No Power brakes full wheel lock

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Cobra
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No Power brakes full wheel lock

Post by Cobra »

On my 97 at full left or right wheel lock i hear a nasty hissing and lose power brakes the brake pedal will sink almost to the ground before they stop the van. It makes the same sound when the van is not moving and i try to turn the wheels from side to side. I've checked the fluids and they are all good well my power steering fluid is actually a little high it was empty however when i got the van. any ideas? the only thing i can think of is the PS pump
1998 GMC Safari AWD, BFGoodrich AllTerrain T/A
Jet performance tuner 91 octane preset, Jet under-drive pulleys
Rancho 999000 series shock, on-board controller to be installed later
DHC rock rails and skid plate Add-A-Leaf
G3500 front calipers
Zexel Torsen Diff
11" drums
180 amp Alternator
Long tru-cool 4590 trans cooler

1997 in storage (project coming soon)

astroturf
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Re: No Power brakes full wheel lock

Post by astroturf »

Sounds like your PS Pump is in need of replacement.

Buy a new unit, not a rebuilt.

Jim
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WoodButcher
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Re: No Power brakes full wheel lock

Post by WoodButcher »

Are you referring to the '97 w/ 3500 calipers???
'93 Safari shorty, 350 swap
'05 Astro AWD, lifted, 6 liter, cammed, ported and programmed for fast.
'69 G10, straight 6, 3 onatree, jumped at me when I had a pocketful of cash looking for a spare astro. :)

Topic author
Cobra
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Re: No Power brakes full wheel lock

Post by Cobra »

yup
1998 GMC Safari AWD, BFGoodrich AllTerrain T/A
Jet performance tuner 91 octane preset, Jet under-drive pulleys
Rancho 999000 series shock, on-board controller to be installed later
DHC rock rails and skid plate Add-A-Leaf
G3500 front calipers
Zexel Torsen Diff
11" drums
180 amp Alternator
Long tru-cool 4590 trans cooler

1997 in storage (project coming soon)
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WoodButcher
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Re: No Power brakes full wheel lock

Post by WoodButcher »

I just did this caliper swap on mine, 3" cylinder needs alot of fluid. I posted a thread on the other site
http://www.astrosafari.com/viewtopic.php?f=45&t=12087
and had to make a few mods. Are your calipers meant for a thicker rotor like the ones I got? Maybe shims would help.
'93 Safari shorty, 350 swap
'05 Astro AWD, lifted, 6 liter, cammed, ported and programmed for fast.
'69 G10, straight 6, 3 onatree, jumped at me when I had a pocketful of cash looking for a spare astro. :)

Topic author
Cobra
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Re: No Power brakes full wheel lock

Post by Cobra »

the brakes work perfectly except for that one condition, i'm not sure the thickness of the 3500 rotors but i guess it wouldn't be hard to find out give me a minute to measure

edit:
stock 1997 rwd 1.04 inches thick
stock 1996 SRW G3500 1.53 inches thick
1998 GMC Safari AWD, BFGoodrich AllTerrain T/A
Jet performance tuner 91 octane preset, Jet under-drive pulleys
Rancho 999000 series shock, on-board controller to be installed later
DHC rock rails and skid plate Add-A-Leaf
G3500 front calipers
Zexel Torsen Diff
11" drums
180 amp Alternator
Long tru-cool 4590 trans cooler

1997 in storage (project coming soon)
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WoodButcher
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Re: No Power brakes full wheel lock

Post by WoodButcher »

Yeah, 1/2". I have 1/4" of shim in there and I'm thinking to add another 1/8" when I next get the ambition to tear into it.
I don't know if that has any relation to your issue but it may. My PS pump has had issues for some time before I did the big caliper but I have seen no change yet. (whines occasionally when turning hard at low speed)
'93 Safari shorty, 350 swap
'05 Astro AWD, lifted, 6 liter, cammed, ported and programmed for fast.
'69 G10, straight 6, 3 onatree, jumped at me when I had a pocketful of cash looking for a spare astro. :)

Topic author
Cobra
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Re: No Power brakes full wheel lock

Post by Cobra »

no matter what van i've driven they all whined a little bit at full wheel lock but mine i loud.if i can find my vacuum pump I'm going to try a couple things to see if air is trapped in there somewhere. 1/2 inch is a fair difference but nothing that i think the calipers stroke can't cover
1998 GMC Safari AWD, BFGoodrich AllTerrain T/A
Jet performance tuner 91 octane preset, Jet under-drive pulleys
Rancho 999000 series shock, on-board controller to be installed later
DHC rock rails and skid plate Add-A-Leaf
G3500 front calipers
Zexel Torsen Diff
11" drums
180 amp Alternator
Long tru-cool 4590 trans cooler

1997 in storage (project coming soon)

astroturf
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Re: No Power brakes full wheel lock

Post by astroturf »

What is the life expectancy of the PS Pump?

How often have you flushed the PS Pumps fluid?

Thanks, Jim
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WoodButcher
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Re: No Power brakes full wheel lock

Post by WoodButcher »

astroturf wrote:What is the life expectancy of the PS Pump?

How often have you flushed the PS Pumps fluid?

Thanks, Jim
I never flushed but have replaced the steering box so I did drain and refill. I don't know of a way to flush per se but I think what I did would qualify.
'93 Safari shorty, 350 swap
'05 Astro AWD, lifted, 6 liter, cammed, ported and programmed for fast.
'69 G10, straight 6, 3 onatree, jumped at me when I had a pocketful of cash looking for a spare astro. :)

Topic author
Cobra
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Re: No Power brakes full wheel lock

Post by Cobra »

Vans pretty new to me so i haven't changed any of the fluids yet only topped off so it would pass the testing. Who knows when the last oil change was let alone power steering fluid
1998 GMC Safari AWD, BFGoodrich AllTerrain T/A
Jet performance tuner 91 octane preset, Jet under-drive pulleys
Rancho 999000 series shock, on-board controller to be installed later
DHC rock rails and skid plate Add-A-Leaf
G3500 front calipers
Zexel Torsen Diff
11" drums
180 amp Alternator
Long tru-cool 4590 trans cooler

1997 in storage (project coming soon)
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Re: No Power brakes full wheel lock

Post by Mr_Roboto »

My bet is on the bypass in the gear being messed up honestly. There's probably a pressure regulator for it that's stuck open. Strictly a guess however.
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