That is a very good point -- the roller bearing by its nature has to be
precisely centered. The carbon-faced bearing did not; hence, the entire
actuation system was designed without the requirement for throw-out bearing
centering in mind. I can think of all sorts of ways the centering could be
off, over and above the use of a non-matching arm, as Norm describes. Worn
pins and bushes are the obvious candidates.
The question that occurs to me is: even with a spring retraction system (t
avoid premature wear), wouldn't an off-center bearing be under severe stress
every time the clutch was actuated?
on 8/7/03 7:24 PM, N at twobees@sprynet.com wrote:
> Here's my experience with Roller T.O. bearing:
>
> Last year when I installed the new engine, I too went for the extra $$ &
> installed a roller (brand new). 700 miles later I removed it as it was
> totally fried (I do NOT ride the clutch. But, the bearing was blue from
> overheating.). I replaced it with the old carbon one I had in for the
> previous few years. During the course of the year (July '02 to July '03) I
> had the engine in & out a total of 5 times to replace various clutch parts.
> At one point, I noticed that the bearing carbon was wearing off-center. I
> then re-examined the roller bearing & saw that there were tiny "swirl" marks
> on its face from grit between it & the pressure plate. That got me thinking
> that the bearing wasn't centered. (Brilliant, Watson! A little slow on the
> comprehension?) On further investigation I found that the t.o. arm was from
> the early trans. And, when I switched to a 4-synchro box a number of years
> ago, my (then) trusted mechanic had used the old arm. DUHHHH!!! It's
> different, fella! It's about 1/3 inch difference in length. THAT WAS WHAT
> CAUSED THE ROLLER BEARING TO FRY.
>
> So, would I use one again now that I have the correct t.o. arm? Perhaps IF
> I had a way to adjust it away from the face of the pressure plate when
> retracted. With the stock hydraulic system, that isn't possible without
> rigging a spring & stop. If anyone comes up with a system. Let me know.
> I'm willing to give it a try. I have another roller t.o. sitting around
> waiting for a solution short of a Tilton system.
>
> Norm Sippel
> '66 MGB
>
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
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