Author Topic: RM400 creeping clutch  (Read 662 times)

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Offline Curtis

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RM400 creeping clutch
« on: January 14, 2019, 12:50:08 PM »
I have a 1978 RM400 in good condition, everthing original and adjusted correctly.
When the bike is cold its not too bad but once the bikes warms up the clutch still wants to slightly pull with the lever all he way in.
Was this a common issue on these back in the day? Any ideas on a fix? I was going to try a clutch lever and perch with a longer throw.

Offline John Orchard

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Re: RM400 creeping clutch
« Reply #1 on: January 14, 2019, 01:01:45 PM »
l'm having the same issue with my CR500, l've tried thinner oil, different lever ratios, my next check is to see if l have any warped plates.
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Offline GMC

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Re: RM400 creeping clutch
« Reply #2 on: January 14, 2019, 01:07:24 PM »
Warped plates or grooves in the basket that are keeping the plates in the closed position.

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Offline bazza

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Re: RM400 creeping clutch
« Reply #3 on: January 14, 2019, 02:57:21 PM »
What GMC said, or your oil? Try ATF
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Offline Momus

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Re: RM400 creeping clutch
« Reply #4 on: January 14, 2019, 04:19:33 PM »
If it's a 400C with the RH side mechanism the problem is the magnesium clutch cover oil canning and not pulling the pressure plate clear.
Battled this on my 370. Get a daisy wheel clutch lever set up and over adjust at the line and wind off when under way.

Offline Hoony

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Re: RM400 creeping clutch
« Reply #5 on: January 14, 2019, 07:27:14 PM »
sounds like grooved baskets.....not allowing the plates to fully release.
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Offline John Orchard

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Re: RM400 creeping clutch
« Reply #6 on: January 14, 2019, 09:14:40 PM »
sounds like grooved baskets.....not allowing the plates to fully release.


The basket on my CR looks like new?
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Offline Oldfart

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Re: RM400 creeping clutch
« Reply #7 on: January 14, 2019, 10:06:50 PM »
File the finger grooves out and drill some holes in you top hat

Offline TT5 Matt

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Re: RM400 creeping clutch
« Reply #8 on: January 15, 2019, 01:51:03 AM »
has the sleve on the input shaft the clutch basket spins on been crushed by overtightening the nut?needle bearing that runs on the sleve ok?both will give creeping along with badly galled clutch basket fingersi. remember an  dr650 that you couldn't tighten the clutch hub nut to specs coz no clearance on the sleve/trust washers so just tighten till it started to grab and back off till it was free and use the lock tab to stop the nut from undoing.found a lot of suzukis like that

Offline John Orchard

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Re: RM400 creeping clutch
« Reply #9 on: January 15, 2019, 08:38:08 AM »
has the sleve on the input shaft the clutch basket spins on been crushed by overtightening the nut?needle bearing that runs on the sleve ok?both will give creeping along with badly galled clutch basket fingersi. remember an  dr650 that you couldn't tighten the clutch hub nut to specs coz no clearance on the sleve/trust washers so just tighten till it started to grab and back off till it was free and use the lock tab to stop the nut from undoing.found a lot of suzukis like that


Good point Matt ! l will check that :-)
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Offline Curtis

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Re: RM400 creeping clutch
« Reply #10 on: January 15, 2019, 09:36:27 AM »
All good points thanks guys, (clutch basket in good condition, minimal grooving) ill have a play and report back.

Offline James P

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Re: RM400 creeping clutch
« Reply #11 on: January 25, 2019, 10:53:03 PM »
As well as all the possible causes already mentioned; Aftermarket parts are sometimes slightly different to originals.

In particular, plain and/or friction plates can be slightly thicker than originals - even an increase of just 0.5mm for the entire stack can cause problems in some cases (i.e. depending on the amount of travel and/or free space available). I've also found some aftermarket springs which become coil-bound well before original springs, which limits travel of the clutch pressure plate. Needless to say, any other poorly-made aftermarket clutch part could cause similar trouble!

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Offline micko

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Re: RM400 creeping clutch
« Reply #12 on: February 07, 2019, 05:15:52 PM »
My 370 does it as well, check the flex in the magnesium cover when you pull the lever in.
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Offline Curtis

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Re: RM400 creeping clutch
« Reply #13 on: February 08, 2019, 09:05:42 AM »
WOW!...I just checked..big time flex. Wonder if anyone has succesfully braced the cover?

My 370 does it as well, check the flex in the magnesium cover when you pull the lever in.

Offline Momus

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Re: RM400 creeping clutch
« Reply #14 on: February 08, 2019, 07:01:50 PM »
 ::)

The grade of die cast magnesium they use is virtually unweldable and there is no room between the clutch pressure plate and the case inside.

Easiest way will be to have one cast in aluminium. You could drill the mainshaft and use a pushrod like the later ones if you were up for a bit of machining.