prop spin in neutral (TRS)
 

I recently purchased a boat with TRS drives, the starboard drive rotates with the shift selector in neutral (rotates faster when shifted into forward). Is this just an alignment problem with the shifter, or does the transmission need a rebuild. The previous owner claims that it has done this since he owned it (5+ years). The drives are original on a 40' excalibur hawk (1983).

What type of transmissions are on it Vevet drives?

I am guessing you are fine. See if they turn when in the water. I think what you are seeing is common and when you have the resistence of the water there they will not turn.

Jon

They are the B.W. Velvet Drives.

As far as the spinning it occurs in the water, I have never run the engines out of the water. The prop spins enough to cause the boat to slowly drift forward.

The plates in the trans are warped and providing slight contact. They still could last quite a while in this condition. I think you will find they are reasonable to rebuild

Yup, what mmwalters said. It might last for years or it might decide to give up tomorrow. I'm betting on giving up sooner than later, especially if you've got to shift it above 1000 rpm. It will be cheaper to fix before it gives up. Oh, by the way, when it gives up it will be locked in gear.

what they said

Yup now that I know it is in the water doing it I agree with these guys. Mine spins a very little out of the water and that is what I thought you were talking about. I also agree that it would probably be cheaper to fix it now then after total detonation. I hear that Marc is sapposed to be VERY good at rebuilding them. Also Huber is another good one.

Jon

A buddy of mine has a TRS with the same problem-will actually move the boat forward slightly. A really good trans builder that is also a friend of ours said to run it in neutral like that at about 2000 for a few minutes to loosen up the clutch pack-might be worth a shot before the rebuild. If it scuffs a little off the clutches they might not drag any more.

I have had the same problem many times
Inside the Velvet drives are steel shims with
clutches. What usually occurs is what everyone above has mentioned. Removal of the trans will be nessary.
The cluches are rings normaly flat when placed on a flat surface. Chances are when you remove them and lay one on a flat surface it will be concave. shaped like a cone. I can tell just by spinning the prop on the trailer
if it is hard to spin the clutches are getting warped again. This causes friction against the shims which is what causes the movement of the prop when your actualy in neutral.
The borg and warner velva drive is a very simple transmission inwhich any transmission shop surely could handle.

Contact Bam Marine they have some excellent high performance replacements.
954-545-8681
Simplicity marine drives also offers the original cluches.
941-722-8475

Good luck
Gerry

Ok, here is the scoop. The production trans uses brass friction pates against steel drive plates. When overheated (which is usually caused by slipping under load) the plates will warp as mmwalter & Gerry says. Once this happens the clearance needed in the clutch pack for a clean neutral goes away, the plates are always rubbing. When they warp enough they will lock the trans in gear (per crazyhorse), and kill the engine if put in reverse.

It could work fine for quite a while, would help if you change to type F or FA fluid(ford spec). We use a graphite composite friction plate with a higher COF (coefficient of friction) and more of them. They are much less prone to slippage than the stock plates. Only problem is that they are softer than the brass, and if they do slip they go away altogether, no limping home while locked in forward.

The Ford fluid is a good bet in any case, it does not have the friction reducing modifiers contained in the Dexron fluids.

Marc, I've got a question for you. With the extremely limited hard usage my boat (38 Cigarette flat-deck) sees, and considering I have stock Velvet Drives in front of my SSM#A drives, is it worth upgrading them to something more in line with the supercharged 650 horsepower engines I'm running? Do you have a ballpark figure to upgrade them? I'm not looking to rain money on the boat but I understand these transmissions are nominally rated for 400 hp.
The engines idle at 800 in neutral and 650 in gear. Let me know if you need any other information.

Thanks for the info, looks like I'll be doing a rebuild in the very near future.

Since I'll have the transmission out are there any other components that should be replaced out of general preventive maintenance?

I just talked to a marina in my area and they mentioned the plates may have been shimmed tightly together causing the spin. Does this sound possible? The previous owner says there has never been a burnt smell of the fluid, however the spin was always there since he owned the boat.