117

PROP SHAFT, DRIVE SHAFTS AND DIFFERENTIAL

Figure 2.

shaft. When a new seal is fitted it does not match this

A leather oil seal fitted to a car which is not driven for

ridge and allows a slight leakage of oil (Figure 2).

some years is likely to dry out and shrink, so that next

A solution is to take the quill shaft to an engineer who

time the car is driven a severe oil leak is caused. If you

can remove the ridge and thus hopefully ensure an

decide to renew the seal, make sure you soak it well

oil tight seal. There is obviously a limit to how many

in diff oil for 24 hours before fitment, to allow the

times this can be done as a little metal will be

leather to expand onto the shaft.

removed on each occasion.

Another very important point to note is that if the

However a further option exists. When replacing the oil

breather should become blocked, oil will pour out of

seal the workshop manual instructs you to drive the

the front seal, so do check this is clear and also

new seal fully home into the seating on the

that the diff has not been overfilled before tackling

differential casing. It is possible though to get some

replacement of the oil seal. The breather consists

adjustment within the seating when fitting the oil

of a hole with a split pin loosely fitted inside it.

seal. The aim is to fit the seal in such a position that

The head of the split pin should be jiggled to ensure

the lip rides on a different part of the quill shaft to the

it is clear, and can be found on the offside top face

previous oil seal avoiding the ridge. While this is a bit

of the diff rear casing.

more Heath Robinson than the first method it can

Issue 140 (April 1992), page 24

still be successful and has the benefit of distributing

any slight wear along the surface of the quill shaft.

Differential Oil. A member of the Technical

Issue 127 (February 1991), pages 21,22

Panel gave this advice:

WHEN REFILLING or topping up diffs, make very sure

Oil Leaks from the Differential. A Technical

that the EP90 or 80/90 oil used is to GL4

Panel member replied to a question about

specification. Do not use GL5 as it has been found

leakage from the front oil seal:

that the additives in it attack the copper thrust

THE OIL SEAL LEAKAGE you mention is very

washers behind the planet wheels. This applies to all

common, in fact almost universal on the Stag. It is a

Stag/Herald/ Spitfire/TR and 2000 models.

little-known fact that oil seals are engineered so that

Issue 204 (February 1998), page 30

they pass a very small quantity of oil so as not to burn

David Everett (10952) commented:

the sealing surface and thus eliminate the sealing

IN A RECENT EDITION of the Club magazine we were

qualities. As a general practice, when assembling any

advised not to use GL5 gear oil because the additives

oil seal, always smear it liberally with oil or grease.

corroded some parts of the differential.

This particular seal is made of leather, yes leather! I am

EP oils may use two kinds of sulphur ­ active and non-

told this is because it will happily run well out of

active. All the major companies stopped using active

alignment whereas the modern Neoprene seals are

sulphur at least 10-15 years ago and all the additives

precision components. Just to put it all in

now used are safe. However, as the axle oil is not

perspective, leather oil seals were used on cart and

changed on Stags, some cars will have old oil in them

carriage wheels!

and any very old stock of oil used for topping up may

Only you will know whether the leak you are

be suspect. When replacing or topping up with oil,

experiencing is just the slight misting designed into

GL5 gives maximum protection.

the seal to keep it wet, or if it is truly excessive such

I hope this makes the situation clearer.

that regular level checking cannot keep it supplied

Issue 209 (July 1998), page 53

with oil. A drip or two a day can soon empty the diff.