Last night I was taking apart a TR6 rear end. Externally the rear end was
perfectly clean, internally the ring and pinion and the output shaft bearing
were rusted badly. Some DPO had obviously pressure washed it, water leaked
past the worn seals, and it was put on a shelf to rot. Too bad: it was a
rare 3.45:1 crown and pinion gearset, used on the UK TR5 and 6's, and of
course TVR's.
To the point of my writing. I had never taken a TR6 rear end apart before,
so decided this was a good one to learn on. I wanted to take the diff cage
(containing the sun and planet gears) out of the case. The problem is there
is an interference fit between the case and diff cage. This requires a diff
spreader, shown in some of the manuals, which pulls the case apart enough to
lift out the diff cage. Somebody on the list recently mentioned they spent 6
months looking for one of these, before they gave up. I recall somebody
saying he pried his out with a crow-bar. I tried the crow bar, but no luck.
Stumped, but determined, I came up with a simple solution. Using a great
honking c-clamp, I gently squeezed the case, which slighly pushed the case
apart enough to lift the cage out, allowing me to get at the bits I needed.
How does it work? Difficult to explain without a drawing, but imagine a
basketball, and you want to give it the shape (slightly) of a football. The
diff spreader would pull the sides into the shape required. Or, using a
c-clamp, you would squeeze the middle together (slightly) and drive the ends
into the shape required. From the perspective of the basketball, makes no
diff! Sorry, couldn't resist!
Some metalurigist might want to discuss the properties of cast steel under
tension versus compression, but I am convinced that this is irrelevant given
the small forces and minute clearances required for this job.
Any thoughts on how tough it is to swap the TR6 diffs on TVR's? I recall
somebody saying the body needs to come off, although I also recall sombody
saying that if you cut a hatch in the back deck it can be done without
moving the body. Appreciate any help you can provide on this.
Stephen Hill
1972 TVR
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