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#1012971 - 06/13/18 06:47 PM Re: Brake Caliper Weeping [Re: kalali]  
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kalali Offline
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kalali  Offline
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Joined: Aug 2015
Posts: 186
New Jersey, USA
Gentlemen, thanks for all the input. I had bled the brakes (without doing the ABS pump) using the MityVac a week or so ago before I decided to replace the lines so the fluid is pretty fresh. On the R all the connection points are exposed so I’m really hoping to get the job done and do a simple (re)bleed without the need to get into the ABS module if at all possible, even if it means having to keep the reservoir partially full. This probably means lots of towels and making a mess and having to work quickly so I’ll evaluate the situation as it goes. It might help if I start with doing the line from/to the reservoir first. If anyone thinks this is a real bad idea, please tell me. Just trying to avoid having to remove the tank, etc., etc. Luckily I just need to do the front since the previous owner already replaced the rear line with aftermarket SS line.


1999 R1100R ABS
2000 Buell X1
1983 Honda CB650sc
#1012980 - 06/13/18 10:54 PM Re: Brake Caliper Weeping [Re: kalali]  
Joined: Apr 2018
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The Fabricator Offline
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The Fabricator  Offline
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Petaluma
I am a retired motorcycle mechanic. I have clean MANY brake caliper over the years.

If you let the caliper 'weep' at the seam [or anywhere] it will take the paint off. Then corrosion will commence.

I always take the pistons out [using compressed air to shoot the piston onto a rag OR the entire system intact, pushing the piston[s] out by pumping the brake lever [add fluid to the reservoir]]. I always take the seals out to clean the grooves and then clean deposits in the piston bores, checking the fit by pushing the piston home [with out seals]. I prefer to use the old seals. HORRORS! Because...the following.

A musky brake is caused by several factors. [Rigidity of components is one]. The operative factor in focus now is DISTANCE THE PISTON TRAVELS.

This means the DISTANCE from the rotor to the piston.

Consider that if the DISTANCE is so great that the brake lever has to be pumped several times before ANY contact is made, this is using up lever travel without producing any contact. Now reduce that DISTANCE so that 1/2 the lever travel is used before contact is made. Now reduce the DISTANCE so that 1/4 lever travel is used. Continue this 'reduction' scheme. It is apparent that the closer the piston is to the rotor, the less lever travel is needed to initiate contact. Less lever travel=less mush.

The reason new seals will produce a mushy brake lever feel is this DISTANCE.

People don't realize the seals pull the pistons back AWAY the rotor when the brake lever is released. Just go to your MC, squeeze the brake lever, release, watch the pads pull back. The pads pull back because the pistons pull back.

The seals are square cross section. The seals grip the piston. When the piston moves a little [brake applied] the seals, while still gripping the piston, deform as the piston moves. When the fluid pressure decreases [lever released] the seals [still gripping the piston] return to their original shape, pulling the piston back. If the piston moves more than a little [due to brake pad wear], then the piston will slide SOMEWHAT through the seals.

New seals are supple compared to old seals. Old seals are harder and deform less, there fore, old seals will pull the pistons back less than new seals. I have cleaned MANY calipers on Japanese dual brake front ends. When the bike comes in, the lever action is very firm because the corrosion in the caliper prevents the pistons from retracting very much. Sometimes only the amount of the run out in the rotor. When I clean everything AND use new seals, the lever travel is extreme by comparison, such that I wouldn't be happy with that mushy feel on my bike. Try explaining to the customer used to firm lever feel and good performance from the brakes that a repair just that cost him $300 plus is proper. [They feel like they have air bubbles in the system! Did you bleed them?]

What about the old seals leaking? Doesn't seem to happen. 30 years experience. Never had a customer come back---about that.

Replace fluid. Yes. Fluid absorbs moisture. Why did I clean MANY calipers [and masters]? Moisture. Corrosion. Moisture causes corrosion. Incidentally, I do replace the rubber components in the master. The master is a much different than a caliper. A master piston will travel miles [kilometers]in its' lifetime; a caliper piston 1/4 inch [8 mm]. Increased wear. A clutch master AND slave piston also travel a lot.

The way I change brake [and clutch] fluid.

