Camchain and tensioner seen up close in a cutaway bike engine

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Sympathy For The Clutch

Blog Date 18 November 2019

As a learner one of the most difficult things to master is the operation of the clutch. It is the alien idea of finding "the bite point" while raising the engine revolutions enough to move the vehicle forwards but not so much as to propel the vehicle into hyperspace. It takes a significant amount of practice to get right and even after 30 years I still get it wrong from time to time.

Sharon when she was a learner on her 125 smiling in the sun at Southport
This little learner needed a little practice with the little clutchy thingy 

As a yoof learning to drive and ride while I got the hang of it enough to pass my tests I never once learned anything about HOW a clutch works. For myself it would be around 3 years later I finally discovered how a car clutch works and another few years to understand motorcycle clutches. I would postulate that most of the UK's drivers or riders never actually learn what happens when the operate that clutch lever or pedal.

And why would they? As a computer programmer I don't fully understand how a microchip works, I just use them. I don't know the details of how my baked beans got into their tin, I just eat them. Then again, knowing how something works does have it's advantages. Like clutches for example. 

The plates of the clutch in a CBF125 are spread across the image
Well this doesn't explain how they work...

Knowing that at the bite point a clutch is experiencing a lot of wear encourages me to minimise how much time I hold the clutch at the bite point. Knowing that high revs at the bite point increases wear encourages me to keep the revs fairly low. Knowing that a lot of heavy clutching in traffic can overheat the clutch encourages me to minimise clutch use as best I can.

I can visualise in my mind the clutch in operation. I can see the plates rubbing together, slipping by each other, getting hot, friction material being worn away and in a motorcycle those thin metal plates warping under duress. I feel for my clutch, it has my sympathies.

I also feel for other people's clutches. While sat at the lights on an uphill slope I'll see the car in front - brake lights out - inching forwards. The driver must be controlling their movement on the clutch. 

I must admire their skills. This demonstrates a complete mastery of clutch and throttle control, maintaining the delicate fine balance to perfectly feed just the right amount of torque to the wheels that matches the counter-torque of gravity's pull on the wheels. The steepness of the slope only increases the level of finesse and skill required to do this. 

And yet all I can see is the flywheel and the pressure plate getting hotter and hotter while the friction plate spews forth hot dust. While I appreciate the driver's skill I ache inside with sympathy for the poor suffering clutch. Show a little mercy, please!

Notice how many motorists of all kinds of vehicles hate being still at traffic lights or junctions. Notice how as we might fidget in the queue at the supermarket we also fidget our vehicles in queues on the roads. How many of us stop, find neutral, apply the handbrake (if we have one) and sit to wait? 

Clutches on most motorcycles are easy to replace but not that cheap. Clutches in cars are cheap but they're the devil's job to replace. Show your clutch some sympathy and it ought to last you a long long time. 

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Reader's Comments

Ian Soady said :-
Those car drivers probably have automatic gearboxes. Wonderful things in traffic (actually elsewhere as well especially if your left knee is on the feeble side).

All this clutch slipping stuff was a complete eye opener for me when I bought my first modern bike some 15 years ago (I suppose it would now be classed as an old hack). If you slip the clutch of most of the bikes I've had in my life for more than a few seconds the plates would swell and you'd never be able to get into neutral (or possibly any other gear). So approaching red lights etc you'd always get into neutral while the bike was still rolling otherwise there's be a hopeless task of bouncing between first and second as the clutch got hotter and hotter to the point where you couldn't hold it on the brakes or it stalled. Of course then you had the rigmarole of finding neutral with a dead engine and using the kickstart. Usually as soon as the lights turned green.....

Slow riding (at least intentionally slow) was something never taught in the old RAC/ACU training scheme and the idea of slipping the clutch would have been met with scorn. It was only when I dropped my modern Triumph Tiger twice by trying to ride it like a 500T Norton that I discovered the technique as described by you above. It was a revelation, but I have to remember not to do it with the Norton.
18/11/2019 01:19:57 UTC
Upt'North said :-
Ed, have you forgot your medication again, you seem all won up about this clutch nonsense. You aren't suffering from tea and digestive withdrawal are you?
Ian is right about the auto or automated manual thingy, although these are still wearing out the clutch packs or converters etc.
I'm a handbrake on sort of guy. I suppose having a mechanical background helps with vehicle sympathy.
They're cooked in the tin, no honest, in the tin, amazin.

