[modern] XJ40 rear Differential

Disused Categories Modern
1

Hello,

I am soon going to have to embark on a job I have been fearing since getting
my XJ40, the rear differential output shaft bearings.

My front wheel bearings have a lot of play, and are to be replaced very
shortly, but my rear end has also started to whine louder than normal, I
have changed the diff oil and experienced a minor improvment. I am aware
that quick wear diffs seem to be a common XJ40 failing.

I need to pinpoint what the problem is exactly before embarking on the
remedy. Basically, at 60 MPH I have a noise from the rear end that sounds
like I am being pursued by a plane, though not majorly loud, it is
noticeable. Is this fault easy to rectify or is it a ‘drop the A frame job’?

Thanks in advance.

James Copp-Taylor

1987 XJ40 3.6 (Uhura)

2

James,
The Diff output shaft bearings are not hard to replace, but as you say,
pinpoint the cause of the noise as it could be the wheel bearings or
something else. I did mine a while ago. Getting the stub shaft out is
easy, somewhat harder is removing the retaining collar that holds the
bearing in place. The collar needs to be drilled and split with a chisel to
be removed. You then need to press on the new bearing and new retaining
collar. I used a friend’s 5 Ton press but it would have been much easier
with a bigger press as the retaining collar required quite some force to go
on. If you don’t have a press you need to take the stub shaft to a workshop
as recommended in the Haynes manual. You also need to replace the O ring
seal with a new one.

From memory the Haynes manual suggests detaching the output shaft from the
Hub carrier assembly, but this is not necessary. All you need to do is to
remove the 4 nuts on the flange and then pull the output shaft away from the
diff, allowing the hub carrier to carefully swing down and supporting it so
as to not damage the brake line. This allows you to access to the 5 bolts
on the diff housing and remove the stub shaft.

I had a bit of play in one of the rear wheels, which according to most info
I found in the archives is normally attributed to excessive play in the diff
o/p shaft bearings, but the cause turned out to be previously incorrect
shimming of the stub shaft and my bearings were fine. The JDHT CDROM
describes the whole procedure very well including the shimming required,
which removes excessive in/out play in the stub shaft and consequently the
wheel.

Serge

1990 Sov.------------------------------

Date: Tue, 16 Apr 2002 00:13:05 +0100
From: “James Copp-Taylor” james.ct@easynet.co.uk
Subject: [modern] XJ40 rear Differential

Hello,

I am soon going to have to embark on a job I have been fearing since getting
my XJ40, the rear differential output shaft bearings.

My front wheel bearings have a lot of play, and are to be replaced very
shortly, but my rear end has also started to whine louder than normal, I
have changed the diff oil and experienced a minor improvment. I am aware
that quick wear diffs seem to be a common XJ40 failing.

I need to pinpoint what the problem is exactly before embarking on the
remedy. Basically, at 60 MPH I have a noise from the rear end that sounds
like I am being pursued by a plane, though not majorly loud, it is
noticeable. Is this fault easy to rectify or is it a ‘drop the A frame job’?

Thanks in advance.

James Copp-Taylor

1987 XJ40 3.6 (Uhura)

3

James
Mine used to whine, I would notice it on long trips usually when foot off
accelerator. My mechanic put some new oil in 18/12 ago and I havent been able
to hear it since. I guess it might have been thicker than the usual stuff but
I am certainly pleased.

I can check what he used if you’re interested, I’ll see him thursday.

Martin
93 xj40 3.2 UK>From: “James Copp-Taylor” james.ct@easynet.co.uk

my rear end has also started to whine louder than normal, I
have changed the diff oil and experienced a minor improvment.

4

James,

Bad news. What you describe is a major problem that if you try to take the easy
way you risk doing it twice.

I have repaired and replaced two differentials on my 90 Majestic XJ40. I
replaced a bad one with a used one and it did not last. I changed the pinion
shaft and didn’t take the differential out of the car (tried to chintz and
lost). So I ended up replacing the differential again with a remanufactured
unit. What you describe is bearing noise either wheel or differential probably
differential. The gears rarely wear enough to make that kind of noise you
described. By the way there are two bearings on each wheel inner and outer.
They dry out because there is no way to lube them.

Put the car on a lift with the wheels free, check the rear wheels. I bet your
left rear wheel flops around when compared to the other.

If so, look up at the point where the wheel drive shaft goes into the
differential and move the wheel. If the whole assy moves in-out the large ball
bear (there are two on the pinion shaft. A BB and a Tapered Roller Bearing that
is inside the Differential Housing. The BB is pressed on the pinion shaft and
is the one that blows out most often.

To change the roller bearing you have to take the rear cover off the
differential and to do that you have to take the differential out. I put a new
pinion shaft and bearing in and it helped but did not last because I did not
replace the inner roller bearing.

If I were you I would check both inner and outer wheel bearings on the wheel. If
ok lubricate and move one to the differential check above.On the other hand you could be lucky and I am wrong A used diff cost about$800 installed, a reman about $1100 a pinion shaft with bearings about $150 plus labor of $300 if you don’t take out the inner bearing (ie remove differential. Bon Chance Jay 90 Majestic XJ6 Majestic James Copp-Taylor wrote:

Hello,

I am soon going to have to embark on a job I have been fearing since getting
my XJ40, the rear differential output shaft bearings.

My front wheel bearings have a lot of play, and are to be replaced very
shortly, but my rear end has also started to whine louder than normal, I
have changed the diff oil and experienced a minor improvment. I am aware
that quick wear diffs seem to be a common XJ40 failing.

I need to pinpoint what the problem is exactly before embarking on the
remedy. Basically, at 60 MPH I have a noise from the rear end that sounds
like I am being pursued by a plane, though not majorly loud, it is
noticeable. Is this fault easy to rectify or is it a ‘drop the A frame job’?

Thanks in advance.

James Copp-Taylor

1987 XJ40 3.6 (Uhura)

5

The recommended equivalent (in my opinion) to the original Shell Spirax 90 is any
of the Synthetics with stay lock already added 85/140 wt is recommended. The
standard 80/90 with stayloc is only good for topping off in an emergency per my
owners manual and they don’t make Shell Spirax 90 HD (at least they don’t show it
on their web site)

Plenty of mfg of 85/140 but I used Royal Purple with good results

Jay 90 Majestic

MartinBrsc@aol.com wrote:> James

Mine used to whine, I would notice it on long trips usually when foot off
accelerator. My mechanic put some new oil in 18/12 ago and I havent been able
to hear it since. I guess it might have been thicker than the usual stuff but
I am certainly pleased.

I can check what he used if you’re interested, I’ll see him thursday.

Martin
93 xj40 3.2 UK

From: “James Copp-Taylor” james.ct@easynet.co.uk
my rear end has also started to whine louder than normal, I
have changed the diff oil and experienced a minor improvment.