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1Back to top Go down   1985 k100 RS rear brake Empty 1985 k100 RS rear brake on Fri May 22, 2015 10:46 pm

cracked canoe

cracked canoe
active member
active member
oh dear - another hic-up this spring

thanks for the advice over the past few postings.
just the other day i successfully replaced the battery on my 1985 K100 RS. Thanks for all the advice and encouragement.
unfortunately i need a bit more of it from you BMW motorcycle junkies.  Please.

This morning on my way to work epic failure of the rear braking system.
made it home without incident which is when i had a quick look at the unit.
the brake fluid in the reserve unit was empty and a leak is coming from a rubber portion attached directly to the metal foot brake pedal.
Also it looks as though to get to these components, i will need to remove the brace that holds the foot peg and a portion of the saddle bag. but i could be wrong.  damn i wish i was more mechanically inclined.

any suggestion on what is the best way to approach this repair?
what sort of parts would i need and is there a quote "step by step" guide available within this forum?
as i may have mentioned before, what i lack in hands on skill i probably make up in ambition. 

thanks in advance
cracked canoe

    

2Back to top Go down   1985 k100 RS rear brake Empty Re: 1985 k100 RS rear brake on Fri May 22, 2015 11:34 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
It appears the rear brake master cylinder is leaking at the front, as they do. If no replacement piston/seal kit is available then a new master cylinder is in the cards. The footpeg mount comes off to access the unit, as well as the saddle bag's Z frame (two screws at the point it attaches to the 'peg bracket).
There is no easy way to 'splain how to bleed brakes, but there'll be plenty of info in the search area of the forum, and others will offer up assistance in your time of need.
It ain't so hard if you study the problem a bit as you dive in.


__________________________________________________

“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.

    

3Back to top Go down   1985 k100 RS rear brake Empty Re: 1985 k100 RS rear brake on Fri May 22, 2015 11:40 pm

RicK G

RicK G
admin
admin
Fear not a junkie has arrived. Very Happy 
Sounds like the seal on the piston has failed. You need to remove the master cylinder which involves taking the foot peg plate off and the master cylinder is attached to the back of it. There are 2 allen head bolts holding the M/C on and a further allen head grub screw which is screwed into the pedal and goes into the front of the M/C (it looks like a stud with a small socket head in the pedal end, it could well be full of dirt and not easily seen).
Careful not to let the fluid splash on the paint.
A kit to fix them is available but make sure the cylinder is OK before ordering a kit. If the cylinder bore is worn you need a new M/C however I have had them fixed by using a stainless steel sleeve.  The sleeve is usually a bit cheaper and if you decide to go down that path ask about getting a 1/2in sleeve as the seals are readily available from any brake repairer where the BMW 12mm or 13mm is a one off BMW item. If it needs repair in the future it is a very cheap job.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

4Back to top Go down   1985 k100 RS rear brake Empty rear brake repair on Wed May 27, 2015 9:18 pm

cracked canoe

cracked canoe
active member
active member
so
back at the rear master cylinder
here is a picture of the M/C
hard to see but there is a hose to the reservoir,
a hose going back to the caliper
i have disconnected the spring and
a wire is located for the rear brake lighting system.
any tricks to removing the reservoir?
while i am at this work might as well go whole hog.
any suggestions?
in the future if i am doing repairs and photos tell a thousand words, what is the best way to display these photos?
any help is appreciated.
lastly, not the watch hand but the other is holding onto the foot brake pedal.  i have already removed the spring, any other suggestions to go forward
FYI posted a pic of my ride in the registry section
thanks
cracked canoe.



1985 k100 RS rear brake GetAttachment.aspx?tnail=3&messageId=c1f08f82-04ca-11e5-a133-00237de33340&Aux=114%7c0%7c8D266EEAFC40510%7c%7c0%7c0%7c0%7c0%7c%7c%7c10%7cbernard_mary%40sympatico

    

5Back to top Go down   1985 k100 RS rear brake Empty Re: 1985 k100 RS rear brake on Wed May 27, 2015 10:27 pm

Holister

Holister
Life time member
Life time member


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  1985 k100 RS rear brake Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

6Back to top Go down   1985 k100 RS rear brake Empty Re: 1985 k100 RS rear brake on Thu May 28, 2015 7:23 am

Dai

Dai
Life time member
Life time member
The reservoir mount is a complete nuisance. You'll have to remove the ECU, battery and the battery tray to get at the single screw that holds it down. The first time I had to take my rear master cylinder off I replaced the mounting bracket with a piece of right-angled stainless that uses the top footrest hanger bolt to secure it. Now the whole lot comes off in one lump.

BIG WARNING: AVOID taking the hose off the reservoir if you can. The reservoir plastic gets very brittle with age and there's a high chance that the spigot will shatter. If the hose does have to come off for replacement, cut it lengthways with a sharp craft knife and peel it back. Fit the new one with a smear of silicon grease to get it over the spigot.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

7Back to top Go down   1985 k100 RS rear brake Empty Re: 1985 k100 RS rear brake on Thu May 28, 2015 9:31 am

Dai

Dai
Life time member
Life time member
Thought I'd get this in before anyone asked - it's just to show what I meant by using the top footrest hanger bolt to mount the reservoir. It also shows that I found out about the original reservoir's propensity to shattering; Motorworks confirmed that it's a common problem. The replacement is one I had made for a Guzzi years ago and then never used.

1985 k100 RS rear brake Rmc


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

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