[QUOTE="robzombie, post: 3616607, member: 40932"....It was never offered with vac brakes for a reason.
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According to my technical contacts at GM in the 1980's there was a good reason the PM was used on the 1985 Regal station wagons and the 1986-7 turbo cars, and that was because management wanted an extensive field test of the PM system on a limited run of production vehicles.
The electric-hydraulic pump concept was to be the GM/Bosch first production version of an ABS which was to be introduced in a couple years on a few million cars and lots was at stake.
The 1989 Cadillac, and others GM's, had an ABS brake system and the heart of it is a PM electric pump/master cylinder.
GM and other manufactures used vacuum brakes on millions of turbo vehicles in the 1980s' and beyond with great success!
The big issue with a PM is not "will it fail', but "when it will fail"?
A PM failure will require as much, or more, foot pressure to stop the vehicle as a vacuum system.[/QUOTE]
The reasons you stated may be true but I still say that it [the PM] is a better system than a vac system in a boosted application. I've used both and the vac system comes up short in my book, but that is just my opinion.
Hydro boost is the best alternative if you plan on keeping the P/S which most don't in race applications [not street cars] and is more trouble free than the P/M.
If I ever ditched the P/M I would go to H/B for reliability as the only issues I ever had with that system were leaks due to blown seals in the M/C.
All systems will fail and the P/M gets a bad rap in this department. Like said TURBO DAVE there are now replacement parts available that make it almost bullet proof.
I'm still on the original motor and M/C as far as I can tell and only the switch and ball have been replaced, [by me]. I'd say that 28 years out of anything is pretty damn good. Especially since it was basically a prototype for early ABS systems according to Nick's buddy's.