1150 slipping clutch (unusual presentation?)

[babble]

25k on the bike, all going well, till friday afternoon blast out. The bike had been pulling absolutely fine, holding 110 - 115mph without issue. Then when trying to pull away from a junction - massive clutch slip, 1st and 2nd gear and low revs. After a few minutes break at the roadside, all seemed much better, and i was able to ride home with no slip below about 5500rpm.

So, i reads all the post on here regarding clutch slip - and reconned it must be a blown seal.

Pulled the starter off, everything dry as a bone, no oil, no unexpected detritus, and a friction plate 5.7mm wide. hmmmm.

pulled the slave cylinder apart. It was a bit cruddy, (and the line sheathing was full of water just like it says in all the posts), but nothing suspect in there.

I've just put the bike back together again hoping it was still usable, but alas the slip is now dreadful, difficult to navigate around the block!

Am i missing something? Surely for the bike to be so unridable there would have to be some visable sign of oil contamination?

The current aim is to pull the gearbox off one night this week. Somebody please tell me i don't need to!??

Also, slipping out of sixth gear is an issue. Is there a fix i can do whist i have the gearbox on the bench?

thanks,

David.

 

[Steptoe]

Make sure the clutch fluid reserviour isn't OVERfull -

 

[babble]

Thanks Steptoe,

Unfortunatly I think i've now gone through all the simple stuff..... lever catching, reservoir full, sticking slave cylinder (can the push rod stick?)

I'm really starting to struggle to imagine exactly what the cause is - especially with regard to it's variability.

Could it be master cylinder related? (although the lever feels fine).

Thanks, again,

David.

 

[(RIP) Bin Ridin]

Push rod sticking sounds possible.....

 

[babble]

I had a bit of a poke around at the push rod whilst the slave cylinder was off. It rotates easily, but there was no free lateral movement ( i though there would be some). It looks to be gearbox off to get at the rod anyway.

Good job i installed hifi in the garage last week - seems like i'll be spending some time in there.


David.

 

[(RIP) Kaister]

if its possible - ride it a sort distance WITH NO SLAVE CYLINDER .

tricky - but possible - it'll take that system out of play

 

[babble]

Thanks motomartin,

Did exactly that - (like you say, trick, but possible).

No change, so gearbox off tonight.

I think it's either gonna be a problem with the push rod sticking somehow, or a very thin film of oil on the plates. Time will tell.

David.

 

[Steptoe]

Thanks motomartin,

Did exactly that - (like you say, trick, but possible).

No change, so gearbox off tonight.

I think it's either gonna be a problem with the push rod sticking somehow, or a very thin film of oil on the plates. Time will tell.

David.

If you rode it without the slave cylinder in place, and it still slipped, it won't be a sticking pushrod ( which i don't think is possible anyway ).

 

[Flying banana]

FWIW, I had problems with mine last year. I removed the starter motor, and could see no evidence of oil contamination whatsoever.
The problems persisted, and was sorted by a dealer, and it WAS contamination from the gearbox input seal. Clearly, although i was unable to see the contamination, it was there.

HTH

 

[babble]

Hello all,

Just popped the gearbox off to some disapointment

No sign of any leaked oil whatsoever from the gearbox input, and generally no sign of oil. Dirty and dusty, but not oily (i've still to pull the backplate off to fully see the engine output seal).

Friction Plate measures near 6mm (tapers from inside to outside edge)

The friction plate looks tatty, and does feel kinda greasy (normal??)

Can a very slightly greasy clutch result in total clutch failure?

The steel plates do look a bit odd though. They have a rippled burnished effect on them (is that normal too?)

Not really sure how to proceed now.

Do i break the bank and plum for a full new clutch, or clean up the steel plates and just by a friction plate (seeing as the clutch is certainly not worn out)?????

So many questions..... so little funds in the bank.

On the positive side, the bike was a breeze to work on.

Any help gratefully received!

David.

 

[Steptoe]

Fit a whole new clutch unit, not just a friction plate, no matter how good you think the cover and pressure plate and diaphram look like. The surfaces have been damaged by the slipping clutch heating them up .

Fitting only a friction plate will be ok for the first thousand miles or so, then the slip returns

 

[babble]

Thanks Steptoe, that's what i'll do.

Do you recon i should fit new seals too?

David.

 

[Steptoe]

Do you recon i should fit new seals too?

David.

Not if they're not leaking . Leave alone .

 

[Greg Masters]

.... holding 110 - 115mph without issue.

If the clutch had started to slip as a result of wear, the plate probably got pretty hot during this thrash resulting in ...

Then when trying to pull away from a junction - massive clutch slip, 1st and 2nd gear and low revs.

However, once it's all cooled off a bit....

After a few minutes break at the roadside, all seemed much better, and i was able to ride home with no slip below about 5500rpm.

I'd say this is classic case of a worn out friction plate.

As Steptoe suggests, change the complete clutch but leave the seals well alone unless they are showing clear signs of leakage.



Greg

 

[babble]

hello,

"I'd say this is classic case of a worn out friction plate."

.... except for the friction plate not being worn out? 25k and a measurement of 6mm (4.8 is min thickness according to the spec)

I'm starting to think it may be a manufacturing/material fault. Maybe i cooked the clutch a bit and this caused a bonding agent to chemically break down, which then has acted as a lubricant???..... it's a bit of a conveluted theory..... but what else?

Cheers,

Dave.

 

[Steptoe]

I had to replace my loan bike clutch at 17K miles. Wasn't anywhere near the lower friction plate limit .

But the cover and pressure plate had gone slightly blue, and the cross hatching type marks had disappeared, which means the surfaces had lost their grip. Due to the heavy handedness of the riders .

There are 4 surfaces in a clutch , 1 each side of the friction plate,the cover plate and the pressure plate and all have to be OK, not just the friction plate.

 

[pomm001]

I had to replace my loan bike clutch at 17K miles. Wasn't anywhere near the lower friction plate limit .

But the cover and pressure plate had gone slightly blue, and the cross hatching type marks had disappeared, which means the surfaces had lost their grip. Due to the heavy handedness of the riders .

There are 4 surfaces in a clutch , 1 each side of the friction plate,the cover plate and the pressure plate and all have to be OK, not just the friction plate.

As a matter of interest Steptoe, as you have replaced so many, do you fit genuine or pattern ?
I only ask this because you obviously cannot afford to take chances that it will slip again in a thousand miles, and have to do it again for nowt

 

[Steptoe]

As a matter of interest Steptoe, as you have replaced so many, do you fit genuine or pattern ?
I only ask this because you obviously cannot afford to take chances that it will slip again in a thousand miles, and have to do it again for nowt

I fit sachs , same as the original, but not in a BMW box.