Well, with the pegs and foot controls sorted, and the tank mounted, I went looking for another excuse to NOT begin rebuilding the engine. So I’m now on to the front brake.
The front forks are from an ’82 GS750E, and the front wheel is from an ’81 GS850GL, both of which had two single-piston calipers clamping twin 276 mm rotors. The logical thing would be to just mount the matching OE brakes. But I figured I should see what front brake setup might be possible from the brake components currently in my parts cache:
The mounted disc is from an ’84 GS550E. It is 276 mm. The disc at right is from a ’76 GT550. It will also mount to my wheel, but it’s 292 mm dia. and 6.5 mm thick. (The disc at the left is from a Kawasaki BN125 Eliminator. It has nothing to do with this at all, but it was on the shelf.)
Perhaps one of these discs could work with the right caliper?
Cockwise from the top right:
- 4-piston from some Yamaha sport bike. I didn’t bother going back to look up the year and model because its opposed-piston, monobloc design is much too fat to work with my wheel and forks.
- Grimeca 3-piston caliper from an Aprilia Atlantic 500 maxi-scooter. It is actually a pretty promising candidate, but since it was used in a linked brake system in its OE configuration, I’d have to do some figuring-out on the proper master cylinder diameter.
- Yamaha V-Star 250. Small, twin-piston caliper isn’t known as a super powerful option, but it’s lightweight and would probably be suitable to a bike of Bultakenstein’s mass. (Although the bike keeps getting chonkier with every overbuilt bracket I fabricate.)
- Single-piston rear brake caliper from the off a Suzuki Vinson 500 four-wheeler. I bought this to replace a Honda CB125 mechanical caliper. It has no business on the front of this bike.
- 1980 Suzuki GS650GL. This came with the first set of forks I bought for this project, and the caliper itself should work. However since its off a cruiser with leading-axle forks, the hanger bracket it’s on won’t work with my forks.
If I wanted to make a custom adapter bracket for the Grimeca, V-Star, or GS caliper, I could make any of them fit the forks and rotor currently on the bike. However, after looking everything over, I decided that that’d be too much unnecessary bother. There are plenty of of Suzuki brake parts out there that will bolt up. Since a single disc is more appropriate to this bike than twin stoppers, I narrowed-in on the brake from a GS450 or GS750T; both had a single disc that utilized the same caliper carrier bracket as the GS750E, so I know it will fit my forks and have a properly sized master cylinder. I found this complete but molderin’ setup for under $40 shipped on Ebay. It should arrive in a couple of days:
It may or may not be rebuildable; I’ll find out when I examine it in person. However, I have the option of keeping the hanger bracket but swapping out the caliper itself for slightly earlier iteration from the the GS650GL. The master cylinder and brake hose will—at a minimum—be useful as mockup patterns, helping me determine what length line and piston diameter I need to source.
