Is my transmission falling off? There are no dumb questions. . .

[Jerome74911S]

While doing random maintenance, I noticed that there are gaps at the top of the rubber transmission mounts, where they meet the car's 'body'. I checked the torque on the mount bolts and they were good. I thought the bolts might be too long, so I removed one of the bolts and it shows no sign of bottoming out. I replaced it and torqued to 58 ft-lbs.

I notice that both the engine mounts, as well as the transmission mounts seem to indicate a slight forward tilt to the engine/transmission unit, which I imagine could be explained by the trans mount being too low for some reason.

Is what I'm seeing here normal? If not, what's wrong? The mounts are 2 or 3 years old.

[Davz912/911]

I guess the $50k question is are you getting any movement? Put a jack under the
cross brace and check.

Good luck,

Dave

[gamin]

Isn't there supposed to be a heavy thick washer in there?

[porwolf]

Originally Posted by gamin

Isn't there supposed to be a heavy thick washer in there?

Have you checked this? From the '78-83 PET KATALOG:

The left assembly is from a Turbo, the right one from an SC.

[ischmitz]

Jerome,

I agree it looks "funny" but I believe it is normal. I noticed mine looked the same when I put my engine/tranny back in a couple of weeks ago. I have sport mounts that are about a couple of years old.

I eased my mind when I confirmed the shift rod is centered in the chassis hole. If the tranny was sagging by an inch as your picture suggests the rod would be off-center causing the shift coupler to touch the bottom of the tunnel.

Cheers,
Ingo

[tirwin]

Ok... Following up with my own dumb question. From the picture above, if there is no contact between the bracket (part 1A) and the chassis above through the mount then why do people debate the differences in transmission mount stiffness? If that rubber isn't coming into contact with anything then it's not dampening any vibration, right? Maybe there is more going on that I'm not seeing...

[ischmitz]

The rubber is molded to a metal center tube that is clamped hard to the chassis with the main mounting screw. The outer body of the mount is secured to the cross-member. The rubber provides lateral and vertical play of the transition and isolated vibrations to the chassis. The transmission will twist slightly due to the rotational moment from the engine.

Some replace the rubber mounts with full-metal versions to improve shift precision at the expense of more chassis vibration.

Ingo

[Jesse16]

Normal, you're tightening on the metal sleeve same as the rear motor mounts. Rubber is between that sleeve and the outer which attaches to the body or tranny mount. Have to push up on the motor to see if the rubber is worn, not likely in 3 years.

[Flojo]

@Jerome: these mounts are worn and tired. change.

Originally Posted by porwolf

The left assembly is from a Turbo, the right one from an SC.

no sir.
SC is same as left in the PET-grafik. Right grafik is earlier models, a sort of one-part-bridge.

here's my 79 SC (FIN-PET-check reveals exact parts as in grafik below)

[JJ 911SC]

Yes...



1: SC

1A: Turbo

[KTL]

Originally Posted by gamin

Isn't there supposed to be a heavy thick washer in there?

Correct. There are four large washers used on the trans mounts and four on the engine mounts. Each mount has a big dished washer above and below the mount.

[john walker's workshop]

only 87-89 G50 carreras had a top washer. lets see a shot of the bottom. post #9 shows the clearance between the washer and the mount with new rubber. when they get old and saggy, the washer gets a lot closer to the mount. same with engine mounts.

[KTL]

Interesting on the washer count. '83 and '86 PET pdf diagrams say 4 washers for the engine suspension, 4 washers for the transmission suspension.

I have four on my '79 (not even remotely stock), four on my '87 and have seen four on pretty much every other one i've serviced. Probably a dozen in our local circle of friends cars. Weird.

[Jerome74911S]

Here's a shot of the bottom as best as I could do. Although the rubber is squished thinner on one side, it doesn't look too bad, does it?




This is a shot of the topside of the engine mount. Same age as the trans mounts, about three years.

[Jerome74911S]

This is a bump.

I posted the pictures above, as requested. Possibly it is clear enough that there is a forward slope in the engine/transmission unit, because the rubber in both the engine and transmission mounts is squeezed narrower in the front edge, which I suspect indicates the forward/downward slope I mention.

How this relates to my original question is something I would like to understand before I spring for a set of new mounts - which might just mask some problem.

[DRACO A5OG]

If it bothers you, you can always shave down the metal sleeve about 5-6 MM so the rubber can contact the mounts.

My fanatic track buddy and others did this to their 3.2's. I cannot say if this will improve anything but they seem to think so. I can see how it will reduce slop or twist and allow a more precise shift on turns.

But to answer OP, No it is not falling out.

[schumicat]

that does seem like a lot of squishing. you can get the factory cabrio/sport mounts which are stiffer. the all metal ones are good for track cars but I wouldn't put them on a street car.

[bfunke]

Is your top washer upside down?

[Jerome74911S]

Having the concave side up on the engine mount is the position recommended by smart people on this forum (could one of them have been Grady Clay?), whereas concave faces the rubber on the transmission, according to the same recommendation. There is discussion on this point.

The PET for my car is not clear as to position of that washer.

[porwolf]

Originally Posted by JJ 911SC

Yes...

1: SC

1A: Turbo

You are right. Sorry, my mistake: