BMC Commodore PRM Gearbox

[Jo Burge]

I fitted one of these lovely old clunkers to my lifeboat conversion thingy. It's a 3.4 and performs commendably making all the right pulsing noises and smells that give tugboat-chic. The gearbox shift has become progressively stiffer though. The control is simply a straight brass lever about 2 foot long acting straight on the 'box so the problem must lie with the selector shaft bearings. I can find very little information on these Newage mechanical boxes. Can anyone advise or suggest where I might find out more?

 

[Forbsie]

There are a stack of manuals available Here for PRMs. Scroll down on the left column to Transmissions.

 

[SAMYL]

What model of box is it?

 

[Latestarter1]

What is in a name?

Jo,

The names can be real confusing. Newage mechanical boxes were originally Morris. Newage was created when the separate Austin Marine and Morris Marine entities were brought together under BMC banner. Morris Marine was stronger brand however Austin had the modern engine designs, Morris had decent mechanical boxes.

If your box has a round tapered body with drop reduction on the back it is the Morris box, square plate on top with a bolt on each corner. Unbolt top plate and adjust the yoke to ensure brake bands engage just enough to engage without slipping.

Life became very confusing under Newage as they developed their own clunky hydraulic boxes as well as using SCG boxes branded as Newage. PRM took on some of the Newage stuff but designs totally unconnected with anything produced by PRM in recent past.

Newage, PRM, SCG all part of BMC/BL balls up at one time or another. Newage was carved up into Tempest (Marine engines) Newage (Generators) Newage/PRM (Hydraulic transmissions) and SCG (Heavy duty hydraulic transmissions).

Where are they now; Tempest gone, Newage Stamford split and sold to Hawker Siddley, then on to Cummins, still going strong. Newage PRM have been in and out of intensive care a few times, Newage industrial transmission business seems to have vanished, PRM staggers on building good but expensive marine boxes. SCG were sold to Cummins who in turn sold them to Alvis, who themselves had at one time been a BL company (are you confused yet) BAE systems absorbed Alvis shut down SCG and I think cut a deal with Twin Disc to provide spares support for SCG boxes in service with the military, so SCG is now also consigned to history.

There are enough Nuffield tractor parts out there to keep your BMC 3.4 running forever, the gearbox is on borrowed time, when phosphor bronze clutch plates wear out fit second hand PRM or Twin Disc.

 

[Jo Burge]

Newage gearbox

Thanks for the help. I don't know what model it is but the gearbox is indeed as 'latestarter' describes, a round tapered casing with a square access cover and a drop down drive aft. What might it be then?

 

[SAMYL]

Have a look at www.prm-marine.com and you should be able to identify your box there from one of the pics. The also have diagrams and parts lists which are very explanitary
I would imagine that with your engine it would be one of the bigger boxes which all look vaguely similar with similar layout of components.
I have just finished rebuilding a PRM 260D box which is one of the 'bigger' boxes although at the lower end.
The gear shift is a lever which moves a shaft which is really only a diverter valve, it directs the oil flow to either the forward or reverse shafts with their oil operated clutches.
The gear shift shaft is a rod running in the valve assembly on top of the box and operated by a morse lever or in your case a direct lever attached to the shaft. The rod has holes and passages drilled in it so that when it is turned it directs the oil to different passages going to the forward and reverse clutches, hence changing gear. The shaft itself does not run in any bearings but runs directly in the casting of the valve body, is sealed with O-Rings and is held in place by a plate and two screws. If you remove the screws you should be able to remove the shaft to see what is wrong.
The box I was working on had a very stiff gear change and would not go into reverse. The problem was traced to a build up of rust and crud between the operating lever and the valve casing, it doesn't sound like much but it stopped it working properly, so I would suggest your first port of call would be to remove the lever and clean well behind.
I can't think of anything else that would make the lever stiff as it is just a rod turning in the casting and not connected to anything else.
I hope that helps, please contact me if I can be of any further assistance.

 

[Latestarter1]

Newage Commodore gearbox

SAMYL,

No Morse cable made that is ever going to operate gearbox on the back of this old Commodore because it aint no hydraulic gearbox, particularly a PRM one. I thought I had explained all that in my posting. It is most likely Newage mechanical box to original design out of Morris Marine Motors latterly built by Newage.

Oil immersed phosphor bronze clutches operated by a large brake band. Hence big lever on the side. Not modern rocket ship hydraulic stuff, likely just needs adjustment.

None of the PRM stuff existed when this old lady left Newage.

 

[Jcorstorphine]

SAMYL,

No Morse cable made that is ever going to operate gearbox on the back of this old Commodore because it aint no hydraulic gearbox, particularly a PRM one. I thought I had explained all that in my posting. It is most likely Newage mechanical box to original design out of Morris Marine Motors latterly built by Newage.

Oil immersed phosphor bronze clutches operated by a large brake band. Hence big lever on the side. Not modern rocket ship hydraulic stuff, likely just needs adjustment.

None of the PRM stuff existed when this old lady left Newage.

Had one of these gearboxes on a Newage Vedette. Exact same as described and takes some force to engage. There are two adjustmnets, one for forward where you adjust three toggles to put pressure on the plates and another adjustemnet for reverse where you alter the clamping force of the brake band. As Latestarter said, it not rocket science. If i can find the manual from our 1960 engine i will photocopy the pages and send it to you.

JC

 

[SAMYL]

SAMYL,

No Morse cable made that is ever going to operate gearbox on the back of this old Commodore because it aint no hydraulic gearbox, particularly a PRM one. I thought I had explained all that in my posting. It is most likely Newage mechanical box to original design out of Morris Marine Motors latterly built by Newage.

