Borg Warner Velvet Drive Gearbox Problem

[DBA Forum (B) - Bob Alexander]

Hi, this is my first post so please forgive my posting ignorance. On my maiden voyage from Maastricht to Nieuwpoort in 13m DB all went well for 6 days until gearbox went clunk and started to shake and rattle in forward drive, works fine astern. After lifting the hatches there is now a fine black coating to almost everything, could this be from the breather? Does anyone have any knowledge on these gearboxes - It appears to be a 71C of unknown vintage. I would like to talk to someone on the phone if poss.

[DBA Forum (B) - Andy Soper]

Bob and I have had a chat. He is now safely at Westhoek marina near Nieuwpoort and we have shared possible solutions to his problem. Anyone with experience of Velvet Drive Gearbox could still add to Bob's knowledge!

[DBA Forum (B) - Bob Alexander]

Many thanks for the call Andy, invaluable advice. Changing the box may not be an option as there is no room to lift the engine, does anyone have anything good to say about the Velvet Drive???

[DBA Forum (B) - Charles Fitzhardinge]

Our tjalk Anna Maria has a Velvet AS17-72C (s/n 7977) probably installed new about 1976.
This has worked well for us over the 7 years we have owned this boat.
Our only problem has been persistent loss of ATF, which heretofore soiled our bilge and if not checked weekly sometimes led to brief surging then loss of power - usually loss of reverse when slowing in a lock - potentially embarrassing! ...
Over the past 2 years we have "solved" this by collecting the lost fluid in a drip-tray under the gear box and periodically filtering it (through a coffee filter paper) and re-using it. No problems so far.
Like you, we have hesitated at the cost of replacement, particularly given the access problems.
The gearbox itself performs well provided it has adequate fluid level.
Charles Fitzhardinge
Anna Maria

[DBA Forum (B) - Chris Green]

Many thanks for the call Andy, invaluable advice. Changing the box may
not be an option as there is no room to lift the engine, does anyone have
anything good to say about the Velvet Drive???

Well mine seems to have worked without any hassle for three or four
years now. It even put up with no oil in it for a while until I
discovered its dipstick! :-)

[DBA Forum (B) - Balliol Fowden]

I've never had much experience of these boxes although we have had a few over the years. Perhaps that is because they have a good reputation and we never had to take one apart!

However, I wonder whether your problem is the drive plate. Subject to engine type there woiuld normally be a drive plate / damper plate between the flywheel and the gear box, eiither a spring-loaded plate a bit like a car clutch plate or possibly a plastic / nylon type. Either way they act as a torsional damper and, to an extent, a deliberate weak link in the drive train. I wonder if this has broken up? You will almost certainly need to draw trhe gearbox off to find out but there might just be an inspection cover in your bell housing. A failed drive plate would not generally generate a black deposit in itself, but it could cause clunking and vibration and may have overloaded the clutches.

Balliol.

[DBA Forum (B) - David Puttock]

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[DBA Forum (B) - Bob Alexander]

Many thanks to you all for your replies, this forum has restored some of my lost confidence in barging? and the inherent problems that arise, shame mine started almost as soon as I did!
I'd like to answer the replies in order to make sure that I understand the content.

Charles - when you say that you lost ATF did this come out as a liquid or as a fine mist that covered everything? I am assuming as a liquid if you were able to collect it, could the black coating be from the breather - I originally thought I had an exhaust leak.

Chris - like yourself I only became aware of the component parts after researching the box on t'internet, talk about horses and stable doors!!

Balliol - I saw the drive plate setup on an exploded view of the gearbox but discounted this as the box seems to work fine astern. Still baffled about the black deposit though.

David - When I said that I lost forward drive strictly speaking that may have overstated the fact, what happened was that when the rattling started I immediately closed the throttle, and as I thought I may have picked up something around the prop engaged reverse, seemed OK so gingerly selected forward, prop turned but the box rattled violently and shook with any application of revs, terrible din.
Two days later after organising a tow the rattling was not as bad but I was doubtful about how long that would last, could that be because the box had cooled down maybe? Not confident enough to try this out and break down again, v costly.

Again thank you all for your input, this forum is certainly a mine of information and any thoughts and or suggestions will always be gratefully received - please keep them coming - a problem shared and all that.

Best regards

Bob Alexander

[DBA Forum (B) - David Puttock]

Hi Bob,
In view of your reply,I suggest you try & have a look @the drive plate,this involves moveing the gearbox back.How differcult this may be depends very much on the lay out & acess,but its not a backward step as you would have to do it to remove the gearbox if it is indeed faulty.Are you one hundred percent that you do not have a fouled propeller? Both a broken drive plate & a fouled propeller could cause severe shaking.
Best regards
Dave Puttock.

[DBA Forum (B) - Charles Fitzhardinge]

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[DBA Forum (B) - Charles Fitzhardinge]

Bob
You might like to look at this site which has a lot of pertinent info on the Velvet 71 series (superceded) and the 72 series, including noise sources etc - http://www.harbormarine.net/transmission-service.

When I last trawled the web, thinking as a last resort to replace my unit, there seem to be remanufactured exchange ones available for about $600-1,000 US and somewhat more in Australia (but not exactly carry-on baggage).UK prices seemed high and I did not find any EU ones (I am sure they are there as the drive is not uncommon).
Should you follow this path you need to note the reduction ratio (in my case 1.91:1) as well as the model number.

Charles Fitzhardinge