Sticking gear (air still in clutch line possibly) Heeeeeeeeeeelp

Dogknob1

Dogknob1

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Hello.

Quick synopsis : would go out on a ride on warmer days and bike wouldn't change down the box, mostly from higher gears 6th to 5th but sometimes lower. So after reading all the forums to be found i got a fresh clutch slave,rod and felt from Motorworks, all fitted with new min oil and spend an eternity bleeding it. (cleaned master at same time) Did the Dragon rally the other month and pretty much good as gold in the freezing cold But on the last few outings it's started to play up culminating on Sunday almost home when apparently all i was allowed was 5th!
So gave everything the once over to find that if i cranked the clutch lever i can get microbubbles floating up. Pulled the master apart to make sure it's all clean (rubber look ok but slightly ruffled on inner edge) put it all back to getter, pumped for England and left it with lever tied to bar over night. Checked again this morn still get micro bubbles !!!!! AAAAAAAAaaaaaahhhhhh FFS!

It's a well used 2004

To add to the comedy gold we'er doing a 1000 in 24h around the UK starting Friday night

Should i chuck on another master or just set fire* to the bike and hope for a quick insurance payout

*joking obviously

Cheers Duncan
 
Dogknob1 said:
Hello.

Quick synopsis : would go out on a ride on warmer days and bike wouldn't change down the box, mostly from higher gears 6th to 5th but sometimes lower. So after reading all the forums to be found i got a fresh clutch slave,rod and felt from Motorworks, all fitted with new min oil and spend an eternity bleeding it. (cleaned master at same time) Did the Dragon rally the other month and pretty much good as gold in the freezing cold But on the last few outings it's started to play up culminating on Sunday almost home when apparently all i was allowed was 5th!
So gave everything the once over to find that if i cranked the clutch lever i can get microbubbles floating up. Pulled the master apart to make sure it's all clean (rubber look ok but slightly ruffled on inner edge) put it all back to getter, pumped for England and left it with lever tied to bar over night. Checked again this morn still get micro bubbles !!!!! AAAAAAAAaaaaaahhhhhh FFS!

It's a well used 2004

To add to the comedy gold we'er doing a 1000 in 24h around the UK starting Friday night

Should i chuck on another master or just set fire* to the bike and hope for a quick insurance payout

*joking obviously

Cheers Duncan
Click to expand...
If, after all of the above, you're still getting microbubbles, especially when it's warm what expands most nearest to heat ??

Slave cylinder or master cylinder ?

Sent from my SM-N910F using Tapatalk
 
Start from scratch. Make sure the hoses are good and the unions are tight, it may be a good idea to put new crush washers on the unions.
The slave is a simple cylinder. Fit a new seal and bleed again.
One of them bleeders that suck the fluid through the system may be needed.
 
Sorry if I'm stating the obvious but you did reverse bleed the system?
Just fixed a leak at the back of the slave and it took ages to get all the air out.
 
I might be stating the obvious but does the clutch hose have a continuous rise from the slave to the master cylinder?

There was a dealer ‘fettle’ done some years ago as BMW had tie wrapped the hose during manufacture with a high spot near the slave cylinder which caused clutch problems on some bikes. All it needed was the bottom tie wrap removing and the hose adjusting to remove the high spot.
 
Yes I fed from top with min oil and had a hose off the nipple , crank crank open shut bleed type thing
 
Oh it does! A most excellent tip sir thank you I'll cut that bugger off right now and do some more bleeding bleeding
 
I had exactly the same micro bubbles problem. I believe it’s the master cylinder seals.
Thankfully(?) BMW will only sell a complete cylinder you can’t get new seals from them. Who knows who makes them.
The trick is the move the clutch lever Sloooowly until all bubbles have escaped. Once it’s properly bled the line pressure seems to keep the seals sealing better.
 
Bendy toy said:
I had exactly the same micro bubbles problem. I believe it’s the master cylinder seals.
Thankfully(?) BMW will only sell a complete cylinder you can’t get new seals from them. Who knows who makes them.
The trick is the move the clutch lever Sloooowly until all bubbles have escaped. Once it’s properly bled the line pressure seems to keep the seals sealing better.
Click to expand...
From memory, it's a Brembo system. Ducati and Aprillia will probably do seal kits.

Sent from my SM-N910F using Tapatalk
 
I've had to order a new used low mileage one this morning to throw on the Bike for the 1000 in 24h capers leaving Friday night
But thanks for the extra info
Cheers Duncan
 
Just a thought,whilst you are talking about the clutch,,you don’t actually state whether the lever feels ok or not,
Only that it won’t change down,
Might be worth making sure the gear lever pivot bushes are free and the selection process is good.
Hope this makes sense,as I regularly downshift without using the clutch,and never use the clutch up shifting anyway,
On a clutchless downshift I just slightly preload the gear-lever and blip the throttle.
So I guess I’m struggling to see how a bit of air in the system is totally preventing gear shifting.ie sticking in 5th
 
Fair point Mikey I've cleaned up the the ball joints which where dirty as hell as a precaution anyway but yes all the symptoms (reading others with same thing) point to master & slave issues. Should probably but some new gear link bushes and throw those in too.
Cheers for the info
 
Bleed the slave before you reattach it to the gearbox and while bleeding have the slave cylinder piston pushed back fully into the housing.
 
Thanks Steptoe
I've got the new one fitted and no micro bubbles so all seems good. Cheers for the top tip.
It's going to get a thorough test as we're doing a iron butt tonight 😮
So shit or bust springs to mind
 
Update :
After knocking out the iron butt as the shake down run everything seems fine. Though cold as a cold thing in places so need a hot day top finish testing but pretty sure fixed with newish clutch master.
I've put a very brief ride report on the face book page
Cheers Duncan
 
I’ve never fully mastered clutchless gear shifts do it always get some assistance. Air in the system makes it feel like the clutch is not fully separated when levee is pulled right in. With clean hydraulics, you can feel that the slave cylinder has reached its limit
 
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah
out yesterday in the hot weather and here we go AGAIN !!!!
so it will be fine for a little bit but when all warned up, you can change up through the box but will literally refuse to change back down.
Normally if you're off the throttle for a bit in said gear like 5th or 4th and just wont change down ????
new slave new master pretty sure bled properly! had no trouble on 1000mile run but was cold as hell !
It's like the pressure plate is done or something as clutch doesn't slip ? dry rusty splines ?
How can i inspect the clutch without splitting bike or is it unlucky chucky get on with it .
Cheers Duncan
 
There is a plastic cap above the clutch housing.
3 x M6 bolts to remove, easy to get at if its Non-ABS (once the fuel tank is removed).
A bit tighter to get at if its ABS.
You will be able to look down at the clutch.
 
My gut feeling is still either the external linkage ,or the gearbox selector shaft sticking when the casing is hot.
If the gear selector does not return to centre position ,the selector pawl Won’t be able to engage the next pin on the selector drum.
Has the bike ever been dropped?
Unlikely ,but if the gearbox selector shaft was bent it could bind when hot.
As ive said before, I fail to see a dragging clutch completely stopping downshift,it wouldn’t be nice but it would shift.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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