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]

Thanks guys that is brilliant. Now you've got me going down the rabbit hole. The engineer in me always wants to know what is in the box.

Lots of great links for me to waste time on. (IMG:style_emoticons/default/biggrin.gif) I've always been curious and those are great pictures and the links to the theory of operation are superb.

Bottom line w.r.t. the pressure difference between a /6 and the 4 cylinder is likely related to:

1) the six has a bit more weight on rear and therefore can take more pressure all other things held constant.
2) The six had different rear calipers. I'm not up to speed on all the details but I'm sure piston size, and effective radius (off the pad/rotor interface) will be slightly different.

One last thought for the morning -- don't cheap out for the sake of $30 shipping here or there. You've put endless hours into your restoration. I've spun 914's more times than I care to count. They can spin very quickly especially if doing a lift throttle while braking mid corner. Don't make it worse by getting bias wrong. Don't risk getting your rear bias wrong by being cheap to the tune of $30 shipping (or even $200 or $500 for that matter). It is all trivial if you end up with a car on the side of a tree assuming we walk away!

If you put in the time and effort to adjust it by the factory manual, you'll be fine.

The broader point is keep the big picture in mind. There are some things to go cheap on (trust me I understand - I'm a cheap SOB) but brakes aren't one of them.

[bbrock]

One last thought for the morning -- don't cheap out for the sake of $30 shipping here or there. You've put endless hours into your restoration. I've spun 914's more times than I care to count. They can spin very quickly especially if doing a lift throttle while braking mid corner. Don't make it worse by getting bias wrong. Don't risk getting your rear bias wrong by being cheap to the tune of $30 shipping (or even $200 or $500 for that matter). It is all trivial if you end up with a car on the side of a tree assuming we walk away!

Not to worry. I'm cheap, but you've seen my build, I don't cheap out. The point of this thread is just to get more info. If setting the spring is a simple procedure, using common tools that could be completed locally, that's great. But if it requires sending it out to make sure the job is done right, that's what I do. I've easily spent over a thousand dollars just on shipping on this project and staying in budget requires scrutinizing every purchase to make sure I'm not spending money unwisely. Not compromising on quality and definitely not safety though.

As for spinning. BTDT... twice. Yes, it happens VERY fast. Luckily they are low to the ground and like to spin flat without flipping. First time I spun one was my first Spring day drive. Sprinted down a backroad to an unmarked sharp 90 turn and hit a patch of sand left over from the winter on bald tires. Spun like a top right off the road and into a farmers field while he was plowing for spring planting. Car stalled but fired right back up and I drove it back onto the road and on my way. I could see the farmer shaking his head from his tractor seat as I sped away. Cleaned the shit out of my seat when I got home. (IMG:style_emoticons/default/blink.gif)