front fork spring question

maylar said:

Is there a good reference somewhere about disassembly/reassembly of the forks? The workshop manual is rather sparse on that. Like, if you wanted to replace bushings and seals do you need to remove the stanchions? Any YouTube worth while watching?

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You need the stanchions out to clean the internals and fit the lower bushes, fitting the upper bushes can be done either way, the seals are easier done with a seal driver.

L.A.B. said:

A poke with a piece of wire would probably have cleared it (or did you?) as that is where the sludge will build up.

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I'll remember that. Did take it for a long ride yesterday after refilling the forks with 150cc's of 20wt power steering fluid. Ran pretty good. I thought that motoring around for a couple of hours would cause a better rebound action in the forks (a vain hope, I know), but it didn't. Still have the "clunk" noise when, sitting in my drive, I push down on the forks and there's no evidence of hydraulic rebound control. It just springs back up and hits at top with that clunk. Probably nothing to free-up. I'm going to rebuild as soon as the snow flies. But until then, could I help it out by putting a heavier wt oil in and maybe more of it instead of 150 cc's?

Putting in more oil will almost certainly simply make more come past the seals.

Putting in heavier oil might make them feel a little better. 20/50 engine oil has always been popular. But it is a course band aid.

Forget the clunk until you can fit either damper inserts with bump stops or longer top bushes that trap some oil between the bushes and add a topping out bump stop, both will need a full overhaul. Use the viscosity of oil that gives you the best handling, it may help the clunk or not but proper handling should take priority over a clunk on the driveway.

kommando said:

Forget the clunk until you can fit either damper inserts with bump stops or longer top bushes that trap some oil between the bushes and add a topping out bump stop, both will need a full overhaul. Use the viscosity of oil that gives you the best handling, it may help the clunk or not but proper handling should take priority over a clunk on the driveway.

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If I understand, you're indicating I still might have hydraulic rebound damping, it's just at the top there is no bump stop? I thought the clunk indicated little or no hydraulic rebound control through the entire range.

No, due to a design flaw when they drew up the Commando forks the valve inside the damper body on the end of the damper rod hits the damper body top with a clunk before the bush bump stop comes into play. By fitting a spacer or a longer top bush the hydraulic bump stop of oil trapped between the top and bottom bush comes back into play.

The lack of rebound is another issue, you restore that by fitting new damper rods and damper body tops with a toleranced gap to the rod and this restricts the oil and restores rebound damping.

Here's a good rebuild article with great photos:

https://www.motorcycleclassics.com/mc-how-to/rebuild-roadholder-forks-zmmz17mjzhur

Also - http://www.doov.com/apps/nortoncompanion/1973-74-workshop-categories/g-forks-steering-head-bearings