Front brake performance improvement

[Luca]

Sorry Monte, didn't mean to nit-pick... I just get excited when I get to use a bit of Latin.  Hope you're enjoying vacation... it's nice to get a brake once in a while

[montmil]

Nit pickin' and puns. Oh, my...

[tvrla]

Sorry for coming in late to this one, but I've got a few things to say.

Sintered pads tend to wear the discs, so go with organics.

I know my opinion is counter to a lot of others who feel stainless brake lines are mandatory for good braking. The rubber lines swell a little, but not enough to make much of a difference in normal street riding. Some of my bikes have old rubber lines, others, stainless, and yes, the stainless feel a bit more solid, but they both stop fine for me.

BMW didn't get it right for a long time on matching master cylinders to discs. The 13mm master works very well with the dual discs. This isn't conjecture or speculation. Both my R65s have had 13s and I run 14s on my larger beemers that originally came with 17s. The smaller master makes for far superior braking.

[Barry]

I still have rubber lines and have tested them by measuring the diameter at different points with a digital caliper while squeezing the brake lever far harder than I have ever done while braking. There was no measurable expansion, not even half a thou.

Rubber is only the outer covering. The actual brake line is a small bore nylon or some thing similar and probably little different to the internals of braided lines.  

[Bob_Roller]

There are no inner liners on OEM BMW brake lines, just the rubber and it's not even reinforced with fabric .

[Lucky_Lou]

Rubber is only the outer covering. The actual brake line is a small bore nylon or some thing similar and probably little different to the internals of braided lines.  

When I did my rebuild I replaced mine for the stainless steel ones, there was a section of the old one (79er) which the outer rubber had split off revealing what looked like a fabric mesh as reinforcement. That said the Euro 79 version is a twin disc and probably a different spec to the US one
Lou  

[Barry]

There are no inner liners on OEM BMW brake lines, just the rubber and it's not even reinforced with fabric .  

I confess I've never cut up a BMW OEM brake line but the ones I have were a multi layer construction with reinforcement.  If the BMW ones are just solid rubber they must be very good quality not to expand.  I just did another quick test to make sure I wasn't mistaken and again I measured no expansion.  Perhaps there is some internal expansion of the line that doesn't show on the surface. That could only be if there was some reinforcement in the construction.

[MrRiden]

BMW didn't get it right for a long time on matching master cylinders to discs. The 13mm master works very well with the dual discs. This isn't conjecture or speculation. Both my R65s have had 13s and I run 14s on my larger beemers that originally came with 17s. The smaller master makes for far superior braking.

Now I'm intrigued. My '82 LS has rather unimpressive but sufficient dual discs. I have ridden single disk R65s that seemed to have much better front braking. I never compared the master on these to my 15mm. Now that I have a bad master I'm wondering about swapping it for a 13. Does the pull distance on the handle increase a lot?

[Bob_Roller]

The few members that have had 13 mm master cylinders, when they added the second disc, commented that the brake lever was almost up against the grip with the second disc added for whatever that's worth .

My concern with old OEM brake lines, is brake line failure .

My '81 R65 had a line fail in '91, the line from the master cylinder to the splitter behind the headlight, broke at the swaged fitting that threads into the splitter .

My '02 oilhead had a front brake line failure in April, line broke at a swaged fitting again .

I've replaced all of the brake lines on my 4 wheel vehicles with braided stainless lines in the last 6 years .

[Luca]

I bet that the dry Arizona heat is helping those old brake hoses fail more quickly than if they were in a temperate climate.

I'm not exactly proud of it, but my LS is still sporting the factory brake hose from MC to splitter.

[montmil]

Both my single-disc R65s have rubber brake hoses running from the MC to the OEM hard line junction. Both bike's hoses have semi-flexible, hard 'nylon' interior tubing. I know this as I had the lines made locally and viewed the hose material prior to the construction. The end fittings used are the same as used on many Mercedes-Benz autos and match the OEM metal bits.

I use speed bleeders and take plenty of time insuring the lines are totally free of air. I can still skid the front tire if I really try to do so; which I avoid doing.

My R100S has an OEM rubber hose from the handlebar to the under-tank MC. Stainless braided from the MC to the twin ATE calipers.

Good front braking on all three Airheads. Just not as powerful as the more modern triple disc set-up on the Triumph.

[Luca]

I didn't mean factory brake hose as in BMW rubber, I meant it as in 31 year old BMW rubber  

For the curious, the hose ends that attach to the short steel brake lines Monte speaks of are metric ISO (bubble) flare fittings.  Every now and then they will also creep up on some non-European vehicles.

Bubble flares are a single step flare that mushroom the end of the steel line.  Can't recall the metric size, but when I made lines for the R65 and the old MB I used to own, 3/16" line worked just fine.

[Bob_Roller]

I lived in Chicago until '93, the '81 R65 line failed 2 years before I got here .

[tvrla]

The brake lever with the 13mm mastercylinder doesn't have excessive travel - as a matter of fact I mostly leave two fingers on the throttle with one or two on the lever. There's plenty of room for my hand.

If the lever has more travel than that - something's wrong. My first guess would be air in the system.

Not sure how much difference it makes, but the bike does have stainless lines, and I believe the previous one did as well. My first such conversion was to a 76 R90 I added a second disc. Not knowing anything about different sizes of master cylinders, I had the 14mm (under tank style) drilled for a second line. That bike has rubber lines and doesn't have excessive lever travel either.

[HESIMEUSTIC]

Glad to read this, just ordered the EBC organics for my R65.

I rock the EBC organic disc pads on both my R65s. They play nicely with the OEM brake discs and offer outstanding braking performance... IMO.