BMW K bikes (Bricks)

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1Back to top Go down    Rear master cylinder alternative on Wed May 20, 2015 10:04 pm

brianpen

brianpen
active member
active member
Rather than rebuilding my rear master cylinder on my 87 K100LT, I figure a newer replacement might be a better bet. When scanning ebay it appears many units from newer BMW's appear nearly identical. The R1150RT in particular. The pricing is much more reasonable. Has anyone swapped one of these or similar units? As it is a rear brake, I suppose optimum braking isn't crucial, after all I have been living with a wimpy K100 version for some time now.

    

2Back to top Go down    Re: Rear master cylinder alternative on Thu May 21, 2015 1:30 am

Two Wheels Better

Two Wheels Better
Moderator
Moderator
The manner in which the piston is pulled and pressed by the brake pedal is different from other Beemers, even some other model Ks. I think you'll find that if you want original equipment operation you'll need an OEM-type master cylinder.


__________________________________________________

1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

3Back to top Go down    Re: Rear master cylinder alternative on Fri May 22, 2015 7:16 am

Dai

Dai
Life time member
Life time member
TWB - I think BrianPen is right. The R1150RT rear master cylinder does appear to be the same one as fitted to the K100; my caveat is that the hole spacings may be different. This listing distinctly shows that it's a push M/C in similar fashion to the K100:

http://www.ebay.co.uk/itm/04-2004-BMW-R1150-R-1150-RT-ABS-R1150RT-REAR-MASTER-CYLINDER-BRAKE-8585-/351295869872?hash=item51cadd93b0

Interestingly, there's no rubber buffer between the actuating rod and the M/C piston.

This one shows the same bellows fitting as we have:

http://www.ebay.co.uk/itm/BMW-R1150RT-2004-Twin-spark-51-547-miles-rear-brake-master-cylinder-/161682225730?pt=LH_DefaultDomain_3&hash=item25a502fa42


BrianPen: like you, I hated the feel of the rear master cylinder. I threw away that stoopid rubber buffer and replaced it with a home-made solid stainless steel one. IMHO instant improvement in feedback and braking.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

4Back to top Go down    Re: Rear master cylinder alternative on Fri May 22, 2015 8:34 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I could be missing something here, but aren't the mounting bosses on the R1150 M/C on the bottom of the unit whereas on the K bike master cylinders they are on the top. How can they be interchangeable?


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

5Back to top Go down    Re: Rear master cylinder alternative on Fri May 22, 2015 9:13 am

Two Wheels Better

Two Wheels Better
Moderator
Moderator
I have an R1150RT in my garage too. The rear MC from that wouldn't work on a K100/K1100 unless you replaced the footpeg mounts and brake pedal with something custom.


__________________________________________________

1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

6Back to top Go down    Re: Rear master cylinder alternative on Fri May 22, 2015 12:49 pm

Dai

Dai
Life time member
Life time member
Ah - that bit of information isn't exactly visible in pictures!


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

7Back to top Go down    Re: Rear master cylinder alternative on Fri May 22, 2015 2:06 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
A coupla months ago I looked at as many options I could for my project bike. In the end I ordered a new 13mm rear M/C. There wasn't gunna be an easy answer unless I went the (wicked kewl) BSK Speedworks rearset way, or other. I opted for standard peg plates and stock position....for now.


__________________________________________________

1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

8Back to top Go down    Re: Rear master cylinder alternative on Wed Jan 30, 2019 7:40 am

jdaley

jdaley
active member
active member
I threw away that stoopid rubber buffer and replaced it with a home-made solid stainless steel one. IMHO instant improvement in feedback and braking.


Can you give me more details I am new to K100's please


__________________________________________________
John Daley
Bendigo, Asutralia
    

9Back to top Go down    Re: Rear master cylinder alternative on Wed Jan 30, 2019 8:18 am

MartinW

MartinW
Life time member
Life time member
I've been running a Chinese rear master cylinder purchased of Ali express for $13.33 AU. Easy conversion some models may require a new hose.http://www.motobrick.com/index.php/topic,9364.msg90596.html#msg90596
Regards Martin.


__________________________________________________
K75s Hybrid
    

10Back to top Go down    Re: Rear master cylinder alternative on Wed Jan 30, 2019 11:04 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I, too, am running those Chinese master cylinders on two of my bikes and have a combined 20,000+ trouble-free miles on them. Probably the best $12 I have ever spent on my bikes.

IMNSHO, when it comes to rear master cylinders, f*ck BMW.


__________________________________________________
Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

11Back to top Go down    Re: Rear master cylinder alternative on Wed Jan 30, 2019 7:47 pm

jdaley

jdaley
active member
active member
I am having trouble finding the Chinese part, can you help me please?


__________________________________________________
John Daley
Bendigo, Asutralia
    

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