Peter Zaborski wrote:
> > Has anyone on the list experienced these
> > problems and discovered the cause and fix?
>
> Jim, oddly enough I just fixed the exact same problem on my car. I received
> a lot of help from fellow lister Brian Schlorff. Because we are many miles
> apart, the diagnosis (Brian runs a british car shop in Pennsylvania) was
> done over email. My symptoms were the same as you describe -- when cold the
> clutch was fine, with engine off the clutch was fine, but when warmed up, it
> would stick or bind and then "snap" back into position.
>
> We determined the problem had to be inside the bellhousing as opposed to
> hydraulics. When I pulled the gearbox, I noticed a very slight amount of
> dark gummy substance on the splines of the input shaft. I don't know if this
> was the cause of my binding but it seemed a good candidate. I was also
> suspicious that perhaps the culprit was a worn front cover plate which would
> have made the release bearing sleeve too loose and "tip" when fully
> disengaged (pedal pressed in). Brian was kind enough to try out various
> front cover plates (or "snouts") and bearing sleeve combinations to
> determine if he could detect any cause of binding. He even heated them up in
> an oven to simulate operating temps. No conclusive pattern was discovered
> unfortunately.
>
> Another factor in my case is that I had only about a year previously
> replaced my clutch (and associated parts) and was second guessing myself
> about properly lubricating the splines upon reassembly. Since my clutch
> worked fine for about 3000 miles before the binding began I figured maybe I
> had not lubed the splines sufficiently or properly. In any event, I thought
> for sure my gearbox had to come out to fix the problem.
>
> So I wanted to prepare for the removal in advance and make sure I had all
> parts on hand prior to starting the work to minimize downtime. I decided my
> clutch parts were all still new enough but that I would replace the release
> bearing (since this was the reason I had replaced my clutch the last time --
> more on this later), the release bearing sleeve, and the front cover (or
> "snout"). Since my last clutch job, the TRF magic clutch recipe had been
> reverse engineered and posted and I wanted to use the release bearing from
> that setup. It is a Toyota Landcruiser spec bearing so I figured it would be
> more than strong enough for a TR6. Brian obtained one and matched it to a
> sleeve and snout and sent me the parts. I installed these on my car and have
> had no trouble since (~1600 miles). AS an added benefit, the new bearing
> allows me to use the lowest hole on the clutch release shaft thus minimizing
> the stress on the clutch release components. And the clutch seems less
> "stiff".
>
> I have cc'd Brian in case he has anything else to add (or to correct any
> errors on my part).
>
> BTW, I also live in Calgary so if you want to discuss this further, send me
> you phone # and I'll be happy to call.
>
> --- Peter Zaborski CF58310UO ---
Jim,
I have now been involved with three such cases over the last 2 years and am
currently
working with a customer in San Diego to solve #4. I believe the problem to be
some
sort of imblance that amplifies itself when the assembly is rotating, but even
at this
point after dealing with this a couple times, I cannot pinpoint one clear fix.
The
sucessful remedy so far has been to replace the all of the following regardless
of age
or condition; pilot bush, throwout bearing of your choice, bearing carrier,
sleeve (or
snout) in trans bellhousing. This has worked in every case, without changing
the
clutch pressure plate or friction disc. Be careful to ensure smooth sliding
action
between the bearing carrier and the trans snout. I usually polish both these
surfaces
to bright finish. Check carefully for burrs and file any that you can readily
feel by
hand.
Peter's choice of the Toyota bearing is a good one. It allows the use of the
bottom
hole and generally makes the pedal lighter with a higher balance point.
However,
brand of bearing is not related to the sticking problem as I have used both
stock TR
and Toyota sucessfully. Downside to the Toyota bearing is high cost (about
$50).
Otherwise be sure to measure for a good interference fit of at least .002"
between the
bearing and carrier. I checked one carrier and could slide the bearing on and
off by
hand - not good when all buttoned up inside your bellhousing. Visit your local
LBC
mechanic and check a couple of sleeves/snouts and carriers. Tollerances vary
widely
and I suspect that this may contribute to the problem. I have heard a rumor
that the
sticking was caused by differing rates of expansion between the carrier and
trans
snout resulting in zero clearance, but my own testing of multiple pairs could
not
confirm this - even at elevated temperatures above what is common inside the
bellhousing. That said, I still can't rule that out as a possible cause.
If anyone else has experienced this 'sticking' problem, I'd be intersted to
hear what
you replaced to fix it. My feeling is that this is becoming a more common
problem and
perhaps we could trace it to a more specific failure of one particular part.
Regards,
Brian Schlorff '61 TR-4 '64 TR-4 '72 TR-6 '79 Spit
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