|1955 Velocette Venom.|
Not such a problem you might think, just carefully follow the approved Velo procedure of taking the drive sprocket cover off with machine on stand, insert adjuster peg through hole in aforementioned sprocket and, in gear, roll the rear wheel forward slightly. Problem was that no amount of correct adjustment would cure the issue.
So, next step, dismantle the clutch to check. Friction plates badly worn. Replace and try again. No improvement. Metal plates are noted as worn. Buy new and fit. Same problem. Hmmm... for that matter the basket is also quite worn. Replace but still no improvement. This was all getting rather silly. The time came to stop wasting money on new parts and check it all through carefully. After much head scratching it turned out that the different plates and the basket had come from different suppliers and though all may have been just within tolerances, together they just didn't match up. The main problem being that the tangs on Velocette plates are cut with an angled face. The angle on the friction plates was sharper than that on the basket meaning that the plates would never sit snugly into the basket and would remain always very slightly lifted. Just enough to cause slippage under higher load but also mal-fitting enough to cause drag too.
|KTT Service belt drive conversion.|
So far from this sorry tale of mechanical woes and wasted money the only advantage to me had been that I was now very familiar with the workings (or lack thereof) of Velocette clutches. Velo afficianados seem to go to great pains to defend the wonky engineering of the Hall Green clutch. Though my Venom is probably the favourite in my small stable my mind still boggles at quite how they came up with such a design. Drag is inherant in its design, it is fiendishly complex to manufacture, a b**** to assemble and set up and is housed in a vintage tin case. To speak up for it it does work (but so do conventional push rod designs and often much better) and is very light...
I got in touch with Kevin and shortly after placed an order. Kevin was very helpful, took a deposit and quoted delivery in a couple of months. In the end it took a little longer, not a big problem as it wasn't as if I had too much spare time and my only bike off the road.
When the kit arrived it was all very nicely made and initial fitting seemed easy. It came without the clutch basket bearing race so although the kit is reasonably priced, the race (not supplied by Kevin) is not, so it pushed the overall cost up a fair bit. I guess normally you would use the original chain basket race but in my case it was shot.
|1955 Velocette Venom drive side view.|
Putting the outer case on it was evident that the Velo wouldn't play ball and give up without a fight. First obvious point of contact was the felt seal holder that faces against the clutch. I made up a new double thickness cork gasket and drilled the rivets out that held the felt seal holder in and removed it, as it was going to run dry it didn't seem like the lack of a felt seal would cause any problems. Re-assembling I cursed the Velo tin case with its multitudinous screws holding it all together. The part of the outer case that I would describe as a small shelf under the insection cap was now obviously rubbing on the engine pulley. As I have no idea what its logical function is I took the step of cutting it off. Reassemble and still some rubbage on the pulley. To counter this I made a new central spacer approximately 1/8" over standard to push out the centre of the primary outer cover. It all now seemed good. However cracking the engine in to life caused something to move and it came to a sudden stop. The pulley had rubbed against the new outrigger oil seal. Nothing for it now except to make a spacer to sit inside the pulley. For good measure I also chamfered off the internal right angle edge of the pulley. The spacer made up was 1/16". Back together again and finally bingo, all good.
The clutch was extremely easy to adjust. I even got it right first time - after all that I felt that I was due some luck. Giving the bike a test ride it worked magnificently. The clutch action is extremely light and it will hold stationery in gear for a good while longer that the normal 3 or 4 seconds the standard clutch gives before drag and stall. So finally after all the effort it was well worth it. If it seems like I encoutered a lot of problems fitting it, well I did! But really it's perhaps not too much of a surprise given the very narrow proportions of the Velo clutch and the individual nature of each Velo. So, certainly the KTT belt conversion isn't a buy one day and fit that evening upgrade but it is worth it and I feel has made my Velo a good bit more pleasurable to ride.
|Grove Classics roll on centre stand for Velocette.|
|Velocette Venom 171.|