1966 Volvo Amazon engine transplant! - Page 11

Derek UK · May 17th, 2015, 19:37

As said those rubbers were designed to work in compression not to have something hanging from them. The first sleeping policeman you come across might instantly have you in trouble. I wouldn't even hang an exhaust from them, the bonding, such as it is, won't take the strain. What was wrong with cutting the Amazon cross member and welding in an adaptor piece? The MX5 and M40 gearbox won't be that much different in weight even though the M40 case is iron.
Be safe, re engineer it.

Hat · May 18th, 2015, 10:25

Lots of enthusiasm no doubt, but not sure I would trust this engineering with my life.

Melody121 · May 18th, 2015, 10:33

Thanks for the positive comments..

Derek UK · May 18th, 2015, 11:15

We have your best interests at heart..

Melody121 · May 18th, 2015, 13:23

Fair enough, the comments are not really backed up with anything though.

Is there any evidence to suggest they will just fail? I'm betting no one has tried this before, therefore found out what the tolerance of an engine mount in this position might be.

Your saying I should just re do a days work without question and with no facts to back it up. I have no reason to suspect they will fail. I'm spreading a small load over two big engine mounts.

Even if they do fail, completely, at precisely the same moment, the gearbox can't just fall out. At worse I would have to pull over and get trailered home.

I appreciate everyone's thoughts as it can be very useful input. If you can give a little more detail than "it won't work, start again" I'm all ears

Underdrive · May 18th, 2015, 14:30

While I'm all for 'thinking outside the box' and trying something new, as Derek has said mounts like that are designed to work in compression and when used that way they won't allow the gearbox or engine to fall away from its position if they fail. There are many situations particularly on low sports cars where mounting gearboxes without a 'catchsafe' would save space and manufacturers would have used it if realistic and safe. There are several members on this forum who are engineers with enough knowledge and experience to offer valid and well intentioned advice, and being an ex MOT tester I can say that I would not pass such a modification on safety grounds. There are usually good reasons why some things haven't been done before.

Melody121 · May 18th, 2015, 16:44

Fair point, my argument would be that these are used for exhausts all the time, have the same design and are being pulled tight for their lifespan (which is no shorter than any other rubber component).. Yes the gearbox is heavier, but the engine mounts are 10 times the size.... correct me if I'm missing something...

old fart · May 18th, 2015, 16:53

These mounts,no matter how tough the rubber is,will only be as strong as the glue holding them together,so you've only to drop the clutch a bit sharpish,and they will part company.

Derek UK · May 18th, 2015, 20:03

Those bobbins, 2 used for Mini exhausts that weigh a couple of kilos at most and also have a strap mount as back up, not 40 kilos of gearbox and a prop shaft that's moving in all directions.
We can't stop you from finishing off this design of mount, that's up to you. The MOT fail comment might also be worth thinking about and it would certainly fail an SVA test.
In this case, although you'll have to do the job again, it's safer and sensible to do it right and have the knowledge that even if the rubber mounts do fail ,you have a cross member underneath to keep you safe.

Melody121 · May 18th, 2015, 20:39

Also on the mini there are two bobbins that hold the entire gear selector unit up, no extra straps no MOT failure.

Although a mini's exhaust is light many other cars with heavier exhausts also use this. a good example being an austin healey 3000 which has nothing else holding the exhaust.

Another point is that an engine is three or 4 times as heavy as this gearbox if the glue was that weak the engine would simply slide off the mounts at the first emergency stop. When I have seen broken engine mounts it's always the rubber that has fatigued and torn I've never seen the glue give up.

Could you please point me in the directon of the specific MOT regulation I would be breaking? I'm interested to read it so I can understand better.

The gearbox weight is also spread, the mount is holding up the light end. I can very easily lift and hold it in place and my arm strength is rubbish I guess only about 7 to 10 kilos ish of weight which again will also be assisted by the prop mount. Obviously the gearbox is about 45 kilos but it's bolted to the engine which is supported by the engine mounts. Because of this the load is spread evenly over 5 points of contact that's a lot more than most cars.

May 18th, 2015, 16:53	#108
old fart Master Member Last Online: Mar 28th, 2024 14:15 Join Date: Apr 2012 Location: Droitwich	Gearbox mount These mounts,no matter how tough the rubber is,will only be as strong as the glue holding them together,so you've only to drop the clutch a bit sharpish,and they will part company.

