BMW K bikes (Bricks)

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ianburgess

ianburgess
active member
active member
I have had trouble with the rear brake master cylinder. A replacement has been installed, but there is no return spring on the pedal, which means the pedal appears to just bounce against the master cylinder piston extender thingy which is only plastic and looks a bit feeble.
There is a clip under the pedal fastening bolt where a spring could be attached, but no obvious mounting point for the other end of it.
I have looked at the Clymer manual, riders handbook and parts booklet, but nothing appears to be conclusive.
There is mention of a 2mm gap between the pedal and the master cylinder plunger, but without a spring, there is no gap.
Should there be a spring there or was it phased out when the drum brakes were replaced with disks? I could just put a bungee cord on it, but I'm hedging on between a matching colour or a contrast colour like a racing stripe.
Anyone know of any of the manuals that has clear indication of this area?
Cheers
Ian


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K100RT 05/87 vin 0094099K100RT Dark Blue (ex cop bike)
    

rosskko

rosskko
VIP
VIP
Is this what you are looking for?
Attaches to the stand

Real OEM

Should the rear brake pedal have a spring?  Brake_10


__________________________________________________
1986 K100RT VIN 0093801K100RT with summer fairing for a northern visitor

Basic/2 6308802K100CJ  05/1988

K1100RS 0194321
    

ianburgess

ianburgess
active member
active member
Yep, that's perfect.

Thanks for your help.

Cheers

Ian


__________________________________________________
K100RT 05/87 vin 0094099K100RT Dark Blue (ex cop bike)
    

88

88
Life time member
Life time member
have a look at post #25 and #28 in my renovation thread for close up pics and size of spring.

88KE


__________________________________________________
Should the rear brake pedal have a spring?  Ir-log11 88....May contain nuts!Should the rear brake pedal have a spring?  Ir-log11

"The world is a book and those who do not travel read only one page." - St. Augustine from 1600 years ago & still true!

Bike: K100LT 1988. 0172363. AKA the Bullion Brick! Mods: k1100 screen and stands.
K1: 1990. 6374189. Custom Stealth Black paint.
    

ianburgess

ianburgess
active member
active member
Thanks 88KE
Far better pictures than the manuals, and a really great write up. Nice job on the bike.
Much appreciated.
I hope I get cabin fever soon so I get enough time to read through this forum. The wealth of knowledge is incredible.
Cheers


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K100RT 05/87 vin 0094099K100RT Dark Blue (ex cop bike)
    

Two Wheels Better

Two Wheels Better
Moderator
Moderator
I'm dredging up this aging but useful post because I am needing some detailed information on the brake pedal spring....but not the small one mentioned here which attaches to the centre stand mount between the hold-up springs.

Note that the K11 uses a spring around the actual brake pedal pivot.
Should the rear brake pedal have a spring?  K11bra10

Note that the K100 and K75 do not.
Should the rear brake pedal have a spring?  K100br10

I bought a secondhand K11 brake pedal (same part number and physical dimension as a K75/100 in silver) and am using K100 standard peg mounts, post '85. There seems to be no provision for reducing the earlier brake pedal's full motion as the master cylinder plunges to and fro. The tiny, forward spring does not have enough tension for this bit of the job.

My question is for those who have recently changed a brake pedal. I read recently of brake pedal corrosion from the UK/Irish contingent. Who has a K100 or K75 they've recently had apart who can see if there's a spring round the centre pivot on their earlier brake pedal?

I have a spring but there does not seem to be an obvious attachment point for the inner hook - the outer hook goes against the brake pedal with no issue. don't have access to the variety of footpeg brackets at the mo'.

Cheers.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Just checked my 94 K75RT.  Pedal is returned by the spring shown in the Real OEM drawing.  Goes from pedal to center stand.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

Two Wheels Better

Two Wheels Better
Moderator
Moderator
My bike has the forward spring which threads round the master cylinder plunger screw and attaches to the centre stand bracket, no worries, it's the centre brake pedal pivot spring (and how it attaches) that I'm unsure about.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

rosskko

rosskko
VIP
VIP
Think this is what you are asking TWB

Should the rear brake pedal have a spring?  Dsc_3910

Should the rear brake pedal have a spring?  Dsc_3911

Use a longer bolt and the front mount for the master cylinder I guess on the 100 hanger


__________________________________________________
1986 K100RT VIN 0093801K100RT with summer fairing for a northern visitor

Basic/2 6308802K100CJ  05/1988

K1100RS 0194321
    

Two Wheels Better

Two Wheels Better
Moderator
Moderator
Yes! That is it, absolutely, Rosskko! Thanks for the image. I can do that. It will solve me problem.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

Two Wheels Better

Two Wheels Better
Moderator
Moderator
@rosskko wrote:Think this is what you are asking TWB

Should the rear brake pedal have a spring?  Dsc_3910

Should the rear brake pedal have a spring?  Dsc_3911

Use a longer bolt and the front mount for the master cylinder I guess on the 100 hanger

Looking at this further....I had a squiz at the two bike's ETK catalogue images and sure enough the K100 uses two 6x16mm screws to mount the rear master cylinder and the K1100 uses a 6x16 and a 6x30 with wide washer and collar, as in your piccie. Voila! I like a definitive fix.

This comes of using components, however similar, from two subtly different machines. I am not overly curious how the K100 manages to do without the return spring heft of the K11 variety...that small spring at the front, which I'm using in conjunction, surely only passes for sufficient pressure to pull the MC plunger back to its forward position.

Should the rear brake pedal have a spring?  410


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

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