"Unified" brakes for an XS650?

hardline42 · Posted: May 9, 2006, 9:56 am Post subject: "Unified" brakes for an XS650?

As I'm planning my bobber project I've been thinking of ways to "clean up" the handle bars. So far, and internal throttle and twist clutch are in the works. I'd also like to get rid of the front brake lever and master cylinder, but not the use of the front brakes (in fact, I'm gonna do a dual disc setup). I know Yamaha did a "unified" brake system on the XS1100 where the rear MC line went to a proportioning valve which fed a single rear caliper and one of the front calipers and were both operated by the rear brake pedal. The front MC and lever were kept and the lever operated the remaining front caliper. Would a similar system from an XS1100 work on a 650? Could I add a junction on the front brake side of the prop valve to feed both front calipers and run it all from the rear master cylinder and brake pedal? I'm no expert on hydraulics, but I know a lot of new bikes are running this type of "linked" braking system along with ABS. Anybody have any thoughts?

mo650chopper · Posted: May 9, 2006, 12:40 pm Post subject: Re: "Unified" brakes for an XS650?

The brakes are the single most important system on the bike I wouldn't try it myself especially not just for Cosmetics sake.

hardline42 · Posted: May 9, 2006, 1:39 pm Post subject: Re: "Unified" brakes for an XS650?

Considering that a lot of bobber "purists" only run a rear brake, I'd say what I'd like to do is an improvement where safety is concerned. Plus, with an adjustable prop. valve, the brake bias can be set to optimum front/rear brake pressure distribution for more predictable stopping (I always use both brakes at all times anyway). Another alternative, if seperate brakes are a must, is a twist brake instead of a clutch, and then a suicide cluth/jockey shift, but that has it's own coordination and safety problems I suppose. Any other thoughts?

mo650chopper · Posted: May 9, 2006, 9:54 pm Post subject: Re: "Unified" brakes for an XS650?

I can't say much about the safety or lack there of on the Jockey shift thing as I've run one for years and have one on my XS. I also would't ride a bike with only a rear brake, they make alot of squealing noise in a panic stop but don't do alot of stopping. I just think about how weird a car / truck acts sometimes when you slam on the brakes, wet / dry can be two different needs and wouldn't want to deal with it on 2 wheels. I like having the proportion control in my right foot and hand.

hardline42 · Posted: May 10, 2006, 7:36 am Post subject: Re: "Unified" brakes for an XS650?

I'm interested in how you fabbed up a jockey shift on your XS. Does it run off of the existing linkage, or is it directly attached to the case? Did you convert to a hydraulic foot clutch? Any pics? Thanks for your advice by the way. I may still do a linked brake system to only one of the front disks and keep a separate hand control for the other.

xs650mike · Posted: May 13, 2006, 12:36 am Post subject: Re: "Unified" brakes for an XS650?

The linked brake was on the '82 XJ1100. Having ridden a couple of Guzzis with linked brakes, I have to say I'd rather have control over what's happening with the brakes. If you could figure out a way to proportion the brakes to 80% front, 20% rear it'd probably be workable. Choppers aren't about all out performance anyway. Nothing inherently wrong with a suicide clutch setup, just be sure to hip your passengers not to lean left at a stop. Dunno if I'd want one myself. First thing I did to my WLA was change it to foot shift from the rocker clutch setup.

Wulf · Posted: May 13, 2006, 10:23 am Post subject: Re: "Unified" brakes for an XS650?

Considering that when you hit the brakes and weight transfers to the front, the front brakes handle 70% of your stopping power. Also, you as a rider would have a better feel for how much brake effect you need to apply in any given situation rather than leave that to a proportioning valve setup. Clean is nice... but your safety is much more important so unless you plan on trailering your bike to shows and never actually riding it stick with a good front brake setup. Just my thoughts.
Wulf

hardline42 · Posted: May 15, 2006, 2:18 pm Post subject: Re: "Unified" brakes for an XS650?

Thanks for the info guys, but I can't help wondering why so many new bike manufacturers are putting in linked brake systems if they aren't effective. All of the test results that I've read say that linked brakes increase maneuverability and stopping power as well as decrease stopping distance. I do have experience with setting brake bias with a proportioning valve from when I swapped discs in place of drums on my buddy's car, and the correct bias can be set for a motorcycle as well. My thinking is that by linking the brakes the bike would tend to stay flatter instead of diving, and be more reliable in a panic stop than it would be to modulate both front and rear brakes. I still have the option of a front brake control (left-hand twist brake) and maybe a foot-clutch with a right-hand jockey shifter.

Wulf · Posted: May 15, 2006, 4:05 pm Post subject: Re: "Unified" brakes for an XS650?

It's not that I'm against a linked brake system, particularly when it's a factory setup that the engineers have designed into the bike. The fact that you are somewhat familiar with setting up such a system is a plus in your favor. Brake dive is still an inherent factor of physics unless you have an electronic suspension system that compensates and stiffens the front end ( not likely ) upon braking. If you come up with a viable setup for the xs then by all means keep us informed.
Wulf

Phred · Posted: May 15, 2006, 6:31 pm Post subject: Re: "Unified" brakes for an XS650?

I suspect most linked brake systems use ABS systems (not real familiar with this type of bike, though). ABS would allow both brakes to function at "maximum" effectiveness. Note that linked brakes were not used prior to ABS technology becoming available and realatively inexpensive. A proportioning valve is set to a "best guess average", and braking in other than ideal situations will likely be compromised. Even with an adjustable valve, you will not be able to adjust it correctly to meet constantly changing conditions. IMHO, this is one of those ideas that are good only when technology makes it possible to make them to function well.

royfisk · Posted: July 23, 2006, 7:18 am Post subject: Re: "Unified" brakes for an XS650?

Well guys I think that it would work just fine, probably a few days of playing with the valve for fine tunning. I guy I know set a sportster up this way back in the 70's , although I do not know how many miles were put on the bike I do know that it rode back and fourth to loudon clasic for at least 10 years that was at that time a 80 mile ride one way through little village towns. HE DIDNT EVEN USE A PROPORTIONING VALE. Cant say that I would do it but on a bobber. I ve seen alot of other things that are probably MORE DANGEROUS. Like the famous moped brake drum on the front ends of chopped out FL,s . Or worse yet the infamous spool hub. Try it if it makes you uncomfortable you can always change it back>>>

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