Bleeding brakes (after replacing all lines)
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Bleeding brakes (after replacing all lines)
On my 74 F100, w/manual brakes, the proportioning valve is conveniently placed right under the master cylinder. I recall that on my 77 ford, to bleed the back brakes you had to pull out the little pin on the front of the proportioning valve. The valve on my 74 pulls out a little, but it also pushes in a little too. Looks like it is 'spring loaded' frontwards and rearwards. Here's my question - does the 74 proportioning valve and overall rear brake line bleeding work the same principle as on the 77's?
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Yes, for any light-duty pickup with front discs and rear drums you pull the pin out while bleeding the front brakes. Its purpose is to collapse the metering valve in front so fluid pressure can go straight to the calipers instead of compressing air against the metering plate inside.
I have seen some language in shop manuals before where the requirement was to push the pin in, but I remember this only being heavy-duty large GVWR vehicles that have a different style of proportioning valve.
I have seen some language in shop manuals before where the requirement was to push the pin in, but I remember this only being heavy-duty large GVWR vehicles that have a different style of proportioning valve.
Thread Starter
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Elder User
Joined: May 2008
Posts: 619
Likes: 1
Yes, for any light-duty pickup with front discs and rear drums you pull the pin out while bleeding the front brakes. Its purpose is to collapse the metering valve in front so fluid pressure can go straight to the calipers instead of compressing air against the metering plate inside.
I have seen some language in shop manuals before where the requirement was to push the pin in, but I remember this only being heavy-duty large GVWR vehicles that have a different style of proportioning valve.
I have seen some language in shop manuals before where the requirement was to push the pin in, but I remember this only being heavy-duty large GVWR vehicles that have a different style of proportioning valve.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
You got it. The part that the pin deals with does not touch the rear braking circuit in any way.
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