Hot Rod Forum banner
1 - 2 of 2 Posts

1 Posts
Discussion Starter · #1 ·
I have a 1985 Chevrolet C20 pickup with a hissing vacuum booster. My automotive friends tell me the booster needs to be replaced so I disconnected the master cylinder and check valve, but I'm having a little trouble loosening two of the four bolts connecting the booster drum to the firewall. Any hints? Is a special tool required or would a ratchet with a universal joint do the trick? Also wondering how difficult it is to disconnect the booster under the dash from the brake pedal. And are there any pitfalls to watch out for in re-installing the new booster?

All knowledge, experience, and ideas gratefully received - leprechaun :)

1,971 Posts
not that bad to do i have removed billions of them from so many of these trucks ive junked and whatever over the years you will need a universal 3/8" adapter and socket and extensions and soak the hell out of the nuts with PB blaster etc

the rod on the brake pedal arm is easy youll see when you lay on your back on the floorboard its no big deal at all

two of the booster nuts are more difficult
you just have to work at them

youll get them
dont worry

the new booster will slide right onto the studs easily no issues there either

if this truck has cruise control then make sure the sound is not actually from the vacuum hose at the brake pedal switch

some ppl mistake a bad booster sound for a bad cruise break switch

most of the late 70s and 80s trucks did have cruise control

if the brake pedal is easy(dont have to stand on the pedal with both feet to stop the truck) and it holds about 3 pedal pumps worth of vacuum after the engine is stopped then i would probably just leave it be

gm boosters are not well known for failing, it is a rare occurance for them, it is the fords that usually fail often,

in my own experience that is.,, over the years of wrenching and owning all different kinds of old trucks.,

i have owned over 200 different vrehicles since 1994 and ive only come across maybe three bad gm boosters ever

the last one was in an 83 caprice classic with under 100k miles

i found a new reman booster in a junkyard on another caprice for 40 bucks and i changed it promptly because i bought the car for cheap this way from an old guy and it was a clean creampuff and you had to stand on the pedal with all your weight to stop it ahha.

the car ones are so much more difficult to replace than the truck ones because the nuts are under the dash in a bad place

the truck ones are cake walk

welcome to the forums
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.