Clutch fade / fluid boiling at Altitude

[rtb1965]

I am hoping you good people can help me with a technical issue with my 08 GTR 1400.

I have just returned from the Pyrenees mountains for a touring holiday but experienced the same symptoms in the French and Italian Alps last year.

When the bike is warm i.e. just over 1/2 way on the LCD temp gauge and at altitude (over 1500m) the clutch biting point moves back towards the handle bar and sometimes I will completely loose the clutch. It Leaves me with one gear (generally 2nd) to complete the mountain pass and just hope I don't have to come to a complete halt. Descending and or letting the engine cool resolves the problem but is not always a safe option on some mountain passes. I can only conclude that hydraulic fluid is boiling.

Knowing the problems I had experienced the previous year, I had changed the hydraulic fluid in both brake and clutch systems two weeks before leaving with fresh DOT4 from a new sealed bottle.

On both trips there has been another GTR but the later '10 model, that bike did not suffer the same problems but was perhaps being ridden more conservatively.
The routing of the clutch fluid pipe appears to be different on the later model.

Everything works fine closer to sea level even when ridden hard in hot conditions.

I have searched for but not found anyone else describing similar problems.
I have not had any issues with the braking systems.

What is the solution?
DOT 5.1?
Re-routing the clutch line away form the engine?
Braided hose?

Hoping  you can help,
thanks
Roy

[doebag]

Firstly welcome to the forum.

Secondly, Kawasaki recommend replacing all hydraulic flexibles every four years. It may be that you clutch hose, that is now six years old, is softening with the heat. Though it does seem strange that it does it at altitiude.

I would certainly replace the flexible hose and change the hydraulic seals in the master and slave cylinders.

[Charlie747]

Firstly welcome to the forum.

Secondly, Kawasaki recommend replacing all hydraulic flexibles every four years. It may be that you clutch hose, that is now six years old, is softening with the heat. Though it does seem strange that it does it at altitiude.

I would certainly replace the flexible hose and change the hydraulic seals in the master and slave cylinders.

+1

PS 

[STX1300man]

Secondly, Kawasaki recommend replacing all hydraulic flexibles every four years.

I saw that in the handbook. Does anyone do that? The Pan I just changed from was 10 years old and on the original pipework.

[Zebedee]

Yup when I had older bikes I would change fluids and to bradded lines as a matter of course :)


Sent from my iPhone by mini Elves.

Zeb

[rtb1965]

Thanks for your help.

Should I go for standard Kawasaki lines or after market ones?
If so which brand?

I would be helpful to know if other GTR riders have ridden at at over 1500m in the Alps / Pyrenees or elsewhere and either been trouble free or not.
I don't want to have a another trip compromised by the issue, I really enjoy the GTR  but would I have to be very confident it was not going to be a problem wherever I head for next years trip. 

ta,

Roy

[Ros]

Hi and welcome!

Just a quick note to say that I regularly ride around the mountains (French Alps, Italian Alps and Dolomites) at above 1,500m and have never noticed such an issue.  I have done the Col de l'Iséran several times and at 2,770m never noticed a problem. 



My bike is a 2010 model

It sounds like your problem isn't altitude related - especially if letting the machine cool down resolves the issue...

Cheers!
Ros

[rtb1965]

The thing is, I can predict when it is going to happen now.
I have had the bike getting on for 3 years.
I ride 12 months of the year in the UK and never have a problem.
I ride down to the Alps or Pyrenees and I don't have a problem.
I ride from the Mountains to the Spanish ports when it is 35+ degrees C and I don't have a problem.
But once I go up the mountain with any thing other than a cold engine at the start of the day and it happens.
Last week I did manage to get over Tourmalet from Bareges once (about 2100m I think) at the start of the day riding very conservatively with a cold engine with no problems but I did it 5 more times with a warm engine and it is there every time.
It has to be the mix of heat and altitude that causes the problems, i.e. some of the fluid vaporises and moves or completely looses the biting point.
Remove the heat or altitude or both the gas returns to a compressible fluid and everything works once more.
From what I understand the boiling point of hydraulic fluid is reduced at altitude.
I struggle to see what else it can be.....

[Burchy]

I can't see that you are going to boil the clutch fluid ever.  You have much more chance of boiling the brake fluid because of the heat generated by the pads, but that simply isn't happening in the clutch.  Think about it.  The clutch is used for just a split second on down changes and the only heat it can get is a bit from the engine.  The altitude isn't going to alter that.

A slipping clutch  - That would generate a bit of heat but even so its still a long way away from the slave cylinder

DOT 4 fluid has a boiling point of between 155 and 230 centigrade/.  The lower figure when it has absorbed water.  Just can't see a clutch line getting that hot.  At 3000m the boiling point of water drops from 100C to about 90C. so I guess you could knock 10% of the former figures to get the BPs of fluid at 10000 ft.

Just my 2 penn'orth

[rtb1965]

I don't think or know the heat source is the clutch itself, and it does not make any difference if you use the clutch a lot or or not. 
I am assuming the heat source is the engine....

[virginiajim]

Sounds like the clutch master/slave cylinder to me.  I'm betting on the slave, though.

[rtb1965]

I have done a bit more on this today.
I have been in contact with Kawasaki UK who were helpful.
I have had the slave cylinder off and looked at the clutch rod at their suggestion.
They were considering if the clutch bearing had gone and the rod was spinning generating the heat but then discounted this going by the fairly minimal wear on the rod for a 43k BIKE
The slave cylinder was difficult to remove and had a yellow crumb like substance inside which they suggested was crystallised hydraulic fluid.
The only real route for that to be there would be if the seal on the slave cylinder was not all it should be?
I have never noticed a loss of fluid but I suppose it could be fairly subtle, I have ordered a a new seal and with give the slave cylinder a once over.

   

[Zebedee]

Yucky :(


Sent from my iPhone by mini Elves.

Zeb

[Charlie747]

Yucky :(


Sent from my iPhone by mini Elves.

Zeb

So that's how they make cottage cheese 

[Kwikasfuki]

Lets us know if the seal fixes it. I guess you'll have to go to high altitude to prove its fixed