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Technically Speaking => Engine & Gearbox => Topic started by: Gsxjohn on Sunday, 19 April 2020, 03:23 AM

Title: Clutch master cylinder nightmare
Post by: Gsxjohn on Sunday, 19 April 2020, 03:23 AM
Gents,  I've changed the brake and clutch hoses on my bike. The front brake was a nightmare to bleed. I'm doing the clutch now and the sod won't bleed. I've fitted new seals etc in master cylinder but now noticed that when I pull the lever the piston in the master cylinder doesnt return leaving play on the brake lever, I've stripped it a couple of times now and checked for obstructions in the cylinder, all seems ok. If I push the piston manually before fitting it works ok.
Any pearls of wisdom would be great🤞👍
Title: Re: Clutch master cylinder nightmare
Post by: Hooli on Sunday, 19 April 2020, 03:45 AM
The clutch slave won't return when it's not fitted. There is a spring in there that holds the piston out, so it is always pressed against the pushrod. Have you refitted & tried?

I've never had a problem bleeding the clutch, indeed I've stripped, cleaned & refitted mine within 45mins when it decided to leak one morning before work.

The front brakes however are an utter twat when dry, I always fill them from the bleed nipple with a syringe of brake fluid. It makes a four hour job into a 30min one.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Sunday, 19 April 2020, 05:28 AM
Hooli, it might be my description. It's the master cylinder piston that's not returning. With the reservoir cap off you can see the piston through the feed hole in the reservoir. The slave cylinder is fitted on the bike so is pushed in.

Know what you mean, the front were sods, ended up taking the banjos off the calipers and getting the lines filled that was.
Title: Re: Clutch master cylinder nightmare
Post by: Hooli on Sunday, 19 April 2020, 05:57 AM
Ahh I get you now.

No idea sorry, never had my master cylinders apart. Never needed too.
Title: Re: Clutch master cylinder nightmare
Post by: Andre on Sunday, 19 April 2020, 06:38 AM
I had a buildup of some solid hard crud where the seals go. Would have caused the seals to stick out a bit more than they should. Did you check for that? Only other thing I can think of are the seals themselves: are they the correct ones (i.e. "bad" brand).
Title: Re: Clutch master cylinder nightmare
Post by: KiwiCol on Sunday, 19 April 2020, 07:07 AM
Have a look in the GSX1400 Manual - Part 1, Section 6, page 55.  (Download section, under Manuals) Shows the striped down master, might want to check that spring.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Sunday, 19 April 2020, 07:24 AM
Cheers guys, I'll  have another strip down and double check in the morning. 👍👍
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Monday, 20 April 2020, 03:23 AM
Well I stripped the master cylinder again today. Made sure everything was smooth in the bore of the cylinder, re-assembled and the flaming thing works....nothing different done from before.  Only issue  now is the clutch is dragging so I'll  bleed it again.
Can't complain really, the bikes been sitting  for 2yrs.
Title: Re: Clutch master cylinder nightmare
Post by: Eric GSX1400K3 on Monday, 20 April 2020, 02:53 PM
Heres a tip re bleeding thats always worked for me: when nearly done, i.e new fluid coming out of the lowest point, crack the nipple open so you get flow, but before the lever touches the bar, close the nipple by hand, and with the other hand on the lever you should feel resistance.  Let the lever out again and repeat, this forces air to the lower nipple.  If you close the lower nipple  AFTER  releasing the lever, the vaccum created by the master cylinder sucks air in via the thread at the lower nipple, undoing what youve just tried to do.  If you leave the system for 10-20 min after refilling, this can make it easier too.  Keep an eye on the resevoir, you can also get air trapped in behind the master cylinder and bore that takes a while to pump out.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Tuesday, 21 April 2020, 05:28 AM
Cheers Eric, I'll  give that a try👍
Title: Re: Clutch master cylinder nightmare
Post by: GSXKING on Tuesday, 21 April 2020, 07:42 PM
I borrowed a mates vacuum operated brake bleeder and it sucks the old fluid through. Then you put the new fluid in and draw it thru until it comes out the bottom nipple. No air bubbles what so ever and really good feel through the lever.  :onya: :onya: :onya: :hat:
Title: Re: Clutch master cylinder nightmare
Post by: Dusty ST on Tuesday, 21 April 2020, 11:25 PM
Quote from: GSXKING on Tuesday, 21 April  2020, 07:42 PM
I borrowed a mates vacuum operated brake bleeder and it sucks the old fluid through. Then you put the new fluid in and draw it thru until it comes out the bottom nipple. No air bubbles what so ever and really good feel through the lever.  :onya: :onya: :onya: :hat:

I did the same at the weekend with my new clutch slave cylinder, I'd also renewed the hose, so also filling an empty system.
I find the vacuum bleeder gets the fluid through, but I still need to manually pump fluid through as I can never be sure the bubbles I'm seeing with the vacuum are the bleed nipple connection sucking air in.
Title: Re: Clutch master cylinder nightmare
Post by: Hooli on Wednesday, 22 April 2020, 05:31 AM
Quote from: GSXKING on Tuesday, 21 April  2020, 07:42 PM
I borrowed a mates vacuum operated brake bleeder and it sucks the old fluid through. Then you put the new fluid in and draw it thru until it comes out the bottom nipple. No air bubbles what so ever and really good feel through the lever.  :onya: :onya: :onya: :hat:

For those of us without toys you can do the same with a syringe.

