BMC engine mounts and mini coupling

[Marcus J]

Hi all!

 

So, I really hope one of you out there might know where I could find some of these old engine mounts. They are the metalastic top hat type with three bolts that screw into the bell housing. I've seen that there are some really useful previous threads on here that have exactly the same set up as me with these rear mounts, the bobbin forward ones and the 4" coupling from a mini driveshaft.

 

Unfortunately ASAP and Calcutt don't have them any more and, am I right in saying that Thornycroft don't exist now? Their website doesn't seem to anyway and it's been a long time since I've seen a yellow pages.

 

My mounts are very dead and that has killed the shaft coupling, which I also can't find as it has a register of 85mm, and everything now seems to be 2.5" I think I can solve all of this with a new 5" OD shaft coupling, flexi coupling and then getting an adapter bobbin turned up to go from that to my gearbox flange, which is 5.5" and also has a strange 85mm register.

 

But... unless I can find some engine mounts none of it means anything. Please, any suggestions would be greatly appreciated.

 

Do I try to get a mount turned up? or just mount it solidly? It's a pretty smooth engine after all. The old mounts have a lovely dusting of metal around them so I think any hope of re-using them has been put out of my mind.

 

Many thanks in advance... now I'll try to add some pictures...

 

Edited January 16, 2017 by Marcus J

[cereal tiller]

Hi all!

 

So, I really hope one of you out there might know where I could find some of these old engine mounts. They are the metalastic top hat type with three bolts that screw into the bell housing. I've seen that there are some really useful previous threads on here that have exactly the same set up as me with these rear mounts, the bobbin forward ones and the 4" coupling from a mini driveshaft. Unfortunately ASAP and Calcutt don't have them any more and, am I right in saying that Thornycroft don't exist now? Their website doesn't seem to anyway and it's been a long time since I've seen a yellow pages.

 

My mounts are very dead and that has killed the shaft coupling, which I also can't find as it has a register of 85mm, and everything now seems to be 2.5" I think I can solve all of this with a new 5" OD shaft coupling, flexi coupling and then getting an adapter bobbin turned up to go from that to my gearbox flange, which is 5.5" and also has a strange 85mm register.

 

But... unless I can find some engine mounts none of it means anything! Please, any suggestions would be greatly appreciated. Do I try to get a mount turned up? or just mount it solidly? It's a pretty smooth engine after all. The old mounts have a lovely dusting of metal around them so I think any hope of re-using them has been put out of my mind.

 

Many thanks in advance... now I'll try to add some pictures...

 

Have got the same type on a Thorneycroft BMC 2.5,they are getting weary,will use a conventional Pillar mount to replace them when the time comes

 

Will be a matter of turning up Stepped Spacers to fit above and below the big holes that are left when the old ones are removed.

 

CT

[Marcus J]

Hmm, yes I was wondering about that but I've only got 20mm underneath the feet, so even if i do that I'd have to take the engine and the calorifier all the way out to chop down the engine beds as I don't seem to be able to find any modern ones that low...

 

Marcus

[cereal tiller]

Hmm, yes I was wondering about that but I've only got 20mm underneath the feet, so even if i do that I'd have to take the engine and the calorifier all the way out to chop down the engine beds as I don't seem to be able to find any modern ones that low...

 

Marcus

Can't quite see the aft Mounts clearly in the pic. but I would consider 2 Mounts to replace each of them

 

New mounts (2) set Fore and Aft of the existing with a Bridge of say 12 mm flat linking them?

 

CT

[Mikexx]

I'm afraid the photos aren't very clear though the last one seems the most informative.

 

Can you use a standard anti-vibration mount:

 

http://www.ebay.co.uk/itm/4x-M3-M4-M5-M6-M8-Anti-Vibration-Male-Rubber-Mounts-Car-Boat-Bobbin-Damper-Pump-/252471054767

[Marcus J]

Oo! Thats a possibility I hadn't thought of CT thanks! I could just run a piece of steel across both bearers to extend the beds and work from there...

 

I've just found a company called av industrial who seem to supply asap with the bobbin mounts, and have some turret mounts that would maybe work, but it would be quite a lot of modifying to get them to fit, and they might want an industrial sized order to get the correct rubber in there.

[Marcus J]

I'm afraid the photos aren't very clear though the last one seems the most informative.

 

Can you use a standard anti-vibration mount:

 

http://www.ebay.co.uk/itm/4x-M3-M4-M5-M6-M8-Anti-Vibration-Male-Rubber-Mounts-Car-Boat-Bobbin-Damper-Pump-/252471054767

 

Ah, thanks, but the last photo is of the one i can find. ASAP still sell them.

