iABS BRAKE SERVO

[Davis2x1]

Just a brief up-date on the brake servo on my 2004 R1150RT. I had my bike repaired by installing a new servo. Expensive but I received a two year warranty.

I dissassebled the failed unit and found that the front hydraulic pump motor failed. Once I had the unit open I checked the continuity of the solenoids and motor armature as these were easy to get to by just removing the end plate containing the control board. The solenoids were "OK" but the front motor showed high resistance. As I continued to break down the unit I found the interior of the unit was clean and contained no dirt or metal particles.

After I removed the motors and took them apart I found the real problem. As you can see from the attached picture the motor was worn out. I cleaned out the dirt and found that the comutator had worn thru and came apart.

I am trying to get a new motor but no luck yet.

More importantly, I feel that the failure was due to a miss adjusted front brake switch and possibly the previous owner holding the front brake handle slightly while at a stop or even while riding causing the motor to run. It seems that I read somewhere that the motor should not come untill the bleed hole in the master cylinder is covered.

This might be the reason some units have an early failure.

Photos are available but I can't seem to add them here!!

[PAGoldsby]

Just a brief up-date on the brake servo on my 2004 R1150RT. I had my bike repaired by installing a new servo. Expensive but I received a two year warranty.

I dissassebled the failed unit and found that the front hydraulic pump motor failed. Once I had the unit open I checked the continuity of the solenoids and motor armature as these were easy to get to by just removing the end plate containing the control board. The solenoids were "OK" but the front motor showed high resistance. As I continued to break down the unit I found the interior of the unit was clean and contained no dirt or metal particles.

After I removed the motors and took them apart I found the real problem. As you can see from the attached picture the motor was worn out. I cleaned out the dirt and found that the comutator had worn thru and came apart.

I am trying to get a new motor but no luck yet.

More importantly, I feel that the failure was due to a miss adjusted front brake switch and possibly the previous owner holding the front brake handle slightly while at a stop or even while riding causing the motor to run. It seems that I read somewhere that the motor should not come untill the bleed hole in the master cylinder is covered.

This might be the reason some units have an early failure.

Photos are available but I can't seem to add them here!!My servo motor runs whenever I touch the brake lever or pedal on my '04 RT. I'm interested to know if this is correct operation or not.

[rmeisen]

Unless Davis2X1 is the guy who bought my old 70K 04 RT, Mine worked just like that for its entire life..

[Dave_Faria]

I have a 2004 RT and would be interested in seeing your pictures. My ABS Modulator has 59k miles. When you removed the end plate were the motors in a dry enviorment or brake fluid??? Just a thought,,,, try calling a motor shop to see if they can rebuild your armature.

Dave Faria
Austin, Tx

[Davis2x1]

Here's my second attempt to add the photo.

[Davis2x1]

The first of eleven photos of my servo unit. The bike had 12,000 miles when the unit failed. The section on the right is the control section. The black cover on the lsft contains the float switches for the brake fluid. My unit as assembled with Tri-Wing tamper proof screws. A #4 bit from Mc Master Carr was required.

[Davis2x1]

This photo shows the control board. The white ribbon caables go to the control and brake circuit pressure transducers. The red/black pairs go to the pump motors and the black/black pairs go to the anti-lock solenoids.

[Davis2x1]

This photo shows the brake control side of the servo. The section marked with "24" is the pressure transducer assembly. The left side of the of the photo shows the spool end contained inside the solenoid and the brush end of the electric motors. The visible white ribbon cable feeds thru the unit to the brake side of the fluid section. No signs of contamination here.

[PAGoldsby]

Here's my second attempt to add the photo.Wow! That's one toasted motor!

[Davis2x1]

This photo shows the underside of the fill port and float assembly.

[Davis2x1]

The interior of the brake fluid reservoir. No contamination here either. The control inlets are on the right and the brake outlets are on the left. The front brake circuit is on top.

[Davis2x1]

Here I am taking a resistance reading on the rear pump motor. Meter reads 2.3 Ohms.

[Davis2x1]

Resistance on the front motor armature reads 7.08 Mega Ohms. Basically an open circuit. For reference the solenoids read 1.6 Ohms.

