Brake lines

[disco51]

Pretty convinced now that I need to redo the caliper on my ATE front brake (1979 R65).  My question is... should I go ahead and replace the brake lines as well.  The problem I'm having is that the brake pads won't completely release causing a constant rub on the brake pads.  With the bike on the center stand, the front wheel will only rotate about one revolution before it stops due to the inability to release.  I've read snowbum's article and he seems to think that this problem is either from the caliper needing a new o-ring or from the brake lines (from constant kinking and thus the return port having a one way valve).  I bled the brakes this weekend and even tried to put a small piece of wire in the small return port in the master cylinder with no help.
So, should I get the ATE caliper rebuild set and new brake lines, or just try the caliper first.
If you think I should do the brake lines, then what would you suggest - BMW replacements or something else.
The bike has about 35,000 miles on it and the brake lines look original.
Thanks in advance - really loving the help on this site.  
Jeff

[Luca]

Jeff, Do you mean 1) brake line or  2) brake hose?

1) Brake lines are steel tubing, and our bikes have a little section of it going from the line/hose junction to the caliper.  It shouldn't kink because one installed, both ends are fixed.  However, FYI, you can make your own new ones for a couple bucks with some 3/16 steel brake line and two fittings (tube nuts).  You will need a flaring tool to flare the ends of the line, and our old metric bikes use bubble flares, NOT standard flares.  I got a bubble flaring tool from NAPA for about $35 a few years ago.  Some stores might lend you one for a refundable deposit.

2) I also got the two lower rubber brake hoses for my bike from NAPA.  I brought them an old line to look at.  They somewhat unhappily dug through a book and found something with the  proper fittings.  The length was close enough for jazz.  Had my lines in a couple days for something like $15 a piece, about 1/5 the BMW price.  Not sure how the quality compares to BMW.  You can also make your own braided stainless lines, or try to find some premade with the proper fittings/length.




Make sure that the brake pad pins in the caliper are clean.  If they get crudded up the pads can bind on them.  If this persists long enough you might notice the pad wearing into a wedge shape.  Might as well make sure the anti rattle springs are good and clean too.

If the caliper piston seal was faulty, the bike would probably be leaking brake fluid.  However, small bits of corrosion/crud/gunk on the piston can cause it to bind at the seal before fully returning.  Only way to find out would be to pop out the pistons and look for gunk.  A damaged dust seal would encourage this problem.

Given the age of the bike, I'd just thoroughly clean and rebuild the system if I had the money.  Steel line and fittings dirt cheap.  Hose(s) can be had reasonably.  The ATE seals are a bit pricey, but they should last another 30 years.  Might be worth it to rebuild the MC too.  I actually just cleaned mine and re-honed the bore, but that's because I had already ordered a bunch of parts from motobins and was flat broke.  I can tell you from experience that nothing is worse than filling a system with nasty, nasty brake fluid and then having to tear it back apart to replace or clean another part of it.

One last note.  The ATE kits don't come with the o-ring that goes between the caliper halves, incase you were planning on splitting them.

OK, too much typing.  Hope there was something useful in there

[georgesgiralt]

Hello !
I think your hoses are original. To check look for a plastic (white originally) ring on them. On this ring is the date of manufacture.
If they are original they ought to be changed for new ones.
to improve the braking I'll go for braided lines from Goodridge or similar.
Bear in mind that your life may depend on braking, so, do not go cheap on them ...
As you will have to disassemble the whole braking system, I suggest you renew the callipers and the brake pump also.
Clean them well with brake cleaner and install new seals and you'll find a perfect braking again.

[Barry]

Mine still has the original brake hose and I see no signs of deterioration. Bear in mind the exterior of the hose whether the original or a new one has little to do with containing expansion of the fluid. All brake hoses are a multi layer construction with a small bore inner tube carrying the fluid. Probably good advice to change it though.

Definitely overhaul the calipers. With luck you won't have too much corrosion on the pistons as they are expensive.

One tip. Your pistons sound like they may be quite tight.  Before draining the fluid remove the pads and make sure to push the pistons most of the way out with the brake lever holding one back with a G cramp if necessary. Potential to make a mess here but it's still by far the easiest way and safer than compressed air if they need substantial pressure to get them out.

[montmil]

You have already attempted adjustments using the eccentric bolt?

[georgesgiralt]

The problem with brake hose is that when deterioration shows it is waaaayyy too late !
I've seen an example brake hose cut in it's length and with the interior so badly destroyed that it was making valves. Once the pressure was in, it was unable to get back due to the valves. Thus the brakes where exceedingly hot and quite inefficient...
I think they are date coded in order to be replaced every 5 to 7 years...
Since I put braided lines on my R65, braking has improved tremendously ...  So it is a cost effective solution.

[Barry]

eccentric bolt ?

R65 ATE calipers are normal dual piston just like the later brembo's

[montmil]

eccentric bolt ?

R65 ATE calipers are normal dual piston just like the later brembo's

AhHa... The only ATEs I'm familiar with are the ones on my R100S. Never mind.

[DgM]

The front brake lines for our R65s are the same as the rear brake lines for a Volkswagen Golf of the same era.  Luca was lucky to find a parts store that would spend the few minutes needed to obtain the correct part as opposed to merely the correct BMW part number.

[disco51]

Thanks for the help.  
I was talking about the brake hoses, which I assume I'd need two of (one from the cylinder to the first brake pipe and another from the distribution piece to the second brake pipe).
I've had bad luck just walking into auto parts stores with a part (such as a hose)- the employees always seem to want a part # or the car it came off of.  Not helpful otherwise.
So, any specifics on the connection / hoses I might need?
I plan on opening up the caliper once I get the repair kit.  Hopefully it won't be a complete PITA.
Appreciate the guidance.

[DgM]

I was writing about the hoses from the splitter to the caliper.  The brake lines should last just about forever, not so the hoses.  Always a good idea to replace the brake hoses if over twenty years old.  Or you can count on that powerful rear drum brake to slow you down...

[montmil]

... Or you can count on that powerful rear drum brake to slow you down...

  Say what? Good one, DgM.

[Barry]

A mediocre rear brake is a good thing. A powerful rear brake used on it's own can be seriously dangerous as locking the rear wheel at any speed above 20mph can easily lead to a high side.

[montmil]

The operative statement here is, "used on its own".

I love the powerful rear disc on my Triumph 900 Triple but I rarely use it all by its ownself. Experience does count for something.

And do note the number of new motorcycles having linked front/rear brake systems. This is the manufacturers way of offsetting a rider's inexperience with really good brakes. Plus, I'm sure, hoping to avoid a law suit.

Gimme good, strong, powerful brakes on both ends. Linked or not, I can and do handle 'em.

If I ever buy a 21st Century BMW, it will have honkin' big disc brakes on each wheel. Hopefully, not linked.

[Barry]

The rear brake need not be anywhere near as powerful as the front because as soon as the brakes are applied hard, weight transfer increases grip on the front wheel and reduces it on the rear.  

I think linked brakes are a good thing for an inexperienced rider because they proportion the braking effort to where the traction is 75% to the front and 25% to the rear.  If a bike has an over powerful rear brake I'd say that's the most dangerous control on the bike for a learner rider.