 

The other ones are odd I admit, they're a metal housing with the rubber inside, through which goes the bolt in another steel bush. I can't really get a better photo at the moment without taking them out I'm afraid, and my phone lens is very full of sawdust and so not very clear at the moment! Another thing to fix, but that isn't quite as important...

[Tony Brooks]

Remember the mounts have to accept prop thrust. The front ones and those in the Ebay photo are questionable in this respect. The thrust will be trying to tear the metal mounting stud bases away from the rubber. This is why the rear mounts are as they are. thrust past the rubber into compression between the inner steel bush and outer case.

 

I fear this is going to involve cutting down the "turrets" the existing mounts sit on so modern mounts can be fitted.

 

When such mounts have collapsed in the past I have turned up a couple of spaces and fitted them around the stud between the base of the inner metal bush and the bed. This stopped the set screw heads that secure the mount to the engine foot from vibrating on the bed. However those mounts look pretty far gone to me and it looks as if this may already have been done.

 

 

[Tony Brooks]

An overnight thought. A bobbin type mount will be fine at the front as per the original but if you keep this type at the front make sure that whatever you fit at the back is designed to accept sufficient radial (frontwards - backwards) thrust.

[RLWP]

That's annoying - I think I've seen some of those rear mounts recently

 

Richard

[Tony Brooks]

I thought a member had sourced some over the last few years but can not find a reference.

[RLWP]

I thought a member had sourced some over the last few years but can not find a reference.

I did two or three years ago from Thornycroft

 

I have a feeling I saw some recently in one of our stillages

 

Richard

Edited January 18, 2017 by RLWP

[Tony Brooks]

If Richard can not find his or if he does not want to sell them then think about this.

 

Have a look at http://www.gmt-rubber.com/products/anti-vibration-mounts.php?gclid=CN3XzdXsy9ECFQZAGwodOlwCKg

 

and got to the cone mounting page.

 

The bulk of these mounts fit through and below the engine bed so after careful measurement to make sure it is will work how about this.

 

The engine will have to be lifted or the gearbox and flywheel housing removed. Its a fairly simple job.

 

Remember that you have 3 x 1/4" UNF (probably) threaded holes in each engine foot that secure the present mount by screwing up from below.

 

Cut a disk of (say) 6mm steel drilled to line up with the 1/4" holes in the foot and with a suitable centre bolt for the mounting bolt.

 

Remove the existing mounts and screw the said plates onto the top of the foot centred on the position of the mount centre bolt. ( I am not so happy about hanging the back of the engine off 6 x 1/4" but I think it will suffice.)

 

This adds the thickness of the rear engine feet to the clearance for the top of the new mounts. If the clearance is too great then it would be normal to shim on top of the mounts. If too little you will be forced to lower the top of the turret the mount sits on but I think there is a god chance it will be enough - hence the careful measurement.

 

Cut or unscrew the existing centre bolt off the turret.

 

Use a hole saw to enlarge the hole in the turret so the new mounts can fit through the turret.

 

Centre the mounts to the engine and then mark, drill and tap holes for the screws that will hold the mount to the turret.

 

Reassemble shimming all four mounts to ensure engine-shaft alignment.

 

 

Just a thought that may help.

Get the new fixing bolts and file/turn down the head to about half the original thickness to maximise the clearance under the engine foot when all is installed.

 

 

 

 

[Marcus J]

I did two or three years ago from Thornycroft

 

I have a feeling I saw some recently in one of our stillages

 

Richard

 

Ah Richard! Well, If you do find some I'd be a very willing customer! The forward mounts and part of the shaft coupling have arrived so I'm going to set to work with those on Friday, and wiggle one of the rear ones out whilst I'm at it to see what can be done.

 

If you manage to find some before I start drawing up dimensions and calculating rubber densities I'd be a most happy boaty.

 

Marcus

[Marcus J]

 

If Richard can not find his or if he does not want to sell them then think about this.

 

Have a look at http://www.gmt-rubber.com/products/anti-vibration-mounts.php?gclid=CN3XzdXsy9ECFQZAGwodOlwCKg

 

and got to the cone mounting page.

 

The bulk of these mounts fit through and below the engine bed so after careful measurement to make sure it is will work how about this.

 

The engine will have to be lifted or the gearbox and flywheel housing removed. Its a fairly simple job.

 

Remember that you have 3 x 1/4" UNF (probably) threaded holes in each engine foot that secure the present mount by screwing up from below.

 

Cut a disk of (say) 6mm steel drilled to line up with the 1/4" holes in the foot and with a suitable centre bolt for the mounting bolt.

