Front brake refurbishment/upgrade contemplations...

[TeeCat]

Hello, all...

Lately, having hopefully slayed some other more annoying dragons, I have been wanting to finally address the front brake on my '73. The components appear original, aside from some suspect upper hose routing by the PM (Previous Moron), and the lever is firm (if a bit "wooden"), and stop the bike, but refurbishment or upgrading is needed.

I have been doing a lot of reading, beginning here, and would like to use stainless lines (or a single stainless, if I understand Leo's recommendation correctly). My original thought was to tackle rebuilding my M/C and caliper, but after having priced kits at Mike's and 650 Central, I was surprised to find that it would cost as much or more to do that than to replace them. Were I to do the latter, I would be looking at:

- Early Caliper Set(74-76) Left/Right side, Part #08-6008

because, though it says '74+, it appears to be identical to mine (please see below) as far as I can tell; and

- 76 Type Single Master Cylinder 16mm Bore, Fits: XS650's Early Model 72-76

because it is correct, and should accommodate my very recently replaced front brakelight switch (NOT hydraulic, but electro-mechanical arm type).

I'm looking to see if I'm on the right track here in considering these for replacements, for use with braided line, and the necessary fittings. Essentially, I'm trying to develop a parts list so that I'll be able to avoid any unpleasant surprises, overbuying, underbuying, angst-induced seizures, etc., and eventually boil this down to assembly and bleeding the line.

Again, I'm in research/forethought mode, but getting a parts list will put me closer.

Thank you for looking!

TC

Existing caliper:

 

[CDNTX650]

is someone selling those early calipers new now?

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[TeeCat]

CD, I think they're new at Mike's! I don't recall having seen them before when I was occasionally thinking about my front brake. This new owner seems to be adding to the inventory if I'm correct!

 

[CDNTX650]

fack, XS650direct doesn't have them yet. i want one so i can do a dual disc set-up

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[TeeCat]

Yup, I think they'll mount on either side.

 

[XSLeo]

Ijust noticed them yesturday. From what I could tell from looking at the ones I had. The upper mount bolts one is longer and is threaded for a nut. These bolts can be put on either side.
If they are made like my stock 75 caliper the tee part of the tab on the brake pad may get in the way when used on the other side. If so just cut the tee part off so it sticks out of the caliper a bit. Some of the pads come that way. Just a straight tab, some with the tee.
A one piece line gives you less places for leaks. The two lines have the junction block. More possible leaks. On some years they put the brake light switch in the junction block.
My 75 was that way.
Even on the blocks with a switch you can still use a one piece line. Just use a banjo bolt with the switch built in.
I have been using one on my rear disc brake a coulple years now. Works good.
I'll post a few pics of parts I mentioned.
One is the banjo bolt switch.
One is the joint block switch.
one is the block switch in the block on my 75 fork.
Leo

 

[XSLeo]

Using the stock caliper #08-6008 with the #08-6009 M/C will be a slight improvement in your brakes. Your feel won't get much better.
I know it won't look like the stock one but # 08-0255 with a 13 mm bore will give you better feel and a stronger brake.
As I said in the other thread, I have the dual disc set up using the later single piston calipers. I have used the stock 16mm M/C, a 14 mm M/C and I curently have a 12.7 mm M/C on now.
The stock 16 mm does feel a bit "wooden".
The 14mm has a good feel and gives strong brakes.
The 12.7 mm gives very strong brakes and even better feel. This one at first was too much brake, Now after a few miles to get used to it It feels good. It takes a light pull with one or two fingers to get the same braking as the 16 mm did with a four finger death grip on the lever.
With the late calipers, dual disc I think most will be happy using a 14 mm master cylinder.
On the older two piston caliper, single disc a 13 or 14 mm should work good.
On an early two piston dual disc the 16 mm should work good, I say should because I haven't tried it myself.
On a later single piston caliper single disc The 11- 12 mm M/C's should do well. I think MMM reccomends the 11mm with the later single set up.
I think I will try the 12.7 mm I have with a single piston, single disc set up. From what I hear the weight reduction will improve handling.
Calling MMM and discussing this with him is a good idea.
Grizld1 has some good knowledge on brakes, others on here are good sources of info too.
Leo

