Soft Clutch lever! Please help

Fdcarlin

Joined
Jan 14, 2024
Messages
11
Age
38
Location
Cape Coral, FL
2005 St1300a.
My clutch is normal when the bike is cold, but as bike heats up the friction zone gets closer and closer to the grip. To the point where i dont think i will be able to get the clutch out of gear or downshift.
I did manually bleed the clutch. Sent about 8 oz of dot 4 through the system and dont see any air bubbles.
Replaced the levers brass bushing and pushrod, problem still exists, what should i try next?
Thanks
Frank

Fdcarlin said:
2005 St1300a.
My clutch is normal when the bike is cold, but as bike heats up the friction zone gets closer and closer to the grip. To the point where i dont think i will be able to get the clutch out of gear or downshift.
I did manually bleed the clutch. Sent about 8 oz of dot 4 through the system and dont see any air bubbles.
Replaced the levers brass bushing and pushrod, problem still exists, what should i try next?
Thanks
Frank
Click to expand...
Also, fluid level is normal and doesnt appear to be leaking
 
So if it continues, the lever will not disengage the clutch at all ?

It sounds like any of these.

i. Failing primary seal on the master cylinder (lever)
ii Failing seal at the slave (clutch)
iii. Air in the system, does it improve when you pump the lever.
iv. Relief hole between crank case and slave piston case is blocked - its at the bottom in the crankcase join with the clutch slave housing. Poke it clear and catch what come out. Water, oil, brake fluid ?
v. Your replacement pushrod is too short or the hole in the side of the brass bush is too deep

What were the symptoms before you replaced the bush and pushrod ? If the symptoms are new I'd put the old pushrod back and/ot the old bush.
 
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jfheath said:
So if it continues, the lever will not disengage the clutch at all ?

What were the symptoms before you replaced the bush and pushrod ? If the symptoms are new I'd put the old pushrod back and/ot the old bush.
Click to expand...

i have not let it get to the point of not disengaging at all. Pumping the lever will restore SOME friction enough to get me home. Then it returns to normal functioning clutch when it cools down.
The old bushing was completely worn through, and the new pushrod is identical. Can i shim out the new bushing to make it less deep, and would that make sense to try considering the clutch operates normal when cold?
 
The heat makes the fluid expand, and this can disengage the clutch - if say there was a bit of grit in the hole in the bush. That is because the tiny compensation port in the master cylinder remains closed, and cannot let expanding fluid escape back to the reservoir.

I assume that you made sure that the pushrod is properly seated in the hole ?

The fact that you can pump up more pressure may suggest air, and since that is the cheapest fix, then I would do some more bleeding.

Get a bleed tube tube with a non return valve. Attach that with the spring clips to the clutch bleed valve. Get a ring spanner for the blled valve and put the bleed tube through it before you attach the tube. That allows the spanner to stay in place.

Now armed with a full reservoir of fluid, your handlebars locked full right lock start bleeding.
Pump fluid so that the bleed tube is full and close the bleed valve. It helps if the tail end of the bleed tube is in fluid.

Start
=====
Close the bleed valve.
Pump the lever a few times a reasonable speed but not too fast. You want the fluid to activate the slave piston each time.
On the last stroke, keep the lever held in.
Open the beed valve and watch the fluid come out. ****
Close the bleed valve before it stops flowing.
Take a rest if your hand needs one.
Repeat from Start.

****
What you are doing is agitating the fluid and the pistons trying to dislodge air bubbles and also building up temperature with the repeated squeezing of the fluid.
When you open the bleed valve, the built up temperature and hose pressure helps to push the fluid out. So does the spring of the slave cylinder returning to its normal position. That is one reason that you have to hold the lever in . The other is that it stops fluid going back to the reservoir.

Keep repeating this:
Close.
pump pump pump pump pump hold. release valve, wait for flow to slow down, close valve
pump pump pump pump pump hold. release valve, wait. close..
pump pump pump pump pump hold. release valve, wait. close..

you get the idea.

Each time, the slave piston will be pushing out fluid and air from the slave cylinder. This is hard to get rid of using the techique that you might use for your brakes because with the bleed valve open, the pressure isn't there to operate the slave cylinder. So any trapped air stays there. This method gets rid of it.

