ST1300 clutch fluid replacement

[Obo]

Since I don't know the history on when it was last done, it's due to be done now!

I've looked at the procedures and online videos and @SupraSabre's recommendation to flush it 3x, but I'm wondering if it's better off to drain the entire system (reservoir, lines etc.) as much as possible before I flush, refill and bleed it

OR

is it OK (or easier/better) to just remove most of the reservoir's old clutch fluid from the reservoir and then flush the new stuff through multiple times and bleed it.

 

[Larry Fine]

The latter. Refilling a drained system is a pain.

 

[Andrew Shadow]

Certainly empty and clean the grunge out of the master, but I don't see what advantage draining it would be. The problem with the clutch circuit is the crap that remains in the slave cylinder even when it is flushed. This is the result of its design, and draining the system won't change that. The only benefit to be had would be to remove the slave cylinder so it can be thoroughly flushed, but that isn't practical.

 

[Larry Fine]

Could a slave cylinder be drilled and tapped for a bottom drain bleeder?

 

[jfheath]

The pump, pump, pump, hold, open valve technique works well for the clutch once the air is removed.

I'll try to explain.

Keep the bleed valve closed. Pump the clutch lever a few times so that the slave moves back and forth.
Hold the lever in and open the bleed valve.
The spring in the slave cylinder pushes the piston back forcing the fluid out through the bleed valve.
Close the valve as the flow slows down.

Repeat.
Repeat.
Repeat.

You are not trying to get rid of air at this point, you're trying to clean the slave cylinder bore.

Each pump, pump, pump with a closed valve allows the slave to agitate and mix any old fluid and gunge with the new fluid - effectively washing and rinsing the bore. Each opening of the valve then ejects most - but not all of the fluid mixture in the bore. What remains is a weaker mixture of old and new. You will get an indication of this from the colour of the expelled fluid in the tube.

Doing this each 12-18 months helps to stop the grunge from developing in the first place.

The same agitation should be done with the SMC - except you can move the SMC for its full stroke by hand with an open PCV bleed valve.

 

[ad.hom]

I mean, if you like making work for yourself, sure, drain it then try to get the air out

As the others said, flush through rather than drain it. I have a simple piece of tube that I put into the side of a soda bottle, the job couldn't be simpler.

 

[Larry Fine]

When I did mine, I used a hand-held vacuum pump. I first used it to empty the reservoir, cleaned it, added fresh DOT4, then attached it to the slave cylinder.

Then I opened the bleeder, pumped repeatedly, topped off the reservoir as needed, and kept going until the fluid coming out was as clear as the fresh fluid.

 

[Obo]

Emptying and cleaning out the reservoir was the first planned step, followed by pressure pump-bleed-ensure the reservoir doesn't empty-repeat until everything looked much clearer.

 

[Kevcules]

Could a slave cylinder be drilled and tapped for a bottom drain bleeder?

Interesting idea. That should ensure that no "old" fluid stays stagnant in the slave cylinder. I wonder why they never had a bleed or drain valve installed on it anyways?

If I was your size though, I would just lift the bike up and turn it upside down to drain out the old fluid.

 

[Obo]

Interesting idea. That should ensure that no "old" fluid stays stagnant in the slave cylinder. I wonder why they never had a bleed or drain valve installed on it anyways?

If I was your size though, I would just lift the bike up and turn it upside down to drain out the old fluid.

He might be able to lift an ST1100 but a ST1300 is 200cc's heavier.

 

[SupraSabre]

You want to make short work of bleeding your clutch? Pick up one of these from Harbor Freight!

Brake Bleeding tool

After replacing the clutch slaves on both the 2010, and the 2004, I used this and had clutch immediately!

 

[Esti1300]

Doing this each 12-18 months helps to stop the grunge from developing in the first place.

After my ST purchase, started changing fluids and the clutch fluid was like dark maple syrup. I cleaned that up and went through several flushes using the @jfheath technique.
The following spring and within a few weeks of riding, I noticed the fluid going dark again. Here’s a picture of the fluid a few weeks after I started noticing. Lighter coloured maple syrup this time.
Of course I flushed it again and later that summer, could once again see the colour changing.
The explanation is that there is obvious residual gunk in the system somewhere, most likely at the CSC.


So, for me 3 flushes in less than a year and every time I do it, it takes a little longer for the fluid to change colour. @Obo you may encounter this behaviour with yours.
Fingers crossed, I’ve had no clutch operation issues but a new CSC is on deck if needed.
It has now been just under 12 months since my last flush and will post a picture to compare prior to this seasons flush.
YMMV but I now flush at least once a season

 

[Andrew Shadow]

You want to make short work of bleeding your clutch? Pick up one of these from Harbor Freight!

Bob:
I was given one similar to that. I have only used it once to try it. Have you used the master cylinder auto-refill bottle?
I'm curious to know how well that set-up works. I was to chicken to try it. I know the physics states that it should work but I had visions of brake fluid pouring out all over the place.

 

[Obo]

@SupraSabre I have the basic MotionPro check valve bleeder.

 

[etalors]

@SupraSabre I have the basic MotionPro check valve bleeder.

Really like the MP. No drama. Simple and efficient. Works as good if not better than anything out there.

 

[Andrew Shadow]

The following spring and within a few weeks of riding, I noticed the fluid going dark again.

Which in your case sounds like it was a result of previous neglect and the decreased flush interval that you adopted was warranted.

No matter how clean the clutch fluid system is, the clutch fluid will always begin to discolour before the brake fluid will. The system holds less fluid, the fluid works more often than the brake fluid does, and the clutch fluid is subjected to more heat for longer duration than the brake fluid because the slave cylinder is bolted directly to a hot engine. All of these factors combine to discolour it more quickly. Any attempt to keep the clutch fluid as clear and clean looking as the brake fluid would require a shorter and more frequently repeated flushing interval than the brakes are treated to.

 

[SupraSabre]

Bob:
I was given one similar to that. I have only used it once to try it. Have you used the master cylinder auto-refill bottle?
I'm curious to know how well that set-up works. I was to chicken to try it. I know the physics states that it should work but I had visions of brake fluid pouring out all over the place.

No, I don't trust the bottle, but I have had really good luck with the bleeding tool.

 

[SupraSabre]

@SupraSabre I have the basic MotionPro check valve bleeder.

Yeah, I have one of those too, I like the HF tool better!

 

[Esti1300]

I checked my mtce records and the last clutch flush I did was mid-July last year, prior to my NFLD trip and rode until late November.
Fast forward to last week and this prior to the flush


So not quite as dark and much clearer (see pic in post #12). As previously stated, with every flush it takes longer for the fluid to darken. Slowly cleaning out the CSC.

 

[cjames431]

Bled my clutch after changing the slave. I had a nice firm lever when finished. I put the plastics back on and rolled the bike of the table to rearrange the garage parking. When I rolled the ST into her place the clutch lever was soft and would not allow me to shift at all.
Air? Or ………..?