FJRiders.com

tominca wrote:Have you ever replaced the rear brake fluid? The brake fluid cylinder is on the right side of the bike behind the side-panel below the seat, band the ABS block is readily visible. The ABS system seems to fail more frequently on bikes that do not have routine maintenance of the brake systems and fluids. The diagnostics linked to earlier are pretty simple to do, and you can definitely feel the pulse if you activate the rear ABS.

Yes. As a matter of fact, I flushed about a pint through it during my testing. Still, the rear didn't pulse as well as the front.

I have only owned the bike since February, don't know how well it was taken care of before.

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My '07 doesn't pulse with nearly the frequency of the front, but I don't have a base line to compare to (have not ridden/tested others). It may be (somewhat) normal for them to be different front to back. In my FSM near the beginning, it describes the ABS function and circuits, don't know if that is described in the Gen1 FSM.......... however, it does not answer the question of the frequencies we are seeing. Check ebay for used ABS pumps, I got one for $150 (alledgedly functional) and either it or my old one are going to be test mules/torn down........ eventually. I have more testing to do before I get anywhere near that far.

Today, I took the entire pump assembly out to check it out. Usually, a person can dig around in such things and figure a few things out, even though the manufacturer says it has "No user serviceable parts". Well, MamaYamaha did a fair job at staking this thing together as opposed to bolting it together. There were a few threaded plugs on the sides that had...staked plugs under them. I pulled the motor off and the pump is...staked. The solenoids...staked. Its a one time shot. I'm sure, if I had a mill and time I could carefully machine away the staking and disassemble it, but I am a few thousand thousand shy of that.

So, I tried some more checking and testing. Turns out, on the bottom of the valve block, two of the cups are movable. I assume they retain the springs that return the pistons for the reservoirs. A usual car ABS works by pumping fluid from the caliper back to the brake pedal and into a reservoir that gives some extra capacity in case the driver has a panic stop condition and the return holes in the master cylinder are closed. Then, when the stop is complete and the pedal is released, the springs push the fluid back into the master cylinder reservoir. I am pretty sure this is how the FJR is supposed to work.

I could activate the solenoid and the pedal would go all the way down. Thus, the solenoid and the extra reservoir are working. I was unable to activate the pump simultaneously, so I could not create a full, continuous ABS activation.

I did notice when I ran the functional test after this and the pedal was down, the pump was able to push back against my foot and return the pedal home. Thus, I think the pump is functional as well.

So, the solenoid opens a path from the extra reservoir to the master cylinder, and the pump can push fluid. However, the path from the caliper to the valve is not moving fluid. Thus, it must be an obstruction between the pump and the outlet to the caliper in the hose block.

It would be nice to X-Ray this thing...

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non-techie here... what does "staking" mean? would it be a post that clips internally into place and must be broken to open the device?


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wpbfjr wrote:non-techie here... what does "staking" mean? would it be a post that clips internally into place and must be broken to open the device?


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Its deforming the surrounding metal to hold a separate piece in place.

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