bmc 1.5 with newage mt 103 transmission

[walli]

Hello again to the great forum, that helped me many times. I have a 7 ton sailboat with a BMC captain 1.5 engine and a Velvet Drive AS3-70C transmission from Borg Warner. Ratio 2.10:1. The BMC is older, one cylinder has low compression. The motor leaks oil and does not sound reliable. I bought a used Captain with good compression and which seems to be ok and dry. This engine has a Newage Conventry mt 103 trans and I would like to put this into the boat. I searched the Internet and your forum, but could nowhere find a manual or information about the newage coventry mt 103 gearbox.
My question: What is the ratio of a mt 103 compared to the velvet drive. Can I use this transmission for the boat or do I have to refit the velvet? All information about the transmission would be helpful at the moment.
Best regards,
Douglas

[Tony Brooks]

42 minutes ago, walli said:

Hello again to the great forum, that helped me many times. I have a 7 ton sailboat with a BMC captain 1.5 engine and a Velvet Drive AS3-70C transmission from Borg Warner. Ratio 2.10:1. The BMC is older, one cylinder has low compression. The motor leaks oil and does not sound reliable. I bought a used Captain with good compression and which seems to be ok and dry. This engine has a Newage Conventry mt 103 trans and I would like to put this into the boat. I searched the Internet and your forum, but could nowhere find a manual or information about the newage coventry mt 103 gearbox.
My question: What is the ratio of a mt 103 compared to the velvet drive. Can I use this transmission for the boat or do I have to refit the velvet? All information about the transmission would be helpful at the moment.
Best regards,
Douglas

 

Photo please, I suspect it is Newage of Coventry (now PRM I think), but what the MT130 is I don't know.

 

I  suspect it might stand for manual transmission (mechanical), as opposed to a hydraulic gearbox, but don't know.

Edited August 27 by Tony Brooks

[john.k]

Why replace a common gearbox  with a complete unknown ?.............its obvious you can swap any needed parts from your motor to the new one to fit the velvetdrive.

[Tony Brooks]

8 hours ago, john.k said:

Why replace a common gearbox  with a complete unknown ?.............its obvious you can swap any needed parts from your motor to the new one to fit the velvetdrive.

 

On a marine BMC 1.5D it may not be as easy as that. There are two flywheel housings and one requires an adaptor/cover plate. If the modern flywheel housing is drilled to suit the Velvet drive then it should be a straight swap, but that IF may be a problem.

[walli]

Thanks for the replies. If possible I would like to use the newage gearbox. The velvet drive makes alot of noise and probably should be rebuild before using it.

[Tony Brooks]

Thanks, you have a very good box, it is a PRM hydraulic, but I don't know which model, possibly a 100, but I will leave it to others to tell you that. PRM can probably ell you from the number stamped into the red plate at the top.They should also be able to tell you the reduction ratio. Hopefully it will be about 2:1 so you can keep the prop. Those boxes will run happily in either direction, unlike many, but the nominal ahead and reverse ratios will be very slightly different, but not enough to worry about.

 

Further points.

 

That engine has the old style flywheel housing and the old, obsolete (no longer obtainable) Metalastic rear mounts. This may or may not match the other engine. Again, a photo should clear that up.

 

Both gearboxes need an oil cooler, so that would be a straight swap.

Edited August 28 by Tony Brooks

[walli]

Thanks Tony. The mounts are the same and much better as by the old engine, so everything should fit.

Once more the question: can I use this transmission on a 7 ton sailboat. I do not know much about ratios, propeller sizes etc. As I mentioned above, the velvet drive has a ratio of 2.10:1. For me it would be much easier if I could use the Newage instead of rebuilding the velvet drive.

[Tony Brooks]

30 minutes ago, walli said:

Thanks Tony. The mounts are the same and much better as by the old engine, so everything should fit.

Once more the question: can I use this transmission on a 7 ton sailboat. I do not know much about ratios, propeller sizes etc. As I mentioned above, the velvet drive has a ratio of 2.10:1. For me it would be much easier if I could use the Newage instead of rebuilding the velvet drive.

 

That is why I said contact PRM with the serial number. If you post it here, we may be able to decode it as long as it gives the ratio.

 

If it is a 3:1 ratio, then the engine will rev like the blazes, and you won't go very fast. If it is a 1:1 then the engine will probably overload and produce clouds of black smoke when you try to put some revs on.

 

Unfortunately it needs the engine running to get the oil pressure it needs to put it into gear, so you can't stick it into ahead, turn the engine by hand, and count the prop shaft revolutions.

 

I understand many smartphones can have a stroboscopic rev counter app, so you could get the engine running in gear and compare the crankshaft pulley speed with the gearbox half coupling speed.

 

It should be fine as long as the reduction ratios are the same, after all they work well with 10 ton plus canal boats which also run at displacement speed.

 

 

From the PRM website

Edited August 28 by Tony Brooks

[walli]

I got in contact with PRM newage. I will let you know when I get an answer.

Thankyou

[hider]

Its an old PRM100  I remember these from one I serviced years ago.

PRM used to sell a kit to do without the filter which they say is no longer needed. But its probably easier to just use a new filter.

 

The number Mt 103 is just a casting number.

[Tony Brooks]

4 hours ago, walli said:

The mounts are the same and much better as by the old engine,

 

FWIW

 

Those mounts poke through the feet on the flywheel housing from underneath, and their flange is then to the foot secured by three 1/4 AF hexagon machine screws, again from underneath. When the mounts collapse the heads of those machine screws tend to hit and bounce on the engine bed, not a major problem on a wooden bed, but noisy on steel and may wear through a GRP bed. In the later case, water can get into the centre of the bed and rot whatever is in there. It may be balsa wood, paper rope etc.

 

If they are badly collapsed, you can pack the centre of the mount up with penny washers below the mount centre - always assuming you can still align the engine.  See below

 

As routine, when we had an engine out of the hire cruisers, we used to halve the thickness of the  hexagon head to give a little more clearance from the bed.

 

The traditional engine foot packing shim (rectangular with a cut-out to go around the main securing screw/stud/bolt) will work, but it stays close to the hexagon heads, so I always favoured penny washers where possible on 1,5Ds with packing shims underneath the said washers if needed.

[Tony Brooks]

I just realised that the Velvedrive is, I think, an inline gearbox - that is the output coupling is in line with the engine crankshaft. The PRM has an offset drive that can be fitted to give an offset to the left, right, or bottom. This will have implications for engine alignment. The photo seems to show an offset to the bottom, so you will need space to lift the engine off the beds by the amount of offset. If you have the space above the engine, then a couple of lengths of timber of suitable thickness secured to the beds would do, or longer screws/bolts/studs and metal spacer blocks.

 

If you decide to go down the timber route, we had problems securing them to the GRP beds because coach screws pulled out of the GRP and whatever was in the bed. We solved that by pouring some GRP resin into the holes for the screws and then fitting the screws. It held well.

Edited August 29 by Tony Brooks

[walli]

Hello Tony,
thank you for the information. I took a look at the engine and transmission and now I understand what you are saying. I will have to compare it with the motor in the boat, but as I already see the attachment for the shaft seems to be lower. I will also have to see if I can lift the engine up about four or five centimeters. Since it's a steel boat there should be no problem with the mounting, if it fits.
I was planning to do an easy one to one exchange of engines and transmissions as soon as I know the ratio of the newage. But now things may get a bit more complicated. That is if I have to get the vevet drive overhauled and exchange the newage with it.
The information about the mounts was also very helpful. That might be where the ratteling, knocking noise comes from. When I stand on the engine while running the noise seems to get less.
Thankyou, Douglas