Nobody wants to remember the history on this epic. Converter loading/launching has been covered before on this topic.
The PM caliper is to replace the two currently pictured on the bottom of the rotor. It mounts to the hanger using the two holes on the outer edges at the bottom of the caliper as shown in the pictures. The setup has been used successfully to bracket race on a quicker and faster Hondamatic drag bike than Sam's. The setup on the Hondamatic won't allow you to hit the "Stall speed" of the converter. I'm running 100 horses at the rear wheel with my 1180 cc Hondamatic and still haven't "stalled" the motor. I have repeatedly launched at 6 grand with it, using my modified converter. Jim has that converter information. A smaller horsepower motor just won't launch at as high an rpm using the same converter. Yes the converter generates a lot of heat when being forced to slip. That's why you don't get on the throttle until you see the tree start. That makes for about a one second loading/slipping of the converter. We run an aftermarket oil cooler to try and help control the oil temperatures. Flashing the converter may result in a slightly lower ET, but you can't repeat the flashing consistently. I've tried that. This is bracket racing. Loading it for one second doesn't overheat the oil, does result in consistent launches, and consistent ET's.
I've drilled the launch sequence into Bill and Sam from day one. If you get onto the gas on the starting line before the tree starts, you run the risk of overheating the oil. Sometimes, you end up on the starting line for a while due to things that you just don't know about.(computer problems, vehicles on the far end of the track, etc) Overheat the oil and you lose tenths. The only way to get it back to normal is to change out the oil.
Jim, I used that caliper on the top of the rotor on my setup. It compresses the brace to the swingarm when under load. That won't cause any major failures due to fatigue, unlike your current bottom mounted ones. Applying the brakes with the current setup tries to pull the brace apart at the mounting points. Neither is likely to totally fail, but on the top is almost guaranteed to work. Yes, periodic inspections of any race bike's brake system is always time well spent.
Frank, I've tried looser converters to launch at a higher rpm. The efficiency loss more than offsets the higher rpm launch. ie, you go slower. A lockup converter would solve that but I haven't found someone to offer to make me one. Using this brake, I've gone .012 over my dial-in at a Prostar event in the first round; upped my dial-in by .01 for the second round, and run .001 over on that pass. Back to back runs in competition that were .001 apart on an 11 second Hondamatic using that exact rear brake system. Nobody needs to be spending more money now. We've got the parts that we need for a consistent bracket racing bike.
If you want a record time slip, you do want to flash the converter. I've run these bikes for over 20 years. They can be an ATM. Chad Isley had a reputation for consistent winning with his. Why don't we hear about Chad winning major events today? He's gone away from his Hondamatic to a conventional drag bike. Why? Because he couldn't find the ET consistency that he felt that he needed. Chad cut some great lights with his Hondamatic. It ran low 13's/high 12's. It wasn't a highly modified bike. He launched off of the stock rear drum brake and foot petal. His oil cooling system was stock. Chad was kind enough to recommend me to Sam at the start of the build saga. I offered to put Chad on one of my Hondamatics to show him that the consistency was possible using my rules for when you load the converter, using the correct mineral based oil, and external oil cooler. He declined due to schedule conflicts/funding limitations. The nearest thing to a Hondamatic ATM should be at Valdosta in November with Sam driving.
We should be getting near the rear tire traction limit using the current equipment with some more cam advance. If we could get a higher stall converter that works, we would need a rear rim and tire change. The current narrow bias ply tire is giving us low 1.9 second 60' times. There isn't much more left there. The combination is nearly maxed out. Let's see what Bill does using the "new' rear brake system at a test and tune before Valdosta. Those time slips and his feedback should help end the speculation.
Jon Weeks
