Question about rear air brakes on an 86 F700

Jakex120 · Apr 16, 2020

Well I'm prepared for the worst on this one..bought a f700 dump not running but you know "ran when parked but smoked bad so needs overhaul"..the truck is complete..manual with the 370 gas..so a towing/junker lot had it listed and I took it at less than $2000..thing is it was hauled to my farm on a row back..very large rowback..so about the rear brakes..story from the hauler is that the rear brakes are applied/engaged due to the compressor so the truck was slid off the rowback after oil was poured out in the tire pathways of course. I guess I'm wondering if the rear is just locked up and they knew it or is there other reasons the rear wheels didnt move..Not experienced at all in medium trucks and would appreciate hearing the suggestions and experiences..going into this I kept the attitude that it's a parts truck that maybe I could get running at my farm only..thanks

4x4ford · Apr 17, 2020

Spring lock brake cans more than likely and with out air pressure you can’t release them unless you cage them but with doing that you lose your parking brake

Birken Vogt · Apr 17, 2020

Easiest way is to remove the drain valve from the wet tank and install an air hose in there, then just air it up from an external source and you can chock the wheels, then check and see what works.

funwithfuel · Apr 17, 2020

86 F700 with 370 lima engine. I'm guessing you probably have the dreaded Lucas-Girling hydraulic brakes. If you have 2 large brake chambers pointed inward with 3/16 brake lines jumping from one wheel cylinder to the other on each rear then that's what you have. The park brake side is simple enough. There is a 3/4 nut stakes to a threaded rod in the center of each canister. Chock the wheels and back those threaded rod until you feel a firm stop. See if it rolls.
Please see attached pics.

doublewide · Apr 17, 2020

Gotta love an old Ford. How bout some pictures of this beauty?

Jakex120 · Apr 17, 2020

4x4ford said:
Spring lock brake cans more than likely and with out air pressure you can’t release them unless you cage them but with doing that you lose your parking brake

Yep..that's what I have back there...and just caught a youtube video of caging them...thanks

Jakex120 · Apr 17, 2020

funwithfuel said:
86 F700 with 370 lima engine. I'm guessing you probably have the dreaded Lucas-Girling hydraulic brakes. If you have 2 large brake chambers pointed inward with 3/16 brake lines jumping from one wheel cylinder to the other on each rear then that's what you have. The park brake side is simple enough. There is a 3/4 nut stakes to a threaded rod in the center of each canister. Chock the wheels and back those threaded rod until you feel a firm stop. See if it rolls.
Please see attached pics.

Man..dodged one there..I guess I should be glad I don't have those lol

Jakex120 · Apr 17, 2020

Guys will get some photos up soon..she's pretty rough but solid in the right places..

Old Doug · Apr 17, 2020

I am not being a a$$ but Try and take it back to were you got it even if you have to a loss.

Steve Frazier · Apr 17, 2020

If you aren't familiar with air brakes read up on them real good before attempting to work on them. The parking brake is under extreme spring pressure and loosening the wrong bolt can get you seriously injured if not worse. Be careful!!

Jakex120 · Apr 19, 2020

Old Doug said:
I am not being a a$$ but Try and take it back to were you got it even if you have to a loss.

Really?..if it starts, unlocks the brakes and dumps the bed ..all for the $1600 it cost me...sounds like good advice to me

Old Doug · Apr 20, 2020

Jakex120 said:
Really?..if it starts, unlocks the brakes and dumps the bed ..all for the $1600 it cost me...sounds like good advice to me

I thought it had the lucas Girling brakes.

Jakex120 · Apr 20, 2020

Ah..I see..must be some the worst brakes ever and expensive to fix..to be honest the standard hydraulic power brakes I have read about would've been idea..
Do types of braking systems have anything to do with tons/lbs the truck can safely haul? ...or does that(tons) depend on what the bed hydraulics can dump?

DMiller · Apr 20, 2020

He is likely to have never seen the Hydraulic actuator LGs on the Fords. If has a compressor will be Air Maxi cans.

funwithfuel · Apr 20, 2020

Jakex120 said:
Ah..I see..must be some the worst brakes ever and expensive to fix..to be honest the standard hydraulic power brakes I have read about would've been idea..
Do types of braking systems have anything to do with tons/lbs the truck can safely haul? ...or does that(tons) depend on what the bed hydraulics can dump?

They were basically wedge brakes, but hydraulic. S cams replaced wedges, and now air disc(boondoggle big step backwards)
Lucas was a p!ss-poor attempt to make heavier trucks (up to 30k) sneak in under CDL requirements. They were legal, up to 26k because they were hydraulic not air. They never should have been. Glad you got air, kind of a unicorn. 370 glasser with air brakes. You gonna post those pics?

Jakex120 · Apr 20, 2020

Yes..here's a few as it came loaded on the hauler..will get more up later as I get to looking it over more...

DMiller · Apr 21, 2020

Need a photo under the hood, master cylinder will be Juice Brakes and Lucas Hydraulic Maxis under it.

Birken Vogt · Apr 21, 2020

We had one with full air, it had the big BW diamond brake pedal and colored Synflex hoses everywhere. The front brake cans were the tiniest I have ever seen, whatever size they were.

funwithfuel · Apr 21, 2020

I think with those Dayton's, the only juice brake would be L-G or Wagner A2LS. And after blowing up the pic from the front, I can see S-cam brackets.

doublewide · Apr 21, 2020

Jakex120 said:
Yes..here's a few as it came loaded on the hauler..will get more up later as I get to looking it over more...View attachment 215614
View attachment 215615 View attachment 215616

Looks good so far...

Keep 'em comin'!

Question about rear air brakes on an 86 F700

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