I'm just at this stage, and my banjo is also cocked, its a nightmare, - great tip ill also slacken the bleed pipe mounting bolt and also perhapses remove the speed sensor just to get it out of my face - If I cross thread the CSC I'll need mental rehabilitation!!
Article [13] ST1300 - Clutch Slave Cylinder Replacement
- Thread starter MaxPete
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I'm just at this stage, and my banjo is also cocked, its a nightmare, - great tip ill also slacken the bleed pipe mounting bolt and also perhapses remove the speed sensor just to get it out of my face - If I cross thread the CSC I'll need mental rehabilitation!!
OP
OP
Howdy all!
As some may know, I am a mechanical engineer and hydraulics is my “thang”. I have to say that Honda did a really crummy job on the design and routing of the circuit for the ST1300 clutch slave cylinder. There are waaaayyy too many fittings and bits and pieces (and thus too many opportunities for either or a fluid or air leak) in the run from the master up on the handlebars down to the slave in the bowels of the bike. Also, as pointed out above, a substantial portion of the lower part of the hydraulic circuit has a “dead end” around the bleeder nipple in addition to the dead fluid that sits in the slave cylinder itself.
….and THAT is a key point: there is no outlet port in the clutch slave cylinder casting. There is only an inlet port and the bleeder side is simply bolted onto it along with the long line from the master up on the bars.
Thus, the fluid just sloshes, or is pumped, in and out of the slave cylinder - but it is always the same fluid. The fluid in the “bleeder” portion of the system is essentially static unless it is flushed out and the small pocket of fluid in the slave itself may still not ever be flushed - until a repair is required. Therefore, to be formal and correct - the clutch slave system, like hydraulic brake systems, is not a true hydraulic circuit because the fluid never returns to the reservoir up on the handlebars. That is why master-slave hydraulics need to be carefully designed to permit clean fluid to periodically be flushed into the entire system - which our good friends at Honda did not do.
All of this blather means that much of the fluid in the system really cannot effectively be flushed without a total disassembly, which few owners are likely to do - and so the whole circuit is doomed to have a pocket of old fluid and moisture sitting in it, which promotes the grotty condition, and wearing out, of the typical 10-20-year-old slave cylinder.
Anyhow, as #Igofar points out, the repair is quite doable by the average ST Owner and so just watch for the symptoms of clutch slave cylinder failure and be ready with the tools, a new slave, the numerous copper crush washers, and a little dab of Vaseline - and you’ll be back on the road in short order.
Cheers,
Pete
As some may know, I am a mechanical engineer and hydraulics is my “thang”. I have to say that Honda did a really crummy job on the design and routing of the circuit for the ST1300 clutch slave cylinder. There are waaaayyy too many fittings and bits and pieces (and thus too many opportunities for either or a fluid or air leak) in the run from the master up on the handlebars down to the slave in the bowels of the bike. Also, as pointed out above, a substantial portion of the lower part of the hydraulic circuit has a “dead end” around the bleeder nipple in addition to the dead fluid that sits in the slave cylinder itself.
….and THAT is a key point: there is no outlet port in the clutch slave cylinder casting. There is only an inlet port and the bleeder side is simply bolted onto it along with the long line from the master up on the bars.
Thus, the fluid just sloshes, or is pumped, in and out of the slave cylinder - but it is always the same fluid. The fluid in the “bleeder” portion of the system is essentially static unless it is flushed out and the small pocket of fluid in the slave itself may still not ever be flushed - until a repair is required. Therefore, to be formal and correct - the clutch slave system, like hydraulic brake systems, is not a true hydraulic circuit because the fluid never returns to the reservoir up on the handlebars. That is why master-slave hydraulics need to be carefully designed to permit clean fluid to periodically be flushed into the entire system - which our good friends at Honda did not do.
All of this blather means that much of the fluid in the system really cannot effectively be flushed without a total disassembly, which few owners are likely to do - and so the whole circuit is doomed to have a pocket of old fluid and moisture sitting in it, which promotes the grotty condition, and wearing out, of the typical 10-20-year-old slave cylinder.