 

Remove the existing mounts and screw the said plates onto the top of the foot centred on the position of the mount centre bolt. ( I am not so happy about hanging the back of the engine off 6 x 1/4" but I think it will suffice.)

 

This adds the thickness of the rear engine feet to the clearance for the top of the new mounts. If the clearance is too great then it would be normal to shim on top of the mounts. If too little you will be forced to lower the top of the turret the mount sits on but I think there is a god chance it will be enough - hence the careful measurement.

 

Cut or unscrew the existing centre bolt off the turret.

 

Use a hole saw to enlarge the hole in the turret so the new mounts can fit through the turret.

 

Centre the mounts to the engine and then mark, drill and tap holes for the screws that will hold the mount to the turret.

 

Reassemble shimming all four mounts to ensure engine-shaft alignment.

 

 

Just a thought that may help.

Get the new fixing bolts and file/turn down the head to about half the original thickness to maximise the clearance under the engine foot when all is installed.

 

 

 

 

 

 

Thanks so much for all that Tony, it's all a great help.

 

Funnily enough I found that website last night and was wondering about the cone mounts too, but trying to mount them to the engine foot as in the original system, upside down. I haven't had time to figure it out but I feel that that way or your way might work. They certainly seem low enough if it's just that part above the flange, though I think I thought they had too great a diameter. Your method would solve that as there's much more room on the turret than the foot.

 

Whilst I'm a boatbuilder, it's mostly with wood and sorting engine mounts for me is usually a matter of fitting what the engine manufacturer says, rather than calculating thrust loads and so on, so it's good to know that maybe it's not such a crazy idea. I can see what you're saying about the bobbin mounts, it certainly seems as though they wouldn't be taking much of the fore and aft thrust, and so whatever I do is going to have to take that into account.

 

The same website also has H mounts which i was thinking could be mounted into the turrets, but I think they would then need new inner bushes turned that had a flange to sit on the rubber, which brought me back to the original top hats...

 

I wonder if it would be possible to simply buy a fairly standard rubber bush with an inner steel sleeve and put it in the old hats? If the outer hat needed renewing then they could be turned up, but in practice, all they are doing is containing the bush and putting the weight of the engine on the upper outer edge of the inner bush... I think?! The bottom part of the bush then sitting on the turret, or, as you rightly say about mine... many washers!

 

If I could find the right standard bush this might solve the supply problem, depending on how hard it is to get the rubber out of the old hats of course!

 

Until I get the old ones out though, I'm not entirely sure that could possibly work, they could well also be cones of rubber inside i suppose... which would rather scupper my thinking.

 

Marcus

Edited January 18, 2017 by Marcus J

[Mikexx]

 

Remember the mounts have to accept prop thrust. The front ones and those in the Ebay photo are questionable in this respect. The thrust will be trying to tear the metal mounting stud bases away from the rubber. This is why the rear mounts are as they are. thrust past the rubber into compression between the inner steel bush and outer case.

 

I fear this is going to involve cutting down the "turrets" the existing mounts sit on so modern mounts can be fitted.

 

I'm wondering if some hollow rubber tubing as per:

http://www.ebay.co.uk/itm/SPARE-PARTS-SOLID-RUBBER-BUSH-GROMMET-SLEEVE-VIBRATION-MOUNT-BUSH-SHOCK-ABSORBER-/331777208466

 

Might work if you dismantled the current mount and replaced the rubber bush. You would need to remove the top or bottom washers from the inner sleeve which may be easier said than done.

 

I'm sure a sharp knife should cut the material to the right heights though will require a lot of care.

[Tony Brooks]

I suspect the hole in the engine foot will be too small to accept the body of an inverted cone bush if the bush is to be capable of accepting the load.

 

As far as reusing and filling the existing outer tube and maybe the inner bush is concerned, remember rubber works best in sheer and compression. The comparative small flange on the existing outer case makes me suspect that unless whatever rubber insert being used is bonded to the inner bush and outer case the rubber may well be extruded out of the gap between case flange and inner bush at the top of the mount.

 

Another thought.

 

If you did use bobbin mounts at the back you would probably need to find another way of absorbing the prop thrust. Remember the old Mini tie bar between the cylinder head and front bulkhead. This had rubber bushes in eyes at both ends. Could you find a way of fitting something like this between the engine/gearbox assembly and (say) the bed or a bulkhead. That should transmit thrust while allowing the engine to move a little on its mounts.

[Marcus J]

 

I suspect the hole in the engine foot will be too small to accept the body of an inverted cone bush if the bush is to be capable of accepting the load.

