velvet drive terrible noise only in gear

[Choices]

That's the plate I now have. Not sure lubing it will do much. Will just throw it off.

[sdowney717]

I see, makes sense to face it so the trans hub gets as much insertion into the DP as possible.

Curious as to what standard versus heavy duty really means here.
Thicker steel? Stronger springs? Does it really last longer? His boat wont see much use.

[sdowney717]

Plan tomorrow to put it back together, likely over the next 2 days.
He got the 107 plate, it is an upgrade from the triangular 6 spring plate Mercruiser used.

[sdowney717]

It is all together and will start and test today.
However,.... I did find out when putting trans back in, the output flange has some noticeable play. I did not notice that when taking it out.
I would estimate play of about 10 thousands .010 inch.

Seeing this is the newer style reduction drive and uses a spacer, anyone think the spacer is collapsed? Or is something worn down.

I have the 1 11/16" socket for the flange nut. I was reading in the trans manual, they mention bearing preload rolling torque of 15 - 30 inch pounds, and I see some spacers are solid (preferable) some meant to collapse? Some forum posts mention around 200 ft lbs on the flange nut.

So is that enough play to cause this noise? There is no leaking oil from the trans rear.

I also pondered trying to tighten the flange nut. Can the nut be at 200 ft lbs tight, and the end shaft still have too much play?

[sdowney717]

Also wanted to say, the damper plate bolts are shouldered, which means they align the damper plate concentrically with the flywheel, just any old bolt should not be used. And I could have used 6 bolts, but the old triangular plate had only 3, 3/8 grade 5 bolts. The flywheel has 6 machined shouldered bolt holes that can be used. The trans slid on in easily, was easier than when I did this on my engines.

My engine uses a small circular plate and 9 grade 8 1/4 inch non shouldered bolts to hold it on. which may mean the plate can move a little sideways. Might make it harder to bring together.

https://bpi.ebasicpower.com/shop/mar...c-070-008-1918

[rslifkin]

Are you really sure this is a reduction drive? I just looked at the video again and this looks like a 1:1 Velvet Drive, I don't see a reduction housing on it. For comparison, here's a photo of a reduction Velvet Drive:

[sdowney717]

Originally Posted by rslifkin

Are you really sure this is a reduction drive? I just looked at the video again and this looks like a 1:1 Velvet Drive, I don't see a reduction housing on it. For comparison, here's a photo of a reduction Velvet Drive:

Hi, the video just sounded the same noise, ignore the photo, it is not the trans we are dealing with

This is ours
https://photos.google.com/share/AF1Q...lyS3RUQnJOT1Nn

[rslifkin]

Originally Posted by sdowney717

Hi, the video just sounded the same noise, ignore the photo, it is not the trans we are dealing with

This is ours
https://photos.google.com/share/AF1Q...lyS3RUQnJOT1Nn

Gotcha. Definitely a reduction unit then. The good news is, if there ends up being an issue in the reduction unit, you can slide the shaft back and pull the reduction housing off the trans without taking it back out of the boat.

[sdowney717]

Originally Posted by rslifkin

Gotcha. Definitely a reduction unit then. The good news is, if there ends up being an issue in the reduction unit, you can slide the shaft back and pull the reduction housing off the trans without taking it back out of the boat.

I was think something like that too.

[sdowney717]

I rebuilt one of mine, the older original reduction unit style has the double uni bearing and bolt on rear collar.
This kind has a spacer separating 2 roller bearings.
I probably could do this work myself, if I got motivated to help him some more. I dont think there should be so much looseness in the rear flange I have read about .005 is ok.
But if noise is gone, wont plan on doing any more to it.
Still want to know how 200 ft lbs of torque on the nut relates to this spacer and maintaining proper pre-load on the 2 cone roller bearings. sometimes I have to take things apart to understand how they work. I would think the spacer is pressing on the inner bearing races of both bearings. And the nut pressure is forcing the outer cone bearings together like a sandwich with the output shaft and bushing assembly to the outer prop shaft connector flange.

So somehow, 200 ft lbs of nut torque translates to 15 -30 inch pounds of rolling shaft torque pre load?

[sdowney717]

Originally Posted by Choices

That's the plate I now have. Not sure lubing it will do much. Will just throw it off.

It never throws off all the lube you put into it due to surface tension of the thick oil.
His old plate showed wear and trails of rust. That inner hub has fingers that interact with the springs and it has faces that slide against the steel stamped parts, it is under a constant moving pulsing force generated as the pistons fire.

I am thinking if it is too loose, then the spacer is too long and it can be ground shorter. That will bring the cone roller bearings closer together and tighten the clearances. So it might not be too hard to fix it better as in no need to buy new spacers.
Those roller bearings are supposed to have a preload, meaning they run tight enough that there is no play. So 10 thousands of looseness, means grind 10 thousands off the spacer at least. It is a trial and fit method to get it correct.

I wonder if a too loose rear bearing like that will cause that kind of noise?

[sdowney717]

My crude drawing of the spacer cylinder relationship to the shaft, flange, housing. So you can see shrinking the spacer, tightens the cone bearings.

[sdowney717]

Totally silent, fixed, no more awful noise.
So a little play in the output bearing does not mean any noise.
The damper plate was really worn out.

Only thing extra I might have liked was 3 more damper plate bolts.

Just got back from the marina to post a success story.

[OldDan1943]

Originally Posted by sdowney717

Totally silent, fixed, no more awful noise.
So a little play in the output bearing does not mean any noise.
The damper plate was really worn out.

Only thing extra I might have liked was 3 more damper plate bolts.

Just got back from the marina to post a success story.

Fantastic!!!

[Ski in NC]

Did you try to snug the output flange big nut? 0.010" of play in that pair of tapered roller bearings would concern me.

[sdowney717]

Originally Posted by Ski in NC

Did you try to snug the output flange big nut? 0.010" of play in that pair of tapered roller bearings would concern me.

No did not, thought about it next day but it was already together.
I could not feel the slight looseness when it was full of oil, only after it drained for a week. I asked him if he wanted to look into it, but for now he did not.
The flange is not rocking loose on the shaft. And there is no leak. If the nut was that loose, oil would leek out the end. The large nylock nut seals oil from seeping past the shaft and flange. it is one reason they want you to use a new nut on a repair, but you can use Permatex RTV

[Choices]

It is really amazing how much racket that plate can make.