18/11/2019 01:36:09 UTC
Upt'North said :-
As an aside the Pan is on about 67500 and on the original clutch. The only maintenance has been a fluid change or two. Don't know if that's good or not.
18/11/2019 01:37:54 UTC
Ren - The Ed¹ said :-
Yes, some of those vehicles will be automatic. Some of those automatics will have fluid "clutches" which won't wear out in the same manner. Still, the majority of vehicles in the UK are manual with a clutch and quite a few of the modern autos don't use fluid clutches.

While as a one time instructor I taught and saw the positive benefits of slipping the clutch for slow manoeuvring, back then as today I would wince as the not-very-sturdy clutches on Suzuki GS500's were brutalised in the name of achieving a u-turn. I mean u-turn with your feet up - really? I know it was and still is a demonstration of your ability to control the motorcycle but who ACTUALLY doesn't put their feet out if needs be.

Yes Upt', I need tea, biscuits and a holiday in warm sunshine. What I really need is to retire. I know they're cooked in the tin, I dun sin it on tellee-me-vision and if it on TV then it must be true - Boris told me.

67,500 miles? Not bad but it is hard to define the work a clutch has done. If that was all motorway miles and Scottish Highland miles then 67,500 miles is nothing. If that's all commuting around a city centre at rush hour then I'd say that's damn fine care of your clutch. Where and what type is the Pan clutch - dry, wet?
18/11/2019 02:17:10 UTC
Upt'North said :-
It's a wet multi plate hydraulic thingymabob.
It's on the front of the engine and is relatively easy to get at.
For the 13 they put it at the rear and it hasn't got a father apparently.
18/11/2019 04:14:09 UTC
Upt'North said :-
On clutch sympathy......
Many, many years ago when Adam was a lad I was taught to ride to the "System", very enlightening it was too. Part of the training and test involved an obstacle course with poles to ride around, with a hump or two and muddy stuff.
The idea was to ride around it avoiding hitting the poles, over the humps, through the mud and out. It was timed and penalties were given for scattered poles and lateness, lying under the bike squealing like a girl wasn't a fail but great fun as long as it wasn't you.
When you had "mastered" it, you then did it one handed. What, I hear you shout.
The R80's had a lockable throttle-good bit of kit-and the throttle was set at 2000 or so rpm and the bike controlled with only the clutch and rear brake.
It was torture for anyone with mechanical sympathy, the clutched stank and smoked badly. Really badly.
At least we didn't have to buy and fit the clutches.

18/11/2019 05:00:05 UTC
ROD said :-
As a shorter person I avoid putting my feet down as much as possible. As a result over many years on larger heavy bikes I have mastered slow riding with feet up, and yes I will make a u-turn with my feet up.
I believe that the clutch receives the same wear rate from slipping the clutch if the feet are on the pegs, or on the ground?
18/11/2019 06:58:00 UTC
Ren - The Ed¹ said :-
Yes ROD the wear would be the same :-) You keep your feet up you skilled rider you!

Watched a YouTube video for the ST1100 clutch change, looks acceptably simple. I haven't seen one for the ST1300 yet, I go look see.
19/11/2019 04:33:29 UTC
ROD said :-
I have never worked on a pan, but I thought that the clutch setup was the same for the 1100 and 1300?
19/11/2019 06:54:19 UTC
Upt'North said :-
The clutch on the 11 is accessible through the front although the downpipes and a lot of plastic spoil the party.
The 13 is a different kettle of fish with the clutch on the back hidden by, well just about everything from the headstock back. The slave can be worked on apparently by only part disassembly and then laying the bike over on a mattress, from memory, which may be wrong I think the Honda workshop manual advises to remove the engine.
19/11/2019 11:20:30 UTC
Ren - The Ed¹ said :-
Looking online at YouTube vids it's clear the 1100 has the clutch at the front of the motor and is covered by a simple casing with 9 bolts. Once the fairings and crash bars are removed the actual act of replacing the clutch is relatively simple.

