Center engine mount

rymes · September 2, 2019, 10:44pm

I have a 1968 V8 250 with a four-speed and overdrive. I replace the two front engine I have a 1968 V8 250 with a four-speed and overdrive. I replaced the two front engine mounts, and the transmission mount rubbers. I also ordered the part for the middle motor mount, but I’m not certain precisely how it is supposed to be adjusted.

When I found it, The nut was loose, meaning the shaft could slide around in the mount. Is this supposed to be tightened down? I can only assume so. If anyone can provide some details, that would be wonderful.

Tom

Robin_O_Connor · September 2, 2019, 10:58pm

Its a support and just needs to be snugged up, bring the lower threaded bush up to the bottom and then tighten the top bush down.

rymes · September 2, 2019, 11:28pm

Thank you! I figured that had to be all there was to it, but I have learned over the years to ask anyway.

Here’s what I ended up with:

rymes · September 2, 2019, 11:38pm

And for what it’s worth, here’s what my front engine mounts looked like and the bottom spring pad in the transmission mount!

rymes · September 3, 2019, 12:15am

Nope. Scratch that. I had to loosen it up from the fully snuggled up position because the yoke at the front of the driveshaft was fouling the transmission tunnel. Seems odd to me, given that the front mounts are new. Has anyone else encountered this?

Robin_O_Connor · September 3, 2019, 12:22am

It needs to be in a neutral position, i.e. when the engine and trans mounts have the weight then you bring the lower bush up to rest underneath the cradle and then snug down the top bushing screw.

rymes · September 3, 2019, 1:08am

Thanks, Robin, but the only way to bring the lower part into contact with the mount is to snug the top down all the way, which causes the driveshaft to foul the tunnel.

Are there supposed to be shims under the front motor mounts? My working hypothesis is that the engine and trans pivot around this middle mount. Since the rear of the transmission is too high, it would follow that the front of the engine is too low, and it’s not due to collapsed mounts, as I just replaced those and they look fine. Also, my MGB has shims under at least one of the motor mounts, so…?

rymes · September 3, 2019, 1:59am

There is part #c18242, but that’s for an E-type. I suppose it might be worth a shot.

Robin_O_Connor · September 3, 2019, 4:44am

Are you sure you have the correct stepped washer
I have just been out to the garage where my 3.4 is sitting waiting to be placed in the engine bay and confirmed that mine is threaded as per this item;

rymes · September 3, 2019, 10:48am

Oh! The bottom washer is threaded?!

That would explain it. I will investigate and get back.

rymes · September 3, 2019, 2:58pm

I’m going to have to remove the rod and free the washer, it seems. I did find the instructions in the manual, in the prop-shaft section. Of course, my manual pre-dates the addition of the 4-speed with overdrive to the options list, so things like the non-existent center bearing make interpreting the manual a bit challenging.