Anyhow, as #Igofar points out, the repair is quite doable by the average ST Owner and so just watch for the symptoms of clutch slave cylinder failure and be ready with the tools, a new slave, the numerous copper crush washers, and a little dab of Vaseline - and you’ll be back on the road in short order.
Cheers,
Pete
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Thanks Pete, appreciate the breakdown explanation of the inner workings of this backward engineered part.
Mine isn’t broke (yet) but reservoir fluid gets brown rather quickly (1 season). Is that just wear and tear on the fluid or is some fluid from the cylinder actually making it back to the reservoir with each operation of the clutch? Just trying to understand.
I realize I just can’t flush my way to a clean cylinder but for now, it ain’t broke so…
New parts on standby.
Mine isn’t broke (yet) but reservoir fluid gets brown rather quickly (1 season). Is that just wear and tear on the fluid or is some fluid from the cylinder actually making it back to the reservoir with each operation of the clutch? Just trying to understand.
I realize I just can’t flush my way to a clean cylinder but for now, it ain’t broke so…
New parts on standby.
With new (dry) fluid in the MC and lines, moisture in the trapped fluid in the CSC itself should migrate to the dry fluid (through diffusion, without physical movement of the fluid), and eventually all the fluid in the system will have a similar moisture content. (So damp/dark fluid in the CSC will make the new fluid in the MC and lines dark pretty quickly too) Flush the MC and lines often enough, and the moisture content of the whole system will be kept low. (But need to wait long enough between flushes to allow moisture to equalise)
While moisture will move through a system like that, that doesn't work for actual debris of course, which will unfortunately tend to settle in the CSC as the lowest point. (Frequent flushing will of course help prevent wear and debris though, so...) I do wonder if it would be worth cutting another port in the bottom of the CSC (and having the line from the MC feed into that, with only the bleed line mounted at the top) but that would probably need a replacement casting (or welding a boss, tricky with an oil contaminated alu casting!!) and would need a longer line from the MC. I might investigate that 'next time'...
Really though, as a 'flush' only really changes the fluid in the MC and lines, not much fluid is used, so frequent flushing is quick and cheap insurance...
While moisture will move through a system like that, that doesn't work for actual debris of course, which will unfortunately tend to settle in the CSC as the lowest point. (Frequent flushing will of course help prevent wear and debris though, so...) I do wonder if it would be worth cutting another port in the bottom of the CSC (and having the line from the MC feed into that, with only the bleed line mounted at the top) but that would probably need a replacement casting (or welding a boss, tricky with an oil contaminated alu casting!!) and would need a longer line from the MC. I might investigate that 'next time'...
Really though, as a 'flush' only really changes the fluid in the MC and lines, not much fluid is used, so frequent flushing is quick and cheap insurance...
Andrew Shadow
Site Supporter
Depending on how you are defining brown, this may be normal. If you are using the colour of the fluid in the brake master cylinder as your reference, this is not a good comparison as far as the amount of time it takes for the fluid to change colours. The clutch fluid is subjected to much higher heat than the brake fluid is as as the slave cylinder is bolted directly to the engine case. It also is activated more often that the brakes are during most riding conditions. No matter how pristine a condition the clutch hydraulic system is in, its fluid will always discolour more quickly than the brake fluid.
Andrew Shadow
Site Supporter
I have never seen the inside of the slave cylinder, so you have answered my question about the path that the fluid takes. This is what I suspected from looking at the exterior of the slave and from the pictures that people have posted here showing all of the crud inside of them.
I find it surprising that Honda would do this. Hydraulic systems on vehicles are hardly a new technology. They should have known better. It would not have been very difficult to design the slave cylinder so that the hydraulic line connects on the bottom. This would allow fluid to be pumped through it and out the top through the bleed nipple. It would provide for much better flushing of the system. If there is some technical reason preventing this, they could have designed the slave with a hydraulic passage, be it internal or external, that would carry the fluid from the connection point at the top to an entry point at the bottom of the cylinder. This would achieve the same thing.
Why would they want to build a vehicle that requires very little maintenance, and would last a very long time?
That would keep folks from buying new vehicles every couple of years
Rumor has it that Jeep discontinued its Standard Cherokee because nobody every brought them back for service work because they were so reliable, they morphed into the Liberty models that require much more frequent service etc.
