can some on identify this ?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

C30trailerspecial · 10-05-2012, 07:29 PM

Can some one identify this and what it does please

ok the truck is a canada import right hand drive, body tag says 1981 into Australia by GM-H (general motors Holden) c30, 350, truck 4 speed, dually, lwb

this cannister looking thing is mounted on the right front inner gaurd, it has a brake line coming from the rear of the master cylinder into the side of it and exiting the other side of it Im asuming going off to the front brakes. at the back of the cannister thingy is a cable going off to the dash, the cable is hand operated like say... a choke cable.

it has two vac hoses one (the one with red tape) goes off to the back of the truck and lopes around up to the front left inner gaurd to some kind of valve looking thing on the left inner gaurd, the other vac hose goes across the radiator to what looks like a vac tank on the other left inner gaurd. this same vac tank has a hose coming from the intake manifold to provide the vacume.

hers a pic of the vac tank

now... I cant think why it would have anything to do with the brakes because the brakes are fuild boosted from the power steer pump

the brakes in the truck work flawless, but the cannister thingy is leaking brake fluid..

what is it and whats it for???

stock75 · 10-05-2012, 08:41 PM

Cruise control I imagine.

clinebarger · 10-05-2012, 09:13 PM

Vacuum trailer brakes, Only good for trailers with vacuum over hydraulic brakes.

bigd65 · 10-05-2012, 09:31 PM

The brakes are HYDROBOOST. they are used for Diesel engines because the don't make vacuum. The POWER STEERING PUMP feeds the HYDROLICS for the brakes.
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clinebarger · 10-05-2012, 09:55 PM

Quote:

Originally Posted by bigd65

The brakes are HYDROBOOST. they are used for Diesel engines because the don't make vacuum. The POWER STEERING PUMP feeds the HYDROLICS for the brakes.
Posted via Mobile Device

Vacuum Trailer Brakes, Has nothing to do with the Hydro-Boosted service brakes.

Very common back when people pulled heavy loads with gas powered engines. Ive seen quite a few on older large (triple axle) Race & Horse/Livestock trailers.

Trailer brake types....
Surge over hydraulic.
Electric over hydraulic.
Air over hydraulic.
Vacuum over hydraulic.
Electric brake.
Air brake.

C30trailerspecial · 10-05-2012, 10:15 PM

Quote:

Originally Posted by bigd65

The brakes are HYDROBOOST. they are used for Diesel engines because the don't make vacuum. The POWER STEERING PUMP feeds the HYDROLICS for the brakes.
Posted via Mobile Device

this truck is a petrol 350

C30trailerspecial · 10-05-2012, 10:18 PM

Quote:

Originally Posted by clinebarger

Vacuum Trailer Brakes, Has nothing to do with the Hydro-Boosted service brakes.

Very common back when people pulled heavy loads with gas powered engines. Ive seen quite a few on older large (triple axle) Race & Horse/Livestock trailers.

Trailer brake types....
Surge over hydraulic.
Electric over hydraulic.
Air over hydraulic.
Vacuum over hydraulic.
Electric brake.
Air brake.

vacuum trailer brakes? Im starting to get it now... so the cable that goes to the dash could be used to apply the trailer brakes without using the foot brakes.... kinda like electric trailer brakes

clinebarger · 10-05-2012, 10:51 PM

Quote:

Originally Posted by C30trailerspecial

vacuum trailer brakes? Im starting to get it now... so the cable that goes to the dash could be used to apply the trailer brakes without using the foot brakes.... kinda like electric trailer brakes

Yes, Well kinda sort of

. The trailer would have it's own stand alone hydraulic brake system that is contolled by vacuum input from the control unit....Hydraulic input from the service brakes or manual input from the cab mounted lever.

Low/no vacuum....trailer brakes applied.
High vacuum....trailer brakes released.
Vacuum inbetween is modulated by the contoller via input.

bigd65 · 10-06-2012, 08:49 AM

I was referring to the last picture. That is a HYDROBOOST SYSTEM, looks just like mine, however my 82 was previously diesel. I am going to remove the HYDROBOOST and put a regular booster on it. I did notice something, THAT BOOSTER SET UP IS ON THE WRONG SIDE (LOL), maybe that's the problem, it's on the wrong side :-)
Posted via Mobile Device

C30trailerspecial · 10-06-2012, 04:35 PM

clearly you didnt read my opening post.

Your41Plague12 · 10-07-2012, 10:56 AM

Quote:

Originally Posted by C30trailerspecial

clearly you didnt read my opening post.

