Noisy Diff

[Tasmindevil]

After a terrific BBWF and visit down to see the folks my next task is to look at the Diff that is making a bit of a noise, it drones at certain RPM and seems to have some backlash, basically a clunk and some movement. It has had new rear bearings, suspension and UJ’s all round but symptoms seem to point towards the diff.

So questions?

I gather it is a 3.54 Powerlok diff fitted to XJS’s but do later ones fit, are these fitted to other TVR’s and Jaguars, would a later XK8 diff fit. I am looking at secondhand ones or refurbs but there are some scary prices out there. Does anyone have a good one lurking in the back of there garage they would be happy to exchange for numerous beer tokens or any pointers on reliable garages to have the diff refurbed?

Also I discussed with a few at BBWF about the feasibility of cutting out the boot floor above the axle and replacing it with a aluminium plate, the idea is to install a frame on the underside with tapped holes and seal/screw the plate to this. This would allow access to the axle and brakes for maintenance and secondly I am looking at adding an additional fuel tank for a potential event in November so the plate could be used to mount this.
So how structural is the floor above the axle, opinion so far is none but I would be interested in your views.

Cheers
Hamish

[C O Jones]

Hi Hamish, when you do find out what it is - let us know. We spoke about it at BBWF.

Mine has been noisy like this for a couple of years, it has been checked over by a (non TVR specialist) garage who found nothing to worry about, and has passed two MOTs at a different place.

I'm not too worried about the whine - but the clonk does concern me, it feels like somebody is bashing the chassis with a hammer right under the back of the seat (i.e. my a**e).

Steve Heath's bible does recommend cutting holes in the boot floor and suggests the alloy diff mount might crack but that steel replacements are available.

Russ

[Tasmindevil]

C O Jones said:

Hi Hamish, when you do find out what it is - let us know. We spoke about it at BBWF.

Mine has been noisy like this for a couple of years, it has been checked over by a (non TVR specialist) garage who found nothing to worry about, and has passed two MOTs at a different place.

I'm not too worried about the whine - but the clonk does concern me, it feels like somebody is bashing the chassis with a hammer right under the back of the seat (i.e. my a**e).

Steve Heath's bible does recommend cutting holes in the boot floor and suggests the alloy diff mount might crack but that steel replacements are available.

Russ

Hi Russ,
I spoke to a specialist today and he suggested a humming noise is probably a bearing, a whine at speed or on lift off of the load pedal could be the pinion gear, the clonk is an issue that also concerns me as it feels like the diff taking up slack. He said there is a crush washer that pre tensions the gearing and over time wears and you have more movement of the gears, I think this has happened to mine, I have been quoted £395 for a strip down and new bearings and a re tension of the crush washer. If new pinion/gears are required then thats a lot more, I have seen circa £500.
I'll let you know how things progress,
All the best
Hamish

[Number 7]

Those prices sound about right - I paid about £350 five years ago for a rebuild with a few parts. I'm down south, so that's not going to help you. What about somewhere like Dreadnought?

7.

[adam quantrill]

What mileage do you do per year? Anything around 3k or less - just change the diff oil and drive it.

These things fail only rarely, they are built for a 2 ton car after all. If the noise bothers you - get a louder exhaust!

[Tasmindevil]

adam quantrill said:

What mileage do you do per year? Anything around 3k or less - just change the diff oil and drive it.

These things fail only rarely, they are built for a 2 ton car after all. If the noise bothers you - get a louder exhaust!

Ha ha, Louder exhaust is planned !!! I would live with it but the clunk is worrying and as I hope to do an event in Nov I decided to change it out, talking of which I have just picked one up from Douglas Valley, top blokes and great price £150 plus postage/VAT. It is from a v low mileage 350i but one of the latter ones that had the LSD, trailing arm models had the normal jag diff, A frame the LSD. I will give the diff a once over, remove my old one and strip it down and may look at a rebuild subject to the gubbins inside.
Next job that exhaust !!!!
Cheers
Hamish

[MJG280]

'Cutting out the boot floor above the axle and replacing it with a aluminium plate'

Mine has a piece of ply over the hole which I mastic in place seems ok. If not stuck down it floats up. Makes life so much easier.

Edited by MJG280 on Tuesday 27th July 20:32

[Tasmindevil]

MJG280 said:

'Cutting out the boot floor above the axle and replacing it with a aluminium plate'

Mine has a piece of ply over the hole which I mastic in place seems ok. If not stuck down it floats up. Makes life so much easier.

Edited by MJG280 on Tuesday 27th July 20:32

Now that's a plan !!!
Cheers

[jagracer]

Tasmindevil said:

C O Jones said:

Hi Hamish, when you do find out what it is - let us know. We spoke about it at BBWF.

Mine has been noisy like this for a couple of years, it has been checked over by a (non TVR specialist) garage who found nothing to worry about, and has passed two MOTs at a different place.

I'm not too worried about the whine - but the clonk does concern me, it feels like somebody is bashing the chassis with a hammer right under the back of the seat (i.e. my a**e).

Steve Heath's bible does recommend cutting holes in the boot floor and suggests the alloy diff mount might crack but that steel replacements are available.

Russ

Hi Russ,
I spoke to a specialist today and he suggested a humming noise is probably a bearing, a whine at speed or on lift off of the load pedal could be the pinion gear, the clonk is an issue that also concerns me as it feels like the diff taking up slack. He said there is a crush washer that pre tensions the gearing and over time wears and you have more movement of the gears, I think this has happened to mine, I have been quoted £395 for a strip down and new bearings and a re tension of the crush washer. If new pinion/gears are required then thats a lot more, I have seen circa £500.
I'll let you know how things progress,
All the best
Hamish

£350 isn't bad if that includes bearings a seals. I have been quoted £420 but mine will need some new beville (spelling) clutches which will be extra. Adjusting the crush tubes on the bearings is easy enough, I've done a few on mine over the years but the big problem is setting up backlash the CW and pinion.

[njhucker]

If you need parts, or a reconditioned unit, try Ward Engineering. Just had them email me with a price list, as I have a noisy bearing in mine.
http://www.ward-engineering.co.uk/

[pwd95]

Nice link Nige, I'll pop that in to favorites.