Problems with clutch drag,strada

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Dave L
Posts: 93
Joined: Mon May 14, 2018 10:31 am
Location: Mallorca

Problems with clutch drag,strada

Postby Dave L » Sun May 19, 2019 10:56 am

The clutch plates don't seem to be separating even though there is easy movement in operation of the clutch lever and mechanism.Im worried that the plates aren't wet enough and might be sticking together,this is after I stripped, cleaned and reassembled the clutch and since I've ran and tested it successfully.On inspection, by removing the small plate and looking in when engine running, there isn't a lot of oil being flung about and the bottom of the basket is not in an oil bath.Should it be?Any clues?

double diamond
Posts: 555
Joined: Thu Apr 28, 2011 1:20 am

Re: Problems with clutch drag,strada

Postby double diamond » Sun May 19, 2019 3:58 pm

Are the steel plates oriented correctly? This can affect disengagement. There is a sharp edge on one side of the plate and a more rounded edge on the other. The rounded edge should face outward.

Matt

JimF
Site Admin
Posts: 1124
Joined: Fri Oct 23, 2009 2:49 am

Re: Problems with clutch drag,strada

Postby JimF » Sun May 19, 2019 7:56 pm

I would have you check the plates for flatness.

A carpenter friend that rides motorcycles gave me a small pane of true “plate glass“, taken from the window of an old house I reckon, that I use to set each clutch plate on to check for flatness.

Plate glass is cheaper, lighter and easier to move than a granite machinist’s surface but it’s getting hard to find.

I had a similar problem as you have and I was surprised to find warped plates in my clutch pack because I could not discern the warped plates using only a visual inspection.

Fortunately I had spare plates and I used the flattest of all the plates I had to create a clutch pack and that solved my clutch dragging problem.

Jim

Paul W.
Posts: 11
Joined: Mon May 20, 2019 11:14 am
Location: NYC/NJ

Re: Problems with clutch drag,strada

Postby Paul W. » Mon May 20, 2019 4:25 pm

While going through a 450 recently I discovered something which could contribute to clutch drag.
Basket rotation became stiff as I tightened the clutch nut. Suspecting the two 20x42x8mm bearings I replaced them, but the condition persisted.
On a hunch I then measured the spacers between the bearings. The inner was 11.70mm thick. The dimension of the outer spacer needs to take into account a 1.7mm-thick snap ring inside the casting, so according to my calculations it should measure exactly 10mm.
I found that mine was 10.10mm, which obviously put an axial load on the inner races as the clutch nut was torqued, squeezing them together.
(I can almost see how a a tired junior machinist might've misread his micrometer while making a batch). After skimming off the extra .1mm and reassembling the basket now spins freely.
Since then I found another clutch (also a 450) suffering from the same condition. These slightly oversize spacers may have found their way into more than my two engines, though not likely into a Spanish bike. It's something I'll check from now on.

Dave L
Posts: 93
Joined: Mon May 14, 2018 10:31 am
Location: Mallorca

Re: Problems with clutch drag,strada

Postby Dave L » Mon May 20, 2019 6:16 pm

There is no discernible sharp or rounded edge to the steel plates.The plates were stuck together and needed gently prising apart with a screw driver.I found this was the case when I first dismantled the clutch and washed the parts in petrol.This has obviously not cleaned the plates sufficiently and they have stuck together again.What is the best way to clean the plates?They are otherwise in good condition.

themoudie
Posts: 649
Joined: Sat Jun 14, 2014 12:44 am
Location: Scotland

Re: Problems with clutch drag,strada

Postby themoudie » Mon May 20, 2019 11:37 pm

Aye Dave,

I would take all the plates and clean them in a bath of brake cleaner (5 litre tin from your nearest autoparts supplier), using a brass suede shoe brush (NOT BRASS PLATED STEEL BRISTLES!), then a stiff toothbrush.

Once you have 'clean' plates, you can then make all the checks previously mentioned in this posting, again! Are the steel plates flat? Are the fibre plates flat? are there any burrs on the steel plates or fibre plates driving tangs? If so remove them with a fine file. Do you have a stiff clutch basket?

May I also ask if the clutch has been sitting in oil for a long time (greater than 12 months)? If this is the case the fibre plates may swell and you will not wash all the oil out and the swelling may remain. :(

What viscosity is the oil? If it is a straight SAE 40 W mineral, then this can be difficult to remove from the fibre plates. :(

Is the oil a mineral or caster based oil? If it is old castor oil, you'll need to strip the motor to de-clag the whole shebang! :cry:

Are the components (rods, roller and ball) of the clutch operating mechanism all in good order? Wear here will reduce the clutch lift.

If all your steel plates are in good condition and not warped, and the clutch operating mechanism is OK, then a new set of fibre plates could be the best option.

All the best, Bill


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