[olddog]

I bought a used replica - already built. It has a HTOB. No idea what the make or model is. The car has about 20-25K miles on it. It was completed about 2003.

The only problem I ever had was self inflicted. I flanged the exhaust, and the new plates were close enough to boil the hydraulic fluid. I drained the fluid, rerouted the line, refilled and blead the air. Bleeding the air sucked. The HTOB has no bleed port. I had to loosen the hydraulic line, which included making a wrench.

I have read that there are some details on installation and setup that if done in-correctly causes failures. I also think there were some poor quality HTOB sold at one time (perhaps they're still being sold). These two factors gave them a bad reputation.

I believe there are HTOB sold with a bleeder port. No idea how to determine quality, but I think there are some OEM units sold, which should be reliable.

Bottom line: in theory, arguably in reality, a HTOB is a very clean install that elegantly solves a ton of issues that other designs have. If it fails, it requires disassembly. If it is reliable, you will wear out a clutch before it fails.

So in short all the arguments boils down to one thing, if it is reliable all the arguments against it are mute.

All the arguments why an external slave is better is based on, it is easier to fix, when it fails.