2020 CRF1100 DCT Left Hand Rear Brake Modification

I don't really know much about how master cylinders work so my only concern would be using the double banjo could affect the braking if it forces fluid up to the handlebar reservoir when using the foot pedal and to the foot pedal reservoir when using the hand lever. Maybe someone can chime in if they know exactly how they work and whether that could be an issue.

I can't say for sure, but my supposition is that you have a piston that pushes fluid out a cylinder and down a hose. If the piston can withstand its own pressure, it would stand to reason it could withstand that pressure from any source, no?

Edit: maybe not, I guess its possible that with a double banjo the rear master cylinder would just push fluid up into the front reservoir and you would have no rear brake at all.

seo68 said:

I can't say for sure, but my supposition is that you have a piston that pushes fluid out a cylinder and down a hose. If the piston can withstand its own pressure, it would stand to reason it could withstand that pressure from any source, no?

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Yes but the niggle in the back of my mind is that when no pressure is applied the reservoir is connected to the fluid that will get compressed when the piston moves. As the pison moves it blocks off the reservoir port and then can compress what is in the brake line.
So in effect pressing the pedal will block off the oem reservoir and force oil up the pipes but the handlebar reservoir will still be open and be pressurised and vice versa.

I think your niggle may be correct

If it is correct then the only options are connect via the teardrop or do away with the oem setup and connect direct to the modulator.

So I think I better have another look and see if I can design some form of teardrop with a clamp at the top to stop the coggling as I really want to keep the pedal, at least for the time being.

My Hohey stunt teardrop doesn't do that.

Yes @Hood Your thinking is correct. Once the LH lever is free, the reservoir port is connected with the fluid on the cilynder and hose. Think if there is temperature and some expansion, this excess fluid have to return to reservoir.
Some brake and clutch systems, use a kind of check valve in the piston itslef, but that configuration is when the fluid from the reservoir hose enters the cylinder at the end, not at the middle.
Then, pushing the piston, closes this check valve, closes the return to reservoir, pressurizes fluid and send to the brake or clutch, but from a cylinder side opening.
Just opposite as the AT rear brake, when the reservoir fluid is at the side, and the pressure exits on the end of the cylinder.
You will fabricate a good aluminum tear drop, with a bracket, and 2 sealing O-rings, to hold good pressure. 😋

Anyone have the oem teardrop that they could take measurements from for me? I am not really wanting to remove it just for measuring then have to put back on and bleed before having to remove again later to do the modifications.
I may just see if I can order an oem one to measure up from as they shouldn't be too expensive.

Just looked up the list price for the oem teardrop, under £15 so I have just ordered one so I can get dimensions or maybe just tap out, who knows
Which brings me to another question, anyone know what the pitch of the banjo bolt is? I think probably M10 x 1.25 but possibly it is M10 x 1.0

Hood said:

Just looked up the list price for the oem teardrop, under £15 so I have just ordered one so I can get dimensions or maybe just tap out, who knows
Which brings me to another question, anyone know what the pitch of the banjo bolt is? I think probably M10 x 1.25 but possibly it is M10 x 1.0

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M10x1.25

Relhok said:

M10x1.25

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Thanks, thought it would be but good to get confirmation.

Well hell, I went out and looked and my tear drop wiggles when I pump the brake too.

However, I removed the rear pedal and don’t care about losing the rear cylinder. Do any of you guys know of a banjo coupler that would allow me to bypass the rear cylinder and connect the brake line between the front and rear cylinder to the brake line between the rear cylinder and the modulator? My googling is only bringing up couplers for making brake lines, not connecting banjos together.

I’m not sure how easy it is to expose the modulator, but I realized I have two brake lines right next to each other. My googling is just failing me so far.

Personally if I was removing the rear pedal/cylinder I would also remove the pipe and just connect direct to the modulator but it would likely be quicker using the style of adapter you have found above. You should be able to get some M10 x 1.0 banjo bolts easily enough if you can not find a connector with the correct pitch.

Eh I’m debating about just getting a longer brake line to go to the modulator, but I’m not sure how hard of a disassembly it is to get access to it. I’ll need to dig into the service manual to see if they break it down.

Hood said:

Something like this is what I envisage.

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You are the Master!!!!!
As I think, making another grove for a second O-ring will be better.
Of course, if there is room for this.
Great!!!!!! 👏 👏 👏

ViperTech18 said:

You are the Master!!!!!
As I think, making another grove for a second O-ring will be better.
Of course, if there is room for this.
Great!!!!!! 👏 👏 👏

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Yes, two O rings may be likely but I will have to wait until I get the oem teardrop to see what the dimensions are. I think it is supposed to be in tomorrow so if it is I will pic it up on Saturday.