Integrating front and rear brakes

[tctenng]

Hello all, long time no post but life has slowed a bit and I can finally refocus on my XS.
I have been toying with integrating my front and rear brakes. I understand all the physics involved and why it's better to keep them seperate but due to a birth defect my right hand is fairly small and while I have no problems with the throttle and gripping the bars, braking can be problematic especially with gloves and I think integrating the brakes is a safer option for me.
Anyone done this on an XS? Will the rear master cylinder handle it??? Do I need to add a proportioning valve??
I also understand that the XJ's had integrated brakes but have unable to find an XJ in the local bone jards to pull the system and "play".
Any opinions, ideas or even an old XJ brake system for cheap??

As always any help will be greatly appreciated.

Gregg

[John]

XJ brake parts

Gregg,
I believe I may have what you need to convert your XS brakes to a linked system, ala the XJ1100. I just checked my XJ parts inventory, and I have a rear master cylinder/porportioning valve, and the junction block under the head light where the rear brake line, and front brake hose tie in. I also have the steel brake line that goes from the rear master to the front block. I have the front brake hoses also, but I really don't know how good they are. If you are interested, e mail me at xs11parts@hotmail.com, and we'll discuss it there.

[Jerry]

An added note...

The XJ uses a smaller diameter front master cylinder (14mm) than the XS. Reason: the XJ unit has to move only one caliper, not two. If you convert to the XJ system you may want to swap ou the front MC at some point, as using it on only 1 caliper will make it 'touchy' and will require a light hand.

[mitch]

xj brakes

From my understanding you will not be using the front brake lever at all. You might try hooking both front calipers onto the rear system when u get the XJ parts, that way all 3 brakes will come on at the same time by just pushing the rear brake pedal. Make sure u install the mitering valve, should work fine just take a little getting use to Good Luck and Merry Christmas ..................MITCH

[John]

Linked brakes

Mitch, If all three calipers are linked to the rear master cyl, then there may be a problem of the rear master not being able to 'stroke' enough fluid to properly apply all three brakes. IMHO
Jerry, On the subject of the front being too 'touchy' for just one caliper, I would think that the front master from an XS650 would work fine. They were only single disc in the front weren't they? He could possibly heat and bend the front brake lever to be able to reach it easier. I've think I've got all the peices he'll need for the conversion. About the only problem I can think of will be running the steel line from the rear m/c to the front junction block in front. I'll bet together, we'll be able to help him through this

[mitch]

Yup

John you are probley right about the stroke but it might be worth a try . I think it depends on how much use he has of his right hand. Thats why i suggested it ,I think if everthing is up to par with stainless lines the rear master cyl could handle it , just an educated guess mind you. Hope he can get it working . I met a 1 armed rider at a rally here, he moved the clutch to the throttle side and intergrated the brakes to the rear master cyl on a virgo and it worked fine! It was amazing to watch him pull away with one hand operating the throttle and gas at the same time . Good Luck..........MITCH

[mitch]

front brake

Another example is what Ed Condlydid with his Xj with the smaller front mc, He hooked both front calipers to it and closed out the mitering valve. I drove his bike and the front mc was rather touchy, very good brakes which surprized me ! Like you i thought the mc would have a problum handling the extra caliper but it was very good . Just a thought ................MITCH

[fusionking]

The smaller the m/c the higher the presure. Adding a caliper will increase braking. Simple physics. My only worry is not having a backup if you lose your brakes. Remember the old car single m/c days??? One little problem and you lost it all!!!!!!!

[TheDjost]

How about mechanically linking another master cylinder to the brake pedal. Hell, you could even use his original master cyinder from the handlebar.

I'm writing this and I'm imagining a second master cylinder on the rear pedal to actuate the front brakes, and KEEP the original one on the handlebar. I'm also picturing some guy trying to steal this "special" bike... What a wipe-out if he tries to emergency brake!!


-Justin

[tctenng]

Well my earlier reply never showed up so I'll try again.
Thanks for all the feedback, all you guys are great!!
I think I will try putting all three on one MC and do some testing. Is the XJ metering valve adjustable? That may be an issue if it only was designed for two calipers. I could also try two on the rear MC and leaving one front on the front MC and modify the lever as sugested.
I don't quite understand how a smaller MC creates more presure, seems like smaller volume would create less pressure.

Gregg

[fusionking]

It's not about volume. You CAN'T COMPRESS LIQUID. It's more like leverage. To make it easier (maybe) look at it this way, If you made the calipers smaller you'd lose PSI. Mopar performance had a decent adjustable porportioning valve a while (10 yrs.) back. I'm sure others got 'em now if You look around. HTH

[John]

Hydraulics

Garry,
I understand all about hydraulics. Small pump piston, large cylinder piston= pressure, but even with a basic system like a floor jack, you need volume also. Fluid needs to be 'moved' to the large piston, and if the pump has too small a displacement there will not be suffient pressure build up, to firmly apply three calipers, with out pumping the brakes. I understand that fluid is not being 'moved' but some fluid must travel within the lines to apply the piston, and then force exerted against the piston by the m/c will build up pressure within the system.

[TheDjost]

Brake caliper don't need a lot of travel. They just need pressure. Connecting the MC to more calipers will increase the travel of the piston, hence the brake lever, but keep in mind that most of the free play in the lever is to tighten up the mechanical part of the assembly and to get the piston on the other side of the return passages(spooge hole). Once the piston is past that... not much else is needed in terms of piston movement(unless the brake lines are too expandable). Then it's all a question of pressure build up. With SS lines, I would think that one MC would be enough for three calipers.

-Justin

[flb_78]

if you could get a complete braking system off a xj1100 i dont think you would need to make all 3 calipers run off the same mater cylinder, my xj (when it was still running) had good braking just off the foot brake, id leave the hand brake on to operate one front brake just in case..

[fusionking]

Hey John! Jacks are designed with stroke built in them because it is needed. Have you ever let your rear drum brakes on your car get of adjustment? You have to "jack" them to get presure! When you ajust the clearance you have a "Hard" pedal again. This is the same way just very little travel. The jack presure is figured the very same way. One pump don't get you much there either (travelwise) Also jacks have a check ball so they don't back up....brakes don't. I like flb_78's comment....ditto!!! A backup is a good idea....a bad hand is better than none!!!(IMHO) P.S. To do it right when you add calipers you WOULD increase piston size to retain "feel"....Take'em away you decrease it (as per XJ)