Gearbox pulley
As I had the gearbox out and needed the pulley off, it seemed silly not to strip it at least for an inspection. There was some wear at the rear circlip but little else seemed bad. Some form of compression is needed to take apart and reassemble the unit. I made one from some threaded rod and bits from under the bench. One does not want the spring flying out under tension! The two pulley halves are also rotated apart and want to fly back over the cams, they need letting back gently. I used a vice and a strong grip to unwind and wind them back.
Once this hazardous operation is complete, the compression can be taken completely off. DO NOTE which holes the spring comes out of! There are several choices giving different tensions to the spring.
The cam, spring and inner pulley half then slid off. Two areas internally showed some wear or light damage on mine. The large bearing area that takes all the sliding and twisting loads showed wear of the plated surface. Eventually this may need replacement, as yet I have no wear limit data for the part. I cleaned the muck and staining off with some chrome cleaner.
Next, the sliding pulley inner face sits up against a circlip and washers when it is closed. The inner face was scarred a little by the circlip ends. Why? The circlip sits crooked as there is a grubscrew adjuster shoving it across. Check the picture - the shim washers are dented.
What I did with that is turn the circlip around until the flat part was in line with the screw, not the eye ends. I've no idea if it will stay there but made me feel better at least.
The last part I did something to was the back face of the cam. The main circlip pictured earlier sits under pressure against the alloy, and eats its way slowly in. If the clip recedes enough, the cam will migrate towards the gearbox. It may hit a mounting bolt or even fall to bits. At the very least it will let the belt drop into the pulley more easily, raising the gear ratio.
I decided to fill the recess with a mild steel shim, hand made and glued in place with metal filled epoxy.
Stuck in and clamped, it made a fairly neat job. I used JB-weld. Possibly it could have managed without glue. Spot the key way? I did in fact file this section out of the shim as well, but the photo wasn't as good as this one.
All that remained was to reassemble, (don't forget the key) twisting the pulley halves back about 1/3 of a turn against the spring to re-engage the ramps and then compressing until the circlip could be fitted.
Back on the gearbox (nut tightened against a rope again - torque unknown as I don't have a figure) it looked like the pulley might need a little adjustment. I got the idea from somewhere (wish I could find where!) that the pulley at rest should have the belt flush with the pulley top. Mine was down slightly. Slacken the grub screw to let the pulley close.
And that was it. Running the car afterwards, it is apparent that the engine is revving higher. Whether due to the new rear engine mount (another page!) or the circlip shim, or me getting the spring not quite right I don't know yet. Certainly the shim will have moved the cam inward and closed the pulley about 1mm. The belt adjustment above will ONLY affect the gearing at take-up, first gear if you like. The pulley will come off the stop almost immediately. The car is actually pleasant to drive like this, as previously it was dropping the revs against slopes and headwinds, giving a heavy engine vibration coming I suspect through the dying rear mount. The 180 degree crank engine smoothes out a bit at higher revs. I shall leave it "as is" for now and see how it runs and what fuel usage is like.
Aixam