Don't loose the 'prime'. Prime means the system is purged of air so that the pumping mechanism is not trying to pump air. If it is pumping air, it will not work because it is not able to pump air. The pump [master cylinder] will loose prime if air is allowed to enter the system at the pump location. Air down at the caliper end is ok. Remove the calipers, then bind the brake lever to the handle bars. [Rubber band?] If air can enter the master cylinder reservoir, the the fluid will drain out of the master, loosing the 'prime'. Binding the lever in the applied position will close off the bottom ports in the master, thereby preventing drainage. Do your caliper work. Connect the caliper. Release the brake lever. Suck out fluid from the master reservoir to the bottom. Fill with fresh fluid. Attach a clear tube to the bleeder valve on the caliper, looping the hose higher than the bleeder.. TRIGGER WARNING!!! STOP READING NOW TO PREVENT SHOCK!!! [Now comes the heresy!] Open the bleeder valve. Start pumping without letting the fluid level in the reservoir fall so low it sucks air into the 2 ports in the bottom of the reservoir. Just pump away. The pump [if it has not lost its' prime] will pump out more than it sucks back when the lever is released. THAT IS A SHOCK TO THOSE WHO HAVE ALWAYS 'PUMP-OPEN BLEEDER-CLOSE BLEEDER'-RELEASE LEVER'. Those people say it will not work. That it will suck air at the bleeder. They see air in the hose at the bleeder. That air is coming from around the bleeder threads and is not getting into the caliper.

I did it that way for 30 years.

I did it that way to my R1150GS with ABS when I replaced the brake lines. The fluid will pass through the ABS pump just fine. There may be a section of un-purged old fluid in the pump. I am not concerned. I have replaced fluid on an ABS system at the pump. What a hassle. Spilling that corrosive fluid onto all those components with all those cracks and crevasses that can not be cleaned without disassembly. Yuck.


Tom, The Fabricator.
#1012998 - 06/14/18 08:49 AM Re: Brake Caliper Weeping [Re: The Fabricator]  
Joined: Nov 2002
Posts: 5,038
AndyS Offline
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AndyS  Offline
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Posts: 5,038
Somerset, Great Britain.
Originally Posted by The Fabricator

I did it that way to my R1150GS with ABS when I replaced the brake lines. The fluid will pass through the ABS pump just fine. There may be a section of un-purged old fluid in the pump. I am not concerned. I have replaced fluid on an ABS system at the pump. What a hassle. Spilling that corrosive fluid onto all those components with all those cracks and crevasses that can not be cleaned without disassembly. Yuck.


I am not understanding.
On the 1150 the brake system is divided 4 ways:
a/. Front Master cylinder to Servo
b/. Servo to Front wheel
c/. Rear Master cylinder to Servo
d/. Servo to Rear wheel.

You say "the fluid will pass through the ABS pump just fine" but it doesn't pass through. They are independent systems.

#1013000 - 06/14/18 11:17 AM Re: Brake Caliper Weeping [Re: AndyS]  
Joined: Aug 2015
Posts: 186
kalali Offline
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kalali  Offline
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Joined: Aug 2015
Posts: 186
New Jersey, USA
Originally Posted by AndyS


You say "the fluid will pass through the ABS pump just fine" but it doesn't pass through. They are independent systems.



My understanding (or assumption) is this statement is true for the ABS-II system thus frequent bleeding at the wheels will ultimately/gradually flush the pump. The Servo system is probably different.

Last edited by kalali; 06/14/18 11:18 AM.

1999 R1100R ABS
2000 Buell X1
1983 Honda CB650sc
#1013003 - 06/14/18 12:33 PM Re: Brake Caliper Weeping [Re: AndyS]  
Joined: Jun 2010
Posts: 14,435
dirtrider Offline
The Oracle
dirtrider  Offline
The Oracle
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Joined: Jun 2010
Posts: 14,435
Ohio
Originally Posted by AndyS
Originally Posted by The Fabricator

I did it that way to my R1150GS with ABS when I replaced the brake lines. The fluid will pass through the ABS pump just fine. There may be a section of un-purged old fluid in the pump. I am not concerned. I have replaced fluid on an ABS system at the pump. What a hassle. Spilling that corrosive fluid onto all those components with all those cracks and crevasses that can not be cleaned without disassembly. Yuck.


I am not understanding.
On the 1150 the brake system is divided 4 ways:
a/. Front Master cylinder to Servo
b/. Servo to Front wheel
c/. Rear Master cylinder to Servo
d/. Servo to Rear wheel.

You say "the fluid will pass through the ABS pump just fine" but it doesn't pass through. They are independent systems.



Morning Andy

The very early 1150GS (remember the 1150GS came out earlier than the 1150RT) did have the old ABS-2 system. But it didn't have a pump (servo pump) as it had an ABS modulator (chain & piston system).


D.R. ___
Sent from my rotory dial wall phone!
#1013017 - 06/14/18 04:12 PM Re: Brake Caliper Weeping [Re: kalali]  
Joined: Nov 2002
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AndyS Offline
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AndyS  Offline
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Posts: 5,038
Somerset, Great Britain.
Thanks DR.
Thanks for jogging my memory on that.
However for any casual readers here...remember that what is described in The Fabricators post will nit work on your 1150RT and later 1150GS' that have iABS.

