Shagged clutch; increased backlash?

[xwhatsit]

Hello,

My clutch (which has been a horrible little thing from when I got the bike) is getting worse and worse and I'll need to replace it soon to make my life liveable. It caused me to stall in a terrifically embarrassing way on the Cheesecutter ride.

Symptoms point to a gouged/grooved clutch basket. Clicking with clutch in and rolling to a stop; jerky as it engages; disengaged with the lever fully pulled in, but roll forward a little bit and it starts dragging -- roll forward a little bit more and it's back to being disengaged.

I'm reasonably clear on that. However I'm interested whether replacing the clutch basket and making it all nice and pristine will fix another symptom the bike has. It's got a rather nasty amount of backlash in the transmission. This causes me to use to clutch rather a lot in the first place, to avoid looking like a beginning car driver bunny-hopping with my head snapping back. Does a worn-out clutch/clutch basket cause lots of backlash?

I've checked what else could cause it; this model CB has no cush-drive rubbers, so there's nothing to replace there; I always do my best to keep the chain in good nick/tension; sprockets are good.

Thanks guys.

[F5 Dave]

Well on a single teh chain & sprockets as you mention. Obv you chkd 4 tght spts. Hey I'm gettgin lazy & txtg lik a kid! Arrgh, best I go home now.

Erm, sans cushdrive, erm, sorry? You mean the wheel has no cushdrive? (sorry too long ago when ex had one). The clutch cush drive will cause those symptoms of lash. You have to drill out the rivets & pac some spacers to reduce it. Not that hard, just putting it back can be interesting.

Ideally you need to turn up some rivets & smear them over. On my race 50 I drilled & tapped & used countersunk bolts instead of rivets. Not probably the best on a bigger bike, but erm, nah.

Re the rest the basket is likely worn, a file may do ok, but you may have to get some weld built up on the big troughs if that bad or find a new basket. Check steels are straight.

[xwhatsit]

Cheers for the reply.

I've got annuver clutch in the spare bottom end I've got kicking around, god knows what condition it's in though.

Most 250RSs have cush drive rubbers in the hub. French and Japanese models' hub (wot mine has got -- at least going by JT Sprockets description of the hub) have a different set-up; the rear sprocket has different mountings and doesn't have the cush drive around the sprocket bolts like the normal ones do. As the engine and clutch is identical, could it be that there is simply no cush drive at all? Or is there a rubber cushioning somewhere inside the hub, not where the sprocket bolts attach?

Chain is good; the original chain produced the same symptoms, when I replaced it with a nice new O-ring, which was fitted and aligned by Mt Eden, the symptoms persisted.

Not so keen on filing the basket as from what I've heard it's a temporary solution at best. I'll take a look at the other clutch and see if I can nab the basket. Hopefully new plates aren't needed, but the engine has been overheated a few times.

Do you think just the worn clutch basket could cause backlash, though? Or once the plates are engaged, does it not move around?

[F5 Dave]

Simple to check rear hub, either it is bolted direct to the hub, but if there is a dirty big circlip then the typical honda large rubber tube cush drive will be there. Don't think my old XR of that vintage had a hub cush.

The cush in the clutch hub will be there though. But how worn it is can be found by trying to rotate the hub from the gear it is riveted to. some movement is expected, but if it is moving a cm before any resistance is met then it will be enough to make it feel like it is slamming around with every increase or decrease in power.

Check the steels on glass with a feeler gauge, or against each other in different positions (they can 'cone').

"Not so keen on filing the basket as from what I've heard it's a temporary solution at best"
Who told you that? A Honda parts saleperson?
Having a filed basket is a dam site better than having a ripply one.
Filing it will stave off wear better. Have done it a dozen times at least to good effect.

[xwhatsit]

Reading up on it, I'd heard that filing it will improve things in for a little while, but because of the increased movement allowed by the filing, the steels are allowed to slam into the basket with greater force when the clutch engages, meaning it wears even faster than before.

What I meant was rather than pulling it down twice, I'd like to see if my spare clutch basket in the other bottom end is any good and use that instead. At any rate it may require less filing.

[F5 Dave]

What increased movement? You only file down to the limit of the troughs.

Without doing this the plates are forced into one place only (mind you they settle in largely the same place anyway), but the point is there isn't any extra wear from filing.

By all means if you have a better one then pull it out & inspect it. If it has a lot of play it gives you some time to pack the clutch cush drive before you put it in.

Honda clutch cush drives of that era are likely rubber donuts. As they are fully enclosed any material that will survive could be used to take up the extra space. Nylon is a good choice.

[xwhatsit]

What increased movement? You only file down to the limit of the troughs.

Without doing this the plates are forced into one place only (mind you they settle in largely the same place anyway), but the point is there isn't any extra wear from filing.

This is just what I read;

There are lots of threads on this but the expected life of a filed basket varies on how much you filed off and how much you use the clutch. The more you file, the wider tha gap is for the tang on the fiber plate to move around in. In a wider gap the tang will have more time to get up to speed before it slams into the other side causing it to wear faster.

It sounds plausible to me but I don't know shit.

Ixion reckons that my symptoms may be caused by warped plain plates, which sounds very interesting. In that case the clutch basket may be in good condition after all.

As far as I can tell from the Haynes manual blow-ups, there's no cush drive in the clutch. No rubbers or circular springs or anything. Perhaps there is something hiding in my hub. I have got a spare hub, which is the more common one with cush-drive rubbers, but that means getting a new rear sprocket and other hassle for really little gain; I've had worse gear change feel on much newer bikes, chain life isn't that appalling for a single.

Ah, such fun. Maybe I should buy a Ducati

[F5 Dave]

I doubt the basket is in good condition on a 25yr old bike but hope springs eternal. The clutch hub won't be listed as a serviceable item so you won't see any stuff in a manual. But it is common practice to replace parts in the basket assembly.

By 'plain' plates he means steels as opposed to friction plates.

Pull it down & stop theorising what is wrong, it's a 20min job.

[xwhatsit]

Pull it down & stop theorising what is wrong, it's a 20min job.

Ah, but this is KB, where procrastination reigns supreme

Yes my exams are over as of today, so now I can afford to piss about with such things.

Plain plates is my wording, sorry (I think I picked it up from Mr Haynes) -- yes I mean the steels.

[FROSTY:Me]

Re filing the basket No question filing will speed up wear and eventually you'll be back to square 1 BUT lets put it into a time frame--the basket has taken 24 years to get to the state its in--even if the life is reduced to 1/4 of how long it has lasted so far --then you have 6 years riding.