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95 R1100RS front brake dragging


JimmR75

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I have a new-to-me R1100RS with ABS. 57K miles on it, 3K+ by me in the past 90 days since purchase.

 

I installed Spiegler lower (right and left) brake hoses. Bled front brakes via caliper bleeders, seemingly successfully. ABS lights extinguish normally at beginning of a ride, but brakes are immediately and obviously dragging after application.

 

I have had the front wheel off previously to install a new tire several hundred miles ago. Axle, pinch bolts and caliper bolts are torqued properly and in sequence.

 

No pad change or removal since purchase.

 

I can "relax" the dragging by cracking the bleeders on each caliper, but it returns immediately upon application.

 

What could the line replacment / bleeding at the calipers have changed to make the brakes drag?

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I have a new-to-me R1100RS with ABS. 57K miles on it, 3K+ by me in the past 90 days since purchase.

 

I installed Spiegler lower (right and left) brake hoses. Bled front brakes via caliper bleeders, seemingly successfully. ABS lights extinguish normally at beginning of a ride, but brakes are immediately and obviously dragging after application.

 

I have had the front wheel off previously to install a new tire several hundred miles ago. Axle, pinch bolts and caliper bolts are torqued properly and in sequence.

 

No pad change or removal since purchase.

 

I can "relax" the dragging by cracking the bleeders on each caliper, but it returns immediately upon application.

 

What could the line replacment / bleeding at the calipers have changed to make the brakes drag?

 

Morning JimmR75

 

The usual cause of a dragging brake caused from the hydraulic side is the master cylinder piston not fully returning to uncover the fluid take-up port.

 

That bike doesn't have hand guards does it? If so is the R/H side handguard preventing FULL brake lever return?

 

Other things that can prevent the brake system pressure from dropping to "0" is an overfull master cylinder (doubtful if you have opened a caliper bleed screw a few times) or some sort of inadvertent check valve in the front brake hydraulic system. (like a pinched hose, or incorrect banjo bolt)

 

A plugged take up port hole in the bottom of the master cylinder reservoir could also cause a dragging brake but you would have had difficulty bleeding the front brakes if that hole was plugged.

 

I really don't know what to tell you other than it sounds like you have some sort of restriction in the front brake system or the master cylinder reservoir is so full that the cover/&/gasket is retaining pressure on the front system.

 

So maybe start by verifying that the front master cylinder piston (& lever) is FULLY returning. If nothing found there then remove front master cylinder reservoir cover & suck a little fluid out, then pry the front brake pads back to see if the fluid level (easily) raises in the reservoir as you pry the pads back.

 

Basically with the front brake lever released there should be free flow of fluid back into the master cylinder reservoir through the small hole in the bottom of the reservoir.

 

There is a very very slight possibility that the ABS system could be causing the pressure retention but that usually results in a dash warning light & failing the ABS ride-off test.

 

 

 

 

 

 

 

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DR am i right in saying that, because the front master cylinder piston does not normally move very far, there is a posiblitity that when the unit is bled, debris on the shaft of the piston may cause it to not return fully? It is a problem that can arise when bleeding brakes and then the piston travels way beyond its normal range of movement.

 

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James in OK

I remember reading about an adjustment screw in the front master cylinder. Search forums for dragging brakes and I'll bet you find it.

 

I have no idea why it is now an issue, but the post I'm remembering was AMAZINGLY similar. Adjustment solved the problem.

Edited by James in OK
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I remember reading about an adjustment screw in the front master cylinder. Search forums for dragging brakes and I'll bet you find it.

 

I have no idea why it is now an issue, but the post I'm remembering was AMAZINGLY similar. Adjustment solved the problem.

 

Morning James

 

A mis-adjusted master cylinder piston screw sure could cause a dragging brake but it would also prevent brake bleeding. He says his brakes bled out OK.

 

So unless someone messed with that screw since he bled the system then that screw probably isn't the issue.

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JimmR75,

 

Not to discount what has already been said here, but I'll just tell you what happened to me a year ago on my '99 R1100S.

 

My front wheel started dragging, getting worse by the mile on the way home from a 100 mile ride. I doubt it would have made it home if it had not started raining, cooling and lubing my discs. Ever been GLAD to see rain on a ride?? I was.