May 17th, 2015, 19:37	#101
Derek UK VOC Member Last Online: Yesterday 14:29 Join Date: Jul 2006 Location: Chatham	As said those rubbers were designed to work in compression not to have something hanging from them. The first sleeping policeman you come across might instantly have you in trouble. I wouldn't even hang an exhaust from them, the bonding, such as it is, won't take the strain. What was wrong with cutting the Amazon cross member and welding in an adaptor piece? The MX5 and M40 gearbox won't be that much different in weight even though the M40 case is iron. Be safe, re engineer it.

May 18th, 2015, 10:25	#102
Hat Senior Member Last Online: Feb 18th, 2017 15:16 Join Date: Mar 2014 Location: essex	Lots of enthusiasm no doubt, but not sure I would trust this engineering with my life.

May 18th, 2015, 10:33	#103
Melody121 Member Last Online: Dec 15th, 2015 20:17 Join Date: Jan 2014 Location: Chesterfield	Thanks for the positive comments..

May 18th, 2015, 11:15	#104
Derek UK VOC Member Last Online: Yesterday 14:29 Join Date: Jul 2006 Location: Chatham	We have your best interests at heart..

May 18th, 2015, 13:23	#105
Melody121 Member Last Online: Dec 15th, 2015 20:17 Join Date: Jan 2014 Location: Chesterfield	Fair enough, the comments are not really backed up with anything though. Is there any evidence to suggest they will just fail? I'm betting no one has tried this before, therefore found out what the tolerance of an engine mount in this position might be. Your saying I should just re do a days work without question and with no facts to back it up. I have no reason to suspect they will fail. I'm spreading a small load over two big engine mounts. Even if they do fail, completely, at precisely the same moment, the gearbox can't just fall out. At worse I would have to pull over and get trailered home. I appreciate everyone's thoughts as it can be very useful input. If you can give a little more detail than "it won't work, start again" I'm all ears

May 18th, 2015, 14:30	#106
Underdrive Senior Member Last Online: Apr 9th, 2024 10:10 Join Date: Jan 2014 Location: stranraer	While I'm all for 'thinking outside the box' and trying something new, as Derek has said mounts like that are designed to work in compression and when used that way they won't allow the gearbox or engine to fall away from its position if they fail. There are many situations particularly on low sports cars where mounting gearboxes without a 'catchsafe' would save space and manufacturers would have used it if realistic and safe. There are several members on this forum who are engineers with enough knowledge and experience to offer valid and well intentioned advice, and being an ex MOT tester I can say that I would not pass such a modification on safety grounds. There are usually good reasons why some things haven't been done before.

May 18th, 2015, 16:44	#107
Melody121 Member Last Online: Dec 15th, 2015 20:17 Join Date: Jan 2014 Location: Chesterfield	Fair point, my argument would be that these are used for exhausts all the time, have the same design and are being pulled tight for their lifespan (which is no shorter than any other rubber component).. Yes the gearbox is heavier, but the engine mounts are 10 times the size.... correct me if I'm missing something...

May 18th, 2015, 20:03	#109
Derek UK VOC Member Last Online: Yesterday 14:29 Join Date: Jul 2006 Location: Chatham	Those bobbins, 2 used for Mini exhausts that weigh a couple of kilos at most and also have a strap mount as back up, not 40 kilos of gearbox and a prop shaft that's moving in all directions. We can't stop you from finishing off this design of mount, that's up to you. The MOT fail comment might also be worth thinking about and it would certainly fail an SVA test. In this case, although you'll have to do the job again, it's safer and sensible to do it right and have the knowledge that even if the rubber mounts do fail ,you have a cross member underneath to keep you safe.

May 18th, 2015, 20:39	#110
Melody121 Member Last Online: Dec 15th, 2015 20:17 Join Date: Jan 2014 Location: Chesterfield	Also on the mini there are two bobbins that hold the entire gear selector unit up, no extra straps no MOT failure. Although a mini's exhaust is light many other cars with heavier exhausts also use this. a good example being an austin healey 3000 which has nothing else holding the exhaust. Another point is that an engine is three or 4 times as heavy as this gearbox if the glue was that weak the engine would simply slide off the mounts at the first emergency stop. When I have seen broken engine mounts it's always the rubber that has fatigued and torn I've never seen the glue give up. Could you please point me in the directon of the specific MOT regulation I would be breaking? I'm interested to read it so I can understand better. The gearbox weight is also spread, the mount is holding up the light end. I can very easily lift and hold it in place and my arm strength is rubbish I guess only about 7 to 10 kilos ish of weight which again will also be assisted by the prop mount. Obviously the gearbox is about 45 kilos but it's bolted to the engine which is supported by the engine mounts. Because of this the load is spread evenly over 5 points of contact that's a lot more than most cars.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)