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1Back to top Go down   K1100LT 4 pot brembo rebuild Empty K1100LT 4 pot brembo rebuild Tue 6 Jul 2021 - 4:13

attitude

attitude
active member
active member
bought the bike with seized brakes so I am going through the brakes top to bottom.
4 brake pistons are very difficult to move.  one piston ends up moving then you have no air pressure to move the remaining.  gets even more fun when you get 2 out and run out of fingers to plug the holes as you blow in air.
Ended up scratching the pistons to get them out with pliers.  Now I know why they sell the repair kits with 4 new pistons.
Its almost impossible to get all 4 brake pistons out of this 4 pot caliper with out damaging the pistons.

I prefer the old 2 piston brembos like the rear brake on this LT.  The dust seal on the 4 pot is very tight, gets dirty and gets tighter.
regards,
Jerome in Portland Oregon

A week later and I have overcome the challenge.  I did not want to split the calipers and splitting would not have solved the problem of getting a stuck piston out.  OSHA has limited the pressure in air blow guns to 30 psi so i used a tire chuck and an old air valve to get a good shot of pressure into the caliper and move one more piston out.  Another piston would not budge so I resorted to the nuclear option:  broke out the plastic center of piston and epoxied in a short bolt, after epoxy set up I had something to grab, twist and pull to remove the last piston.  Epoxied bolt can only protrude about 1/4 inch or you wont get the piston out after it is free.
Motorworks web page recommends not splitting these calipers and you dont have to split them to rebuild, it just makes cleaning bores a little harder.  I sawed off a toothbrush head to get in the piston bores to clean.
Hope this helps someone get the job done quicker.
Now to replace caliper bolts that previous owner could not use the correct size allen wrench on Sad

Jerome in Portlanld



Last edited by attitude on Mon 19 Jul 2021 - 0:05; edited 1 time in total (Reason for editing : solved the problem)

    

2Back to top Go down   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Tue 6 Jul 2021 - 8:40

Laitch

Laitch
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@attitude wrote:. . . one piston ends up moving then you have no air pressure to move the remaining.  gets even more fun when you get 2 out and run out of fingers to plug the holes as you blow in air.
The thing is that you could remove them two-at-a-time. 
Technique always looks easier on video though; take Miracle Knives for example. Laughing



Last edited by Laitch on Wed 21 Jul 2021 - 13:47; edited 1 time in total (Reason for editing : Enhanced relevance)


__________________________________________________
1995 K75 81,000 miles
K1100LT 4 pot brembo rebuild Usa-lo10
    

3Back to top Go down   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Wed 7 Jul 2021 - 8:48

Dai

Dai
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Hydraulic method is better. IIRC the braking pressure is 300psi; you won't get that with air pressure. Also, as shown, it's controllable - I have serious doubts about compressed air and flying pistons. I've used a similar method (i.e. the master cylinder and calipers were still on the bike!) and used a spanner of suitable thickness to stop the pistons from coming all the way out rather than an old brake pad.

That's a really old CB750 m/c he's got on the bench...


__________________________________________________
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
    

Kr4mo

Kr4mo
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I have used a grease gun and fitting for this before. wrote:
@attitude wrote:. . . one piston ends up moving then you have no air pressure to move the remaining.  gets even more fun when you get 2 out and run out of fingers to plug the holes as you blow in air.
The thing is that you could remove them two-at-a-time. This man didn't need fancy equipment. He was resourceful, and a similar technique could be used with air pressure.


Technique always looks easier on video though; take Miracle Knives for example. Laughing

    

5Back to top Go down   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Wed 21 Jul 2021 - 17:56

92KK 84WW Olaf

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I had just been thinking Dai knows his onions.....  bounce


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

6Back to top Go down   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Wed 21 Jul 2021 - 21:06

Dai

Dai
Life time member
Life time member
Thanks Olaf Razz


__________________________________________________
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   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Mon 26 Jul 2021 - 19:08

warmshed

warmshed
active member
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@Kr4mo wrote:
I have used a grease gun and fitting for this before. wrote:
@attitude wrote:. . . one piston ends up moving then you have no air pressure to move the remaining.  gets even more fun when you get 2 out and run out of fingers to plug the holes as you blow in air.
The thing is that you could remove them two-at-a-time. This man didn't need fancy equipment. He was resourceful, and a similar technique could be used with air pressure.


Technique always looks easier on video though; take Miracle Knives for example. Laughing

That's fine for one sided pistons on the calliper but does not work as well on a 4 pot. 
You can use a spanner across the pistons but they will only come out an extra amount as the spanner is thinner than the disc plus the thickness of the pads.

    

8Back to top Go down   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Mon 26 Jul 2021 - 23:39

Laitch

Laitch
Life time member
Life time member
@warmshed wrote:That's fine for one sided pistons on the calliper but does not work as well on a 4 pot. 
The Miracle Blade is not for everyone, either.  Smile


__________________________________________________
1995 K75 81,000 miles
K1100LT 4 pot brembo rebuild Usa-lo10
    

9Back to top Go down   K1100LT 4 pot brembo rebuild Empty Re: K1100LT 4 pot brembo rebuild Thu 29 Jul 2021 - 18:46

Dai

Dai
Life time member
Life time member

@warmshed wrote:That's fine for one sided pistons on the calliper but does not work as well on a 4 pot.

From experience I'd disagree. BMW recommend removing the pistons without splitting the caliper and to push the point, will not sell you the small o-ring that seals the two halves (stupid idea - available in bags of 50+ from ebay. I digress). My Bandit also had four-pot calipers and in both cases, a bit of jiggery-pokery with the thickness of the spanner/steel bar allowed me to get all four pistons to the point where I could wiggle them out with my fingers. The Nissin calipers on the Bandit were very reluctant to give up a couple of their pistons. Even if you have just one piston of the four that wants to come out,

- stop it from moving with a bit of steel braced against the other side
- get the other two moving
- put a bit of steel between them when they finally decide to meet in the middle so that the bit of steel also covers the other two pistons
- remove your original bit of scrap and start pumping
- the easy-move one will hit the steel bar pretty quickly and you may need to apply some hand pressure to prevent the bar from rotating out from the other two pistons
- eventually the last one will move

I have never had a caliper seal burst yet but I guess it's not beyond the realms of possibility that it could happen if a piston is corroded enough. I've also never been beaten by a corroded piston yet but having said that, I'm not looking forward to doing the next one because... you know... Murphy's leprechauns and all that.


__________________________________________________
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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