Clutch Master Cylinder...a rebuild.

Jim C-G

Jim C-G

Joined
Jan 3, 2006
Messages
894
Location
Cow Head, Newfoundland, Canada
Bike
ST1300A '05
I'm not a mechanic, but I have some tools.
First time I've ever worked on anything hydraulic on a motorcycle, but I am retired with more time than money so here's my rebuild from last summer.
You too, can try this at home.
 
Brilliant. It is very difficult working on the bike, and taking a video. Especially with brake fluid on your hands. Especially with your first attempt at doing this job. Very brave, very nicely done.

Some points for the future.

I assumed that you fitted the rubber boot ? They have a circular spring clip in the brim of the boot, and this needs to be pushed firmly into position. It can usually be felt to 'give' as the spring decreases in daimeter. I usually do this with a carfully chosen head from my socket set.

Did you check that the push rod went into the hole in the side of the brass bush. Even the 'experts' get this wrong. My brand new ST1300 was delivered with the pushrod pressing on the side of the bush, rather than in the hole. This meant that the clutch was pressed in slightly. I rode it for 7 miles before the pressure in the fluid built up and left me stranded with no drive.

The silver clip in the bottom of the reservoir was in correctly. The blanked off side covers a very tiny hole in the casting. This hole needs to be clear. You can fit a steel strung guitar top E string through. I undersatnd that it is common practice for guitarists to leave their spare string ends flailing around. Not me. I'm a very neat guitarist. But I'm sure that if you mention that you are fixing your clutch lever they will understand why you snipped a short length off.

The purpose of that hole is to relieve pressure build up due to engine heat in the fluid. Fluid can expand back into the reservoir through this hole, whenever the lever is relaxed. If it cannot, then it presses the clutch in instead - just like my situation above.

Re that washer. You've manage it now, but in case you do others (like the brake lever), I find some narrow strips of thin plastic (say 3 strips) inserted through the hole of the washer and used to guide it over the piston, helps enormously.

Thin plastic ? Guitarists often keep their music sheets in thin plastic folders. They are little more than paper thickness, but more robust. I'm sure that they won't mind if you snip a bit off while they are discussing with you the reason for snipping their guitar string. (You didn't go for the bit over the hole, did you ?)
 
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jfheath said:
Some points for the future.
Click to expand...
Looks like I hit most of your points and I will file away the plastic idea for the washer for future reference. Mind you, at 15+ years and just shy of 200,000 km, I am not sure if I will be doing this to this bike again. I know I'll be changing the hydraulic fluid more often too. Thanks for the suggestions.
 
jfheath said:
The silver clip in the bottom of the reservoir was in correctly. The blanked off side covers a very tiny hole in the casting. This hole needs to be clear. You can fit a steel strung guitar top E string through. I undersatnd that it is common practice for guitarists to leave their spare string ends flailing around. Not me. I'm a very neat guitarist. But I'm sure that if you mention that you are fixing your clutch lever they will understand why you snipped a short length off.
...
Thin plastic ? Guitarists often keep their music sheets in thin plastic folders. They are little more than paper thickness, but more robust. I'm sure that they won't mind if you snip a bit off while they are discussing with you the reason for snipping their guitar string. (You didn't go for the bit over the hole, did you ?)
Click to expand...
Guitarists, be wary when John's around! He's up to something!!
 
Jim C-G said:
I'm not a mechanic, but I have some tools.
First time I've ever worked on anything hydraulic on a motorcycle, but I am retired with more time than money so here's my rebuild from last summer.
You too, can try this at home.
Click to expand...
If your clutch housing was that nasty, you do realize that your Clutch Slave Cylinder is probably 3 times worse ;)
It would probably be a good idea to replace the CSC rather than rebuild it because the piston often wears down metal on metal damaging the bore etc.
If you think your housing rebuild improved things, wait until you do the CSC, you'll think you have a new bike!
 
Igofar said:
If you think your housing rebuild improved things, wait until you do the CSC, you'll think you have a new bike!
Click to expand...
It is! I've put about 3,000 km on since I did the rebuilds and it feels like 2006 all over again (an '05 that I got on the road in April of '06)
Yes, the CSC was pretty bad. No scoring on the piston that I could see. Honda Canada is notorious for not having stock of parts. Originally was given a 3 week delivery on a CSC assembly, then it became an unknown stocking time, so I ordered the rebuild kit from Brakecrafters. Editing the video from that part of the maintenance work now.

Oh, the picture in the thumbnail is all the old CSC parts in the pan.
 
Hi Jim,
I have just discovered my clutch not disengaging fully. The 1st symptom was a while back, clunking when selecting 1st gear which progressively got worse to the point where when out on a ride last week the clutch had to be pulled all the way in to avoid stalling the bike. 1st option I tried was replacing the fluid which seemed to improve things a bit although the 1st lot of fluid I bled out was black suggesting perhaps some rubbers were worn somewhere at 40k miles and 14yrs old. Having just watched your informative video it looks like ill be doing the same as you did. My shed isn't as large as yours so I either need to perform the task in the garden, English weather permitting, or have a major clear out in the shed to create some crawling about space, which I'm not looking forward to at 66 yrs old.
 
Bob H said:
English weather permitting, or have a major clear out in the shed to create some crawling about space, which I'm not looking forward to at 66 yrs old.
Click to expand...
I anticipate your pain. try to make sure that you have every tool required ready to go and at arms reach once you get on the ground. Minimize the number of times you have to get up. That's about all the real advice I can give you. Do the CSC and the CMC at the same time. You'll feel the difference.
 
Jim C-G said:
I anticipate your pain. try to make sure that you have every tool required ready to go and at arms reach once you get on the ground. Minimize the number of times you have to get up. That's about all the real advice I can give you. Do the CSC and the CMC at the same time. You'll feel the difference.
Click to expand...
Thanks Jim, getting down is not too bad, its the getting back up again that's the problem :)
 
Hi Jim. I threw out my discount snap ring pliers as I only used them once years ago and they were not that great then so purchased a set of four last week from a well known tools supplier over here called Screwfix for a mere £14. Thought I overhaul the CMC 1st, (start with the easiest job 1st) which has improved the lever resistance somewhat but not the operation of the clutch so replacement CSC has been ordered along with crush washers and gasket from David Silver spares which should be delivered in about a week or so (Covid and lorry driver shortage being to blame). Tools are assembled as per your list and step stool is to hand. Have done a dry run and with a bit of grunting, puffing and cursing I can reach the CSC but won't be taking things apart until the parts have arrived.
I have since read elsewhere on here that even after changing both the CMC and CSC swelling brake lines can be a cause of improper clutch disengagement. I hope it doesn't come to that as replacing them seems an even worse task by having to tear half the bike down to get at the lines. It seems that where I have got away with self replacement of the seized secondary brake master cylinder and typical servicing costs including tyres and battery replacement during my 14 year ownership, the pan is now playing catch up what with the exhaust pipes needing replacement as well.
 
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