Replacing a Triumph Bonneville clutch shouldn’t be too ghastly an enterprise. Yet, as NVNL discovered, there are always some questions to which the answers are not immediately apparent…
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‘Things fall apart; the centre cannot hold; ………
The best lack all convictions, while the worst Are full of passionate intensity.’
William Butler Yeats
With all the replacement parts ordered, on a Sunday afternoon I collected all the items around me on the Little Red Bench by Sealey (never mind Little Black Dresses by Coco Chanel — get yourself a decent workspace), and the dismantling of the T140’s clutch began. No threads were stripped, no knuckles bloodied, no bolts sheared. Birds sang, the dogs lay contentedly on the shed floor. The footrest bolt was hard going until I remembered Daddy’s Little Helper – a yard of scaffold pole. Even the exhaust co-operated. The job just went well. I locked the shed and went off to enjoy the evening safe in the knowledge that all was well prepared and the replacement parts would arrive on Monday.
The seven plate clutch was an item I’d been keen to try for a number of years because of the claims made about its lightness when disengaging. The standard Triumph ‘B’ Range clutch in late seventies/early eighties 750s has an undesirable (there, I’ve said it) heftiness to its character and if there is a cheap (ho! ho! ho!) way of improving my bike as things come to the end of their service lives then I’m keen to try new stuff.
I’m guessing here but the plates seem to be thinner than the standard ones and mysteriously have a smaller surface area. It makes some sort of sense in terms of not sticking, but how do they grip? Again, I am but the dimmest of thirty-five watt headlamp bulbs, it looks as if each little friction pad has a larger surface area. Aren’t people inventive? Each of the six old Surflex plates has twenty-four little pads whereas each of the seven new plates has but twelve larger pads, hmmn. The seven new plain plates are all made to the Meriden pattern and in theory I could just have bought one new one to add to the original six plain plates, but I didn’t, OK?
The clutch springs fitted to the 750 are stronger than those fitted to the 650 I am told. I am also told that the 650 type springs do a perfectly adequate job in service on a T140 but help towards a lighter action — might as well try them, I suppose; we pass this way but once.
This is the point at which things fell apart and I began to feel as if the centre would not hold. My dislike of having a bike decommissioned overnight is very strong and although the Norton and the Ducati were both ready to roll at a moment’s notice, and although I tend not to ride during the hours of darkness, I was prey to thoughts of the parcel going astray, the wrong bits being in the parcel anyway and me suddenly losing the use of my hands, even perhaps those naughty dwarves who live in the carburettor going over the side and taking my spanners with them. The fact that I hold at least one duplicate set of tools was no consolation to me.
Needless to say Postie turned up with the right parcel containing the correct parts at exactly the right moment on Monday, my hands worked as well as they ever do and the carburettor dwarves are the figment of someone else’s imagination. However the job became a nervous chore and the words of Jack Yeats’ less well known brother William were right on – my best lacked all conviction while my worst was full of passionate intensity.
It is a fact that the clutch basket slops around on its little silver rollers during the assembly process. It is a fact that I know and understand this slopping around, but the worst side of my character was telling me with great passion not to trust this but to buy some more rollers and maybe a new clutch basket ‘just to be on the safe side’.
Mercifully my best side managed to muster sufficient conviction to apply a little commonsense and just get on with a simple job. Another bijou crisis was negotiated with diligence and advice – I couldn’t remember whether or not to oil the individual plates: in the end I didn’t.
Adjusting the spring tension was tricky, not in terms of tightening all three springs evenly, I will never forget how to do that, but with regard to how far to compress them. Given that my aim in replacing the plates and springs was to achieve a lighter action at the handlebar lever while delivering a high bite factor and that the new springs did look a little less butch than the old ones… how tight should I set them?
I guess this is the dilemma of this type of arrangement in many cases, so top marks to Yamaha for designing this dilemma out of the SR500 clutch. Dear old Meriden on the other hand required the application of a little craftsmanship.
So I rang a team of experienced craftsmen. ‘I generally tighten them till the top of the bolt is level with the dome of the retaining nut and go on from there,’ said a Nottinghamshire accent. So I tightened them till the top of the bolt was level with the dome of the retaining nut and adjusted for even pressure.
Then I adjusted the clutch pushrod (establish light contact between top hat and grub screw, back off half a turn and lock – no sensitivity or judgement required on my part), set the cable length and gave the lever a squeeze. Fine, lighter than before. So far, so good.
Random Bonnevilles on eBay.co.uk
With the cover off I adjusted the primary belt using a calibrated caliper thing then sealed the case and worked on towards a test ride.
The exhaust was reassembled with Foliac graphite compound as suggested by someone (thanks for the tip fido) on the RealClassic message board. It went back together nicely and according to the advice given will disassemble nicely too, but not of its own accord. We’ll see.
Things nearly fell apart again when I couldn’t find the Duckhams 20/50 to put it the chaincase but my best side was in the ascendancy and I used some nice ‘Diesel’ 15/40 on a trial basis. So daring, so daring.
Out of the shed and into the yard to check how well the clutch actually worked, seemed fine. Then again, not much can be told about the clutch from a quick pootle round the car park.
A quick ten miles of mixed conditions convinced me that I had chosen the right clutch parts, for the first time my T140 has a light clutch which grips strongly and disengages well throughout the range. I even pulled to a standstill in fifth gear and then snicked down through the box and readily into neutral.
Amazing, function beyond my most optimistic longings!