Auto trans rear engine mount

[panamacarrera]

Does anyone have any advice on reassembly of the rear engine mount?

Reading the JSM and looking at the length of the spring I have to compress it looks like an impossitask but I'm sure I'm not the first person to attempt this.

Thanks

Nigel

[Bob.]

Hi Nigel,
Mine had been incorrectly assembled, the workshop manual is unhelpful and as I found, the parts manual is not much better, with a poorly presented diagram and part numbers transposed. It took me some time and research to work out what I believe is the correct assembly. I posted images on jag-lovers a while ago, have a look here.
https://forums.jag-lovers.com/t/series- ... unt/365172
Hope this helps,
Bob

[panamacarrera]

Thanks Bob, that's really helpful. As you say, the manuals are next to useless and, as in the post on JAG-lovers, I have some missing parts.

How did you manage to compress the spring? My spring is best part of double the length of the bolt/stud and I can't see a safe way to compress the spring yet still have access to the thread on the end of the stud.

Thanks again

Nigel

[Bob.]

Hi Nigel,
First make sure you have the correct spring for an auto, it has about 5 coils against about 3 (from memory) for the lighter weight manual.
The spring is compressed as you raise the mounting plate up against the body. Use a stout hollow tube to allow the gearbox mounted stud to progressively pass through the plate. Bolt the mounting plate to the body, remove the jack and fit the rest of the mount.
Hope this helps,
Bob

[panamacarrera]

It helps massively, thanks Bob.

Easy when you know how.

[flyer295]

Are you sure this is correct?
Like a lot of others I'm having trouble with this item.
I cannot work out the sequence in which this is assembled.
The mounting bush has been pushed into the support bracket - Correct
If one temporarily ignores the 2 spring seats and the spring itself (mine's a manual) I'm trying to work out the sequence of parts that go on the stud.
Working from the top down (according to the parts catalogue) it starts with
special washer, with rounded edges (C29011) (purpose unknown)
Mounting lower support washer (C35666)
One spacer (C30157) (Although I have 2)
Mounting bush (C30159)
Washer (C36131/1) No longer available.
Half nut
Basically this goes together but it means the spacer can float up & down inside the rubber mounting. (there's a 2mm clearance between the rummer mounting hole and the spacer o/d
If 2 spacers are fitted then the rubber mounting can move up & down on the stud as the combination of 2 spacers is longer than the thickness of the rubber mounting.
So which version is correct or are neither of them ?
I have seen a version that has the rounded washer between the two spacers. This will surely wear the inside of the rubber in no time flat.

[MarekH]

Dear Nigel,

The only reason to specify a different spring for auto versus manual is that the autobox is much heavier than the manual gearbox, so will require a stiffer (or longer) spring. An old and tired autobox spring will probably be o.k. for a manual gearbox, but not vice-versa.

To attach the tie plate, start with some overlength bolts. Wind those in with some washers on them to take up a bit of tension, then progressively go round one by one and replace them with ones with more washers on them, until you have would the plate in a bit more. Then switch to shorter bolts, then eventually to the oem bolt length.

This way, you can safely wind in or wind out all sorts of weights and tensions in a safe manner. Any procedure with block of wood or jacks is less safe and is poor advice.

All this spring (and its ancillary components) does is set the height of the rear of the engine and how it will move under load as you go over bumps (hence the shims). The squidgy foam bits are just bump stops and the spring is the damper, to use a shock absorber analogy, and that's all there is to it.

kind regards
Marek

[Bob.]

Responding to Flyer295
This is the assembly with C29011,the damper washer, shown sandwiched between the two spacers C30157.

The parts book illustration omits one of the spacers whereas, as you have found, in reality the design uses two.
The damper washer is designed to move within the rubber bush, that is why it has a radiused edge and also why the spacers are smaller in diameter than the bore of the bush.

The damper washer is an interference fit in the bush (ignore the fact this is a polybush) and as the name suggests damps the vertical motion.

Without the spring, the assembly looks like this with clearance between the bottom of the rubber bush and the lower washer to allow vertical motion. (Ignore the castellated nut, it should be a Nyloc half nut).


Hope this clarifies,
Bob

[Tarapoochy]

Hi all,

Sorry to resurrect a topic that most people probably thought was done and dusted, but I still don't quite follow the postings on this and other threads about the auto gearbox mounting.

I agree with the series of pictures posted by Bob, but these and others I have seen completely miss out part number C41266 the plate with 3 bolts to the rear of the gearbox sump to the bottom of the mounting bolt! I assume it just gets bolted below the big washer C36141/1, but strangely it is nowhere to be seen in the pictures!

[Bob.]

Hi ?,
Not so strange really as this reinforcing plate was only introduced fairly late in S3 production and I don't have one. As per your image from the PM, it was only introduced from engine number 7S14001 which means August/Sept 1973, so most S3s don't have one. This rather poor image shows C41266 fitted.
Bob