Article [13] ST1300 - Clutch Slave Cylinder Replacement

Hey guys...so it seems like it'll be my turn soon, to tackle this job. And I apologize in advance if this has been mentioned, I tried as best as I could to read through the entire thread. Has anyone attempted to remove the oil cooler ITSELF in an attempt to make more room? I've got a LOT of maintenance I need to do on my bike, coolant included And seeing as the oil filter has to come off anyways...maybe the cooler itself might give me more space. So has anyone tried this?
 
accordvtec77 said:
Has anyone attempted to remove the oil cooler ITSELF in an attempt to make more room?
Click to expand...
A word of caution if you decide to go this route.
Several years ago several of us attempted to find a P/N for the O-ring that goes between the oil cooler and the engine block. We have never been able to find one. I have not read that anyone has found it since then. The parts lists do not even state if a new oil cooler comes with the O-ring or not.
If you remove the oil cooler, be careful not to damage the O-ring as you will have to re-use it.
 
I did mine on the side stand with only removing shifter linkage and oil filter. I also changed the coolant and engine oil at the same time so I had some fairings off as well. I wouldn't remove the oiler cooler. I didn't find that the three bolts on the CSC were difficult to access with a 1/4 in drive ratchet. I found the most difficult part was getting the banjo fitting bolt started in the new CSC. My bleed line banjo fitting was cocked at an angle and wouldn't let the bolt align correctly. I had to remove the bolt on the bleed line bracket on the left side of the bike by the bleeder valve. With the bleed line completely free the banjo fitting bolt installed easily. I then reattached the bracket by the bleeder valve. Be very careful not to cross thread the banjo fitting bolt into the aluminium casting of your nice new CSC!
 
I wrote the article on the clutch slave cylinder replacement and I found no need to remove the oil cooler. Quite a few (20?, 30? or more) other folks have also done this task and nobody has mentioned removing the oil cooler - so it seems unnecessary and as Andrew points out, risky.
 
accordvtec77 said:
Hey guys...so it seems like it'll be my turn soon, to tackle this job. And I apologize in advance if this has been mentioned, I tried as best as I could to read through the entire thread. Has anyone attempted to remove the oil cooler ITSELF in an attempt to make more room? I've got a LOT of maintenance I need to do on my bike, coolant included And seeing as the oil filter has to come off anyways...maybe the cooler itself might give me more space. So has anyone tried this?
Click to expand...
No need to remove the oil cooler housing.
You have plenty of room with a simple K&L center jack lifting the bike up just enough to deploy & raise the center stand.
With a few special hand tools you can remove and replace the CSC easily.
Standing by the white courtesy phone if needed.
:WCP1:
 
Andrew Shadow said:
A word of caution if you decide to go this route.
Several years ago several of us attempted to find a P/N for the O-ring that goes between the oil cooler and the engine block. We have never been able to find one. I have not read that anyone has found it since then. The parts lists do not even state if a new oil cooler comes with the O-ring or not.
If you remove the oil cooler, be careful not to damage the O-ring as you will have to re-use it.
Click to expand...

Yeah...I came to that same realization about that o-ring when I took another good look at the parts catalog. Well alrighty then...I will scratch that idea. But thanks for the advice everyone! It's appreciated!
 
Thanks to MaxPete and Igofar I was able to finally do this!
Igofar gave me detailed instructions over the phone and the pics that MaxPete really helped me understand what Igofar was talking about.
One tip...
Pay attention to the reservoir between the bleed nipple and the vacuum pump. If it happens to fall on its side and you don't notice, you will very quickly be pumping brake fluid into the pump and all over your hands.
 
Just did this on my 2005, 103000 mile machine. Thanks everyone for the write-up, it is a straightforward job just on the side stand, albeit a little fiddly at times.
It would have been much easier if I hadn't had to rebuild my vacuum bleeder that had seized since last used last year (just a strip, clean and grease with silicone grease needed). And if I hadn't left my 1/4 drive socket set on my desk at work. Gave me an excuse to buy a tiny 1/4 ratchet from Amazon, which will come in useful I'm sure. Only the bolt between the CSC and the oil filter really needed 1/4, I did the others with my 3/8 set.

