BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

So, I know a while back, I saw someone (I think it was here) changed out the front brake lines with a single line from the master cylinder to each caliper. I don't know who it was, or even how long ago, but I'm hoping either someone knows, or anyone can tell me the possible down-sides of doing that. I'm curious as to if it'd make the brakes unusably sensitive and such not. Thoughts?

I've done it on my Rockster (I've had that setup on all my previous bikes too tbh).

I prefer it.

I assume your bike is NOT ABS?

I find it gives better braking, and it's FAR easier to bleed than the OE non-ABS setup with all it's stupid fittings.

Maybe a stupid question, but why should it be easier to bleed 2 straight lines as opposed to the original set-up with the different fittings and router? I believe there is no difference at all as for bleeding you just need to get to brake caliper and the lever (what is in between these 2 points makes no difference). Obviously for an ABS bike there is more involved but again there is no difference if you have 2 straight lines or the o-set-up. To the contrary, I would consider 2 straight lines not ideal because it means routing an additional line thru the jungle of cables in the front or around the front fork ...

What makes a difference in braking is to use the steel braided lines instead of the standard rubber lines. In any case it is recommended to replace the rubber lines after 10 years and buying steel-braided lines then does not make much difference to buying the o-rubber-lines.

Brgds
Oliver

Regarding the two lines vs. the one line to the T and then the two short lines, there are a couple of diferences

1) The two lines hold more hydraulic fluid so it will take slightly more volume to fill the lines, however, once filled there is no difference in actuation.

2) If there is entrained air in the system, it is a bit more difficult to bleed from the from the stock system, as ocasionally air gets trapped in the 1 to 2 T splitter, not the case with the two lines from the MC to the wheel cylinders.

boxermania..so there will be no difference in braking performance, only in the volume of fluid contained in the system?

My R already has SS lines and is NOT abs.

omg1010 wrote:Maybe a stupid question, but why should it be easier to bleed 2 straight lines as opposed to the original set-up with the different fittings and router? I believe there is no difference at all as for bleeding you just need to get to brake caliper and the lever (what is in between these 2 points makes no difference). Obviously for an ABS bike there is more involved but again there is no difference if you have 2 straight lines or the o-set-up. To the contrary, I would consider 2 straight lines not ideal because it means routing an additional line thru the jungle of cables in the front or around the front fork ...

What makes a difference in braking is to use the steel braided lines instead of the standard rubber lines. In any case it is recommended to replace the rubber lines after 10 years and buying steel-braided lines then does not make much difference to buying the o-rubber-lines.

Brgds
Oliver

Air traps.

the OE non ABS system's extra bits and pieces can and do trap air bubbles which then need bleeding - to bleed that little u-shaped junction you really need to take the tank off - which is , imho, just stupid.

That Y-piece is indeed a potential air trap.

Envied riceburner's superbike front brake lines for a while... along with those original Stantons!

Custom front brake lines are on my To Do list, but it is possible to get a decent brake line bleed for the OE configuration with some patience.

I've never had a problem replacing brake fluid by bleeding my non-ABS brakes, but I've never gotten air in the lines.
Is that bleeder valve in the "Y" fitting solely for getting air out of there?

Sunbeemer wrote:I've never had a problem replacing brake fluid by bleeding my non-ABS brakes, but I've never gotten air in the lines.
Is that bleeder valve in the "Y" fitting solely for getting air out of there?

what else COULD it be for??? (the bleed valve I mean).


(apart from providing an air-trap in the first place...)



Fairly obviously the u-bend fitting is there so that BMW can use exactly the same set of hoses* on both ABS and non-ABS bikes.


* m/c -> u-bend; u-bend -> T-junction, t-Junction -> left caliper; t-Junction -> right caliper.

Yes - the bikes have 4, FOUR different pieces of cable, which makes for 5 banjo fittings and the 3 T-piece fittings.

Sunbeemer, yes, that's a bleed.....personally, I never had to use it on on my R during the hydraulic fluid changes.

Not on my former R but I have had issues over the years bleeding air fron the T type splitter, as it tends to lodge at the top of the interior cavities.

boxermania wrote:Sunbeemer, yes, that's a bleed.....personally, I never had to use it on on my R during the hydraulic fluid changes.

Not on my former R but I have had issues over the years bleeding air fron the T type splitter, as it tends to lodge at the top of the interior cavities.

I just ordered stainless steel hoses and speed bleeders, but did not take this T splitter into account. Any suggestions for getting the air out of there on a non-ABS? Should it be bled last?

Thanks,
-Rick

The speedbleeder I ordered for my rear brake worked great in that Y piece. Before I put that in, I had constant air from the threads with it open just a little bit. Now the front brakes are great.

-Rick

If you are replacing the brake lines, why not run directly from the master cylinder to the "Y'? Why bother with the junction and bleeder mounted on the frame?