A Clutch of Questions
Posted: Tue Aug 10, 2010 3:01 am
Patient: Brunhilde, 1974 R90/6, with 200,000 kms.
Symptoms: A gearbox on its last elbows, or at least in its autumn months - clunkier, louder whining and some false neutrals recently. Also a clutch that has always been a bit heavy and grabby. Two broken clutch cables in 45,000 kms.
It has been 5 years and about 45,000 kms since I last had the gearbox out. I am impressed by how much cleaner it looks in there compared to last time, when I replaced the input shaft and RMS seals and cleaned out decades of gunk.

Ok, not clean, but mostly dry, and that’s good. Splines still well greased but badly chewed, as they were last time. Anyway, I now have a reconditioned gearbox to install and I’m checking out the clutch.
Thickness of the friction plate is still within spec. The splines look ok and it slips onto the new gearbox input shaft nicely, with not too much slop.

The pressure plate side has uneven wear. Not much of the inside 50% of the friction surface has had contact with the pressure plate.

There are no scores on either pressure plate or pressure ring surfaces, but there is some detectable unevenness. It is sounding worse, isn’t it?
Now for the really troubling bit. The diaphragm (such an odd word) spring does not measure up. Mr Clymer would like the spring height to be in the range 18.5 to 19.5mm, and mine measures 17.5mm. The finger tips have quite sharp edges –

- and have left significant teeth marks where they contact the back of the pressure plate. Depth appears about 0.5mm

As I type this and ponder just what questions I want to ask, I discovered that the answers were being shouted at me by the anal, obsessive side of me. GET NEW PARTS, etc. (bastard thinks I’m made of money).
The other side, the one that gave me permission last time to just shove everything back together after cleaning the oil off the friction plate, the ‘she’llbe right, mate’ side, would rather spend the money on fuel, tyres and beer. (we have mate, thanks for that)
Ok, please help me. Would you put it back like this? Any of it?
All comments welcome. Please feel free to shout.
I’m off to make a call or two about used parts …
Symptoms: A gearbox on its last elbows, or at least in its autumn months - clunkier, louder whining and some false neutrals recently. Also a clutch that has always been a bit heavy and grabby. Two broken clutch cables in 45,000 kms.
It has been 5 years and about 45,000 kms since I last had the gearbox out. I am impressed by how much cleaner it looks in there compared to last time, when I replaced the input shaft and RMS seals and cleaned out decades of gunk.

Ok, not clean, but mostly dry, and that’s good. Splines still well greased but badly chewed, as they were last time. Anyway, I now have a reconditioned gearbox to install and I’m checking out the clutch.
Thickness of the friction plate is still within spec. The splines look ok and it slips onto the new gearbox input shaft nicely, with not too much slop.

The pressure plate side has uneven wear. Not much of the inside 50% of the friction surface has had contact with the pressure plate.

There are no scores on either pressure plate or pressure ring surfaces, but there is some detectable unevenness. It is sounding worse, isn’t it?
Now for the really troubling bit. The diaphragm (such an odd word) spring does not measure up. Mr Clymer would like the spring height to be in the range 18.5 to 19.5mm, and mine measures 17.5mm. The finger tips have quite sharp edges –

- and have left significant teeth marks where they contact the back of the pressure plate. Depth appears about 0.5mm

As I type this and ponder just what questions I want to ask, I discovered that the answers were being shouted at me by the anal, obsessive side of me. GET NEW PARTS, etc. (bastard thinks I’m made of money).
The other side, the one that gave me permission last time to just shove everything back together after cleaning the oil off the friction plate, the ‘she’llbe right, mate’ side, would rather spend the money on fuel, tyres and beer. (we have mate, thanks for that)
Ok, please help me. Would you put it back like this? Any of it?
All comments welcome. Please feel free to shout.
I’m off to make a call or two about used parts …