Engine Mounts - what hardness ?

[seadog30]

I have to replace some shot mounts what hardness rating should I use ?

The engine is a VP2040 with a standard gearbox and propshaft, the engine weight is 170 Kg and with the gearbox I assume a total weight of approx 200 Kg.

The engine mounts appear to be available in 35, 45, or 55 shore hardness, what should we use ?.
Should I use the same rate for all 4 ?

Advice please.

Edit - should have noted, the existing "shot" mounts are so rusty and manky that I can not read the rate on them.

 

[Adamastor]

There is a calculation based on the torque of the engine as mitigated by the spacing of the mounts, and exacerbated by the gearbox reduction.
Have a look at this http://www.defender.com/pdf/vetus_motor_mounts_catelog.pdf for a better idea of what I mean.

 

[seadog30]

There is a calculation based on the torque of the engine as mitigated by the spacing of the mounts, and exacerbated by the gearbox reduction.
Have a look at this http://www.defender.com/pdf/vetus_motor_mounts_catelog.pdf for a better idea of what I mean.

Thanks Adamastor

The Vectus chart seems sugest type K50 (45 shore harness)

Is this correct ? should I used the same rate all round ?

Regards -

 

[Adamastor]

The mounts are usually sold in sets, so if you have four legs on the block get a set of four.
My candid advice is that you put something like Tectyl on them to inhibit corrosion, and MAKE SURE THE LOAD ON EACH MOUNT IS EQUAL! I've seen poor adjustment kill engine mounts faster than I ever thought possible.

 

[seadog30]

Thanks for comments Adamastor, very good point "MAKE SURE THE LOAD ON EACH MOUNT IS EQUAL!".

My concern was also, should the front pair of mounts be the same hardness as the back? (the gearbox end has more weight on them)

Regards

 

[sailorman]

http://www.avindustrialproducts.co.uk/silent-marine.htm

 

[chrishelen]

For my perkins perama I was advised 45 front 55 rear.

 

[ghostlymoron]

AFAIK the front and rear mounts are rarely the same hardness. Unless someone comments on here with experience of the same engine as you, I should take some advice from AV.

 

[macnorton]

Each pair should be rated for the weight at that point so the gearbox end should be harder than the lighter front end, the mis-conseption that they should all be the same is often a cause of excessive vibration.

Thanks for comments Adamastor, very good point "MAKE SURE THE LOAD ON EACH MOUNT IS EQUAL!".

My concern was also, should the front pair of mounts be the same hardness as the back? (the gearbox end has more weight on them)

Regards

 

[Jcorstorphine]

I have the same issue with my Ford engine but I have the reverse situation due to the front engine mounts being in the middle of the engine and thus taking about 75% of the engine weight. The other factor I have to take into account is that I have a hull mounted thrust bearing and a double flex Carden Shaft so I do not need to allow for prop thrust so I am tottaly confused. Sorry to OP for hijacking his post with my question

 

[Heckler]

AFAIK the front and rear mounts are rarely the same hardness. Unless someone comments on here with experience of the same engine as you, I should take some advice from AV.

On the VP MD22 they are both the same, 45 if IIRC
Stu

 

[Caer Urfa]

I have changed a number of engine mounts over the years and if you look very carefully 'they might' have a number on them which applies to the shore hardness, even better if a makers name are on them.

They might be all the same, however for what its worth make a note which one came off the where front/back

Mike

 

[peteK]

For my perkins perama I was advised 45 front 55 rear.

What model Perama?as I have theM20 and was thinking of replacement mounts.

 

[chrishelen]

What model Perama?as I have theM20 and was thinking of replacement mounts.

M30

 

[peteK]

M30

Thanks.