 

[XSLeo]

Looking at Mike's he has a listing of all the new stuff. He has them scrolling across the page.
Leo

 

[TeeCat]

Leo, thanks very much for all this additional information. For a brake neophyte like me, it's a lot to digest! Sifting through it several times, though, and considering what you have said about the various M/C sizes, I think I'm actually more concerned about just knowing the state of repair that the system is in than I am about changing the feel of the lever. All things considered, I'd like to stay with as close to stock M/C and caliper as I can - basically replace each of them with a new unit - but go with one stainless hose, eliminating the junction. If this basic plan would be okay, what additional fittings (bolts, washers, etc.,) would I need to complete the picture? I suppose that either you or Travis could tell me what particular hose to order, though I'd have to measure. And I suppose the banjo bolt at the M/C should swivel, right? And if I eliminate the junction block, I'd just use a loop of some kind to keep the hose close to the lower triple tree, right? I don't have the bike in front of me... sorry...

By the way, here is my brake switch, which I would like to keep:

Thanks again, Leo!

TC

 

[XSLeo]

I just had a thought, your caliper has the short steel line that screws into the caliper. You will need to get a fitting that will screw into the caliper on one end and have the braided line fitting to screw on the other end.
I'm not sure on the size of the threads in the caliper. I don't have one anymore to check.
I think most brake lines use an AN-3 fitting.
I was looking for that type of connector when I first started looking at brake upgrades. I think I found them at Russle or Goodrich. Both make brakelines and fittings. I don't have there websites book marked.
You might even find them at the parts store.
Hold on I just looked in my scrap parts box and found a line. The fitting that screws into the caliper is 10 mm in diameter. Thread pitch is maybe 1.00.
Just checked on the russle site, they have a 10x1.00 x AN-3 fitting listed. They don't list a price anywhere I could see.

 

[5twins]

The earlier 2 piston caliper is considered by many to be a better stopper than the later single piston unit. Yours probably just needs a disassembly and cleaning. You don't need to replace anything, just take it all apart (MC too) and clean it out. If both pistons aren't working and moving properly, the brake won't work worth a shit. Clean everything out, replace the line and maybe the pads. That should be all you need to do. Unless of course, you want to piss away several hundred dollars for nothing, lol.

You can fab up a strap to mount in place of the junction block to use as a guide for the new single line .....

 

[TeeCat]

Leo, thanks for this additional information. I'm flagging this in case I decide to go the replacement route. I do want to go with the braided line, though, and reroute it.

twins, I can fab a strap, no problem... I'm getting pretty good at making small aluminum/soft metal bits. However...

I'd still like to be sure, going in, what I'm ordering. If I'm keeping everything stock except the braided line, then I'd need new connections at the M/C, and at the line end of the short steel line. So, what do I need at each end? Do Leo's suggestions about the caliper-end fittings still apply if I stay with the existing parts?

I'm assuming that the pistons are free. I just want to try to avoid getting into this and then realize I need parts, having the bike down for longer than needed. This will be my first brake work, so I want to learn to do it right.

Lastly, twins, does your hose come across your headlight, and then down and back across? Any preferred routing? I'll have to measure for line and ascertain the right type, right fittings, etc.

Thanks, guys, for all the help thus far!

TC

 

[5twins]

If the system isn't leaking anywhere then you probably don't need any rebuild parts. Brakes are like carbs - 99% of the time, a "rebuild" consists of a disassembly and thorough cleaning. The caliper is stone ax simple. The only moving parts are the pistons. The only seals are the square section rubber rings that seal the pistons into the body. On your 2 piston version, there is also a small o-ring around the fluid cross-feed hole between the caliper halves. Over time, brake fluid works it's way into the groove and under the square sectioned seal. It dries there and a crusty build-up accumulates. Eventually, this forces the o-ring out more and that causes the piston to bind or stick. The last caliper of this type I serviced barely worked at all. One piston was stuck solid so only one moved. It had like half a brake and didn't stop very well at all.