#1013029 - 06/14/18 06:41 PM Re: Brake Caliper Weeping [Re: The Fabricator]  
Joined: Jan 2006
Posts: 69
PatML Offline
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PatML  Offline
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Posts: 69
Devon, UK
Fab detailed explanation thank you. I am about to service my front brake calipers (2001 R1150RT) and this gives me enough confidence to do it without forking out for the expensive seal and piston kits. Even starting to think I might split the calipers despite reading warnings that they will warp. Guessing that if I do the four bolts a little bit at a time each, like cylinder heads, to keep the pressure even across the whole thing, it should be OK. Any views on reusing the o-rings here?


Pat Lurcock
Devon, England
2001 R1150RT (Silver)(with oily fingerprints)
#1013039 - 06/14/18 10:07 PM Re: Brake Caliper Weeping [Re: kalali]  
Joined: Aug 2015
Posts: 186
kalali Offline
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kalali  Offline
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Joined: Aug 2015
Posts: 186
New Jersey, USA
Just finished replacing the OEM lines with Spieglers. Overall a fairly straightforward job. While the fittings all matched the front top line from the reservoir to the ABS fitting was a quite a bit shorter. I guess that's a good thing. The other lines were all about the same size/length.I used The Fabricator's tip about tying the lever to the grip and left some fluid in the reservoir - close the drain hole, and had very little mess when I removed the lines. I did have a little panic after I replaced the lines and no matter how much I pumped the lever - very slowly with plenty of fluid in the reservoir, I could not build any pressure. I then went ahead and bled the calipers through the bleeding nipples using both MityVac and slow pumping of the lever and kept adding fluid and that (finally) made the lever nice and firm. I think I used almost 2/3 of the brake fluid container and the fluid is now crystal clear. All in all, it took longer than I expected but the job was not particularly difficult evener a novice like me. Thank you all for your valuable input and encouragement. Much appreciated.


1999 R1100R ABS
2000 Buell X1
1983 Honda CB650sc
#1013049 - 06/15/18 03:49 AM Re: Brake Caliper Weeping [Re: kalali]  
Joined: Jun 2017
Posts: 52
BF204 Offline
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BF204  Offline
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Joined: Jun 2017
Posts: 52
Winnipeg, Canada
Glad it went well....mine had 2 little clips on the original rubber line that held the speedo cable and either the clutch (?) or throttle (?) cable... The Spiegler lines are thinner, so those clips don't hold onto the new line. I did a temp / ugly job looping them with black zip ties, but it would've been nice if the kit came with a couple of those cable clips. Forgot to mention that before...


'99 R1100R
#1013087 - 06/15/18 11:45 PM Re: Brake Caliper Weeping [Re: PatML]  
Joined: May 2016
Posts: 474
Lowndes Offline
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Lowndes  Offline
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Joined: May 2016
Posts: 474
Roswell, GA
Originally Posted by PatML
Fab detailed explanation thank you. I am about to service my front brake calipers (2001 R1150RT) and this gives me enough confidence to do it without forking out for the expensive seal and piston kits. Even starting to think I might split the calipers despite reading warnings that they will warp. Guessing that if I do the four bolts a little bit at a time each, like cylinder heads, to keep the pressure even across the whole thing, it should be OK. Any views on reusing the o-rings here?



Hey, PatML,

I completely disassembled my calipers and reused all the OEM O-rings (one each caliper) and seals. They were pristine, only the brake lines were deteriorating (from the inside) due to TIME, not miles. The seals and O-ring must be better material than the lines.

+1 on The Fabricator's post above. The pistons are "pulled back" ever so slightly by the seals.

Couple of tips on bleeding - 1) suck the system dry before replacing the lines: MiTyVac. 2) it's easier to push bubbles UP rather than DOWN when refilling the system after replacing the lines. MiTyVac does a good job of this, too. 3) put a couple of wraps of white PVC or Teflon plumbers tape on all the bleed nipple threads before starting. This saves DOT4, paint, plastic, etc, 4) keep a spray bottle full of clean water and several clean and wet shop rags handy. Water neutralizes DOT4 instantly. They are miscible. 5) While bleeding the system BUMP the banjos with a rubber mallet and bump the front forks against the stops to help dislodge tiny bubbles in the fittings. 6) drop a quarter (25¢) in the MC reservoir before starting any of this. It CANNOT seal the ports but will save your dash, plastics, the windshield from DOT4 etching. AMHIK. I just leave 'em in.


Old Fart Newbie
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