I still prefer to fill from the bottom though, after all air floats so it pushes it the way it wants to go.
Title: Re: Clutch master cylinder nightmare
Post by: VladTepes on Wednesday, 22 April 2020, 04:59 PM
Jeez Hooli, why are you so anti gravity ?   :lol:
Title: Re: Clutch master cylinder nightmare
Post by: Notty on Wednesday, 22 April 2020, 11:43 PM
Quote from: VladTepes on Wednesday, 22 April  2020, 04:59 PM
Jeez Hooli, why are you so anti gravity ?   :lol:
Gravity is there other way up here clearly :)
Title: Re: Clutch master cylinder nightmare
Post by: Hooli on Thursday, 23 April 2020, 03:34 AM
Quote from: VladTepes on Wednesday, 22 April  2020, 04:59 PM
Jeez Hooli, why are you so anti gravity ?   :lol:

Our gravity works in the correct direction old bean.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Sunday, 03 May 2020, 02:59 AM
Gents, clutch still not working🥵 got new seal kits for master cylinder and slave incase I'd got bad set. Both fitted and free moving in respective cylinders, started to bleed it and all going well and suddenly master cylinder piston doesn't return and sticks.
I've fitted new Hel clutch hose as well.
Anyone come across this?
Title: Re: Clutch master cylinder nightmare
Post by: Del on Sunday, 03 May 2020, 03:22 AM
@Gsxjohn  - hi fella just read through the post

have you tried bleeding from the master cylinder - as in the banjo bolt at the top - Ive fitted more than my fair share of refurbished calipers and you can get an amazing amount of air bleeding this way

Clutch as teh clutch line is so long you could have air in this aswell

Worth a try mate good luck

Del
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Sunday, 03 May 2020, 04:13 AM
Del, I've tried reverse and from master cylinder. Even had banjo off slave cylinder till fluid through. There's something causing the master cylinder locking up and not returning when handle released.
Title: Re: Clutch master cylinder nightmare
Post by: Del on Sunday, 03 May 2020, 06:33 AM
could it be a duff line that is collapsing when under pressure - you could try putting old lone back on and see if that rules the issue out

if the line is the only thing that is different then I would look at that
Title: Re: Clutch master cylinder nightmare
Post by: seth on Sunday, 03 May 2020, 06:52 AM
As @Del  said
Dont assume anything .
Put back to standard and give it a try then try the new lines.
My top tip for bleading the clutch is to use a clamp in the slave cylinder piston so it can't move as when you blead it the piston moves against the clutch springs .
I find it makes the whole job easier.
:cheers:
Title: Re: Clutch master cylinder nightmare
Post by: Eric GSX1400K3 on Sunday, 03 May 2020, 02:07 PM
Quote from: Gsxjohn on Sunday, 03 May  2020, 02:59 AM
Gents, clutch still not working🥵 got new seal kits for master cylinder and slave incase I'd got bad set. Both fitted and free moving in respective cylinders, started to bleed it and all going well and suddenly master cylinder piston doesn't return and sticks.
I've fitted new Hel clutch hose as well.
Anyone come across this?
Have you measured the master cylinder od and the housing id? Sounds almost like the cylinder is getting skewed in the bore.  I think air in the system is unlikely if youve bled from the banjo as well. Ive got Hel lines on mine and no issues, doubt also that a line is collapsing. 

Didnt use a clamp, found the clutch plate spring pressure is enough to allow to bleed.

Maybe post some pics of the master cylinder and bore and resevoir?
Title: Re: Clutch master cylinder nightmare
Post by: grog on Sunday, 03 May 2020, 06:15 PM
Gsx, Subaru clutch bleed has sim prob. Trick is to get outlet above master cylinder, only way to do it. Maybe a length of clear tube off slave bleeder, fastened up high. Tiny little master pumps until clear fluid, no bubbles. Re attach to slave, more very short stroke master pumps. My opinion only, master not coming back because air in system is compressing, no fluid pressure to return it.
Title: Re: Clutch master cylinder nightmare
Post by: KiwiCol on Sunday, 03 May 2020, 06:36 PM
Good call Grog, I had trailer brakes like that fairly recently. 

