BSA B50 -500 APG Build

[Koncretekid]

Finally getting around to doing some work on the Bonneville Bike after taking some time to finish up a Norton Commando restoration for a friend.  Last year at 150 mph, we were out of gear.  Nearly 7,000 RPM on the long stroke motor and right at the peak hp.  The new rear wheel I made from a VTR 250 will not accept a smaller sprocket then a 36 tooth and we've already machined the B50 cases to take a larger front sprocket.

So I sourced a CBR F1 (I think) rear wheel at Ty's Motorcycle Salvage and with Doug's help, we narrowed up the cush drive which will accept at least down to a 34 tooth and maybe smaller.  The big change is going to be fitting a hydraulic caliper and master cylinder.

[Koncretekid]

For the brake side, the original rotor was small and I couldn't find a caliper that would fit between my frame rails and grab the rotor.  I wanted the caliper ahead of the wheel so I could remove the rear wheel without removing the caliper.  And with the caliper rearward, I was worried about clearance to the fairing.

Another trip to the salvage yard and I came up with a gigantic disc in good shape and it was flat and not dished.  Again with Doug's help (or more like Doug with my help) we made an adapter to fit the Honda wheel and accept the new rotor.  I still had clearance problems with the frame but managed to just fit a Kawasaki caliper into the slot.  I don't have much fore and aft movement but the 35 tooth is installed and I should be able to fit a 34 or 36 if needed.  Now I have to find a front master cylinder with a remote reservoir as my handlebars are nearly vertical.  Any suggestions?

Rear view shows how tight everything is with the narrow frame.

Incidentally, at 7000 rpm with the 36 tooth, I should have been at 153 mph but I guess I was closer to 6800 rpm.  With the 35 tooth, I should be at 158 mph at 7000; with the 34 tooth, 162. Unfortunately, I'll need about 15 more hp to get there and I have no more ideas (almost none at this point) to get there, so good salt conditions, fair winds, and following seas may be required!  

[saltwheels262]

Tom, I have used hydraulic clutch master cylinders and front brake master cylinders that were vertical . you should have no problem as long as the fluid level is above the transfer ports.

Bf262

[bak189]

On special LSR brake problems we have had great success using parts off the larger scooter that are now on the market........and they are cheap on E-Bay......I would not use them on road race projects.....but they work great on LSR....

[sofadriver]

I used a GSXR 750 front master. They have a remote reservoir. Easy to find on flea-bay

[Koncretekid]

Thanks for the tips.  I looked up Suzuki front master cylinders and ended up ordering an aftermarket one from China as the shipping was cheaper and I have plenty of time.  Surely being new it will work.

And I looked up rear brake calipers from scooters and found some that probably would fit better than the late model Kawasaki one I mounted. Modern rear calipers are mounted so that they float on two pins so alignment is not as critical as a fixed mount.  The mounting bracket captures the rear axle as well, so that adjustment for different sprockets does not require moving the caliper.  I'm not sure though whether the scooter calipers such as a nice Piaggio one for sale on ebay would work with the full 6mm thick rotor that I'm using. Many of the ones sold for scooters are only mechanical and do not appear to be robust enough for use at 150!  Another one that looks promising is an earlier 1980's Kawasaki caliper like "Bones" on DLRA is using.  The question is the width of the unit as to whether it will fit within rigid tubular frames members.

Next step is making a long hose to reach the front master.

Tom

[Old Scrambler]

I see you have little space to work in...................take a look at the rear brakes on the Aprilia 650 Pegasso and BMW F650 single units.

[WhizzbangK.C.]

I was looking at self retracting calipers to eliminate the drag that normal disc brake systems have.

Example.  http://www.summitracing.com/parts/wil-120-5750

[bak189]

We used a cable operated mechanical caliper on our 143mph Rotax/Can-AM bike with 200lbs. rider and had no problem stopping.....( one-way run only...SCTA/BNI said "Not Legal" back in 2001...Thanks Bill)...........
PS> We have tried the Wilwood Hydr. retracting caliper (new) but found we had to pump the lever several times to bring the pads up to the rotor...............................................................................................

[wobblywalrus]

The brake will have a more solid feel if it has a short hoses on each end and a metal tube mid section, rather than being hose for its entire length.

[JimL]

Tom, Speedway has long braided stainless premade lines at very good prices.  They have adapters to get from AN3 to metric or whatever, including banjo.  I used small thick wall spacers, threaded 10mm on one end, to accept the original hose banjo.  You can use steel with one fitting brazed to make a straight end for the AN3 female.  This makes a good way to "turn the corner" near the steering head of the frame.

I would consider the stainless braided for your bike which has some history of a little vibration, if I recall.  Its also easier to disassemble after the yearly salt dunking event.

JimL

[Koncretekid]

Not much to report except to say I got a long SS braided brake line and a new master cylinder mounted for the rear brake.  I still have to figure out an easy way to back off the pucks before I make my next rim.

In other news, I participated in a podcast about my land speed bike and how I got involved.  The site is Adventure Sports Podcast by Travis Parsons in Longmont, Colorado.  I tried to promote our sport and you can get the podcast here: http://www.adventuresportspodcast.com/2015/05/ep-033-tom-borcherdt-land-speed-racing.html

Tom

[Peter Jack]

Well done Tom. You covered the subject really well and I know how tough it can be to handle an interview. I seem to always remember one more critical thing an hour or more after it's all over. 

Pete

[salt27]

Tom,
 I installed coil springs over the brake pad retaining pins so they would push the pads apart.

With new pads there is very little piston retraction thus still a good feel to the brake.

   Don

[Jack Gifford]

... I was looking at self retracting calipers...

I'm a little bit confused (nothing new!). All OEM calipers I've dealt with had self-retraction designed into the cross-sectional shape of the seals.