Z1000 A2 Rear Brake Master Cylinder

[Taffus]

Explained here

[RALPHARAMA]

Update!!

Removed the plastic base with a small allen key - Could easily see the two screws that release the base but as they are made of something resembling the consistency of Philidelphia Cheese I could not unscrew them.

You need to use JIS screwdrivers not philips. Philips are designed to "cam out" ie chew the heads if too much force is used. The Japanese use JIS standard screw heads which are very different to a philips head.

You can of course bodeg the job and hit a philips screw driver into the JIS screw and gorilla it out...........

JIS is technically different to philips, but the difference is minimal and a good quality philips bit is far more use than a worn or poor quality JIS bit. Despite the cock talked by many, the real reason so many screws got/get mashed on bike engines is because folk usually don't own the correct size screw driver for the fasteners (on engines they are almost always #3) or they use crap quality tools from the Far East of worn tools. DIYers have rarely been taught to use a screwdriver properly, as a professional has been, so their technique usually leaves a lot to be desired.

I build engines all the time and I don't own a JIS screwdriver. To illustrate my point here's a pic of me torquing up the JIS screws on a Z1A motor.



You'll note that despite them being correctly tightened to Mt Kawasaki's designated torque settings, the freshly re-plated screws have lost none of their plate. I wouldn't describe my work as bodging.

[chrisu]

Ok I'll bite

How can you criticise JIS screwdrivers Ralph if you've never tried one?

[RALPHARAMA]

Ok I'll bite

How can you criticise JIS screwdrivers Ralph if you've never tried one?

I'm NOT criticising them!!!!

I'm just saying that the criticism of using the extremely similar Philips profile bits is over egged!

[tlc]

I recently got my snap on Philips No3 screwdriver shaft replaced by Snap On

The difference is amazing.

[Kev1R]

It could certainly be part of the issue I had with the screws


Possibly a new set of good quality screwdrivers for the main sizes, is what I need as some in my collection are getting on abit.

I am grateful for all the input on this, and as a bonus - That's my next birthday present sorted!

[chrisu]

JIS and Phillips are different. I can't count the time a Phillips has tried to 'cam out' where a JIS screwdriver just undoes it. Yes a new phillips will do most screws but JIS won't cam out and you don't need to hit it with a hammer or undo it with a torque wrench either.

Have a read of this

http://revlimiter.net/blog/2014/09/the-japanese-phillips-jis-screwdrivers/

[RALPHARAMA]

undo it with a torque wrench either. [/url]

I was doing up the fasteners with a torque wrench to ensure they were at the CORRECT tightness!

I tend to use a hammer with a bit to a) shock a corroded fastener and b) to reshape a butchered screw head ie one that has been previously attacked with the wrong size/type of screwdriver.

[Taffus]

undo it with a torque wrench either. [/url]

I was doing up the fasteners with a torque wrench to ensure they were at the CORRECT tightness!

I tend to use a hammer with a bit to a) shock a corroded fastener and b) to reshape a butchered screw head ie one that has been previously attacked with the wrong size/type of screwdriver.

Is that where you had been before with your philips screwdriver and not a JIS one????

[johny brando]

Kev there are two tiny holes in the master cylinder, make sure these are clear, think one is called a relief hole. A very fine piece of wire should open up the hole, which is probably full of shite......had the same problem on my A2.

Scotts correct ! Theres 2 tiny holes . 1 down stream of the the Piston seal this one acts when the levers is released after being pressurized .... this to allow released pressure to escape back into the reservoir the other tiny hole is upstream of the Piston seal & this one keeps the Piston chamber primed & it is this one that is likely blocked & trying to clear this using back pressuring via Caliper Bleed nipples etc will not clear the blockage, as back pressure cannot (by design) access this area , you will have to remove the piston & seal & then clear the tiny drilling using compressed air is best ...wire of any description can & likely will do damage. While your in there at the same time it's probably wise to put a rebuild kit through it & when bleeding the system take off & invert the Reservoir to start the procedure & this will ensure the reservoir is fully primed. Good luck & Cheers, Johny Brando.

[Kev1R]

Johny

Many Thanks for info - the inner workings of the rear brake have always (until recently) been a complete mystery to me.

You may have missed the entry towards bottom of page 1
Tis all done fixed and working ok.

Also as mentioned for the rebuild kit I purchased - surprisingly the piston was oversize and could not be fitted - Would be interested if tthere are any theories on this - were there 2 different types of Master Cylinder?

[Pigford]

Johny

Many Thanks for info - the inner workings of the rear brake have always (until recently) been a complete mystery to me.

You may have missed the entry towards bottom of page 1
Tis all done fixed and working ok.

Also as mentioned for the rebuild kit I purchased - surprisingly the piston was oversize and could not be fitted - Would be interested if tthere are any theories on this - were there 2 different types of Master Cylinder?

Maybe o/s to compensate if it has been "re-bored" to provide a smooth useable surface when they wear

[johny brando]

Johny

Many Thanks for info - the inner workings of the rear brake have always (until recently) been a complete mystery to me.

You may have missed the entry towards bottom of page 1
Tis all done fixed and working ok.

Also as mentioned for the rebuild kit I purchased - surprisingly the piston was oversize and could not be fitted - Would be interested if tthere are any theories on this - were there 2 different types of Master Cylinder?

Kev , I never knew there was an oversize Piston kit available ! but yes I think Piggy's correct ! You should have been offered the option of the oversize ...not to have it forced on you with warning !
As Oxygen suspended in water within "OLD" Brake Fluid cause's oxidization & erosion on the seal face of the inside of the Cylinder wall ,this in turn normally causes a Spongey brake or No brake at all ! So this would to be allow for either a fine cylinder re-bore & hone to directly accomodate the oversize piston .....or better still to allow for a (better option)= S/ Steel sleeve to be made & pressed in after boring the Cylinder to the sleeve's O/D size. Cheers Johny B.

[Fred the Zed]

Kev there are two tiny holes in the master cylinder, make sure these are clear, think one is called a relief hole. A very fine piece of wire should open up the hole, which is probably full of shite......had the same problem on my A2.

Scotts correct ! Theres 2 tiny holes . 1 down stream of the the Piston seal this one acts when the levers is released after being pressurized .... this to allow released pressure to escape back into the reservoir the other tiny hole is upstream of the Piston seal & this one keeps the Piston chamber primed & it is this one that is likely blocked & trying to clear this using back pressuring via Caliper Bleed nipples etc will not clear the blockage, as back pressure cannot (by design) access this area , you will have to remove the piston & seal & then clear the tiny drilling using compressed air is best ...wire of any description can & likely will do damage. While your in there at the same time it's probably wise to put a rebuild kit through it & when bleeding the system take off & invert the Reservoir to start the procedure & this will ensure the reservoir is fully primed. Good luck & Cheers, Johny Brando.

I've has the rear master cylinder apart today as bleeding it is difficult and I wanted to make sure it was clean. One question..... what the 22mm nut for on the side of the unit? It was locked solid and I didn't want to force it.

Fred

[DavidZ1R]

If I remember correctly, Phil at z power told me the pistons on the rear brake repair kit don't fit, I had to buy a genuine kawasaki one, the front repair kits are okay, , mine is the a1.