I could only find one BLOG about the ST1300 clutch and the images suggest the clutch is still at the front but much more of the engine casings need to be removed. Of course this is the internet, this could be for a BMW k1600 for all I know...
20/11/2019 09:16:23 UTC
Upt'North said :-
Ed, to clarify, I've checked the facts and here is the definitive detail of a ST13 clutch set up.
It differs from the ST11 in that the slave cylinder is at the rear of the engine but yes indeed the clutch still remains at the front.
To access the slave on the 13 is the more difficult part and requires the "ET" finger apprentice and seven wobbly ends on the extension bar or a lot of dismantling to get to it.
I've thought back and can't actually remember a discussion about changing a 13 clutch, I naively thought it would be on the same end as the slave. Although I also haven't heard of many 11 clutch changes either, I put this down to them being Honda's.
Looking at the engine views I would say the 13 would be a more entertaining clutch change than an 11.
The 11 isn't quite as easy for some as you allude to because the downpipes, I think on the right bank, can prevent the slave cylinder removal. It would appear some have removed it in an Ay Presto moment and others have had to slacken/remove the headers. This could well be due to whether the headers have been changed to aftermarket or not.
Apologies if I misled anyone. I'm off to flagellate myself.
20/11/2019 09:53:05 UTC
Marv said :-
Yeah, generally if I know I'm going to be stopped at a set of traffic lights for longer than 30 seconds, then I'll shift into neutral and hold on the brakes. Or pull in the clutch on the lever and hold on the brakes.
20/11/2019 10:24:44 UTC
Ren - The Ed¹ said :-
I concur re the slave cylinder. It seems a search of "ST1300 Clutch" leads to a tidal wave of distressed motorcyclists cursing Honda and a handful of guides showing how you can remove the slave without removing the engine - honest - if you have expensive specialist tools, 12 hours, skinny fingers and magic spanner dust.

It's another of those "why oh why" moments. Why the hell would you make the slave so inaccessible? Of course because in the factory that slave cylinder goes in at the start of the engine build process when access is as simple as "pop" and it's in. Then you wrap it all up in frame and exhaust and fairing and wire and coolant pipes...

So with the 1100 at least the job looks easy because the video creator has already removed the exhaust as well as many other things? Yes, it's a bit like opening the Haynes manual. In their nice clean workshop with their brand new engine already stripped and on the polished bench just popping the camshafts out to reshim the tappets looks so easy. Try it with the engine in the frame, surrounded by pipes and wires and cables, in a cold and dirty shed in January and lit by a fading torch and your mate's flickering standard lamp.

Lies I tell ya LIES!
20/11/2019 10:32:03 UTC
Ian Soady said :-
You think that's bad....

The horn on my Norton Commando failed so I fitted a couple of Fiammas to replace it. Foolishly I then decided to remove the defunct item. It was fixed to the bottom of the battery carrier, which in turn was part of the rear isolastic (ask your dad) engine mounting system, which in turn acted as both an engine / gearbox mounting and the location for the centre stand pivots. I could unbolt the horn but there was no room to get it past either the swinging arm / isolastics or the gearbox.

The only way to get it out was to remove the whole lot so after a couple of hours struggling and cursing I decided that I would leave it where it was and suffer the weight penalty. Unfortunately as I'd managed to remove the fixing bolt but couldn't get it back in I had to cable tie it in position.

It was still there several years later when I sold the bike to a bloke from Norway. I wonder whether he ever sorted it out?
20/11/2019 11:47:48 UTC
ROD said :-
At least the Pan does not require :- Bodywork, tank and seat removal. Rear Wheel Removal. Driveshaft Removal. Gearbox Removal, and contortions with the rear sub-frame to access the clutch.
Posted Image
20/11/2019 07:23:32 UTC
nab301 said :-
I have a'99 11 S version of the above which has 123k miles on the clock , purchased in '04 of which I've clocked about 110k miles admittedly with very little urban commuting but still on the original clutch. The only bike clutch I've had to replace was a '95 F650 back in '98 which used to slip for a few hundred miles everytime I changed the oil . I guess the previous owner had used incorrect oil , easy to replace but loads of plates and not cheap.
How long did the RT clutch last and how long did the job take ?
20/11/2019 08:57:44 UTC
Upt'North said :-
OK Rod, you win.
Top trumps on clutches, who'd have thought it.
20/11/2019 11:35:09 UTC
Ren - The Ed¹ said :-
"Yeah but MY clutch is harder to change than your pathetically EASY clutch so ner!" Top trumps difficult clutches, the game no-one wants to win.