Another satisfying job done on the old girl. Next to sort out some small leaks on the half moons of the rocker cover gaskets. About due for a valve check anyway.
 
Esti1300 said:
So continued flushing will not necessarily get rid of potential sludge in the CSC. Only way then is to remove and clean or remove and replace?
Click to expand...
I don't have the answer to that question. Because the fluid inlet and outlet ports are both in the upper part of the casting, several people on this site have speculated that the fluid is taking a short-circuited route between the two. While this won't affect the ability to bleed any air out, it is assumed that this fluid route prevents the ability to efficiently flush out any sludge from the bottom half of fluid cavity, and is mostly flushing the upper part only. These seems to be supported by the fact that most people who have taken it apart have always found it to be quite messy and full of sludge in there.

With enough bleeding, the fluid will eventually all get replaced. If there is a direct route between the inlet and the outlet ports, whether or not there is enough fluid volume going through the bottom part of the cylinder to flush out accumulated sludge is the question.

I haven't taken one apart myself so I can't say whether there is a direct route between the two ports or not. It is possible that there is an internal passage that routes the incoming fluid to the bottom before it enters the cylinder, which would allow for a more thorough flush. Nor have I read on here that anyone has reported what the actual internal fluid path is between the inlet and the bleeder nipple.

Maybe someone who has an old one hanging around can open it up and have a good look and let us all know what the fluid path is. If the fluid path does take a direct route between the inlet and outlet ports as speculated, this would be a good incentive to decrease the interval between flushes to prevent sludge build up as much as is reasonably possible.
 
The line from the master cylinder to the CSC and the line from the CSC to the bleed port are both fitted to the top of the CSC with a double banjo bolt. Fluid can flow from the master and out of the bleed port without passing through the CSC.

Internally, fluid flows straight from the banjo on top of the CSC straight into the piston bore. Nothing clever in there unfortunately!

'Best' you can do without removal is probably squeezing the clutch lever (extending the CSC piston slightly) then opening the bleed port (the piston returning pushes some fluid out). I can't imagine much fluid moves though!
 
mjc506 said:
'Best' you can do without removal is probably squeezing the clutch lever (extending the CSC piston slightly) then opening the bleed port (the piston returning pushes some fluid out). I can't imagine much fluid moves though!
Click to expand...
I did just that hoping the pressure build up and release might move some of the sludge out the bleed port but I just got more clean fluid being pushed out faster :shrug1:. What can I tell ya, guess I will keep a close eye on it and if it means flushing twice a season, so be it.
 
Several times....try to keep up :rofl1:
I've replaced a couple dozen units in the past few months, and have a slightly different method of doing them.
I've got it down to about an hour.
Since this is an Article, and a very good one, I didn't want to take away from the gist of it.
:WCP1:
 
Fred Primmer said:
I did mine on the side stand with only removing shifter linkage and oil filter. I also changed the coolant and engine oil at the same time so I had some fairings off as well. I wouldn't remove the oiler cooler. I didn't find that the three bolts on the CSC were difficult to access with a 1/4 in drive ratchet. I found the most difficult part was getting the banjo fitting bolt started in the new CSC. My bleed line banjo fitting was cocked at an angle and wouldn't let the bolt align correctly. I had to remove the bolt on the bleed line bracket on the left side of the bike by the bleeder valve. With the bleed line completely free the banjo fitting bolt installed easily. I then reattached the bracket by the bleeder valve. Be very careful not to cross thread the banjo fitting bolt into the aluminium casting of your nice new CSC!
Click to expand...

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!!
 
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.

Andrew Shadow said:
Because the fluid inlet and outlet ports are both in the upper part of the casting, several people on this site have speculated that the fluid is taking a short-circuited route between the two.
Click to expand...

….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.
 
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...
 
Esti1300 said:
but reservoir fluid gets brown rather quickly (1 season)
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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.
 
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