Braking:New Master Cylinder, still brake problems.

[Milo_357]

hey gang,

Installed a new 16 MC to my front brake yesterday on my 1982 R65, and rode home from Chattanooga with it.  

While I was not WITHOUT a front brake, I did not get the performance I expected.  I went from a leaky 12mm to a 16mm.  EVerybody & their brother said I'd see a noticeable improvement. Well, not so much.

What I did notice was the brake was MUCH stiffer/firmer.  I did NOT stop any better.  You could even say it was harder to break due to the stiffness.  

Can anyone suggest what steps I could take to improve my breaking.

I didn't take them off, but the pads APPEARED ok.  I had removed the front tire in an aborted attempt to install a due front disk.

Thanks,

Dell

[Bob_Roller]

Can't remember your original posting, but I assume you have a twin front disc set-up.

At least for the R65, the factory master cylinder was a 15 mm for twin discs .

Do you still have OEM rubber brake lines ?

You may want to scuff up the pads, they can get 'glazed' and not provide their full capability .

The brakes on the R65, were nothing to write home about, so I don't know what you are comparing them to .

[Mike V]

Dell,

Take a look at the chart from the attached link from Mike Morse's Vintage Brake site.  It explains hydraulich brake ratios and the affect on "feel" in respect to MC size and size of rotors.  When Mike refers to a "wooden" feeling, he is referring to stiffness (hard lever feel) or lack of lever modulation.

http://www.vintagebrake.com/mastercylinder.htm

-Mike V. / San Diego
 

[Teo]

Brakes on the R-65LS - I hear a number of the Phorum griping the brakes of the LS as being underpar.  

My '82 has the standard size master cylinder (15mm?), stainless lines and EBC floater disks.  The lever is light and the brakes stop extremely well, even chirping the front wheel if I am too agressive.  

What's the problem some people seem to have with R65LS brakes?

Teo

[Milo_357]

Hey gang,

Bob, your probably remebering a post I made where I was discussing the possibility of installing dual fronts.  That did not work out.  Maybe in the future if I can find a second "shallow" bowl disc.  Right now I have the single front disc.

I do not have and LS, just the standard R65.

>> Do you still have OEM rubber brake lines ?

Yes, and a couple people have commented I should switch to the steel mesh.  You agree?

>You may want to scuff up the pads, they can get 'glazed' and not
>provide their full capability .

Ah, something new to learn...  

>The brakes on the R65, were nothing to write home about, so I don't >know what you are comparing them to .

Oh, joy, just what I need on mountain road...  So, steel lines and dual disc to improve?  I have the lines, caliper, and one disc from my 65LS parts bike, but the second disc is cracked and I need a "shallow" bowl replacement.

If you lay flat a dual disc next to a single disc brake, you will see that the "bowl" of the single is deeper that the dual disc bowl.

Mike, I will look at that site.  Thank you!

Teo, if you get the chance, could you look at your fron discs and let me know if there is a part number stamped on them?

Thanks everyone,

Dell

[Matt Chapter]

I've ridden my R65 through the Tail of the Dragon and had no problems with the front brake.  I have an '86 so (I think) a 14 or 15 master cylinder, single disc.

There is something wrong with your setup, unless you are carrying a serious overload.

I'm curious as to why you went from the 12 master to the 16.. I woud have stuck with the original size.

Also, I definitely agree with replacing the brake lines, and when I did, it was actually cheaper to get SS lines than the original equipment from the dealer.  I'm sure my original rubber lines were collapsing, it was really difficult to bled the system.  I got my lines from an indie BMW guy, he measured the originals as on the bike and ordered them from his supplier.  I have also heard that some manufacturers make SS brake line kits for the R65.

[Barry]

I went from a leaky 12mm to a 16mm.EVerybody & their brother said I'd see a noticeable improvement.

A 12mm master cylinder can only have come from a single disk set up probably an 81-84 and shouldn't have been too bad. At least it would be better than mine which has the 78 - 80 13mm master cylinder.

Nobody who understood the issues would have recommended a 16mm unless you were thinking of twin disks and even then it's probably a touch too big as 15mm was the stock size used for an 81-84 with twin disks. You would need an incredibly strong grip to use a 16mm on a single disk and even then I think you'd have brakes with no feel bordering on dangerous.