That would keep folks from buying new vehicles every couple of years
Rumor has it that Jeep discontinued its Standard Cherokee because nobody every brought them back for service work because they were so reliable, they morphed into the Liberty models that require much more frequent service etc.
OP
OP
Hi Sadlsor:
I certainly don’t intend to discourage anyone. Replacing the CSC really isn’t that big a deal.
There are a couple of slightly fiddley steps and the working position is somewhat awkward (on your back, under the bike, looking up into the murky area between the front of the swing arm and the back of the engine) but it isn’t expensive and you are unlikely to run into rusty or broken fasteners.
As I said, follow the article, assemble the tools, and be sure to have your little jar of Vaseline ready to go.
Pete
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Your starting to sound like a Genuine Honda Service Department with your....."have your little jar of Vaseline ready to go"
Sadlsor
Site Supporter
OP
OP
Your starting to sound like a Genuine Honda Service Department with your....."have your little jar of Vaseline ready to go"
hehehhee....yeah, I guess so.
The nearest dealer to me (200+km away in London, ON) which shall remain nameless, is very large and well equipped, but sadly, they have a reputation for screwing over just about everyone who walks through their door.
I have bought two bikes from them - but there not ever be a third.
NOTE: for those who are not in on the joke....the real purpose of the Vaseline is to help stick the three crush washers into the sandwich made up of the clutch hydraulic line (which comes down from the handlebar-mounted master cylinder) and the short line which runs out to the bleeder nipple above the rider's left foot peg.
These two hydraulic fittings are in an assembly (from bottom to top):
- a copper crush washer is on the bottom next to the slave cylinder body;
- then the bleeder line fitting;
- then another crush washer;
- then the line from the master cylinder;
- then another crush washer which seals under the head of the banjo bolt;
The problem is that the working position is a tad awkward and when I wrote the article, we found that sticking all those fittings and copper crush washers together with Vaseline makes the job much easier. When you bleed the system, the Vaseline just gets washed out the bleeder nipple and if any residue is left, it will just blend-in with the brake fluid/hydraulic oil.
...of course, if you choose to go and have this work done at your friendly local Honda dealer using their ridiculous and expensive: "Step 1 - remove engine from bike" method, you will need the Vaseline for an entirely difference purpose.
Pete
OP
OP
Having just completed this job (this thread was invaluable!!!), my guess on this Honda process is that they can't get torque wrenches on the bolts with the engine in the frame. I'm betting they did this to ensure that they can properly torque all the fittings for the csc.
Also - wth was that gasket made of! Getting that off took by FAR the longest of the entire process!! Absolutely baked on and turned to steel (03 ST, 96k miles). half way through I was grumbling that I shouldn't even have started removing it - it came off the csc cleanly but stuck hard to the block. grrr....
Your torque wrench fit even on the Banjo bolt? As for that#$*&(##$ gasket, I sprayed gasket remover, wd40, nothing touched that thing.
Another trick to removing the gasket is what you use.
Wire brushes, razor blades, exacto knives dig into the gasket, braking it apart in many places, making it almost impossible to remove.
I have found the safest and easiest method for
me is to use a 3/4 inch wide wood chisel.
It’s thick so it does not flex and damage the aluminum housing, and the trick is where to start…
I come straight up from the bottom, on the right side of the housing, half of the chisel rests flat against the flat surface of the rear cover, keeping it true, and half pushes up the right side of the gasket, causing it to tilt, without breaking it, so your spray and oil can get behind it to loosen it up.
When using a thick/strong chisel, the gasket usually comes completely off the three pushes etc.
Patience is your friend here.
Wire brushes, razor blades, exacto knives dig into the gasket, braking it apart in many places, making it almost impossible to remove.
I have found the safest and easiest method for
me is to use a 3/4 inch wide wood chisel.
It’s thick so it does not flex and damage the aluminum housing, and the trick is where to start…
I come straight up from the bottom, on the right side of the housing, half of the chisel rests flat against the flat surface of the rear cover, keeping it true, and half pushes up the right side of the gasket, causing it to tilt, without breaking it, so your spray and oil can get behind it to loosen it up.
When using a thick/strong chisel, the gasket usually comes completely off the three pushes etc.
Patience is your friend here.