Author Topic: Mk 4 Clutch not releasing?  (Read 4136 times)

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Offline Evanc

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Mk 4 Clutch not releasing?
« on: 16 Feb 2014 at 09:40 »
Hi Guys, I have got most of my Douglas's problems sorted but I feel my clutch may not be releasing fully. When I pull in my clutch and select first there is significant clunk, no matter how long I hold the lever before I select the gear. When I ride and change up through the gears the shift is harsh and again "clunky", However if in gear on the stand the rear wheel does not spin in any gear with the clutch lever in. If it was in a car it feels like the spigot bearing is seized, but I am assuming the bike does not have a spigot bearing/bush. My brother has a similar bike and his clutch does not act like this. Any clues?
Evan

Offline eddie

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Re: Mk 4 Clutch not releasing?
« Reply #1 on: 16 Feb 2014 at 12:49 »
Evan,
         The first question has to be "Do you know what linings are fitted in your clutch?" Early generation asbestos free linings gave these sorts of symptoms. These early linings were of a grey composition material which tended to give off some dust which collected on the guide pins through the flywheel and resulted in the clutch being sluggish to release. Other causes of sluggish release could be weakened clutch springs or a distorted pressure plate (causing the clutch to lift on the tilt). Oil on the plate may also cause the clutch to drag. If the problem is caused by either dust or oil, you could try the quick fix that has worked for quite a few owners in the UK. Block the drain hole in the bottom of the bellhousing and pour in enough petrol to wash the bottom run of the clutch lining, then lift the clutch and operate the kickstart about 20 times, remove the plug and drain the bellhousing. This usually transforms the clutch action. Finally, apply a couple of shots of grease to the release cam to make sure the bearing hasn't been washed dry.

      Regards,
                    Eddie.

Offline Evanc

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Re: Mk 4 Clutch not releasing?
« Reply #2 on: 17 Feb 2014 at 09:40 »
Hi Eddie, I have no idea what sort of clutch linings I have but I am keen to try what you have proposed as I have not had the bike for long and I do not feel like pulling the motor out. I will let you know how I get on, thanks a lot, Evan

Offline Evanc

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Re: Mk 4 Clutch not releasing?
« Reply #3 on: 22 Feb 2014 at 21:36 »
Hi guys, Here's where I'm at with my bike. Before trying what was suggested I took my bike for a ride. The gearshifts were harsh and often gears were missed, it seems to either go past a gear into neutral or only went half way. If it did this it was very hard to then find a gear. Brought bike home and then found the clutch would not release at all. Carried out cleaning procedure and felt a noticeable clunk when kickstarter was operated with clutch released. I then was able to spin the back wheel in gear with clutch released, (until the bike was kicked over and the clunk happened the clutch would not release) I then took the bike for a ride.
The bike was totally transformed! the gearshifts were smooth, I did not miss a gear, the bike for the first time since I have owned it, was a pleasure to ride!
I rode it for approx. 10km and I then lost the gearshifts again. The clunk when 1st was first selected was not there, but The gearshifts started getting difficult and I started getting neutrals instead of finding gears again.
The concerns I have is what may have caused the clutch to not release? and what was the clunk? Is there something floating around in the clutch that could cause my problem or do I have a gearbox problem as well?
Also wondering the best way to remove the engine or gearbox as it appears as though it will be a fairly difficult operation as the frame seems to have been built around the engine.
Thanks for any help, regards Evan

Offline David Lawrence

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Re: Mk 4 Clutch not releasing?
« Reply #4 on: 24 Feb 2014 at 14:18 »
Hi Even,
Firstly good luck with identifying the problem with your clutch/gearbox, I am sure more advice will be forthcoming from members with more engineering skills than I, however, I can possibly be of some assistance, it sounds from your comment regarding the engine removal that you do not have a copy of the manual.
The London Douglas Club does keep a stock of both the Douglas works manual and the spares list. The manual although not overly detailed does cover all the stripdown and routine maintenance, for example how to get the engine out! retiming the motor etc.The spares book is very useful as it displays all the components in exploded form, it is also the basis for supplying parts through the Club spares system.
I should point out that the Club only supplies parts to paid up members, this is for various reasons. However, we are quite happy to supply the manuals to anyone requiring them.
The cost is not prohibitive, £9-00 each plus P&P
Should you be interested please email me directly via the email ikon under my name.
Dave

Offline eddie

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Re: Mk 4 Clutch not releasing?
« Reply #5 on: 24 Feb 2014 at 19:35 »
Hi Evan,
             From the symptoms you have described, I would think that you have a problem with the clutch friction plate. Either the disc is loose on the splined hub or the hub is excessively worn on the six splines that provide the drive to the gearbox. You will find that the splines on the gearbox input shaft are longer than the splines in the clutch hub. If the clutch plate is truly centred on the splines, any wear leaves a lip either side of the plate - preventing the plate from floating free when the clutch is lifted. The crankshaft in postwar Douglas engines is located by the front main bearing - causing the rear main bearing to move in the crankcase as the engine warms up. The clunk you heard could also have been caused by the crank moving back under the pressure of the clutch springs - but don't worry about it, this is normal.
     If you do have to separate the engine and gearbox, you may be lucky and be able to remove the six 5/16"BSF nuts that retain the pressure plate. With these removed, you can take off the pressure plate which in turn frees the friction plate - if not, you will need to remove the whole flywheel assembly
         If the splines are excessively worn, you will need a new clutch friction plate and a new splined adaptor for the gearbox - these are available to LDMCC members through the spares scheme. When removing the pressure plate, be careful, there may be 1/16" thick spacers on each of the six studs.

  Regards,
                 Eddie.

Offline twirl

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Re: Mk 4 Clutch not releasing?
« Reply #6 on: 02 Oct 2015 at 16:19 »
The clutch of my MK4 was spoiled and did not work. May be because of a mistake of myself, the outer plate was rather bent. After dismantling, I fixed the outer plate without the clutch-springs on the flywheel and smoothed it with cautious strokes along the outer diameter. Then I spend some time with the driving studs until outer plate and pressure plate could be assembled perfectly, when line mark on the periphery was coincident. After reassembling, the clutch worked smoothly, but rather asymmetrically. This may be caused by different lengths of springs and even driving studs. When I fixed my outer plate on my very old lathe, the thrust disk had an impact of nearly 0.02 inches. I shaped it on the lathe. Although I shaped the rivets a little bit, too, I think this is not really a problem. After reassembling the clutch, it worked very fine.
I nearly spent one day on my attemps and had to dismantle the clutch several times. So I never locked the slutted nut to fix the flywheel on the crankshaft really. At last, I locked it with loctide but not with a split. This didnít fit really. Next time I dismantle a Douglas, care will be taken not to spoile the outer plate!