Re: clutch problem need help

[Tim Buja <buja@domain.elided>]

Ralph Vrana wrote:
>After driving my car for a couple of weeks I seem to be having a clutch
>problem.  I have talked to my fellow british car nuts and they have no
>answer.
... (heat related symptoms)
>Does anybody have any suggestions,  I am at my wits end.

This sounds very similar to a problem that I've heard of with TR6s in
the US.  The clutch works fine when cold, but is either very slow to
engage (or will not engage) when hot, and almost impossible to
disengage when hot.  The problem in the TR6 appears to have been
identified as incorrect machining of the "release bearing carrier",
Stag p/n 154975, TR6 p/n 100157.  This is the part that surrounds the
transmission input shaft and supports the "release bearing sleeve",
Stag p/n 154976, TR6 p/n 147858.  It seems that the part of the
release bearing carrier that holds the release bearing sleeve is too
large in diameter.  When cold, the bearing sleeve slides perfectly on
the bearing carrier, but it binds up when hot.  I've heard
recommendations to have the bearing carrier machined to remove a few
thousandths off the OD.  When you get the transmission out of the car,
slide the bearing sleeve off of the bearing carrier and measure the ID
and OD of the respective parts.  If you can, try heating them up in an
oven to about 250F or so to see how the clearances change with
temperature, and to see if you can slide the bearing sleeve on the
bearing carrier. If it won't slide, you've found the problem.

This problem seems to be prevalent in a new batch of TR6 bearing
carriers made about in the last couple of years.  The bearing sleeve
parts do not appear to have the problem, only the bearing carriers.
I'm not sure if the TR6 and Stag parts are identical now, as the
part numbers do not supercede one another in the Rimmer Bros. catalog.

The Roadster Factory may be able to help you with the measurements
as I've seen them mention the TR6 clutch problem in their publications.
Call their Technical Research Department at (814) 446-4491.  Their
support hours are 12:30pm through 6:00pm Eastern Time, Monday through
Friday.  Ask them what the clearance should be between the carrier
and sleeve at room temperature.  Walter at Stag Specialists may also
have this information.

When you put everything back together, be sure to wrap some
electrical tape around the transmission input shaft splines before
you slide the bearing carrier back on.  If you don't, you'll risk
cutting the oil seal on the splines, causing the seal to leak. Even
though you've only got about a thousand miles on this installation,
you may want to get a new oil seal for the front end cover because
the splines might have already cut the seal when you removed the
bearing carrier.  When you wrap the splines with tape, start at the
transmission end of the splines and work your way to the end of the
input shaft.  When you've got the bearing carrier installed, pull
the end of the tape at the end of the input shaft.  The tape should
unwrap all the way down to the end which will be inside the bearing
carrier.

Let us know what you find...

Tim Buja - Rockford, Illinois, USA - 80 TR8, 73 Stag, 72 TR6