Clutch, or something more serious?

**xwhatsit** · 23rd May 2008, 13:54

Originally Posted by avgas

how tight are your springs - i had a similar issue with one of the GB's. Drained oil and went to pull clutch plates out and noticed that one of the bolts holding the spring was a bit loose.

Causing this sort of unusual `false neutral' style slipping though? Limited to first gear?

It'd be nice if it was just the clutch, but I'm a negative fellow

**Ixion** · 23rd May 2008, 16:21

To prove the point, if it's reasonably predictable, try keeping your foot on the gearlever while accelerating. If it doesn't do it it's almost certainly selectors. If it still does it, may or may not be.

**erik** · 23rd May 2008, 19:40

if it was the dogs disengaging, wouldn't there be a thunk noise when it re-engaged when you throttled off?

The clutch is going to be subjected to the most force when the engine is at it's highest output, maybe since first gear lets the engine accelerate harder, it subjects the clutch to higher force than the slow acceleration in 6th? I'm just guessing, haven't thought about it enough.

How worn is the clutch? I've heard you can put washers behind the clutch springs to increase the force, maybe you could try that and see if it still does it (assuming it's the clutch slipping).

**xwhatsit** · 23rd May 2008, 21:35

Yeah I dunno, it's all very confusing. Will try holding down the pedal, Ixion. Maybe that trick will let me once again reign supreme at the Traffic Light GP for a little while longer until I've built a new engine

The clutch isn't the best. I think, Ixion, you said a while that the steels are likely warped. I was complaining about the clutch `clicking' and engaging/disengaging/engaging/disengaging with half-clutch and inching forward at the same time. I can disengage clutch, the bike will happily sit there; roll the bike forward a little with my feet keeping the clutch lever in same position, then it will bite and start to pull me forward. Go a little further and it's entirely disengaged.

So it's not really a happy clutch anyway. Might just rebuild it anyway and see where I get.

Thanks for all the advice guys!

**Ixion** · 23rd May 2008, 21:47

Hm. Could be worn/collapsed gearbox bearings. They could cause the clutch effect and also push the gears out of mesh. But I'd expect to hear some noise from a shot bearing.

Bottom line, it's had 30 hard years. They've taken their toll. A rebuild is unlikely to cost all that much.

**xwhatsit** · 23rd May 2008, 21:54

Originally Posted by Ixion

But I'd expect to hear some noise from a shot bearing.

You'd be hard pressed to hear it over all the other noises she makes

I'm well aware of the `30 hard years' and am by no means complaining that she's falling apart now; I think I'm the first owner to change the oil regularly

Stuff like this is expected, in fact, since putting her back together after that top-end carnage she's been remarkably solid, aside from the oil leaks.

I'm sure this engine will stay together while I build up another one out of my spare bits. Ground-up engine build, make sure everything's right to begin with. Last another 30 years

**FJRider** · 23rd May 2008, 22:01

I would say replace clutch plates FIRST, then go from there. Its the simpler CHEAPER option for a first step to find problem.

**Ixion** · 23rd May 2008, 22:03

Of course, since it only does it in first, and only a few thou rpm short of redline ("Wind it up in first gear away from the lights, and a few thousand RPM before redline,"), you COULD always just change up a little earlier. Just a wild thought.

**xwhatsit** · 23rd May 2008, 22:15

Originally Posted by Ixion

Of course, since it only does it in first, and only a few thou rpm short of redline ("Wind it up in first gear away from the lights, and a few thousand RPM before redline,"), you COULD always just change up a little earlier. Just a wild thought.

Oh I've been doing that of course, but remembering a few thou short of redline is 6,000-6,500rpm, and that's where the power comes in, it becomes a limiting factor on an RS

Stop giving me reasons to not attempt building up a complete second engine! You're just worried about all the questions I'm going to ask you again and again

**TygerTung** · 24th May 2008, 01:01

Mine jumps out of first, but at about 5-6k rpm, so when you are up at pole position, go to do a really good launch, revving it hard, dump in first, then boom, into neutral, so ya go into second and it's only doing about 4000 and everyone blasts past you.... damn.

It might be a common problem, I might see if if holding the lever down works, that would be great if it did!

**xwhatsit** · 25th May 2008, 01:13

Alright, not sure about this.

It seems holding down the lever stops it from happening almost all the time. However I'm not 100% sure -- my subconscious stops me from winding it out very hard in 1st gear, at least without immediately shifting to second (hard to do with your foot on top of the lever), it just feels like a nasty thing to do to the engine and my brain won't let me. (Perhaps that's why I ended up fouling the plug on Pippi the A100? Not hard-hearted enough to thrash the bikes I ride?)

So I'm not sure if I was giving it the full treatment when testing this out. It did slip/pop out once however with my foot on the lever, but that was going up a hill at even higher RPM/throttle than it popped out before, and my foot may not have been hard down on the lever.

I mentioned before that it only happens when engine is hot. It also only seems to happen when using the clutch from a standing start (of course I've let off the clutch completely by the time it pops out); if I'm already in gear rolling along at 5kph then give it heaps it doesn't seem to want to happen. But yet again, limited testing data.

So really, not very good testing, and who knows. Probably best to ignore all the above and order clutch plates, maybe rebuild one of my spare clutches with new friction plates. Measure springs, see if steels are flat. Take a look at that `little hooky thing that turns the selector drum' while I'm at it, then go from there.

At the end of the day, it's not a huge problem (yet, hopefully doesn't get worse). Just have to avoid filtering to the head of the lights unless I can see only Grandpa in his Morrie Thou and a refridgeration truck are at the front.