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I'm curious about the return spring. My TR6 does not have it but I read in an article in the now-inaccessible VTR Maintenance Handbook a while back about adding a spring. There were actually two applications- one to pull the clutch operating shaft away from the slave cylinder to reduce pressure required to push in the clutch, and the other as shown in TDSkips photo. I currently stand in need of the latter as sometimes when I take pressure off of the clutch nothing happens until I have very little pressure on it at all and then WHOMP! it lets out all at once. Not fun in stop and go traffic. Would the addition of the spring help this or am I looking at a different problem altogether? (clutch/TO replaced 2 years ago) Would the spring put too much pressure on the clutch hydraulics?
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Hi,
TR6 don't have the external return spring. Triumph made a number of small changes to the clutch mechanism, mostly to reduce servicing, perhaps lower cost of manufacture, and to "lighten up" the pedal in response to owner feedback. However, personally I think the changes took the margin out of the mechanism, meaning that all the individual items must be in top working order with no wear and tear, and, as a whole, make for the clutch problems we so commonly see today in those cars.
One change was to a smaller master cylinder. Another to the non-greasable shaft and narrower bushings in the bellhousing (actually in mid-TR4A production). Also, the slave pushrod was changed to non-adjustable and the external spring was removed. Without looking at the service manual, ISTR the TR6 either has an internal return spring in the slave or just relies upon hydraulics in combination with the pedal return spring to return the piston.
There have been several articles and books addressing problems with TR6 clutches that have called for installing a spring and adjustable clevis, sort of a retro-fit of the TR4/4A arrangement, which was almost trouble-free with the early coil spring release plate (TR4) and far less problematic with the later diaphragm clutch (TR4A). I believe the most recent to recommend this is Kas Kastner's latest, but I haven't got a copy yet.
If (when) I have a TR6, you can bet that first opportunity I'll be retro-fitting it with: .75" diameter master cylinder, TR4/4A style slave with external return spring and adjustable clevis, greasable cross shaft and wider cross shaft bushings. IMHO, one thing to avoid especially on the 6 cylinder cars is a clutch release plate with heavier than stock pressure. These cars have enough problems with faster wearing crankshaft thrust bearings, without adding a heavy clutch to the mix. A heavy "racing" clutch will wear them very rapidly, unless modifications are made to beef up the thrust bearings themselves.
It sounds to me like your car has some wear on the driven plate, and the "self-adjusting" clutch slave cyl. is insufficient to compensate. The good news is that this is the opposite symptom of the the usual, broken cross shaft pin.
First things are: see if you are getting a minimum of 5/8" travel out of the slave cyl. pushrod when the pedal is pressed (if not, either MC or SC are worn), check that the clevis pin and lever have no slop due to wear, and confirm that the clevis pin is installed in the center hole in the lever.
If those are okay, next I think you would be wise to get the return spring and the adjustable clevis/pushrod. There have been some sellers on eBay, and I think TRF or Moss might now be stocking a kit now.
My best guess, you may have had some clutch slippage, possibly due to a slow returning slave cyl. that might have accelerated wear. There is no way to adjust to prevent the wear or to compensate for any wear that has occured, with the stock TR6 setup. So this would be the most cost efficient external attempt to fix it.
The next step logical would be to get a .75" master cylinder, which will make the clutch pedal a little heavier to operate.
The ultimate fix, in additon to the above, would be to pull the gearbox and replace at least the driven disk. But, you might get by for a couple years before needing to do that, if the other fixes are made.