XJ11 - Rear MC questions

[KA1J]

First, a photo of the rear MC



To fill the MC, do I remove the top three nuts on top of the cap or do I undo the larger bolt below the cap and to the left and fill through there?

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I just rehabbed the front right caliper, controlled by the right grip MC and had thought that caliper was the grabbing problem from last year. I'm waiting for caliper paint to come in so that caliper is not installed. I went to push the bike to an area in the garage easier to work in & the bike wouldn't budge though it backed in fine last fall.

Putting it on the center stand, the rear wheel moves freely and applying the rear brake works the caliper as expected. Raising the front wheel, the caliper was locked tight and would not budge. I had to free it by knocking it out with a piece of wood & a mallet. Squeezing the brake with the caliper removed took effort for the front piston to move though the rear was gripped as I pushed and the rear wheel spun freely again when I removed the brake pressure.

So now I'm looking at what to do; It appears the rear caliper is not seized and works fine. It also looks like the front caliper is seized and will take some effort to remove the piston. Since I want to clean & if necessary, rebuild all the calipers; My thought is to now remove the front shoes and keep squeezing out the piston till it's free, adding fluid all along to the MC so I don't start pushing air. When it comes to the rear I can plug the front banjo and squeeze out the rear one easily the same way.

So now the question of the removal of the MC as I'm going to replace the hoses with SS braid hose; It looks like there's two bolts holding the MC in place. After removing those, does the MC come out easily? Is there anything I should do in a particular order to make removing the MC & reinserting it easy? It looks like there's a fair amount of related parts in the MC area & I'd hate to miss something while disassembling or not get it back right during reassembly.

Also, if the rear MC spooge hole is plugged, would the rear caliper work perfectly as it does and the front be seized? Or would both brakes show the seizing issue?

Thanks!

[lancelot455]

To fill my master i removed the bolt. it does not hold much fluid and i needed a really small funnel to fill it. Had to do so several times while i was bleeding the brakes.

[CatatonicBug]

I have an XJ MC on my bike, and I use a bendy drinking straw to make a tiny funnel to pour the fluid in through the bolt hole. I cut a slit in the end of the straw and open it up so it looks like a slurpee straw, so I can pour the fluid on the "slurpee spoon" end.

[Smash]

We took the top off (the three small bolts) to keep an eye on and fill the fluid through a few bleeds and such. Didn't even think to use the bigger bolt! ha.

[Jerry]

Remove the plug, below the cap, and fill the MC through there. Use a plastic syringe to fill the MC.

Removal. This is from memory, several years ago, so may not be entirely accurate. The XJ has a secondary item (proportionong valve) on the back side of the MC. This device splits the braking pressure betweeen the front and rear brake cylinders. My recollection is that I removed the lower part of the rear fender - its plastic - to get better access to the MC. May net be required, though. I recall unhooking the sensor wire, removing the bolts, disconnect the line going to the front caliper at the union where the rubber line comming out of the proportioning valve meets the solid steel line on the frame of the bike. Remove the line going to the rear brake cylinder. MC should come out with little effort, though you may have to twist it a bit to get the proprtionong valve and front hose out of the frame.

The wire that is attached the MC runs to the bike's computer, and tells you when you are low on fluid. A similar wire runs to the front MC.

Reinstall is basically the reverse. You will need to bleed both the front-left and real calipers. Start with the front-left.

From your description, I would guess the rear MC is working OK and your problem is with the left-front caliper. Normally, if the spooge hole is plugged, it will affect both front-left and real calipers. However, it is not a bad idea the disassemble and clean everything. Keep in mind the XJ will require 1 extra SS line, the one that runs from the proportioning valve to the steel line that runs up along the frame. So, you will have:

1. Rear wheel.
2. Left front to steel line on frame.
3. Right front to front MC.
4. Proportioning valve to steel line on frame for left front caliper.

This assumes you are keeping the stock set-up.

Good luck.

[KA1J]

Some great replies!

Yes, I'm keeping the stock setup though I'd be fine with the two front being controlled by the front MC & the rear dedicated to the pedal. I am though keeping the original setup, I just hope the proportioning valve will be adjusted the way it was originally intended.

I'll use the bolt plug to fill it from. Not sure about removing the rear fender, I'll have to look into it & see what's needed. Space is at a premium around the MC. I'm always concerned about digging into something compressed if there's nobody close by to go to if there's a hangup.

This forum though makes it possible & it is such fun to restore such a pretty bike.

[CatatonicBug]

1. Rear wheel.
2. Left front to steel line on frame.
3. Right front to front MC.
4. Proportioning valve to steel line on frame for left front caliper.

This assumes you are keeping the stock set-up.

You forgot one. There is a line that runs from the front end of the metal tube under the tank to the joining point on the forks. This line has a coiled wire around it to protect it from getting scuffed by the forks moving around. There are 5 total flexible lines and one solid metal one.

[Woof]

This forum though makes it possible & it is such fun to restore such a pretty bike.[/QUOTE]

They really are good looking bikes.

[Jerry]

You forgot one.

Its been so long since I put SS lines on the XJ I forgot about that one.

BTW, while you are in looking at the rear MC, you might want to pull and lube the rear brake shaft. when I got my XJ this shaft was crudded up enough to create some drag, as it did not want to consistently return to its stop. I pulled the shaft, sanded it with some 400 grit, lubed it with wheel bearing grease, and reassembled. Have not had to look at it since.