When you think you have a good resistance in the lever, tie it back overnight

-----

I cannot work out why the feel is softer as the engine heats up - unless the heat is coincidental, rather than the cause. It is still possible that the primary seal in the master cylinder is worn. If the slave cylinder seal is worn, then fluid will be seeping past into the air gap between the piston and the clutch . That leakage could increase as the cylinder expands. Making sure that the weep hole is clear will help to identify if that is the case. But if this was the case there would be a drop in the fluid level in the reservoir.
 
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@jfheath thank you, that is an excellent description of the bleed procedure. I have done it a couple times today with that exact procedure, except i did not have a non return valve attached… i will pick one up and try it
 
I would rebuild the master cylinder before even thinking slave cylinder. You should have some oil dripping soon if slave is bad
 
oude geit said:
I would rebuild the master cylinder before even thinking slave cylinder. You should have some oil dripping soon if slave is bad
Click to expand...
Thank you, i usually go to ebay for parts is there a source you would recommend to order a rebuild kit, or is it best to go to local honda dealer?
 
Whoa, whoa-- sounds fairly normal to me. My release on my ST1300 clutch is near the end of the stroke cycle. in fact my clutch travel is in the millimeters from engaging. Makes it easy to speed shift.
Not sure you actually have a problem.
Are the gears grinding?
 
ST-Traveler said:
Whoa, whoa-- sounds fairly normal to me. My release on my ST1300 clutch is near the end of the stroke cycle. in fact my clutch travel is in the millimeters from engaging. Makes it easy to speed shift.
Not sure you actually have a problem.
Are the gears grinding?
Click to expand...
The problem is that when it is hot i have to fully squeeze lever all the way to the grip. Then it engages very close to the grip.
When cold i can change gears by barely pulling lever a couple inches
 
Fdcarlin said:
@jfheath ...... except i did not have a non return valve attached… i will pick one up and try it
Click to expand...
John is suggesting pumping with the bleed valve closed to build pressure to make the slave cylinder move, and then closing the bleed valve before the fluid flow stops. This method closes the bleed valve before any air can enter the system. There will be no benefit to a one-way valve using this method.

The point of the one-way valve is to allow the bleed valve to be left open continuously during the bleeding process without allowing air ingress.
 
When things get hot, they start expanding, and the clutch slave cylinder piston is probably binding and sticking.
I wouldn't waste time on the master cylinder rebuilt kit, as they almost never go bad.
As far as leaking out the weep hole on the rear crank case cover...you can't always count on that, because the hole gets clogged up, and it just pools inside.
This should give you an idea.
This is the MOST neglected part of the motorcycle!
When they start getting cruddy, and folks flush them, they start working a little better, so they think their problem is fixed.
Then the piston tilts against the crap, and wears metal on metal, which is why heat causes them to stick etc.
Everyone always tells me how good their clutch is....until I fix it and show 'em :rofl1:
2018-05-31 13.12.35.jpg20220501_131325.jpg20220501_131752.jpg20220501_131907.jpg20220501_170127.jpgE6FFE26E-4119-44FF-8FF9-04C431A964CD.jpeg
 
Fdcarlin said:
The old bushing was completely worn through, and the new pushrod is identical
Click to expand...

Is it a Honda bush and push rod ? If not, did you put the old and new side by side or measure the depth of the hole. I ask because a friend came with a brake issue. They would not release. It turned out that the push rod was a tiny fraction too long.

Crucial question, not answered - Did this behaviour start after you had replaced them ?

Andrew Shadow said:
John is suggesting pumping with the bleed valve closed to build pressure to make the slave cylinder move, and then closing the bleed valve before the fluid flow stops. This method closes the bleed valve before any air can enter the system. There will be no benefit to a one-way valve using this method.

The point of the one-way valve is to allow the bleed valve to be left open continuously during the bleeding process without allowing air ingress.
Click to expand...

Yes, it's not necessary to use a one way valve, but having one there keeps the short section of tube between the bleed valve and the one-way valve full of fluid, so you can see the reassuring air bubbles coming out. You can normally achieve the same thing with a length of vertical tube from the bleed valve - but the clutch bleed valve is not far off horizontal.


Igofar said:
I wouldn't waste time on the master cylinder rebuilt kit, as they almost never go bad.
Click to expand...

