Engine mount advice please

[Bugeyze]

I need to replace the LH engine mount, the rubber has almost completely detached from one of the steel plates, see pic. The last time I touched these was when I installed the engine onto the bare frame. Any advice on pitfalls etc' and possible cause of delamination appreciated.
Thanks.

 

[Bob_Spidell]

Re: Engine mount advis please

I've had the same issue on several mounts. I believe the main problem is poor quality parts; i.e. the rubber is not properly bonded to the backing plates (same problem occurs with a lot of aftermarket 'stock' exhaust mounts).

One thing that helps is to adjust the clearance on the top mount; if the gap is too large this allows the weight of the engine settling to put a large side load on the lower mounts, which (at least) contributes to the 'shear' load on the mounts and drooping and delamination. IIRC, the spec is for a 0.015" gap; installing aftermarket parts can create a gap of a quarter-inch or more. Originally, there were shims available to be placed under the backing plate of the upper mount; I have not found them to be available at any of the 'usual suspects' here in the 'States. I took some large--approx. 1.5"--fender washers and cut notches in them so they could slide past the stud the holds the upper mounts (you can/should only do the adjustment after the engine is installed as the gap varies). This seems to have helped, as when the engine settles more of the weight is carried by the top mounts and the shear load on the lower mounts is reduced.

 

[dougie]

I've also had a least three of these fail. I thought build quality as well, but mine probably were stressed a little bit more on my race car.

Here's what can happen to the full motor mount when really stressed.

Stock on the right imploding. New heavy duty on the left.

 

[HealeyRick]

An old hot rodder's trick is to countersink a bolt through the rubber and mount, leaving some room for the engine to work against the rubber for cushioning a bit before it comes up against the bolt. More fully described here: https://www.gmh-torana.com.au/forums/topic/81586-bolt-through-engine-mount-mod/

 

[steveg]

Dougie - who sells the new heavy duty mounts?

 

[dougie]

Dougie - who sells the new heavy duty mounts?

AH Spares

https://www.ahperformanceparts.co.u...-RH-engine-mounting-uprated.aspx#.W8-Z5mRKgy4

 

[steveg]

Thank you, Dougie, I ordered them.

 

[Bob_Spidell]

Well, does anybody sell 'ugraded' rubber mounts?

 

[dougie]

Well, does anybody sell 'ugraded' rubber mounts?

Not that I've found. I did incorporate Rick's "old school" upgrade a few years back with the heavy duty motor mounts.

 

[Bugeyze]

Thanks for all of the suggestions, I will replace and shim the bump rubber down.