 

After a lot of head scratching and looking, I found that several of the front caliper pistons were not retracting at all. I disassembled the front calipers and found debris from the decomposing OEM brake lines clogging the passages in the caliper and acting like a check valve. I split my calipers and thoroughly cleaned everything. There were some comments on the forums about BMW says NOT to split the calipers. Screw that, they're MY calipers now (YOU might prefer to pay the $500 each for new calipers). There are 4 socket head bolts and an O-ring. Stupid simple. And you can't really clean everything without disassembly.

 

Anyway, that was the cure for MY problem. I installed a set of Spieglers and have been rolling freely since.

 

Bleeding the system is a separate issue.

 

If you didn't at least remove the pistons and blow out the passages when you installed new lines it might be YOUR problem, too.

 

I learned that the bleed nipple is directly connected to the brake line beside it. That means the pistons are on a "dead end" in the hydraulic system; you DO NOT flush the pistons/cylinders or caliper passages when you bleed or flush the brake lines. You can force the pistons all the way in with wedges, OR use a vacuum type bleeder (MityVac) system that will identify any plugged passages by NOT pulling the pistons IN. Using Teflon plumbers tape on the bleed nipple threads helps A LOT, too.

 

This was ONE of the plugs found when I split the caliper. It was like finely shredded brake line. DOT4 is not friendly to many things including old style brake lines.

More (all) pics here: Brembo caliper cleaning 6-16

 

HrEl9G8Z_0Qotcg-xGpNrRerp4kAvF2D0bbht1DPI-PLCHywtDLK6ZGKFNbTu3x3Gr7MzWu6teumfCh-sSEFlVZ1Lr2Q3s2Af2wld5Bocfew-HmBtz1UMz5Rfa5sjM4Sm7iboYP-Ebq-KJX13HIPHDKArFKiDRzZOXM6SFjIuH8gxfhYAKDdcmHym2nSwRuEYV6PhlttdkffpTrBhEgKYZh9VFJYWa0s9bPopAA-mcwadSjNE_2sg6bmoRXe6ldNGFbEqovwGVHUEGsikHrzla3yba6RYeGgSwHBvtDRzZmFhuAb-sJvy4RrmOX5NP2uEsRZw2rWgP9TS96KVBLqJSgTMHG7WVJV2wGYxFMNdGgLIuYVqtwcMxIJMCCK5bcnd90PyJoobnjwzQ2Bj_oVzpA56e1RBkc6ciMJLHCCDE3jtrpcGc3Zn01lC-m_oNQVss0Ti-DUWYKL6NYDEeYkLP6B87Ta0rscWOEV-_C4ywqXVfTiqPrUNBEJt_AWqP493pqtVy98emzuLdOKdg0eCgbt5hy5lHtAVcKjFqrnuR5LGkFUkZ5oqjMV_b4ph6gsZrehlCPTBhXhleiSDslRETkKyzh8-IzcS7tEG37rrhKTcsgVBOOQPA_a=w728-h638-no?.jpg

 

 

Be VERY CAREFUL when removing any of the rubber piston seals. The two pistons/cyls in each side of the caliper are different sizes and the two seals in each cyl are DIFFERENT and DIRECTIONAL.

 

Hope you get it resolved quickly. Time's a'wastin.

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Update on troubleshooting:

I have bled the system carefully and have good front brake lever pressure.

The lever is moving freely and returning to rest at the fully extended position without binding or resistance.

The binding is the right caliper not releasing, the left is working properly.

Before I disassemble the calipers per Lowndes guidance and excellent photos linked above, I am going to clean the pistons and manually manipulate the caliper.

I am skeptical that the issue is blockage or contamination as this problem developed as a result of replacing brake lines. The brakes were fully and properly functional before this.

 

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Update on troubleshooting:

I have bled the system carefully and have good front brake lever pressure.

The lever is moving freely and returning to rest at the fully extended position without binding or resistance.

The binding is the right caliper not releasing, the left is working properly.

Before I disassemble the calipers per Lowndes guidance and excellent photos linked above, I am going to clean the pistons and manually manipulate the caliper.

I am skeptical that the issue is blockage or contamination as this problem developed as a result of replacing brake lines. The brakes were fully and properly functional before this.

