To dual disc or steel line?

[mango]

Hello there all- sorry to be such an occasional poster/mostly a lurker... There's a 2 year abouts here to keep me busy.
 
I finally replaced the steering head bearings on the '82 R65, hoooeeee- did they ever need that. Also, knock on wood, got the final drive gear oil seep to stop. It was just those two o-rings on the brake lever (it takes 2  - 2mm x 10mm ones for those who are in similar straights.) Thanks for all the fantastic info here, sure made it all easier & mostly fun.
 
The next real issue is an insufficient front brake. In the rain yesterday they were even softer and howled at most stops. I bled it while doing the other work but it's still not very confidence inspiring. There's plenty of meat on the pads, the rotor has ridges & valleys but not too significant. The brake line looks original (45K on the odometer) but no cracking. It is a little long tho, a PO installed low bars and looks to have kept the line.

I was thinking how 2 is usually better than 1, so...I've got the dual disc set up from an '83 R100cs and all the lower parts look identical. The Master cylinder would need a major rebuild as it was left exposed & rusted but all else appears healthy.

so..?s

1)Could I just install the rotors, slave cylinders & hoses, keeping the R65 master? Does it push a sufficient volume of fluid?

2)Adding another 10+ pounds of metal up front won't exactly help the handling much but will it hurt a lot?

3)Should I persue other other solutions: Rebuild the existing master & slave? Is there any way to test 'em? Braided steel line for just the one caliper? New rotor & pads?  

Your thoughts would be great to hear, it sure would be nice to limit the trials & errors...

I've added a pic cause I haven't before. Haven't seen the sun much for a few weeks so no outdoor pics and a chaotic garage. Keep warm & dry & out of the path of wandering tornados (another reason I'm glad I'm not in Oklahoma anymore...)--- Dan

[Bob_Roller]

From the experience that I've had with my '81 R65, that's the same ressult with OEM parts on braking in real wet conditions, kind of a' soft feel', and a squealing from the front , and not much braking power.

I have the OEM dual disc set-up on my '81, so I can't tell you if there is a significant improvement  over a single disc.

You need the larger master cylinder, if my memory is correct, it is a 15 or 16 mm, the single disc is a 12 mm, ( the number is cast into the master cylinder body).

Some riders claim that they have more 'feel' with a smaller master cylinder when used with the dual set-up, so I guess that would be up to you to figure out what best works for you.

 The brake lines , if they are original, probably should be replaced, even if it's with OEM rubber lines, 26 year old rubber brake lines are probably not helping your braking at all.

I installed a set of Luftmeister braided stainless lines in 1991, and from my personal experience, I would not go back to OEM rubber lines, that and the fact that they were only $10US more than OEM rubber lines.

I just installed EBC floating steel rotors, and EBC graphite pads, and it seems to be an improvement over OEM, but I only have less than 100 miles on the new set-up, so I can't give too good of a review on them yet.

As far as handling, I don't think that with the type of riding that an R65 gets, that the added weight would be detrimental to it's handling.

[steve hawkins]

I picked up on something you said in your initial intro, and that was when you put the brakes it the front, it howled.  This can be an indication that the brake disc is already toast.  

Check the holes in the discs for radial cracks, this is what I had on my bike.

I have had ebc discs on a BMW K100 and can recomend them also, when used with their own pads.  But there are also good cast iron dics out there for wet weather.

I would also go with the path of least resistence.

Check your disc carefully - if it is cracked, replace it - not with BMW OEM.

Then look to do your line first - you might find that is enough.

Steve H

[Bob_Roller]

If you do install the second disc, you need to get longer bolts for the rotors, the single disc bolts are not long enough.

[drewboid]

I can't comment on braided lines but I just installed a second disk on my girlfriends 1984 R65 - she was complaining that it didn't stop quickly enough. she does not have a lot of hand strength so I left the original 12mm master cylinder. I can get the lever almost all the way back to the grip but she can't.
It makes an ENORMOUS difference in stopping power! Quick and panic stops are no longer a problem. The carrier for the disk is different from most of the other airheads so make sure you have the correct one. right and left are the same however.
A right side caliper is more difficult to come by - I used a Brembo that was from a Ducatti! an exact match to the 38mm BMW with 107mm mounting hole spacing. I mistakenly bought a late model BMW caliper with 107mm spacing that I thought would fit but the holes were threaded! Learn from my errors.
Braided lines may be next but right now all is well. I didn't use a splitter for the brake lines but removed the bleeder on the left side and ran a SS line from the left caliper to the new right side caliper. Bleeding may take longer but hydraulic pressure is hydraulic pressure whether the calipers are in series or fed via a splitter. ( YMMV )
the added weight to the front end has been mentioned as a downside but the LS model came with dual disks standard. My opinion - go for the second disk.

[mango]

Thanks for all the input. Think I'll try just installing the 2nd disc and see where it gets me. Spend $ on steel lines next. I haven't found any cracks but I'll get a really good look when the wheel's off. I've got the longer bolts, do the nuts get locktite? Yes the master is only a '12', but sounds like it'll still work ok.

Cheers- Dan

[drewboid]

The nuts on my R65 were Nyloc - nylon insert cap nuts.
Use loctite if you want but not necessary in my opinion.
Do use a torque wrench.

[thrang]

One of the problems with OEM lines when they get old is they can expand under pressure making the breaks feel soft and spongy. Personally Iwould not like to run BMW stock hoses for mre than four or five years before I'd replace them.

When I swappped to motobins braided on the Bimbo and the difference in breaking power was astonishing. When your neck is on the line, the cost of stainless baided is more than worth the extra expense.

[tagordon]

Braided lines are definitely money well spent.
Even if you don't see it, you can feel it.
Hold tightly onto your brake line & pull the lever.
You will feel it. You may feel that it is a very small amount of movement in the line. Well, a hydraulics tech explain this to me. Figure the length of the line & the volume inside. When it swells the pressure drops significantly. He did the math as if it were as simple as 2+2=4. The smallest expansion is greatly significant.
I changed to a braided & was astonished with the difference. I had much more controlled responce to the pull of the lever. Some call it a more progressive braking. That's probably the correct way to state it. I am not a tech by any definition of the word. Just a rider trying to care for my ride.
I love to ride fast. But only if I am certain I can stop when I need to.
And as said earlier, it matters not if you use a splitter. Once system is bled the presure is the same at all points all the time.