The line I'm using was an eBay special and pretty much free. I bought a lot of 3 and sold the other 2 which paid for mine. It was a couple inches longer than ideal but I compensated for that by looping it over to the left headlight ear before going down with it .....

It runs straight down from the MC behind the headlight and between the headlight ears, just like the original. So, you can compensate for a slightly long line through creative routing.

For measuring line length needed, I get about a 4' length of solid copper electrical wire (one strand from standard house wiring), route it, mark it, remove, straighten, and measure.

I'm not sure about the fitting sizes. The top is probably an M10 banjo but I don't know what the bottom is. I would call 3M at 650Central. He's the brake expert.

 

[gggGary]

Heads up here, the 72 and 73 disk brake system IS different than 74 to 76. Not sure if the caliper is different but the disk mount is. Dual disks are not possible on a 72 -73 wheel, fork.

 

[TeeCat]

Gary, thank you. I'm not going the dual route, but I was considering replacing my M/C and caliper. But based on what twins is saying, maybe I should just plan to disassemble both and clean them without replacing any parts except the conversion to braided line, and replacing the pads.

twins, thanks for this. Yes, in the time I have had this bike, the brake has never leaked a drop, and feels firm and stops the bike, but there's sometimes a sort of groan when things are cold and I move/roll the bike, so I do wonder about whether both pistons are up to par. So I suppose I would do well to call MMM and see what he suggests as well.

TC

 

[CDNTX650]

The earlier 2 piston caliper is considered by many to be a better stopper than the later single piston unit. Yours probably just needs a disassembly and cleaning. You don't need to replace anything, just take it all apart (MC too) and clean it out. If both pistons aren't working and moving properly, the brake won't work worth a shit. Clean everything out, replace the line and maybe the pads. That should be all you need to do. Unless of course, you want to piss away several hundred dollars for nothing, lol.

You can fab up a strap to mount in place of the junction block to use as a guide for the new single line .....

Oh mine is a rebuild with new M/C and it works well.....but compared to the 320mm dual 4 pot Brembos on my 999.....it sucks...

 

[gggGary]

+1 on an R&R specially the caliper clean em buff the pistons get the gunk out from behind the seals and "usually" you are good to go. Note; I have not done a set of early brakes yet.....

 

[TeeCat]

Well, guys, I sent a note to MMM (I prefer to document things like this so I don't forget details), and heard back. He indicates that he should have everything I need for what I want to do (though he didn't say whether he has the braided line), but really didn't get more specific than that. He did recommend a seal kit for the caliper, so I'm getting some conflicting opinions on that aspect, though I'm not flatly opposed to that. New pads are obvious, but I have to determine what type (T or not).

Also, he's suggesting a smaller M/C. Based on Leo's explanation, I understand the "why", but I'd really prefer to stay with what I have, partly because I don't want to replace a brand new switch and introduce other variables. Basically, what I want is a safe, serviced stock system, but upgraded to a one-piece braided steel line.

So, if this makes sense to you guys, I was thinking of asking Mike to gin up an itemized parts list for me so I can send him a check when I get ready. As some have pointed out here elsewhere, it is a matter of personal security policy for me to refrain from making telephonic credit card purchases.

Thanks so far, guys!

TC

 

[XSLeo]

On the credit card thing lots of folks except Pay Pal, that way your credit card numbers are less apt to get misused.
I don't have the tools, a lathe for one, a boring machine another. But someone who has, if they could bore out a M/C so a sleeve could be installed, the sleeve could be made for any bore size. Stainless steel might be nice but brass would work too.
That way you could have your stock M/C sleeved to a 14 mm bore to improve the brake and still look stock.
Any one out there willing to try?
Leo

 

[TeeCat]

Leo, I suppose I'll just try to agree on a parts list with him when I'm ready, and send a check. It never occurred to me to ask if he accepts PayPal, but I don't see anything about it on his site. Also, I'm in no real rush because I'm not actually experiencing problems with it... I just want to be sure what's going on in there, and the only way for me to do that is to service the system and upgrade the line.

Your sleeve idea is a good one! Can't imagine why that would not work if one had the wherewithal. So basically, less volume for fluid increases potential pressure, I suppose?

TC