I think Rod was just making work for himself frankly. Surely (don't call me Shirley) it'd be easier to take the engine out forwards and leave the rest of the bike behind? Or cut out a section of the bell housing?
21/11/2019 06:38:35 UTC
ROD said :-
Hi Nigel (nab301),

First of all, I am not any sort of authority on BMW Boxers.
I purchased the Bike in March this year, and before I went to look at the bike I had never even put my leg over a boxer.
When I had purchased the bike I felt that there was excessive play in the transmission, and looked on the forums to find a common fault of wearing the splines on the clutch plate. If this is not rectified then the worn clutch plate can damage the gearbox input shaft, which would then need a gearbox rebuild.
It is also recommended that oilhead boxers have these splines lubricated every 36000 miles.
The bike I purchased is a 2002 R1150RT and had 47000 miles on the clock when I purchased it.
With this in mind I decided to change the clutch at the 48000 mile service.
I purchased a modified clutch plate which has a 6mm longer spline shaft which is said to solve the problem.
I would estimate that the original clutch was less than 50% worn, and with the full service it took two casual days to complete.
The BMW is very well engineered and everything is fairly straight forward, although the job is time consuming.
The excessive play in the transmission has disappeared and the bike is running very sweet!

Upt'North, I was not trying to win anything!
Obviously it depends on how the bike is ridden, but the pan clutches seem to last over 100k.

Ren, The bike is built around the engine, so engine removal was not really an option.
The clutch can be replaced by leaving the rear wheel, drive shaft and gearbox together, and splitting the unit at the bell housing, but I wanted to check and lube the drive shaft / rear drive unit.

21/11/2019 07:46:33 UTC
Upt'North said :-
I'm guessing if this is a 36,000 mile service item then a lot of owners of boxers have paid a great deal for franchised servicing over the years. Is it still the same interval for the later boxers or have they fixed the issue, although I appreciate BMW would consider it an opportunity not an issue.
P.S. You still win........
22/11/2019 10:12:51 UTC
ROD said :-
Yes this was my reaction when I read the forum, but I have not seen the lubing mentioned in any of the service schedules.
The comments about the 36000 miles (some said 40000 miles) were from oilhead enthusiasts, and ex BMW mechanics.
I believe that the issue was rectified on the water cooled Boxers or maybe earlier.
I have posted a youtube link if you are interested.
22/11/2019 01:39:41 UTC
ROD said :-
oooohh whoops,
Just realized that I may not be winning anymore, as I may be removed from the site because of the language on the youtube link!!!
22/11/2019 01:49:09 UTC
Ren - The Ed¹ said :-
Just as long as you keep the naughty words off this actual site you'll be fine Rod. I'll watch the video later and I'll brace myself to hear words that I don't know the meaning of what with me being all innocence, sweetness and light.
22/11/2019 02:19:24 UTC
nab301 said :-
@ Rod , thanks for the reply , I think it's a bit late for me to worry about lubing the clutch splines , although I have done the drive shaft splines and replaced the front half of the drive shaft the last time I had the swing arm off.

The watercooled boxers may have solved the clutch problem with a wet clutch but an Aussie guy on a BM forum I frequent has posted that there has been some alternator failures on the w/c models run by the local Police force . Our type boxers =external belt drive alternator , reasonably easy to replace / repair. W/C models = internal alternator meaning engine out and complete engine stripdown , according to him, parts = $1500aud and labour = $5000aud!!! which according to Google is anything up to 3k stg......

23/11/2019 08:02:36 UTC
ROD said :-
The new watercooled boxers have more electrics to run, and a lower output wattage from the alternator (700w on the oilheads and just over 500w on the w/c) so I am thinking that the w/c alternators get a harder time?
24/11/2019 09:44:00 UTC
Upt'North said :-
Do the WC run LED lights, this could account for a lot of the difference.
24/11/2019 11:03:36 UTC

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