I'd fitted a new master cyl n buggered if I could get it to bleed properly, never had issues before. Solved it by making the outlet higher than the master cyl, easy on a trailer, bit harder on a bike, but will work the same.
Title: Re: Clutch master cylinder nightmare
Post by: gsxbarmy on Sunday, 03 May 2020, 08:08 PM
That's a good call @grog - I've had issues before depending on how the handlebars were turned and found with the clutch if the bars were on hard left lock it was a so and so to get all the air out. Front wheel facing straight ahead and with bars level sorted that.
Title: Re: Clutch master cylinder nightmare
Post by: Hooli on Sunday, 03 May 2020, 08:13 PM
Quote from: gsxbarmy on Sunday, 03 May  2020, 08:08 PM
That's a good call @grog - I've had issues before depending on how the handlebars were turned and found with the clutch if the bars were on hard left lock it was a so and so to get all the air out. Front wheel facing straight ahead and with bars level sorted that.

When doing the clutch or the front brakes I turn the bars until the fluid in the reservoir is level with the edge of it.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Monday, 04 May 2020, 02:22 AM
Many thanks to you all for the advice greatly appreciated. Tried all the above, even slave cylinder hung from rafters to get above master cylinder...took it off the bike first🤣
No air in the system🥺
Refitted and tried clutch, pushrod moves about 5mm, when released the clutch lever doesn't fully return there's about 5mm free play.
How much free play is normal?
With clutch in and in gear I can't turn the back wheel.
The engines been out for about 2yrs.
Title: Re: Clutch master cylinder nightmare
Post by: Del on Monday, 04 May 2020, 02:58 AM
sorry if Im revisiting old ground - you say the engine has been out for about 2 years
- when did it last run because if it has been sitting for 2 years not running and being used the clutch plates can seize together and therefore you wont be able to move the wheel when in gear (I recently had this with a bike that was sitting a year) I removed the clutch and soaked in oil for 24 hours refitted and all was good

the above could also be the reason your clutch lever isn't returning all the way

Del
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Monday, 04 May 2020, 03:24 AM
Del, I've been thinking that way too.
The more I've gone over everything I've done and been suggested it would be the next logical step🥺 Bugger!!
Title: Re: Clutch master cylinder nightmare
Post by: grog on Monday, 04 May 2020, 05:45 PM
Unfortunately i agree,plates stuck together.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Monday, 04 May 2020, 08:04 PM
Well I know what I'll be doing this weekend. It was only meant to be a winter project and the old girl was running like a dream when I took it off the road :rolleyes:
Title: Re: Clutch master cylinder nightmare
Post by: gsxbarmy on Tuesday, 05 May 2020, 02:40 AM
Just make sure when you take the clutch plates out that you don't mix the order up or get them back to front as you free them off.
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Tuesday, 05 May 2020, 02:47 AM
Many thanks Barmy, am I right in thinking you don't have to drop the oil to remove clutch?
Title: Re: Clutch master cylinder nightmare
Post by: Del on Tuesday, 05 May 2020, 03:21 AM
I recently did mine on my bandit and my ZRX1100 and this worked for me - I had an old clean sweetie tub that I filled with slightly heated clean oil  (didn't tell wife what pot I used) I placed each plate into the oil in teh order I took them off - as in last in the oil was 1st back on

I reckon you do have to drop the oil to do this or you may be able to put the bike on a plank of wood so that it leans over more that way you will only loose a little oil

good luck

Del
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Tuesday, 05 May 2020, 03:57 AM
LOL, the Boss would kill me if I did it in her new kitchen.
Luckily we've ovens at work so it'll save on bruises😂. Cheers Del👍
Title: Re: Clutch master cylinder nightmare
Post by: Gsxjohn on Saturday, 09 May 2020, 05:04 AM
Stripped the clutch today, verniered everything, all in spec. Nothing seemed stuck as such, just sticktion due to oil on plates...must have been enough to stop clutch disengaging.
Reassembled plates, everything kept in order as advised  by Barmy👍...clutch out all plates were loose...no pressure on them🥺 cuppa then stripped again and reassembled again 🤯 clutch works. No idea what the issue was.
Big thanks for all advice👍👍
Title: Re: Clutch master cylinder nightmare
Post by: gsxbarmy on Saturday, 09 May 2020, 07:56 AM
Result - sometimes just the oil itself can "stick" by a vacuum forming, which is easily broken when you take the plates out. Good news that its all working again though  :onya: :clapping:
Title: Re: Clutch master cylinder nightmare
Post by: grog on Saturday, 09 May 2020, 05:59 PM
Good news. Just was bad timing, new hose and stuck plates. My old GS1000 used to get stuck after 3 or 4 weeks sitting. Persevered Mate, well done.
Title: Re: Clutch master cylinder nightmare
Post by: seth on Saturday, 09 May 2020, 06:33 PM
Great news well done in persevering with it all .
So glad you finally got sorted.
:cheers:
Title: Re: Clutch master cylinder nightmare
Post by: Del on Saturday, 09 May 2020, 08:02 PM
good to hear fella