s14kev

I was just about to install a set of CEP semi solid motor mounts.

It seems all semi solid mounts are of similar design and most use LORD rubber isolators. I noticed the central bolt in the CEP mounts are made of A2-70 stainless (304 equivalent). This is somewhat weaker than typical grade 8 fasteners. How much load does this central bolt really take? Should I swap it out for a grade 8 or 10.9? It's an M10 x 1.5 x 80mm fully threaded bolt so it is somewhat hard to find (partially threaded are easy to come by).

I found an older post using a similar design semi solid mount with a bent central bolt:

https://rennlist.com/forums/944-turb...or-mounts.html

Not sure if this was incorrect installation or truly an example of how much load these things take. I figure the torque tube is the main torsional support for the engine whereas the motor mounts are just something for the motor to rest on so really they act in compression and the central bolt is really not under too much load or am I missing something?

Oddjob

I had a stud break on a semi-solid engine mount. The Mfr/supplier sent me replacement bolts, grade 10.9 to use in place of the original studs. I don't know what grade the studs were.

s14kev

Do you mean the central "stud" broke which in the case of the CEP mounts is actually a stainless bolt? The Lindsey ultramounts use a threaded rod with nut at each end.

In the picture of my CEP mounts below you can see the two smaller yellow zinc plated bolts are grade 10.9 whereas the central larger M10 central bolt is A2-70 stainless.

Oddjob

Yes, the stud (threaded rod) broke. And LR replaced it w/ bolts.

nofalls

Dumb question perhaps but why does the bolt have to be fully threaded? From the looks of it the threads on the lower half of the bolt shank do not get used.

Van

The mount is recessed more than you think... you need the threads all the way down. (Ask how I know... I tried to replace them with ones off the shelf, and they didn't work.)

s14kev

Yes. Needs to be fully threaded since the black aluminum disk you see is threaded down on the bolt.

I can find metric grade 8.8 zinc plated fully threaded but not grade 10.9 with zinc plating. Grade 10.9 only comes plain finish it seems which I am reluctant to use without any corrosion protection. Hopefully grade 8.8 will do.