I've had a 100% failure rate with every clutch master cylinder I have serviced. ie Just the one on my first 1100 a second hand model with 29000 on the clock.

I Took out the piston, cleaned it up to see what was wrong. There was a black greasy substance which was odd. Underneath a thick black paste which scraped off like cold butter. Then I wondered where the seals were.

The same was true of the slave seals. Thick black cold butter paste instead of seals.

I still don't know what caused the seals to turn to paste. Apart from neglect ?
Many years and 3 Pans later I maybe got a clue - the chap that had fitted a non-Oem service kit and slightly too long pushrod to his brake master cylinder ? It turned out that he had replaced the full service kit - piston and seals as well. Still trying to find the cause of the locked front brakes - they worked first time but would not release - so having checked everything else, we removed the piston again to check that he had not inverted the seal primary seal when he installed it. Cleaned it up and then watched as he struggled to get the flared primary seal back into the bore.

"How did you do it last time ?", I asked
"I lubricated it - it went in really easily"

"What did you use ?"
"Washing up liquid"

My mind went back to that thick black butter that used to be my seals. Maybe. Just maybe.
 
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Fdcarlin said:
The problem is that when it is hot i have to fully squeeze lever all the way to the grip. Then it engages very close to the grip.
When cold i can change gears by barely pulling lever a couple inches
Click to expand...

Mine was a lot like this a few years ago. It would get spongy as it warmed up but was fine when cold. I did have a little fluid loss in the sight glass on the master but I couldn't find any leakage. It slowly got worse over a period of a few weeks.

Igofar said:
As far as leaking out the weep hole on the rear crank case cover...you can't always count on that, because the hole gets clogged up, and it just pools inside.
Click to expand...

Then one morning I went into the garage and there was a large puddle on the floor under my bike. Apparently the large amount of crud had plugged up the hole until it finally blew through when I parked it for the night.
Changing out the slave cylinder is a pain in the butt but I got some new tools out of it.
 
If you look at how the clutch slave cylinder is made (inlet port/outlet port - one-way in/same way out), I will always flush the clutch line three times (minimum)!

Hoping to get as much of the old fluid out of it, possible.
 
I looked at the BIG BOOK and to access the slave unit it says remove the clutch oil - then drop the engine out!

Are they for real!!!!
 
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Mr.E said:
I looked at the BIG BOOK and to access the slave unit it says remove the clutch oil - then drop the engine out!

Are they for real!!!!
Click to expand...

Oh yes - that IS what the Honda service manual says:
  1. drain fluids
  2. remove the engine from the frame
  3. replace the clutch slave cylinder
  4. reinstall the engine in the frame
  5. refill fluids and bleed the clutch hydraulic lines
To sum-up: steps 1,3 and 5 will take about 15-20 minutes while steps 2 and 4 will take frickin' hours. I was quoted about 14-17 hours labour at ~$120/hour + parts by my local stealership for the whole job. The actual task of R&R the slave cylinder (i.e. step 3 above) would take less than 5 minutes, including torquing the three little bolts to 7 ft-lb.

....and as an engineer, it seemed to me that spending upwards of $2000 to remove a 400+ lb engine and risk damaging the fairing, the engine, the exhaust system, and potentially myself - all to replace a small component that costs about $75 and is held on by three small M6x25 bolts - is simply nuts.

I will also say that while my fellow engineers at Honda did a superb job on how the ST1300 works and its reliability and durability (NOT the same thing), they completely muffed making the bike serviceable or easy to maintain. Look at the rigamarole you have to go through to check the oil (get down on your hands and knees and peer through a grimy little sight glass down in the bowels of the engine) and even adding oil (a mercifully rare task on the ST) is a PITA.

So, I searched this forum and found that a member named @stgolfer had replaced his CSC by simply lying the bike down on its left side on a big pile of blankets and pillows - and then reaching up into her innards and doing the job. I decided that I could likely accomplish the same task by just lying on my back and reaching up - although an agile young lad did help me with that. Access is a little tight and you will need a good light - but this is totally doable for anyone who knows which end of a screwdriver to use on a screw.

Anyhow - the method in the thread has been used by....oh, I'll bet at least 20-25 people and maybe more. As I said earlier, it is not expensive, it isn't difficult, it takes about 90 minutes to two hours and it requires relatively few tools.

Cheers and good luck with it!

Pete
 
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