 

As far as reusing and filling the existing outer tube and maybe the inner bush is concerned, remember rubber works best in sheer and compression. The comparative small flange on the existing outer case makes me suspect that unless whatever rubber insert being used is bonded to the inner bush and outer case the rubber may well be extruded out of the gap between case flange and inner bush at the top of the mount.

 

Another thought.

 

If you did use bobbin mounts at the back you would probably need to find another way of absorbing the prop thrust. Remember the old Mini tie bar between the cylinder head and front bulkhead. This had rubber bushes in eyes at both ends. Could you find a way of fitting something like this between the engine/gearbox assembly and (say) the bed or a bulkhead. That should transmit thrust while allowing the engine to move a little on its mounts.

 

 

 

Well, I'm getting through the layers of grime, and I think you're right Tony, the bush definitely seems to have extruded out of the casing. It's all looking a bit like I'm going to have to face facts. With this in mind i've bought the smallest angle grinder i could find in order to chop away at the inaccessible bearer, ready to accept some standard modern mounts with a new foot turned up to accept the stud through the bell housing.

 

As for the mini coupling, I think it's the same sort of situation, I've bought an R and D split half coupling that seems to have clamped on centrally, even though my keyway on the propshaft is more of a vague valley than a gorge. ( I can't change the propshaft until i can move the boat eh?!) then it's going to be a new flexi coupling and a trip to a friend to get a large chunk of stainless turned up as an adapter between that and the odd sized gearbox flange...

[Mikexx]

As for the mini coupling, I think it's the same sort of situation, I've bought an R and D split half coupling that seems to have clamped on centrally, even though my keyway on the propshaft is more of a vague valley than a gorge. ( I can't change the propshaft until i can move the boat eh?!) then it's going to be a new flexi coupling and a trip to a friend to get a large chunk of stainless turned up as an adapter between that and the odd sized gearbox flange...

 

I had a look at my BMC today, sorry I didn't take any photos.

 

While the rear mounting bushes are like yours though seem to be in fair condition, the front ones are massive in comparison to any Mini bush.

[bizzard]

I'd be inclined to mount it solid. Not much increase in transmitted vibration with that engine. Prop shaft can be aligned perfectly. no need for fancy expensive coupling units and the stern tube bearing will last longer.

[Marcus J]

 

I had a look at my BMC today, sorry I didn't take any photos.

 

While the rear mounting bushes are like yours though seem to be in fair condition, the front ones are massive in comparison to any Mini bush.

[Marcus J]

Hi Mike, yes the mounts are pretty big on mine too. It's the flexible coupling that is from an early mini driveshaft, well, the inner rubber spider is, Moss still sell them and do an uprated nylon one, but I'm going to have to get rid of mine as I'm worried that it might not be aligned with itself anymore, and the split half clamp that I now need for my prop (due to the worn keyway) is a bit longer than the old one, and so I don't have the room for the 4" long mini coupling. I'll come back to that after Wednesday though! The new, very boring normal modern mounts arrive tomorrow.. if I don't report back assume the worst; I've lost a hand trying to angle grind off that inaccessible engine bearer!

I'd be inclined to mount it solid. Not much increase in transmitted vibration with that engine. Prop shaft can be aligned perfectly. no need for fancy expensive coupling units and the stern tube bearing will last longer.

[Tony Brooks]

The mini rubber "spider" is held into the two cast coupling flanges by U bolts, just like on a mini so it is perfectly possible (with time care and DTI or simmilar) to readjust the flange faces to all but parallel again.

[Marcus J]

I'd be inclined to mount it solid. Not much increase in transmitted vibration with that engine. Prop shaft can be aligned perfectly. no need for fancy expensive coupling units and the stern tube bearing will last longer.

I'd be inclined to agree with you! I think I'd still have to do the difficult bits of turning up some alternative feet for the rear mounts to hold a single large bolt, and making something to go in place of the front bobbins, so even that doesn't seem as simple as it should be!

[bizzard]

 

The mini rubber "spider" is held into the two cast coupling flanges by U bolts, just like on a mini so it is perfectly possible (with time care and DTI or simmilar) to readjust the flange faces to all but parallel again.

 

Might be the Hardy Spicer type as fitted to the Mini Cooper S and automatics.

I'd be inclined to agree with you! I think I'd still have to do the difficult bits of turning up some alternative feet for the rear mounts to hold a single large bolt, and making something to go in place of the front bobbins, so even that doesn't seem as simple as it should be!

A machine shop would cut four blocks of steel and put holes through them to your measurements fairly cheaply.