| Author | Message | |||
     Diablobrian |
I was wondering if anyone had any experience with designing/building a thumb brake system. Most are run on the left handlebar from what I've found. I am a machinist and I know I'll have to fab some parts, but I was wondering if anyone had any insights from previous experience I could benefit from. | |||
| Rocketman |
I've often fancied trying a thumb brake set-up but I hardly ever touch the rear brake on the Buell. If I do it's usually to slow the bike approaching a red light simply to blend off the speed. Riding hard / fast, if I use the rear brake here, again it's to blend off speed in an effort to hold or achieve a better line or corner approach. Probably after I've already cocked it up. With those scenarios in mind, that's where I'd really like to try using a thumb brake but I'm doubtful there'd be much benefit if any. Worse still for me, I think such a set-up might encourage me to adapt a different style of braking (just to use the thumb) that might end up doing anything but enhancing my riding style / performance. Given that I don't track ride really - I've done a little that's all - I couldn't offer a valid opinion as to whether or not I'd benefit there with a thumb set-up, but I'd guess that's where I'd most likely find it would work well on a Buell. I'm still debating on which way to go with lever set-up. I fancy the CRG short folding levers but I also like the total bling effect of the remote adjustable GP levers CRG offer. Then there's a company in mainland Europe who make a full set-up, reservoirs and levers in billet etc, and I'm spoilt for choice. One problem I'm facing with this lever situation is the placement of mirrors. I'm a firm believer that any S1 Buell has to have mirrors upright off the bars otherwise I see it as detracting from the aggressive upright stance of the streetfighter. So whilst searching out levers I have to include mirrors, and space on the bars for them and their mounts, in my search. Rocket | |||
| Diablobrian |
I have a unique problem. when I stop on a slope I have to put my right foot down. I cannot use my left. Makes it difficult to take off when pointed up hill. If I have a thumb brake problem is solved. I have a long enough brake line and an enclosed clutch master cylinder to adapt. I just wonder if it would be more efficient to use the existing rear master cylinder re-located and make a linkage/lever for that. Except in hard stops that's about the only time I use my rear brake. (Message edited by diablobrian on January 07, 2006) | |||
| Rocketman |
I'm guessing here but I'd say you'd need to find out if the thumb lever you make / use / adapt has a leverage ratio that enables your thumb to apply pressure in a usable manner. Have you considered putting a joint foot brake on the left side with a perhaps discreet lever/ pedal facing backwards, which I would say might suit your purpose better? Rocket | |||
| Diablobrian |
left leg is paralyzed. | |||
| Old_man |
As a hillholder only I don't think It would take a great deal of pressure to work. Try hanging some weight on the pedal to see how much is needed, If not too much, a simple cable attached to the bottom of the pedal might work. | |||
| Diablobrian |
good call, I already have a long enough brake line to do it right though. You are correct that I shouldn't in any case need a lot of pressure. I can always rearrange pivot points to increase mechanical advantage if needed. I have never bought into the old cruiser fear of going over the handle bars if the front brake is applied, so I almost never touch the rear brake, except to tighten a corner without upsetting the chassis, so when I do it is usually a light touch and may even be better and more precise with a thumb brake. I'm trying hard to see silver lining in all of this if you couldn't tell. | |||
| Opto |
It looks like using the front brake to hold the bike when stopped is not on your list of possibilities. I see you have an electric or air shifter in your profile, could the same technology be used to hold the rear brake pedal down with the flick of a switch? Maybe just hook up the clutch master cylinder and see what it feels like without actually mounting it on the bike. See how it goes. Ian. | |||
| Rocketman |
And there I was wondering how you changed gear  How's that electronic shifter perform Brian? It must make that wicked Buell accelerate quicker than clutch changing? I presume you don't clutch at all on up shifts once moving? Anyway, this thumb brake thing. That's such a trick XB I don't think anything less than fitting a proper set-up, like Brembo's one, would do it justice. Can I believe the expense bothers you? Nah, you've spent a fortune already. Go with the real deal - then tell me how you like it. Rocket | |||
| Jackbequick |
Brian - Do you want to modulate the braking or just have instant release? If the latter, maybe a "line lock" type solenoid would work for you. I'm not sure about the sizing of the hardware and if it practical but it was a thought. Here is some info: http://www.rpmoutlet.com/hurst.htm Maybe something with a switch on the clutch lever so that if the clutch is pulled in hard against the grip with some braking force applied, and then held there, it locks the brake line pressure. Jack | |||
| Diablobrian |
those are exactly the kind of input I'm looking for. And yes, I can just pin the throttle and click through the gears when the shift light flashes. Thanks for the compliments too. After some study I think I'll be using the rear master cylinder and machine the lever and mount for it. Something along these lines...