Clearly he was joking.

Anyway, it's cool to see a right hand drive rig. As long as you're not hauling anything that uses that specific style of trailer brakes, I would go ahead and bypass it for now. I would advise, however, keeping the hydroboost brakes. They tend to be a little stronger than the typical vacuum power brake systems. Best of luck with the truck!

rwhit57 · 10-07-2012, 12:18 PM

Since stuff is backwards, where is the heater? Just curious, I don't see it.

INSIDIOUS '86 · 10-07-2012, 01:55 PM

I would trade a perfect truck for your Aussie truck lol
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C30trailerspecial · 10-07-2012, 03:13 PM

the heater is there, the water pipes exit just above and to the left of the dissy.

and yes Im keeping the hydoboost brakes, they work so well,

10-05-2012, 07:29 PM	#1
C30trailerspecial Registered User Join Date: Sep 2012 Location: gold coast Posts: 40	can some on identify this ?? Can some one identify this and what it does please ok the truck is a canada import right hand drive, body tag says 1981 into Australia by GM-H (general motors Holden) c30, 350, truck 4 speed, dually, lwb this cannister looking thing is mounted on the right front inner gaurd, it has a brake line coming from the rear of the master cylinder into the side of it and exiting the other side of it Im asuming going off to the front brakes. at the back of the cannister thingy is a cable going off to the dash, the cable is hand operated like say... a choke cable. it has two vac hoses one (the one with red tape) goes off to the back of the truck and lopes around up to the front left inner gaurd to some kind of valve looking thing on the left inner gaurd, the other vac hose goes across the radiator to what looks like a vac tank on the other left inner gaurd. this same vac tank has a hose coming from the intake manifold to provide the vacume. hers a pic of the vac tank now... I cant think why it would have anything to do with the brakes because the brakes are fuild boosted from the power steer pump the brakes in the truck work flawless, but the cannister thingy is leaking brake fluid.. what is it and whats it for??? Last edited by C30trailerspecial; 10-05-2012 at 07:34 PM.

10-05-2012, 08:41 PM	#2
stock75 Registered User Join Date: Jul 2012 Location: Salt Lake City Posts: 59	Re: can some on identify this ?? Cruise control I imagine.

10-05-2012, 09:13 PM	#3
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: can some on identify this ?? Vacuum trailer brakes, Only good for trailers with vacuum over hydraulic brakes.

10-05-2012, 09:31 PM	#4
bigd65 Registered User Join Date: Mar 2000 Location: Clute, TX. Posts: 1,935	Re: can some on identify this ?? The brakes are HYDROBOOST. they are used for Diesel engines because the don't make vacuum. The POWER STEERING PUMP feeds the HYDROLICS for the brakes. Posted via Mobile Device __________________ 2004 Silverado Crewcab 1972 Chevy Monte Carlo 2017 Chevy Tahoe

10-06-2012, 08:49 AM	#9
bigd65 Registered User Join Date: Mar 2000 Location: Clute, TX. Posts: 1,935	Re: can some on identify this ?? I was referring to the last picture. That is a HYDROBOOST SYSTEM, looks just like mine, however my 82 was previously diesel. I am going to remove the HYDROBOOST and put a regular booster on it. I did notice something, THAT BOOSTER SET UP IS ON THE WRONG SIDE (LOL), maybe that's the problem, it's on the wrong side :-) Posted via Mobile Device __________________ 2004 Silverado Crewcab 1972 Chevy Monte Carlo 2017 Chevy Tahoe

10-06-2012, 04:35 PM	#10
C30trailerspecial Registered User Join Date: Sep 2012 Location: gold coast Posts: 40	Re: can some on identify this ?? clearly you didnt read my opening post.

10-07-2012, 12:18 PM	#12
rwhit57 Registered User Join Date: Jan 2011 Location: Tulsa,Okla Posts: 590	Re: can some on identify this ?? Since stuff is backwards, where is the heater? Just curious, I don't see it. __________________ "Whoever said money can't buy happiness has obviously never seen a speed shop!

10-07-2012, 01:55 PM	#13
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: can some on identify this ?? I would trade a perfect truck for your Aussie truck lol Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

10-07-2012, 03:13 PM	#14
C30trailerspecial Registered User Join Date: Sep 2012 Location: gold coast Posts: 40	Re: can some on identify this ?? the heater is there, the water pipes exit just above and to the left of the dissy. and yes Im keeping the hydoboost brakes, they work so well,



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