Hello,
Having never run a Norton 88 with a laydown gearbox before excuse my ignorance.
firstly, the clutch pushrod is too small. Bought new from A.N. so i wonder if there should be a rod extension from the worm gear. Has it broken off.? How long should the broken bit be ?
A BSA clutch pushrod cut down to size has been adapted for now.
The pushrod bore feels notched , not smooth, and the clutch outer drum moves as i pull in the clutch so worn rollers or clutch drum. I have another clutch to try.
However , the main problem i fail to grasp is the worm not returning and resetting the clutch lever. Should there be a return spring somewhere? Does the return rely on as little friction as possible?
Clutch function
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mushrooms ?
Hi Jon,
I am missing a mushroom under the clutch cover. I suppose i can cut down an old valve to fit instead. That explains why the pushrod is too short.
Possibly explains why the spring pressure will not force back the clutch lever.
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Mushroom
Sure they are available in other suppliers. Plenty of load on these, needs to be stiff.
- Overall length 1.75"
- Stem 0.25"
- Head 1"
- Face has a recess of 1/32" leaving a 1/8" contact face.
Would search one out rather than machine one up. Maybe one of our members has a spare?
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Someone once posted that the…
Someone once posted that the hole in the gearbox main shaft is 0.25" = 6.35mm, and the rod is metric size = 6.0mm. I don't know if that's correct - but it means the mushroom rod would be 6mm diameter. Might be wrong! But obviously it has to move easily...
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clutch hurrah
well i have my clutch working fine now. .The missing mushroom , correct clutch cable and an early thrust cover made all the difference. also found a couple of friction/plain plates that helped.
thanks for all members advise and owners club spares for parts.
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Don't quite understand what you have here but if you look at the diagram for a Norton clutch (technical tab above). When you pull the lever the cable connected to an arm turns the brass scroll. Brass scroll is used to change rotational moment into linear. A rod passes through the shaft from the brass scroll pushes a mushroom mounted under the clutch cap, pushing the clutch cap against the spring pressure thus releasing the plates. When you release the clutch lever the spring pressure pushes the mushroom thus the rod which in turn pushes the brass scroll back in position and the clutch cable returns with the lever to the closed position.
Sometimes there is a ball bearing between the rod and the mushroom to reduce friction against the brass scroll end plate.
When you adjust your clutch you need to set up the arm on the scroll to give you the best mechanical advantage during the travel of your bar lever.
To sum up; the clutch cap is lifted against spring pressure by turning the scroll. When clutch is home there should be a gap between the rod and the scroll. When you adjust the cable again the gap should be there. When you pull the lever you need to get the maximum movement of the scroll by ensuring you are pulling at the optimum angle. e.g. half of the movement of the clutch mechanism would see the scroll lever sitting at 90 degrees to the shaft.
If all this is sucking eggs I apologise...