[xj40] Transmission Mounting Assembly


I thought this had been thrashed to death years ago, but now I’m
confused - OR, the XJ40 on-line book is still incorrect in respect
of the assembly sequence of the transmission (rear engine) mounting.

It has long been known that the Haynes manual, Chapter 7, Section
7, which has a series of pictures showing the dissassembly
sequence of a worn tranny mount is incorrect in stating
that ‘Refitting is the reverse of removal’ because in the worn
mount they are dismantling, the large foam buffer appears to
have ‘slipped’ and is shown in the incorrect position in relation
to the central spring cradle.

I had thought that this had been corrected in the write-up in the
XJ40 on-line book but apparently that shows the incorrect assembly
sequence too. Reading a number of Modern list archive posts on the
subject and by reference to the parts catalogue, the correct
sequence of assembly is as follows:-

Starting from the crossmember(‘gearbox mounting bracket’ in Jag-
speak) and working up:-

  • Spring cup, lower (large)
  • Spring seat, lower (rubber ring)
  • Coil spring, lower (white/ green colour code - larger dia.)
  • Central spring cradle c/w locating centre weight.
  • Foam Buffer
  • Buffer (retaining) ring (sometimes with travel restraint strap
  • Coil spring, upper (white/red colour code - smaller dia.)
  • Spring seat, upper (rubber ring)
  • Spring cup, upper (attached to transmission housing)

Unless anyone disagrees with this sequence of assembly of the
transmissdion mount, I intend to ask Pascal to correct the XJ40 on-
line book, section 8.2 (which currently reads the same as Haynes!)–
Bryan N ('91 Sovereign 4.0 L)
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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Hi Bryan,
I wish id spotted this before i attempted to replace my missing foam buffer.

I couldnt work out where to install the replacement aftermarket rubber part - and ran out of time - so ended up fitting the old spring seat lower (which was like new) to the top of the lower spring and then fitting the buffer retaining ring. The rubber buffer just seem to large in diameter to fit. It looked the the upper spring was connected to the central spring cradle.

does anyone have any photos showing where the rubber or foam buffer sits once assembled? at least for now its much better as the lower seat rubber is doing something compared to the missing foam.

None related but i spotted oil coming from my rear axle - prop side oil seal. Is this a diff out or can be done by removing propshaft (drive shaft in the usa i think)?


Ian …

This bit me years ago.

Not only were the instructions incorrect in the Haynes manual, so were the sequence of pictures showing the proper assembly.

Hi Grooveman
I will have a second go - and try to fit the large rubber buffer below the holding plate - that will be fun but hopefully i can do it. My car is an 88 and has the retaining strap - an added bit of joy. wonder why the got rid of this

Did you have to replace the rear seal on your diff at anytime perhaps?

Hello Ian …

My '89 has the metal retaining strap also.

The only work I’ve done on the original differential (other than fluid changes) was replacing the 2 output shaft bearings. Because of the design of the rear suspension this is a common problem. When they start to go bad the noise gets louder and louder.

My 94 has the strap too.

I just found this photo on another forum

Hopefully round two will get the rubber isolator in the correct location


One other thing you should take note of Ian is to mark the position of the mounting bolts.
That way, on re-installation you can retain the correct factory alignment.

Thanks - you mean mark them in relation to the position on the bracket? i didnt do this the first time - i will mark them net time. luckily didnt feel any vibration afterwards, phew!

found this also - nice picture https://www.ebay.co.uk/itm/JAGUAR-XJS-3-6-4-0-MANUAL-REFURBISHED-RE-BUSHED-GEARBOX-MOUNTING-BRACKET-CBC4125-/223458007923

Having looked again the first link i sent it shows the wrong sequence was followed - with the central spring cradle sat above the buffer retaining ring.

Looking at the thickness of the rubber buffer - it feels to me as if it will compress the lower spring quite a lot when fitted the correct way round - this must make it really stiff. So the ebay link and photos show the correct assembly sequence as per Bryan’s notes. Thanks all

Well quick update - managed to get the mount off and new rubber spacer fitted. Realigned bracket with marks on the frame where washers had left an indentation from original fitting. No vibration and fees good.
Changed the diff oil and hoping my oil leak is not going to be a problem. I cleaned off the soil and will observe. Manage to grease all the UV joints whilst under there. Hope my diff, LSD, will be ok.

You’ve got an LSD? lucky guy!

Yes - i didnt know until I had both wheels in the air and spun them when i was moving the driveshafts to align the nipples for greasing