and easy to replace or rebuild. Inexpensive too.
If it aint broke don't fix it. it is easy enough and inexpensive enough to fix when it does break.

Best of luck

[Rowglide]

Maka
Mine is not “easy enough” when it does break as it requires removal of the engine to get it out. And in my boat with my engine that is no small task. And that is why I will rebuild it now.

[sandiegoskipper]

Without a pic this solution is ideal (in my head alone). A double nut with the correct thread-lock cement?

Skip

[Rowglide]

It is part #15 ( and #1) these nuts are very shallow, and the nylock portion is just onto the thread with very little thread protruding. Double nuts (even thin ones) would be too thick. #15 has a bad reputation and MUST be replaced when removed. This is simply good practice when dealing with nylocks anyways.
BUT.... I am trying to find out if the original part # (4775Q) is the same as a later part # (4775L). Current owners of Velvet Drive could not help with this question. But I have searched and the 477Q is not available anywhere I have looked.

[jimbunyard]

Originally Posted by Rowglide

It is part #15 ( and #1) these nuts are very shallow, and the nylock portion is just onto the thread with very little thread protruding. Double nuts (even thin ones) would be too thick. #15 has a bad reputation and MUST be replaced when removed. This is simply good practice when dealing with nylocks anyways.
BUT.... I am trying to find out if the original part # (4775Q) is the same as a later part # (4775L). Current owners of Velvet Drive could not help with this question. But I have searched and the 477Q is not available anywhere I have looked.

Since I can't put my hand on either or both, the internet wisdom says they are the same thread 1" x 20 (extra fine).

The 4775l is readily available for as little as 3.73 US, the 4775Q, 46.00 from Borg Warner Nut 4775q - Marine Parts Express

4775Q https://www.asapaerosupplies.com/rfq...0302948/4775q/ for sizing information

4775L 4775L 120 Thread Locking Nut - Drivetrain America

For 4.00 plus shipping it'd be easy to check for sure (or, more remotely, it may be possible to just call them and ask...). If the 'L' is too thick and the 'Q' is unavailable, it's easy enough for a machinist to thin the 'L' version to spec.

The shaft is splined after all, I'd reuse the old one, with locktite and the proper torque, but that's just me...

[Maka]

Originally Posted by Rowglide

Maka
Mine is not “easy enough” when it does break as it requires removal of the engine to get it out. And in my boat with my engine that is no small task. And that is why I will rebuild it now.

Ah ha.
In that case I stand corrected, you are doing the right thing.

Keep us posted please