Oil immersed phosphor bronze clutches operated by a large brake band. Hence big lever on the side. Not modern rocket ship hydraulic stuff, likely just needs adjustment.

None of the PRM stuff existed when this old lady left Newage.

Your post was titled PRM Gearbox and the wording indicated that your really hadn't a clue about anything else.
Anyway I made an effort to help which is all that matters.........

 

[Jcorstorphine]

Instructions for setting gearbox

I have found the instructions for setting the old type Newage Gearbox. If you would like the data, send me an email link and I will forward information.

 

[pheran]

SAMYL,

No Morse cable made that is ever going to operate gearbox on the back of this old Commodore because it aint no hydraulic gearbox, particularly a PRM one.



None of the PRM stuff existed when this old lady left Newage.

Unless I have misunderstood what you are saying, I fear you are wrong. I had a boat with twin 3.4 Commodores which were fitted with PRM hydraulic boxes, Model 60s if I remember correctly.

 

[Latestarter1]

Newage

Yes you did misunderstand me.

I started an engineering appenticeship at JG Meakes Marlow, in the days of the doughty Mr Jack Hobbs. Meakes had been the Morris Marine agent since it was first set up in the 1930's. Morris became Newage BMC with Meakes given an even bigger territory.

Meakes was building the Sealion range on Dutch hulls with Newage BMC 5.7's when I started although the majority of our business was still gasoline engines. In the 60's the world was changing customers wanted single lever controls on big engines and having gearboxes which did not need regular adjustment was a big plus for the hire boat market. Mechanical boxes were on the way out.

Newage BMC designed a nasty psudo hydro mechanical gearbox, fitted SCG on the 5.7's and by the time I was working for Meakes, PRM was part of Newage. Mechanical boxes were then only available on smaller engines Vedette up though to the 2.2 with just a few Newage PRM's on larger engines like the 3.4 as the SCG box cost almost as much as the engine.

My point is that when the 3.4 originally came out there was no hydraulic option. The SCG was far too expensive, yes, later versions had Newage PRM boxes, but repeatedly pointing Jo Burge at modern PRM hydraulic boxes is as much use as a rubber eye.

Even by the early 60's Newage was falling apart, we fitted Rootes Lister TS3's instead of 5.7's in later Meakes Sealions with Borg Warner gear boxes and never looked back. I was released from indentures to take up apprenticeship in Merchant Navy. Stupidly I mentioned the word Newage and I found myself in charge of the Mk3 Vedettes in the life boats.

Visited Meakes in later years, Newage was now Tempest and proved even worse than Newage and had been ditched in favour of DAF Marine dealership, Morris/Newage/Tempest parts going back 40+ years went to local scrap man, well almost.

Anybody with GENUINE requirement for a brand new Morris Vedette SV exhaust manifold PM me, when that is gone just left with memories.

 

[scottie]

latestarter

I still have nightmares about frozen austin + morriss life boat engines . Trying to start a frozen engine in a life boat in scottish winter months was to be avoided

Did some of thr BMC gearboxes not have an external hydraulic system useing clutch cylinders

 

[Latestarter1]

Newage nightmare

Yep,

That was exactly the Newage junk I was referring to, a mechanical box with BMC automotive origins operated with external hydraulics.

Design team starved of cash and obviousy on recreational drugs.

Then sombody showed my a stuff from Borg Warner and Twin Disc, heaven!

 

[scottie]

Newage nightmare

Nitpicking but Morse did make some very heavy cables which could move these boxes but were very special
I think that morse controls were just being introduced into the UK by Perkins around that time
I wonder how the industry would like to be back in these times with the mechanical linkages etc

 

[Latestarter1]

Heavy duty morse

The heavy duty Morse stuff I forget the designation, for mechanical boxes has been out of production for years.

Lancing have very limited number of old stock cables left and they made me a 'new' control head out of the last of their spares stock a while back now.

However this Morse stuff was only capable of operating small Morris Marine as on Navigator and Watamota J type boxes, just puddle jumpers, nothing serious.

I do not think any right minded person would want to mess with adjusting clutches and cables....

I am now well past my sell by date, however do not live in the past, firmly on the page of full authority electronic engines with smart transmissions such as Twin Disc Quickshift.

I do no remember past with that much affection.

 

[scottie]

Heavy duty morse

No I was not talking about the teleflex D range

I was being smart and talking about some extra heavey cable which I have be involved with some years ago.

 

[jazzyjeph]

Had one of these gearboxes on a Newage Vedette. Exact same as described and takes some force to engage. There are two adjustmnets, one for forward where you adjust three toggles to put pressure on the plates and another adjustemnet for reverse where you alter the clamping force of the brake band. As Latestarter said, it not rocket science. If i can find the manual from our 1960 engine i will photocopy the pages and send it to you.

JC

Hi do you still have the adjustment details for the Morris gearbox as I appear to have one atached to my BMC/BL 2.5, so far this is the only place on the internet I have found any information regarding Morris gearboxes. Also do you know/ does anyone know the type of Gear Oil required and the amount to put in and how do you tell without a dipstick, mine just has a pressure refief cap on it. Regards.

 

[Jcorstorphine]

Send me your details

Hi do you still have the adjustment details for the Morris gearbox as I appear to have one atached to my BMC/BL 2.5, so far this is the only place on the internet I have found any information regarding Morris gearboxes. Also do you know/ does anyone know the type of Gear Oil required and the amount to put in and how do you tell without a dipstick, mine just has a pressure refief cap on it. Regards.

If you send me a PM with your email address I can send you some scanned copies.

John