Borg Warner Velvet drive and Perkins 4107 issues

Rosie1963

Rosie1963

Well-Known Member
Joined
19 Mar 2014
Messages
193
Location
Ipswich
ramblinginrosie.blogspot.co.uk
Last Autumn I paid a vast amount of money to a marine engineer to replace the very crunchy bearings on a Borg Warner 70c gearbox - the engine needed to be lifted out of the yacht for this to happen. He said he replaced the bearings (after a long search for the parts where I tried to help but was not involved in the end). The engine was never bench tested (Lazy - as it was out of the yacht for three months) and was only run onboard when back on a mooring. Now after a overwintering in a marina the engine has done 4 hours under load since the gearbox was rebuilt.

My question is that there is a decisive crunching sound when (just) engaging astern or forward. Once the lever is moved further forward or aft (in astern) the crunching noise stops. The noise remains though if the lever is not shifted further forward or further back depending in what gear you are in. As I have never used been used to what a Velvet Drive should sound like - should I be get any crunching noise at all on the gear shift in a hydraulic system - specially one with the name Velvet in it? I wonder if any other Velvet drive owners out there could either reassure me that is either normal or that it need some further investigation.

Many thanks,
 
I have the Borg-Warner velvet drive on the back of a Perkins 4236 with a fixed 3 blade propellor. It does not crunch when going in and out of gear, does not even clunk, very smooth engagement. Once engaged there is no further detectable noises from the box. The selector does need a bit of work when adjusting to get it at the right point otherwise there is sufficient hydraulic drag to keep the propellor turning in neutral and a bit of reverse is required to cancel this.

Further investigation is needed I am afraid. Do you have a folding propellor?
 
Is the boat new to you? The reason I ask is that when I picked up my yacht I thought that there was a bag of ball bearings rattling around. It turned out to be cavitation as my boat is has a propellor that is too big. It was clear after investigating that the noise was around the hull area where the propellor was and not the gear box. It did sound like rattling bearings. A previous owner decided that they wanted low reving, hi water speed, so specified the over sized prop. At normal revs cavitation noise is the result.

Stick a long bladed screwdriver on the gearbox and place your ear on the handle and listen, internal noises are easy to detect this way. Move the screwd driver around testing at different bits. It could help to narrow down the noise.

My yacht is a Rival 41C. Good luck.
 
Had her 4 years now - constant refurb year on year. The gearbox always made an obvious crunchy sound - two separate engineers agreed it was bearings. The noise has improved but I am not getting velvety smoothness as reputed by the name of the gearbox. The crunching is not prop related I am sure. The prop is under spec'd - I have checked that, but if I go a prop-up, I cant get the prop in the aperture. So I have considered that. Feathering prop is on my Christmas list......
 
Rosie1963 said:
Had her 4 years now - constant refurb year on year. The gearbox always made an obvious crunchy sound - two separate engineers agreed it was bearings. The noise has improved but I am not getting velvety smoothness as reputed by the name of the gearbox. The crunching is not prop related I am sure. The prop is under spec'd - I have checked that, but if I go a prop-up, I cant get the prop in the aperture. So I have considered that. Feathering prop is on my Christmas list......
Click to expand...

Borg Warner Velvet Drive 70 Series is pretty rare transmission, was around in the 1960's when I went on a short course on BW gears however 70C gone by the 1970's but vital overhaul parts common with 71 Series freely available from ASAP Supplies and noting comments re: bearings are standard off the shelf sizes from any bearing factor worry starts to set in.

Is this a reduction version or direct drive transmission?

Does not take an 'engineer' to overhaul a a BW transmission, it is a simple fitting job which is easy to complete in one day. I would ask the clown who had the box apart if he ran it up after completing the repairs to remove it and fix it at his dime. If you are a competent fitter and in any doubt, very easy to set up on a test rig using an electric motor, just needs a short length of thick wall rubber tube tube and jubilee clips to test transmission.

Simply pass the problem back, hope you have not paid your bill yet!
 
many thanks for this very informative reply. I paid. I paid A LOT.its a Borg Warner 2:1 reduction gear with reverse gear, rebuilt 1983. S/S 1 1/2inch propeller shaft driving
bronze 2-bladed fixed propeller (right handed)
 
I have old shop manual and parts book, PM me if you require pdf copy.

The main box hydraulic box has just two large bearings and is pretty much bomb proof. The reduction box is a separate module on the rear of the main transmission. Sounds very much like your grinding noise is coming from the reduction unit and not the main transmission case.

There used to be a video on Youtube outlining the steps required to rebuild a BW 72CR and process is exactly the same for 70/71.

Put Borg Warner transmission into Ebay and you will find parts a go go, many from the U.S however suppliers always happy to ship, alternatively there is a 1.91:1 71CR for £350 which is a little over priced but if you get your cash back may be a way of cutting losses as rebuilding the reduction section can be more expensive than main box if it has been allowed to grind away for a few years without attention.

Good luck
 
While your at it check the fluid level, and make sure the selecting lever travel goes all the way when engaging gear, done by adjusting cable, if you disconnect the cable, and move the lever you will feel it engage the detentes for forward/neutral, and reverse. As already stated there should be no noise. If no feeling then remove lever (be ready to catch the ball bearing and spring) clean the assembly and refit add a tiny bit of grease to spring and ball.
 
I can recommend Lancing Marine at Portslade, they overhauled one for me and did a great job not the cheapest but the best and they will advise by phone. They have a proper test rig
 
Well the latest on this is that a third part engineer has had a look at the gearbox and says that he cannot see any evidence of the gaskets been prized apart of that the rust on the bolts being disturbed and is highly suspicious of the gearbox being taken apart at all! So I think that the best bet is that I haul the boat out, take the gearbox out and drive it down to Lancing Marine to have a look at and see where we go from there. If they think it has not been touched I am not sure what further steps I can take with this cowboy engineer?
 
Hi...you can probably get the gearbox out afloat,with no need to haul out. If you are alongside in a marina berth should be a doddle,as long as you can slide the coupling/shaft back far enough to get the spigot out of the flywheel/drive plate....be aware the box is heavy.....and make a wood jig to rest shaft in...good luck...+1 for Bellamy at Lancing.
 
I had a BW velvet drive on my boat and for the 8 years in my ownership and thousands of miles motoring, it operated as the name suggested, 'velvet smooth'. I'd get it checked again from a reputable vehicle gearbox repairer, there are many around.
 
You must log in or register to reply here.

Share this page

Top