[Davis2x1]

Removing the motors required a small box wrench and a slightly ground down (in lenght) bit.

[Davis2x1]

Motor removed. Ceramic pump body on the right. Ports with "o-rings" on left are for the pump discharge.

[Davis2x1]

Heres the rear pump motor. On the left is the pump assembly. Center is the field (motor) housing. On the right is the armature and brush assembly.

[Davis2x1]

Here is the last photo of the series. This is the armature from the rear pump circuit. A little dirty but serviceable. Compare this to the first photo of the front pump motor armature.

If I cannot repair the motor or find a new one I will pobably "part out" the unit I have. All in working order except for the one motor.

Hope the above was informative. Questions welcomed.

Regards,

Dave

[BONEY]

Your ohm meter has been around a while.

My dad had one like that when I was a wee one.

Thanks for the photos. I've always wondered what the inside of those things looked like.

[DrPaul]

Davis,
I have an '04 R1150RT also with 12K miles. I have a few questions:
1) How did the unit fail? Warning lights, loss of braking, noise?
2) What is all that gunk in the motor? Bits of itself, dirt?
3) Was the failure sudden or gradual? Did it warn you before it quit?

It seems to me that the servo motors on my '04 are louder than on my '02 but everything else seems the same. Gosh. Now I've got this to worry about on top of the transmission input shaft and FD failures!

[Dave_Faria]

Davis thank you very much for posting the pictures. If you cannot find a small motor shop to replace the commutator without rewinding the motor ask if they will tellyou how to do it yourself. They probably have the magnet wire and with the old wire removed they can probably replace the commutator. They may be able to do it with the old wire still on - I don't know. Anyway I've rewound small transformers so it can be done, probably in a few hours and the savings!!!! Since u've already replaced the unit i would keep it as a spare.

Dave Faria
Austin, Tx

[Dave_Faria]

From the look of the rear motor you cannot tell if there is much of the brushes left. How much of the front motor brushes are still there compared to the rear?? I'm curious if the wear is just the commutator or both the commutator and brushes.

Thanks Agn for your time
Dave Faria
Austin, Tx

[Dave_Faria]

Just for grins I called an electric motor rebuild shop. They don't rebuild small DC motors but, they referred me to an car Alternator rebuild shop. That shop said IF they cannot order the armature they migh be able to rebuild it. They said they would have to see it. I told the guy it was abt 4inches long....

Dave Faria
Austin, Tx

[Davis2x1]

Boney,

The meter is a Fluke from 1977. Its the first digital meter I owned.

DrPaul,

The unit failed all at once. No warning. I was on the road and applied the brakes. The front brake seemed to lock briefly then went to manual brakes. I stopped and shut off the ignition and the ABS reset. Off I went the next time I applied the brakes same thing happened. Since the unit reset itself the electronics must have been "OK". The roll out test work so the wheel sensors were also "OK". Once the brake was applied the unit must have sensed that the pump was not working, via the pressure transducers and then showed a fault.

The crud is indeed material from the commutator and brushes.

I don't recall the flashing light secuence and failed to get a copy of the fault code from the dealer.

I now refain from resting my hand on the front brake lever as a slight pressure will start the pump motor

[PAGoldsby]

I now refain from resting my hand on the front brake lever as a slight pressure will start the pump motorSo, what do we do at a stop light on a grade, then? :dunno

This is an incredible thread! Thanks so much for the time you took disassembling the unit, making nice photographs and providing the play-by-play of the whole thing. Fascinating!

[DrPaul]

DrPaul,
The unit failed all at once. No warning. I was on the road and applied the brakes. The front brake seemed to lock briefly then went to manual brakes. I stopped and shut off the ignition and the ABS reset. Off I went the next time I applied the brakes same thing happened. Since the unit reset itself the electronics must have been "OK". The roll out test work so the wheel sensors were also "OK". Once the brake was applied the unit must have sensed that the pump was not working, via the pressure transducers and then showed a fault.

The crud is indeed material from the commutator and brushes.

I don't recall the flashing light secuence and failed to get a copy of the fault code from the dealer.

I now refain from resting my hand on the front brake lever as a slight pressure will start the pump motorDavis,
Thank you for the update. Great photos and narrative. I just hope I never get to see this problem for real!