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| Truk |
I have heard that Miguel DuHamel (sp), AMA racer for Honda uses a thumb brake. He is not the only one from what I understand. I do not know if there is a supplier of racing equipment that sells them, but could be.... | |||
| Diablobrian |
sure there are several options ready made. this is the largest...http://www.gptechllc.com/products_thumbrakes.htm http://www.ema-usa.com/brakes/brakes_APracing.shtml near the bottom of the page. http://www.ema-usa.com/misc/misc_harris_zstuff.shtml#torb bottom of the page again http://www.speedycom.co.uk/shop/product.php?productid=16708&cat=347&page=1 http://www.demon-tweeks.co.uk/products/ProductDetail.asp?cls=MCYCLE&pcode=A/PCP4 325-6 http://www.iane.co.uk/brembo_racing_brake_cylinders.html bottom of the page I'm sure there are several others I'm missing as well but that's a fair cross-section. I just see this as a project that I should, with proper planning, be able to knock out in an afternoon. I have aluminum stock on hand to machine the clamp and lever, a proper length braided brake line, and a small machine shop in my garage. | |||
| Rocketman |
Brian, yours looks real neat. Go for it. Whilst you're at it make a thumb and foot combo one for me and I'll road test it in the proper fashion!!!! Rocket | |||
| Diablobrian |
The "junction valve" available commercially for a dual setup uses the brake line between the thumb cylinder and foot for the foot reservoir. I could machine a pressure adapter that works for our bikes, but the commercial one will not work with our rear master cylinders. In any case I don't need a dual set-up, but that doesn't mean it cannot be easilly produced. It would not be hard to make a second mount and lever, set-up time is the bulk of the hassle in machining parts. Once the machines are set for the operation that process can easily be repeated. If you are serious I'm sure we can work something out. (Message edited by diablobrian on January 08, 2006) | |||
| Rocketman |
To clarify Brian, you wish to use the original m/cyl but mounted at the bars and run a brake line from it direct to the caliper and remove the foot set-up? Rocket | |||
| Diablobrian |
That is my current intent. Kind of like my shifter. I removed the lever there too. I may end up putting one back on there though to make it a little easier to find neutral. The shifter tends to want to find a gear even when I don't want it to. Then I can just hand shift to neutral. (Message edited by diablobrian on January 08, 2006) | |||
| Rocketman |
Ok, I'm interested. I have a spare m/cyl as it happens and my ss rear line has chafed somewhat and needs replacing, so I'm up for a little prototyping. With two of us going at the costs that should make it more reasonable for you I hope. Rocket | |||
| Diablobrian |
cool I pulled the rear master cylinder last night. I'll have to get Busy on mocking up and getting dimensions for the parts. I still might end up rearranging things a bit and making this a radial master cylinder. I'll have to look at clearance and aesthetics. BTW what is the outer diameter of your fork legs and how high are your handlebars relative to the master cylinder placement? and which bike are you intending to install it on? | |||
| Rocketman |
I'll have to measure tomoz at the workshop but it's my S1W with stock bars and fork legs. Why fork legs? We're talking here of ignoring the stock m/cyl and pedal. Instead we're placing a m/cyl on the bars, near to or integrated with the thumb lever. Then in my case, running a braided line down to the brake caliper, though I might look to joining it in the line so I can still have the use of the foot lever. How am I doing? Rocket | |||
| Diablobrian |
If you join at the slave cyl the pressure will just back up into the other reservoir without a valve arrangement of some sort. The mount for the thumb cylinder will go on the fork leg, there is just no room on the bar of the xb for it. I also need to know how far from the fork leg the inner edge of your grip is. The way I see this, it will allow a little more adjustability, if it works out correctly. It should be easily reversible as well so it can be mounted en either side. If this works the way I intend for it to there is probably a bit of a market out there for racers, stunters (controlling a wheelie without "covering" the right peg), and people just wanting to build repliracers for less than these other outfits are charging. I'll have to ask DaveS how much a rear master cylinder / reservoir assembly from an xbr costs. So I can tell non-buellers what they need and how much it'll cost to "roll their own" as it were. I've continued this in the public forum instead of taking it private in case others are interested in the project, but I fear the KV doesn't get the traffic that the other forums do. Ahh well, their loss. We are getting near the point where I'll PM you with more specifics. | |||
| Rocketman |
Brian, from fork leg to inner edge of grip is about 80mm, but 10mm is used for the mirror mount. Fork tube is about 80mm o.d. The height drop from the highest point of the bars to the fork tube top is about 70mm. There's not a lot of room, if any, for a Buell rear m/cyl me thinks. The brace around the fork tube might also be unsightly and close in proximity to the fuel tank when the bars are in full left lock. I found out that Honda use a m'cyl and reservoir combo with sight glass on one of their crossers, but I know not which one. I've seen a picture of it and it appears small in the picture. Food for thought? Rocket | |||
| Old_man |
Front brake m.cyl? maybe | |||
| Rocketman |
Well, for example, one could use nothing but a small tube with a stopper in the end for a reservoir, ala GP style. The key to making a thumb operated m/cyl and reservoir work for me is to have it small enough so it isn't unsightly. The motocross Honda set-up looked ideal in that it is nothing more than a 'tube' shaped cylinder with integral and sealed reservoir that also included a sight glass. I liked what I saw from a practical and aesthetic standpoint. Whether it would work in our thumb brake set-up I couldn't say without seeing one in the flesh. Here's an interesting article on motorcycle braking systems that happens to include Higbee and Buells. Note in the picture of the GP m/cyl the black rubber tube that acts as a reservoir. Rocket | |||
| Diablobrian |
the tubing for a reservoir is used a lot on race bikes, particularly on the rear as a weight and space saving measure. as long as the stopper seals well it should work just fine. You may need to change fluid a little more often due to moisture absorption, but as long as you are aware of it, shouldn't pose a problem. I'll take a look at what is being made for motocross use. I didn't know that they were using them. It may be a viable option assuming the clamp is adaptable. | |||
| Diablobrian |
old_man: Good idea, if there was enough room on the bars. However most are too large for the space requirements. I had originally considered this. | |||
| Diablobrian |
things have been held up a bit due to scheduling. I will be back on the project soon though. | |||
| Rocketman |
No worries Brian. I'm still working on ideas in my head too. Rocket |