 

Morning JimmR75

 

Have you tried riding the bike? In a lot of cases the spinning brake rotor & wheel flex will push the caliper pistons back enough for the pads to not drag.

 

Ride the bike, use the front brakes ONCE at very low speeds then ride the bike for a ways to see if the rotor gets hot. If it doesn't then you probably have normal brake drag.

 

If you think that there is junk in the caliper (very unlikely) then remove the caliper, remove the brake line & bleed screw from the caliper, put a pieces or wood between the brake pads then take the caliper a long ways from the bike or any painted things & use high pressure compressed air to blow air though the caliper in BOTH directions (If you have crud in the caliper then it will either come out with the compressed air or plug the inlet or outlet so you can't blow any more air through it))

 

 

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JimmR75,..

Hi Lowndes,

I don't know who does your forum picture hosting, but they are not showing up at my end.

 

Hey, AndyS,

 

Sorry they didn't come thru. Is it the lone pic in the forum or the link to the other pics that are not working?? I'm using Google Photos, plus an old Indian trick that a forum guru described. Has worked ok many times before.

 

Is anyone else having this same issue??

 

 

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I had a very small piece of dirt lodge in the caliper on a Honda once; the rotor got very hot, very quickly. I stopped, opened the bleeder screw, and fluid gushed out. I was only a mile from home, so I was able to get back without using the rear brake. I removed the tiny speck of dirt that was preventing return of brake fluid, and the problem never returned, so it's definitely worth pulling the pistons, cleaning things out, then carefully putting them back in — with the caveat that the seals are rather delicate.

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If you think that there is junk in the caliper (very unlikely) then remove the caliper, remove the brake line & bleed screw from the caliper, put a pieces or wood between the brake pads then take the caliper a long ways from the bike or any painted things & use high pressure compressed air to blow air though the caliper in BOTH directions (If you have crud in the caliper then it will either come out with the compressed air or plug the inlet or outlet so you can't blow any more air through it))

_________________________

D.R. ___

 

 

 

 

Oh, crap. I'm in trouble now. I'm going to have to have a VERY SMALL difference of opinion with Dirt Rider. VERY SMALL. OK?? (Sorry, DirtRider. I just think it's important to have a clear understanding of the inner workings of these calipers to be able to service and repair them. They are elegantly simple but kinda mysterious. Also, I think the symptoms JimmR75 describes fit my problem very well)

 

Here goes:

 

Because the bleed nipple port is connected DIRECTLY to the brake line port, any compressed air applied to either will simply clean out that 1/2" long drilled passage between them. The plug in my caliper was in the mating O-ring port between the two halves. With the pistons still in the caliper, that passage can not be cleared:

IMOkoDh9Rw-79BRvQULRBAcpJXJWE-yV-vc2G9nYGre-glw80RpD562xXEub45W97uhdInIjL0aFDCTth-jT3JQv_Pq2FMXOhSbyYhe8nO9BcS34wNtdeZB5Ul_i3pYMPyMMvQd7J-bkPmmaeyjphIk_C9v60Vx1NdclwWJP7_3du0dSkwQruhcFh_b5wv_q7flHVJCpZrcV8NUKCmOtWzWLbEwfQbDkYTleXuL7HmTZ2YGMdkv6APHxq9Le6tTVo2miRzo0mVSl3pUrmXrNCnjzkIhGmZbS6adOaIe37l6sIkDSWrHZjRmQ4H_eTrxGZvyMRvumXfoZwJphTgOBer5IAZSv9xMIsVruvDoIr3K2ZuqDRWxCFsrHAeYFGlItmn9tACknIKOTqwwktOkPGpxQMIuSHW4SgbF1f-AX1obujrtoBIYYW2VNUm3VB2BuXSTcL8QVjD7RvEvjElz3bokcfs0f_aHVJ_wxDU779pQyTcqt8OBEh1kmWlK-fl7rWhvNw-lVG2Lx21YxwIDO2sAj5KJPlzh-aoY7we8Qm1lMNz_2IzYC_OGdK4DONbW475bq4dlOFwk7a6TRYo-YnDdmnuHY4aRBIaHrzNvPa5oa9rGCqPqKhlGuFDE8i3dkrGUS795qRkyg3qsHd2mZ-ws7OPa-Dkk9OkQ8Jc1p_B_qlQ=w851-h638-no?.jpg

 

Chances are I could not have cleared all the crud in my calipers without splitting them. The pics show the crud in the bleed nipple port as well. I wanted to eyeball ALL the ports, galleries, cylinders, seals, O-rings, to check their condition while I had the brake system apart and dry. (And installed Spieglers)

 

You COULD remove the pistons without splitting the caliper, but then you still couldn't get pressure to the transfer port to clear it. (OK, you COULD get pressure to it by plugging the line port and removing an INSIDE piston and restraining the outside pistons, then putting pressure into the bleed port). Still might not clear it.

