Rear engine (manual gearbox) mount

[lowact]

Trying to figure out how to assemble the rear engine mount. The parts manual is wrong I think:


Found these photos by Etypebob on Jaglovers, for ’71 XJ6 automatic (I think). Is S3 manual e-type the same as this?




I don’t have the donut washer (C29011), don’t have the tapered washer (C35666), and only have one sleeve (C30157). Do I need to go shopping?

And then there is the bracket (C42202), evidently added to later cars, do we know why?

The mounting plate (C34805) is attached by 5/16” bolts, via spacers (C7493). On my car the holes through the plate are 1/2 inch, seems stupidly big relative to the bolts. Are all plates like this or have my plate holes been drilled out? And the holes through the spacers are 3/8”, still too big for 5/16 bolts, imo. Are all spacers this diameter?
Thanks.

[Bob.]

Hi Colin,

The only difference between the auto and the manual gearbox mount I am aware of is the rating of the spring to allow for the heavier autobox. The auto has 5 coils and from memory the manual has 3. The pictures you found on jag-lovers are from my auto S3 E Type not an XJ6. There is more discussion here: http://forum.etypeuk.com/viewtopic.php? ... nt#p117937

ISTR reading that plate C42202 was added to later S3s to divert the rear of the engine/gearbox assembly downwards away from the passenger compartment in the event of a heavy frontal crash.

Re plate and spacer holes, sounds as if yours are unmodified. Here are a couple of pictures of mine I took on disassembly which might help, but I have no dimensions recorded.

[lowact]

Thanks Bob. Missing parts ordered. Relieved that my plate and spacer holes probably not modified, still nonplussed about the size, maybe to facilitate installation ...
Re the following pic, copied from your other thread. My understanding is that C34263 and C21932 are the manual and auto versions of the top spring cup/retaining plate, that the item so numbered in the photo maybe should not exist?

[Bob.]

Hi Colin,

You are right, the arrow should point to the top spring retainer, not the gash plain washer which you can see above the retainer in my "as found" pictures in post #2, making it look rather like the STD retainer not the AUTO version which my S3 is.

I would be interested to know if your retainer looks like the one identified in the S3 PM as C34263-STD with the raised section or flat topped as shown for C21932-AUTO. To muddy the waters the PM for the XJ12 S1 auto shows C21932 with a raised section not flat topped like the S3 PM image.

[lowact]

Mine has the raised top, i.e. more spring compression:

Not having a plain washer also means more spring compression. I note the workshop manual says fit one plain washer, or two for automatics. So maybe that plain washer should exist after all. So confusing.

[Bob.]

Thanks for that Colin, at least that feature is clear now. It's a few years since I started from the "I (think) I have all the right parts but not necessarily (definitely not) in the right order" point. I had forgotten the two plain washers for an auto note in the ROM, although the PM only shows and lists one.

[Nialls Shortbear]

That cotton bobbin shaped "rubber" that you are going through all this to replace that lives inside the steel housing, is pretty weird. We just did a couple of these, and by accident we purchased both types available from SC Barratt, the genuine Jag version and an aftermarket thingy.

Now both these cars we were working on are low milers, that we believe, and there was nothing left of these "bobbins" apart from a few orange crumbs. The gear lever on these cars when driving went up and down like the proverbial drawers.

So when it came to do the job on these mounts being discussed here and elsewhere, we with interest found that the genuine jaguar replacement was an orange foamy type thing (bizarrely made in Germany) whereas the 'pattern" as i would say was a solid black rubber jobbie.

We used the black rubber jobbie and sent the others back. I think oil severely breaks down the original one, and either way the design is strange, because it seems like the washer between the 2, yes 2 spacers, is designed to shred the "jobbie" as the mount flexes, be it orangey or black.

I am sure everyone knows the difference between a new one and a non existence one is massive, (1/4" to 2" of movement) and there are always tales of this mount receiving much attention at what I would call a low mileage interval.

Is it just an awful design or was the orange foamy thing totally inadequate?

[lowact]

I figured that, if the centre "donut washer" rubbing within the rubber bush was to dampen any spring oscillation, it would be unwise to opt for a non standard bush material, so I stayed away from the "uprated" polyurethane alternative, and the cost of the orange one made no sense, so I ended up with one of the black ones (SNGB).

Here is my spring compression tool, length of pvc pipe pin-jointed to a little scissor jack, worked a treat, stable as, could knock it around to line up the bolt holes, do the bolts up fully by hand, too easy.


BUT

Here is the end result - spring is compressed as far it is able, i.e. gearbox is sitting down on the rubber bush, spring is doing nothing. I was expecting it to be floating, it used to be floating ...


My car has a manual gearbox. I've just fitted an overdrive unit. So now I am suspecting, with the extra weight of the overdrive, I should be using the stiffer spring, from an automatic transmission mount? is this what is usually done?

[lowact]

Getting there. The auto spring (C19988) is thicker (7,4 vs 6.5 mm wire) and is stiff enough to properly float the heavier weight of the OD. However it is 2 cm longer, too long, I will need the matching flat top retainer plate (C21932) and an additional washer (C36131). Another payday for DHL. Meanwhile it is quite clear, if fitting an OD to a manual box, the gearbox mount needs to be upgraded, from the manual to the auto spec.