Adjusting Brake Regulator Options

[bbrock]

I just finished rebuilding my brake regulator with the PMB DIY rebuild kit and it looks like new. Only thing left is to set the switch to 525 psi. I'm guessing I could send it to PMB to have them set it, but wondering if this could be done locally at a brake shop. Anyone know?

[Superhawk996]

I just finished rebuilding my brake regulator with the PMB DIY rebuild kit and it looks like new. Only thing left is to set the switch to 525 psi. I'm guessing I could send it to PMB to have them set it, but wondering if this could be done locally at a brake shop. Anyone know?

I'd send to PMB. In fact, I just packed mine up to go off for the very same service. You can't beat PMB's price to rebuild, replace old seals, and then to set it.

I used to be a brake design & release engineer among my many former jobs. You don't want to mess with rear bias. Especially so on mid-engine low polar moment of inertia vehicles. Personally I don't know of any retail brake shops with the hydraulic test equipment to attempt setting it and/or to accurately measure it. The consequences of getting it wrong could be catastrophic. Personally, I'll just pay the guy with the right equipment that has done it a time or two rather than risk training someone.

Not saying it couldn't be done but I can't tell you how many pads I've found installed backwards over the years when someone was complaining of noise. (IMG:style_emoticons/default/lol-2.gif)

I've toyed with the idea of putting ABS on . . . that would be sweet! Would just add weight and more complexity which defeats why I want to get back to 914's in the first place.

[bbrock]

I just finished rebuilding my brake regulator with the PMB DIY rebuild kit and it looks like new. Only thing left is to set the switch to 525 psi. I'm guessing I could send it to PMB to have them set it, but wondering if this could be done locally at a brake shop. Anyone know?

I'd send to PMB. In fact, I just packed mine up to go off for the very same service. You can't beat PMB's price to rebuild, replace old seals, and then to set it.

I used to be a brake design & release engineer among my many former jobs. You don't want to mess with rear bias. Especially so on mid-engine low polar moment of inertia vehicles. Personally I don't know of any retail brake shops with the hydraulic test equipment to attempt setting it and/or to accurately measure it. The consequences of getting it wrong could be catastrophic. Personally, I'll just pay the guy with the right equipment that has done it a time or two rather than risk training someone.

Not saying it couldn't be done but I can't tell you how many pads I've found installed backwards over the years when someone was complaining of noise. (IMG:style_emoticons/default/lol-2.gif)

I've toyed with the idea of putting ABS on . . . that would be sweet! Would just add weight and more complexity which defeats why I want to get back to 914's in the first place.

That may be what I'll do. Rebuild is already done though. My regulator looks just like Eric's pic on the PMB site now. It's a pretty simple procedure. Most of the work is cleaning and painting. Mine was really gunked up inside. I went ahead and zinc plated the valve body and spring housing too, but that didn't take long. The actual rebuild is a 20 minute task.

The factory manual has a procedure for testing and adjusting the regulator while installed in the car. The procedure is to install high pressure gauges in the front and rear circuit and then adjust the regulator to get the proper bias pressure. They don't provide a procedure for bench testing though.