 

Clymer has good pics (p.575) on this caliper. They even discuss splitting a rear RS caliper (p.577)

 

Someone found a source for the Brembo caliper parts and seals AND the O-ring: Munich Motorcycle Parts

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Here is where I am and what I have done:

I have not discovered any blockage or contamination during the bleeding process, but have not disassembled the caliper.

The right caliper is the one dragging, the left is working properly.

I removed the caliper from the fork leg, but left the hose connected. I removed the brake pads and cleaned the caliper.

I can move the pistons with the front brake lever and push them in by hand and get corresponding movement of the other pistons, indicating to me that the internal passages are open.

Both lower brake hoses were replaced at the same time with Spieglers.

I am seeing fluid return properly to the master cylinder.

The brake lever operates and returns smoothly and normally.

I thoroughly cleaned the brake pin and applied a very light coat of copper anti-sieze. The brake pads move freely.

The front brakes work properly, but the right caliper is dragging after application, where the left is not.

The difference is what concerns me.

What feature / component moves the brake pads back from the rotor? I don't think the pads are being held in braking positions by hydraulics, I think it is mechanical and they are not being retracted.

Any input or ideas are appreciated.

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Here is where I am and what I have done:

...

Any input or ideas are appreciated.

Have you tried what DR suggested?:

 

Morning JimmR75

Have you tried riding the bike? In a lot of cases the spinning brake rotor & wheel flex will push the caliper pistons back enough for the pads to not drag.

 

Ride the bike, use the front brakes ONCE at very low speeds then ride the bike for a ways to see if the rotor gets hot. If it doesn't then you probably have normal brake drag.

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What feature / component moves the brake pads back from the rotor? I don't think the pads are being held in braking positions by hydraulics, I think it is mechanical and they are not being retracted.

Any input or ideas are appreciated.

 

Morning JimmR75

 

By design the piston seals are what moves the pistons back after apply. That usually leaves just a very light drag (nothing harmful).

 

From there the very slight rotor run out, some wheel deflection while riding, & brake rotor lateral movement all contribute to a little more brake pad kick back.

 

Disk brake pads can & do drag slightly at times. As long as they don't make heat while riding without using the brakes then all is normal.

 

RIDE THE BIKE then don't use the front brakes then see how much drag you have.

 

Or, ride the bike but don't use the front brake then see if the right front brake rotor gets hot.

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The outcome of all this is a set of normal brakes.

Cleaned the pistons and "internal" caliper area, cleaned pads and pins, light coat of copper grease on the pins.

Did not disassemble the calipers.

Rode the bike as advised above and everything is normal.

My guess is that the greatest contributor to the dragging was the layer of "dirt" on all interior surfaces.

Thanks for all the input and suggestions.

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My guess is that the greatest contributor to the dragging was the layer of "dirt" on all interior surfaces.

Thanks for all the input and suggestions.

Great news, and I agree — the caliper pistons operate in a very dirty environment, and when changing pads, I always push them out as far as possible, clean thoroughly, then push them back in, using a C-clamp and the old brake pad.

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  • 3 years later...

Old thread, I know.  I read that one should not split the calipers.  They are assembled at the factory and torqued with an angle gauge, single use bolts.  Splitting them can cause them to leak.  I tried to split the first one but couldn't get the last bolt out.  After reading why you shouldn't split them, I just put the other three bolts back in and snugged them up.  Anybody have a torque value for the bolts?  I read there isn't a value because Brembo advises against splitting.  I've read that they don't supply bolts or seals for the caliper halves, either.

 

I cleaned mine by taking one piston out at a time and blowing them out with compressed air, and wiping out the cavities.  I am installing Spiegler SS lines, once I get everything back together I'll check for leaks.

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