I documented this extensively in the Trail Bike build, but I thought I'd bring it back with an update. You can find the actual fab work here starting at post #40: http://www.oldminibikes.com/forum/p...ail-bike-build-resto-kinda-sorta-maybe-4.html
The prototype needed some changes to work more effectively. One of the problems with the prototype was the inability of the lever to fully apply mechanical advantage. Secondly, the hand brake lever needed to exert full force at about halfway in (which is the ideal). To correct this, one part especially needed work: The rod connecting the lever arm to the brake band was too long (1.75") and accordingly too much travel. It was reduced to 1.25". The next two photos show it as originally assembled. Note the band pivot point. This may have to be adjusted again shifting to the right about 1/4".
Here is the version with the shortened arm. The lever is now against the band in the "rest" position.
The other issue was the cable stop. The cable sheath is supposed to stop at the tab on the left. However, this location interfered with the TAV Driven. The other problem is that any sort of bracket off that tab had too much flex and reduced the mechanical advantage of the lever (this is a big problem on the Trail Bike). So, the stop is moved toward the rear and slopes up (for TAV clearance) and is bolted in two places, and no flex. This is slightly thicker stock also. From the factory, there was no spring. This design uses a spring to make sure the lever returns to rest.
Another look. I used a 5/16" bolt with a stop nut and lock nut to secure the cable. Alert eyes will see two nuts on the axle: I needed a stop because the axle is threaded on both sides and the outer will come off.
The jackshaft and TAV assembly got sorted and Copperhead is almost back together. Was way too cold today to even consider starting the bike and doing a test ride.
The prototype needed some changes to work more effectively. One of the problems with the prototype was the inability of the lever to fully apply mechanical advantage. Secondly, the hand brake lever needed to exert full force at about halfway in (which is the ideal). To correct this, one part especially needed work: The rod connecting the lever arm to the brake band was too long (1.75") and accordingly too much travel. It was reduced to 1.25". The next two photos show it as originally assembled. Note the band pivot point. This may have to be adjusted again shifting to the right about 1/4".
Here is the version with the shortened arm. The lever is now against the band in the "rest" position.
The other issue was the cable stop. The cable sheath is supposed to stop at the tab on the left. However, this location interfered with the TAV Driven. The other problem is that any sort of bracket off that tab had too much flex and reduced the mechanical advantage of the lever (this is a big problem on the Trail Bike). So, the stop is moved toward the rear and slopes up (for TAV clearance) and is bolted in two places, and no flex. This is slightly thicker stock also. From the factory, there was no spring. This design uses a spring to make sure the lever returns to rest.
Another look. I used a 5/16" bolt with a stop nut and lock nut to secure the cable. Alert eyes will see two nuts on the axle: I needed a stop because the axle is threaded on both sides and the outer will come off.
The jackshaft and TAV assembly got sorted and Copperhead is almost back together. Was way too cold today to even consider starting the bike and doing a test ride.