Rear master cylinder aftermarket options

[YoungEngineer]

I recently purchased a K1100LT in the UK after having bought my first K100 in Australia when living there the past few years which I loved to bits. I have to say these bikes really do tend to get into your blood! I would think pretty much every K owner out there is a semi professional mechanic by now and certainly seems to attract a certain type of rider.

I have been overhauling the entire bike and this website has been extremely helpful but I have a question which I have not really come across.

I have come to some issues with the ABS 2 module mostly with the threads which seem to have all been slightly cross threaded at some point. I recovered almost all of them with use of a 12x1.0 tap, apart from the thread in the rear master cylinder which is beyond repair.

Now, I have previously on another bike use a Universal generic master cylinder which worked very well, I would like to do this with the K to save on forking out on a replacement Brembo. My only concern is in the solid brake line which goes from the rear MC to the ABS module will not be compatible. Motobins has a  SS brake line with a banjo bolt on one end and a thread on the other which goes to the ABS module which seems like it would work perfectly with a generic MC?

Also i've noticed most universal MC seem to have either 40mm or 50mm bolt spacing which I assume is measured from centers. I measured 45 from the current Brembo MC which seems a little odd.

Any advice appreciated.





 

[halfwit]

Aftermarket rear master cylinder replacement.
Mine is a K75 non ABS. I was quoted AUS$300 and I baulked at the cost and looked around for a cheap and nasty aftermarket option.
Ebay to the rescue : http://www.ebay.com.au/itm/Rear-Brake-Master-Cylinder-Fluid-Reservoir-For-Honda-CR-CRF-125-250-CRF450-/271471414362?hash=item3f34f50c5a:g:Q-IAAOSwg0VVe4qi
A few modifications : shortening plunger bolt
                               changing mounting bolt distance from 50 to 45mm
                               small ring of Teflon on end of plunger bolt to avoid metal on metal contact
                               adaptor fitting from local brake shop
All up cost was AUS$30 and a couple of hours of fiddling.
The replacement cylinder is 14mm as opposed to the original 12mm which should mean that the brake lever travel should be about a third less but riding seems to be no different.
After a couple of months it's still intact and working well.
To the BMW purist what I have done would be regarded as heresy but its a cheap option to keep the old girl running.
Best of luck

[Laitch]

Welcome, halfwit!

Although reading what appears to be a viable solution isn't particularly comforting when attached to a name like yours, it offers hope—especially if it works well with the other components in the system. You'll find a plethora of heretical suggestions in the Technical Library and Workshop, so you have plenty of company.

[Laitch]

Thanks for the clear photos that accompany your post, too.

[nadrol]

I tried this out and cant say its a great option, but neither is $300 for a new rear master. Overall, it works, and I chose it so I didn't have a reservoir hose hanging down underneath. I did extensive searching and was unable to find a better generic or other OEM master to work in its place. Next best, imo , would be a used k1200 rear master with an adapter plate (as the mount holes are on the bottom).

 I spent $15 on the ebay master and painted it black with VHT caliper paint. I also had to spend $15 (total) on two adapter fittings because the master I bought had m10x1.25 thread instead of m10x1.0. It barely clears the swingarm.

the 90deg puts a decent kink in the reservoir hose, but still functions.

Id also recommend a boot over the actuator end as water intrusion seems likely.

Ill add a picture later.

[Laitch]

There is an epic thread on adapting cheap chinese rear master cylinders for use on Bricks. Young Engineer created this thread to demonstrate what he came up with in 2017 as a solution after he posted this thread in 2016.

Here is a link that starts up with The Mighty Gryphon's pictorial contribution about his master cylinder replacement experience in Young Engineer's 2017 thread. Read the entire thread. There's a lot of helpful information in it from several contributors.

[nadrol]

Link has some extra bits at the front, but yes I am aware of that one. It has the resivoir hose on the bottom of the master when installed.

[Laitch]

Link has some extra bits at the front, but yes I am aware of that one.

You might have been aware of that one but I posted it for the benefit of others who may be needing more information and opinions about the swap than this thread contains.