Brake Upgrade

I'm in the process of doing a front break upgrade and I've run into one question with my specific setup that I can't get a firm answer.

I've got a '78 100/7. Currently a single 40mm ATE. I've got the spoke wheels.

I was wanting to add a little extra stopping power, but didn't want to have to deal with the hassle of wheel/axle/ect compatibility issues. I realize I could go to a complete brembo or other awesome caliper setup and have great performance, however, I'm not looking to break the bank on it (note, already upgraded to steel lines, and better pads)

I'm going for a happy medium for my upgrade.....going to a dual ATE setup.

Now is where my question comes in: I currently have an under tank master cylinder. I'd like to keep an under the tank master cylinder. I am aware that a handle bar mounted one will add performance, but again, not looking to break the bank....just add a little extra stopping power with not a whole lot of $$$.

Is there anyway I can use my current master cylinder with a dual 40mm ATE brake setup? I've gathered 2 possible solutions, but would love to hear other ideas and input.

option 1: run a thin more solid brake line from caliper 1's bleed valve to caliper 2's "input", leaving only one bleed valve for the whole system.....basically "wiring the brakes in series"

option 2: Double banjo bolt at the master cylinder with 2 dedicated brake lines for each caliper.

(option 2b: use a brake line "splitter" somewhere in the system to branch off to two lines.....similar concept to the banjo bolt idea)

I've searched and couldn't find a good answer on this one......however, my searching skills maybe missed something. Any input is greatly appreciated!!!!

Thanks

Some have had the MC machined to add a second output on the left side. I don't know who they used for the work, but there seems to be more than enough "meat" on that side to add one.

Good luck, I'd love to add a second disk, but most I have seen for sale are in the $500 - $600 range for the front end :eek1

This is the stock way the lines feed the twin Brembos on my '94 R100RT.

I had good luck just drilling and tapping the blank boss on the original single disk MC. Both sides look identical now.

Thanks all!

So, from doing more question asking around and such and seeing people who have had success drilling and tapping a single brake MC for dual brakes, it seems like option 2/2b that I proposed, in theory would work. However, as someone pointed out to me, my net pressure gain will be limited. In other words, the original piston meant to drive fluid for one caliper will now be dividing its strength between 2.

The consensus I'm lead to believe: Yes it would work...however, it will likely not increase my breaking power much, if any. As stated in my first post, I'm not looking to "brake" the bank on this one, however, if I'm going to do the upgrade, I want to at least get something out of it.......that said, I'm going to aim for a Master Cylinder upgrade.

Now this brings me to a new question: I already am aware, that the best stopping ability comes from a handlebar mounted MC....no cable stretch, better design, bla bla bla......I get it.

That said, for me to convert to a handlebar would be a bit more work and probably more $$$ than if I just swapped my current under the tank MC to a 17mm under tank MC.

Has anyone out there done a comparison on the same bike with both an under the tank MC and a handlebar MC? I'm curious with the exact same setup how much more power one really gets from a handlebar MC.

As stated, I'm going dual 40mm ATE's. And now am left with the decision of which route to go with MC's. As of now, I'm leaning toward a 17mm under the tank route for ease of instal.....if still not happy, then go for a handle bar route.

maybe in cheaper in the long run to find a r100rs front end

Yes, however, I've already got my hands on a set of dual ate forks. So in my situation, prob not cheaper. I just need to get a second ATE caliper, MC setup, and lines.

If you have the parts, I would go ahead and assemble and use with the existing m/c. You will find that you have a lot more brake lever travel, as you are pushing more fluid. It may be acceptable. No question that the handlebar m/c would be first choice, though!

There is a a fine line between having enough, and too much. Too big a m/c gives a hard "wooden" feel, too small gives too much travel and feels squishy...it's all about modulating and feel, though each would "function."

This page has a good discussion on it... I am sure there will be other opinions, as well!! :eek1

You make a good point. I could simply get a line "splitter" (how much could one cost!?!) with my current MC. It would be a pretty cheap try. As you said, if i like the feel.....no money wasted. If not, go for a bigger MC and all I've lost is some time and the cost of the splitter.

Thanks for the link and thoughts. I appreciate it!