Hi David
I didn't see any replies on this so I will give you my tuppence worth of
experience!
I have to assume that as the main components are the same as the 2500 saloon
then so are the masses of smaller items!
The lash is most likely in the planet / sungear mesh, unfortunately there is
only one way to check, get in there!
The lash is caused by the deterioration or disappearance of the Tufnol shims
(see assumption above, may have been brass in earlier cars!) behind the
planet gears, allowing the out of mesh to increase.
See item 41 on this image http://www.rimmerbros.co.uk/tr6/images/60a.gif
I believe that you could carry on using the axle without too much risk, what
risk there is would be the teeth breaking off due to being loaded too far
from the root, whether this is a big risk will depend on your driving style,
hard launches higher risk!
Rectification of the situation involves entering into the centre of the
diff, this sounds drastic but is not so.
There is no reason to get involved in the intricacies of the crown wheel and
pinion, the pumpkin can be removed and replaced as is without risk of
affecting set-up.
You need to drive out the cross pin that retains the pin on which the planet
gears rotate, if you cannot find both ends of it you may have to remove the
crownwheel.
If you have to remove the crownwheel from the carrier, mark its relative
position as I have found that the flanges sometimes vary and fitting the
crownwheel in a different position relative to the carrier may cause noise
when in use!
When I did my diff (years ago) I bought some shims of the size most commonly
used plus some either side in advance of commencing work, I seem to recall
that I needed the next size thicker to achieve a correct fit as per
specification. I seem to recall that the replacements that I used were
brass, the originals were Tufnol.
I hope this helps you.
Graham.
----- Original Message -----
From: "David Brister" <brister@tiscali.fr>
To: <Triumphs@autox.team.net>
Sent: Wednesday, October 05, 2005 4:19 PM
Subject: TR4A Diff noise
>I seek the views of the learned contributors to this list.
>
> My TR has recently started to make quite a loud thump when engaging the
> clutch from rest or whilst changing gear or on the overrun. This thump
> seems to emanate from the differential. A day or two back I raised the
> car and checked the UJ's (all six), tightness of shock absorbers,
> trailing arms, tightness of the 4 nuts which hold the diff on. I had the
> box weld mod where the diff is bolted done a few years ago. All appears to
> be well except that there is about three quarters of an inch backlash on
> the propshaft (measured on the circumference of the UJ flange nearest to
> the diff.) I suspect this may approach 10 degrees.There are no whines or
> thumps when driving normally.
>
> Is this backlash enough to cause this thumping? If so, what is the likely
> fix?
>
> David Brister. 1967 TR4A
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