Without looking at the ratio of master cylinder area to brake caliper area you can't make any direct comparisons with 85-  on bikes as they had a 48mm brake caliper instead of a 36mm. In terms of area that's a huge difference.

[Teo]

Dell,  The LS has "mag" wheels and uses the same disks as the /6 and /7, etc. bikes.  My EBC replacement discs are "standard" depth.  I will look tonight to see if there is a part number.

At one time I was going to make up a set if wire wheels for the "cool" factor but got tired of looking for specific R65 discs.  The R65 wire wheels took a deeper bowl than the /6 or /7.  The option was to machine a spacer ring to go between the bowl and the hub to be able to use the standard ?6 /7 discs.

Teo

[Bob_Roller]

Thought I'd add this, if you have a second rotor that is cracked, don't get rid of it, there is a company Speigler Performance, they will remove the old rotr and if the hub is still good, no cracksetc...., they will install a semi-floating disc to your hub, if your other disc is heavily grooved and close to the thickness minimun (.180 in.), you may want to give this a thought .

Cost is around $240 for each rotor, they also make up their own braided stainless steel lines on site .

http://www.spieglerusa.com/brake-line-kit-40.htm

[montmil]

Yikes! The AirList lads done scorched Dell's shorts regarding a 16mm master cylinder with a single disc. Much more kinder and gentler around here. Pretty hard on our guy.

Note to all: When Tom Cutter gets his flame thrower warmed up, things get really exciting!

Some excellent info about master cylinders was shared... in between the lashings.

[Milo_357]

Yikes! The AirList lads done scorched Dell's shorts regarding a 16mm master cylinder with a single disc. Much more kinder and gentler around here. Pretty hard on our guy.

Note to all: When Tom Cutter gets his flame thrower warmed up, things get really exciting!

Some excellent info about master cylinders was shared... in between the lashings.

Yeah, the Airlist guys, particularly Tom, forget some of us don't have YEARS AND YEARS AND YEARS AND YEARS of experience regarding Airheads.  Some of us are NOT mechanics, and quite frankly and not inclined that way, like me.  I get very confused just reading about repairs.  Some of those guys act like, if you don't already KNOW the answer to your question, and if you don't phrase is JUST RIGHT, your full of crap and they have the right to blast you.  Well, he does at least.  Snow was quite nice, actually.  And several others.

Personally, if he can't be civil, I'd rather he shut the hell up when I asked about something on the List.  Plenty of nice people out there.

And you right, several people gave me excellent advice, both there and here.  And I am greatful for that.

And yeah, I misspelled it on purpose.  

[Milo_357]

Thought I'd add this, if you have a second rotor that is cracked, don't get rid of it, there is a company Speigler Performance, they will remove the old rotr and if the hub is still good, no cracksetc...., they will install a semi-floating disc to your hub, if your other disc is heavily grooved and close to the thickness minimun (.180 in.), you may want to give this a thought .

Cost is around $240 for each rotor, they also make up their own braided stainless steel lines on site .

http://www.spieglerusa.com/brake-line-kit-40.htm

Thank you, Bob, that was an excellent link.  I actually have all the parts I need, I just have to get another disc and I am going to try and install dual fronts.   I really want the extra stopping power for the mountains.  

[Julio A.]

I have a single Disk and my master cylinder is 16mm. I don't know why since I got it that way. And yes, braking is horrible.

I replaced my lines with SS braided ones and they turned my non existent braking into something that has a remote possibility of being called a brake.

But seriously, I have more braking power from my rear brakes with those SBS shoes than the disks up front.

[Julio A.]

I have a single Disk and my master cylinder is 16mm. I don't know why since I got it that way. And yes, braking is horrible.

I replaced my lines with SS braided ones, replaced the ATE caliper with a Brembo made one and they turned my non existent braking into something that has a remote possibility of being called a brake. The effect was not huge, but an improvement nonetheless.

But seriously, I have more braking power from my rear brakes with those SBS shoes than the disks up front.

[Teo]

I replaced the original BMW discs on my R75/6 with a Ferrodo floater kit.  

Grind off the rivet heads of the old disc and pop them out.  Clean the carrier. Bolt on the Ferrodo discs and voile, a beautiful new updated disc.  

Spiegler would not sell just the floater discs so I could put them on myself; hence, Ferrodo got my money and my loyalty.

Teo