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Early R1200RT ESA Rear Shock EXPLODED!


SHIMHEAD

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Hi all,

Got a good buy on a used ESA rear shock that reportedly had intermittent issues. So I decided to at least try operating it on the bench for the spring preload function. Supplying 12v to the motor connector allowed me to run the preload up and down (by reversing the polarity for each direction). I also monitored the position sensor with an ohmmeter while doing so. It seemed to not return to the position of least preload reliably (judging by the position sensor ohm reading and visually). So my curiousity got the better of me and I disassembled it as far as I could, hoping to ascertain the reason for the inconsistent return to minimum preload. I would assume that if this shock were on a bike that it might trigger a code for the shock position sensor, and potentially stop working due to said code. Clearing the code and relearning the end positions might restore it temporarily??? Anyhow, I thought I would post some pics for everbody to see how this monster works. As I understand it, the later versions of this shock have a Hall Sensor type preload position sensor, which also uses a different ZFE to be compatible. Not sure if the harness connectors would be any different. Here are a few pics.....

 

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Interesting; this is the first I have seen one of these all taken apart. Did you find anything amiss that might account for the abnormal functionality?

 

Jay

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Paul Mihalka

The title of your post made me think that the shock exploded while riding ;) . Glad that's not the case. Interesting to see all the bits and pieces.

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The title of your post made me think that the shock exploded while riding ;) . Glad that's not the case. Interesting to see all the bits and pieces.

 

Ditto.

I have a spare pair off my 2007 RT in the shed. Wilbers fitted at the moment.

\v/

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Jay,

Nothing really obvious. If you notice the mechanism is actually pretty simple. There are two chambers in the main housing, one appears to be a reservoir for hydraulic fluid, the other a simple cylinder with a motor driven screw actuated piston. The piston pushes fluid into the cylinder formed by the housing, chromed sleeve, and lower spring seat/piston. The potentiometer simply tracks the shaft position as it is rotated by the motor (multiple turns for end-to-end travel of the "master cylinder piston". This whole assembly is held on the shock body with a wire circlip, and kept from rotating around the shock body by a setscrew. What does concern me is the obvious hand fitting of the connector for the motor to clear the cover, and the obvious broken off portion of the potentiometer. Again, I assume this to be a modification of an existing Bosch part to allow it to be used in this small space. The potentiometer mounting seems too flimsy to me, and might allow some inconsistency in how it reports preload position. The software in the ZFE might allow for this, but I just don't know. If the screw drive of the master cylinder piston were to bind somehow, that might be a problem as well, where the motor doesn't have the power to rotate it. The "slave" or preload piston does not appear to capable of binding enough to prevent the spring from pushing it back down. I don't have a tool presently to allow furhter disassembly (pin spanner wrenches or specific sockets) of the reservoir bore or master cylinder bore. Still a bit curious there, and I assume a good suspension shop has those tools. Also notice that there appears to be a removeable top cap on the shock body, but there is a warning sticker concerning high pressure nitrogen. I may reassemble it from here, using Porsche convertible top hydraulic fluid, and keep playing with it. I am considering buying the HyperPro ESA shock, and bought this to use while mine was away for upgrading....

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CoarsegoldKid

A friend had three rear ESA shocks stop functioning. Not having seen the culprit or understanding all of what I was hearing but I was told that during the third time it was to be warranted it was found that there is a locking nut that was jammed preventing the shock preload motor to move. Maybe you can see how this could be the case?

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Do you know, or can you measure the total preload travel from Comfort to Sport - and is that likely to be different when mounted on the bike?

 

I ask 'cos I'm not sure if my '06 ESA is working properly despite the lack of fault codes. There is very slight movement if I (gingerly!) put a fingertip between the springs near the bottom and operate the switch. Can't hear the electric motor with the engine running

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You can test by unplugging the motor connector for the rear shock. This is a 2 wire connector under the seat near the right frame tube. Trace the wires from the shock motor to be sure that you have the correct connector. Apply 12 volts to the 2 wires leading to the shock motor and then reverse the polarities. The shock should raise and lower as you do this. This will tell you if the shock is OK.

 

Reconnect the shock wires and try it while you observe the shock. (engine running, trans in neutral) It helps to have someone else operate the button for you. If the shock is not moving, you have a computer issue. The dealer should be able to fix the problem by running their diagnostic computer on the bike and doing an update.

 

I had to do this on my 06RT after converting to Hyperpro ESA shocks last spring.

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Do you know, or can you measure the total preload travel from Comfort to Sport - and is that likely to be different when mounted on the bike?

 

I ask 'cos I'm not sure if my '06 ESA is working properly despite the lack of fault codes. There is very slight movement if I (gingerly!) put a fingertip between the springs near the bottom and operate the switch. Can't hear the electric motor with the engine running

Afternoon Kritou

 

This what you looking for?

 

 

 

rearshockcheck.jpg

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