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Old 06-17-2007, 01:04 PM   #1
RM72chevy
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Manual to Power Brake conversion

Hello all,

I'm going to convert my manual brakes to power using a complete assembly off 79 Donor. I don't plan on using the old MC so my question is, what is this? (see picture) so I have to use it? Can I eliminate it all together?

Thanks in advance
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Old 06-17-2007, 01:53 PM   #2
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Re: Manual to Power Brake conversion

that is your proportioning valve. adjusts pressure for front and rear brakes. if you have discs in front and drums in rear it adjusts them for their certain pressure. if you are using the complete assembly from your donor truck, booster, cylinder and valve you will be fine b/c it has discs/drums also. Good luck
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Old 06-17-2007, 03:33 PM   #3
dh81k30
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Re: Manual to Power Brake conversion

RM72chevy,

That is called a combo ( short for combination ) valve because it also contains the switch for the brake failure warning light. Not a good thing to take off your truck.

If you do not like seeing the valve there, you might consider mounting it on the front frame cross member under the radiator like the factory did in my '81 and '86.

BTW, welcome to the board nuke1!

HTH,
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Old 06-17-2007, 04:24 PM   #4
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Re: Manual to Power Brake conversion

both of hte previous posters could be correct.

what it actually is depends on whether the truck that it's in has drum/drum, disc/disc or disc/drum.
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Old 06-17-2007, 05:29 PM   #5
RM72chevy
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Re: Manual to Power Brake conversion

Disc up front, Drum in rear
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Old 06-17-2007, 05:46 PM   #6
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Re: Manual to Power Brake conversion

Just took a snap shot of the donor, this came off a 78 Chevy from the bone yard. Cost me $10.00
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Old 06-17-2007, 09:47 PM   #7
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Re: Manual to Power Brake conversion

it's a combo/combi/combination valve, then.
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Old 06-17-2007, 10:33 PM   #8
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Re: Manual to Power Brake conversion

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The valve for the 78 is mounted on the front crossmember. If you're not too far from the yard I would go back & get it. That way you have the right one and you can mount it on your crossmember to get it out of sight.

Just my 2¢ worth

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