Author Topic: Clutch drag in first gear  (Read 394 times)

Online scotty

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Clutch drag in first gear
« on: 08.06. 2020 14:56 »
My clutch is dragging in first gear only
From a standing start it feels like the rear wheel is in glue and she has a jerky feel then when underway gear changes are fine up and down the range and the engine runs great and starts easily.
All gears and neutral easily selectable when running and with engine off
Newer SRM 4 spring clutch. Components appear in good order and set for equal lift
Primary and final drive chains not to tight
Clutch lever has 1 &  1/16 inch fulcrum
Rear brake disconnected to eliminate the possibility of a binding brake

Any thoughts appreciated

S
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Offline Swarfcut

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Re: Clutch drag in first gear
« Reply #1 on: 08.06. 2020 15:41 »
Scotty....Here's one.   Check gearbox mainshaft is not binding in the sleeve gear bush.
    In neutral, engine stopped, the raised rear wheel should rotate easily, any binding of the bush and shaft will be apparent. Relative speeds of the shaft and sleeve gear are greatest at start off, lessening progressively as you go up the box, in top gear they are locked together, so the symptoms disappear. Gear selection is not affected, the problem is only apparent when the parts move relative to each other.   Well worth a simple check.

 Swarfy.
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Online chaterlea25

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Re: Clutch drag in first gear
« Reply #2 on: 08.06. 2020 17:50 »
Hi Scotty,
Whats it like if you go to take off in second gear?
If its OK then it would seem to point to the gearbox?

John
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Online scotty

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Re: Clutch drag in first gear
« Reply #3 on: 09.06. 2020 01:19 »
Guys

Thanks for the ideas
Much appreciated !

On the centre stand in neutral engine off the wheel rotates freely with no apparent restriction.

The dragging occurs in both first and second gear when tried from a standing start

I’m going to take the clutch apart next to double check every thing

S
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Online RDfella

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Re: Clutch drag in first gear
« Reply #4 on: 09.06. 2020 10:14 »
That problem's not the clutch, but with it off you'll be better able to check Swarfy's suggestion of mainshaft tight in its bush. Presumably there's sufficient oil of suitable type in the gearbox?
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Online scotty

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Re: Clutch drag in first gear
« Reply #5 on: 09.06. 2020 15:18 »
Thanks RDfella I’ll be getting to that next

Inspection of all the primary drive components revealed nothing out of the ordinary
However, when I pull the clutch lever in and try to turn the clutch centre by hand I do feel some resistance before it rotates

Onto the gearbox 😳

S
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Online chaterlea25

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Re: Clutch drag in first gear
« Reply #6 on: 09.06. 2020 15:56 »
Hi Scotty,
A further thought ?
Are the clutch plates flat? and are the plates free in their slots, are there wear grooves in the chainwheel / centre hub?
A warped plate or 2 can cause all sorts of issues

John
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Offline trevinoz

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Re: Clutch drag in first gear
« Reply #7 on: 09.06. 2020 22:51 »
If the lever has 11/16" fulcrum then I feel that you will not get enough lift. I have never seen one with that value, most are 7/8" or 1-1/16", the latter being the one that I use and it works well with the six spring clutch, no drag and able to select first while standing still.
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Online scotty

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Re: Clutch drag in first gear
« Reply #8 on: 09.06. 2020 23:16 »
Thanks john
All clutch plates flat and in good shape with good tangs
the rest of the clutch looks great with good alignment

With the plates out I can rotate the clutch hub with no real resistance

Oil drained from gearbox..correct amount was present with no metal chunky bits

Sorry Trev my typo.....1 & 1/16 Inch fulcrum on the lever is what I have

S
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Offline Jules

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Re: Clutch drag in first gear
« Reply #9 on: 10.06. 2020 02:27 »
ok you have my attention now regarding different "fulcrums on the lever", where and what do they relate to please so that I can check what I have, I seem to remember years ago the clutch lever requiring "really long fingers" to operate, is that something to do with this? thanks all... *conf*
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Online scotty

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Re: Clutch drag in first gear
« Reply #10 on: 10.06. 2020 03:16 »
Jules
It’s the centre to centre distance measured from the pivot bolt on your clutch lever to the nipple on your clutch cable.
1 1/16 measurement apparently gives you more lift on the top plate for your buck than the 7/8 measurement
Wiser men than I will explain better
S
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Online scotty

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Re: Clutch drag in first gear
« Reply #11 on: 10.06. 2020 03:23 »
So threw the clutch back together gave the gearbox a drink of oil and fired her up
On the centre stand I went through all gears with engine running
Killed the engine...pulled in the clutch lever and tried to spin the clutch hub by hand and it was tight-ish.
Took her for a spin and same drag/jerk in first gear upon take off
Runs like a charm though !
So I guess I’m going into the box next
In frame solution or pull the box ?
Cheers
S
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Re: Clutch drag in first gear
« Reply #12 on: 10.06. 2020 09:38 »
wait! I had the jerk *eek*years ago and it was the cable, even though it seemed ok, it wasn't
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Online RDfella

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Re: Clutch drag in first gear
« Reply #13 on: 10.06. 2020 11:41 »
When I read the initial post (something about the rear wheel feeling as if were glued to the road) I got the impression the engine was willing but the bike was not. That would indicate gearbox issue, primarily mainshaft bush. I now get a different picture – that of a free-to-rotate gearbox but unsatisfactory getaway. As Berger say, could be cable - either the bends are too tight or the cable is contracting under load, ie it’s not man enough for the job. Or, assuming the clutch itself is in order as you say, the lever ratio is not pulling the cable enough.
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Online scotty

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Re: Clutch drag in first gear
« Reply #14 on: 10.06. 2020 15:33 »
Thanks guys 😛

I’ll nick the cable off the B33 and see if there is a difference

On the clutch cable adjustment at the gearbox how much thread should be showing/sticking out in a normal set up ?

Cheers

S
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