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Rear brake leak?

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swampedout

Rear brake leak?

Ive been dealing with brake issues since I bought the truck (we have had our 1 year anniversary recently, celebrated by me given the dmv money to renew the registration

)

Basically, I have a really soft pedal and over time I lose brake fluid going to the rear. Brake light comes on, I refill the MC, bleed the rear and the light goes off. Ive already replaced the MC and booster. Ive looked under the truck but dont see any obvious leaks. Im planning on replacing all the brake lines with copper nickle line next month if I cant track it down before then. I will probably also do new pads and rotors up front while Im at it, although the pads have plenty of material on them.
Also, the parking brake cable is disconnected so no Ebrake whatsoever.

Sam
1984 F250. 460. C6. 4x4.
MSD Ignition. Airbag rear suspension
Whole buncha problems

Machspeed

Re: Rear brake leak?

Administrator

That's really strange. I would have thought you might have a leaking wheel cylinder. With all that you've done, certainly you've inspected those. Maybe leaking at the proportioning valve. Gary and Jim will be on this quick, I'm sure. Keep us posted.

John

"Blackie" - 1986 F150 4x4 - Mildly warmed over 351W HO - Original owner

old55pete

Re: Rear brake leak?

In reply to this post by swampedout

I was gonna say to just pop off the rear wheels and drums. Then I saw that you have a 3/4 ton and that aint so easy as a 1/2 ton because of the full floating axles.

Is there fluid coming out from between the backing plate and the drum on the rear?
There is a rear brake hose that feeds both rear brakes, it is normaly on the rearend housing on the left side between the left rear spring and the diff housing, is it wet? have some one push the brake pedal real hard and see if it is leaking or balooning up under pressure.

As for putting copper tubing in to replace steel brake lines, I dont know about that. I dont think it can handle the pressure. I am gonna leave that one alone as someone may have done it and it is still working without a falure

Steve
86 Bronco, XLT, 5.0 EFI, EEC IV, AOD, IFS, limited slip front and rear, 3.08 gears, Tilt steering, factory AC

85lebaront2

Re: Rear brake leak?

Administrator

Look at the junction of the left side rail and the crossmember in front of the rear fuel tank. It is a low area and collects water and dirt I lost my rear brakes towing our 5th wheel to Gloucester County VA, this meant no brake controller either. Try to find brake fittings and lines in the boonies on a weekend.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: Rear brake leak?

Administrator

In reply to this post by swampedout

The others have covered it pretty well. But the brake shoes will soak up some fluid, although if your leak is enough to require filling the master again then I doubt it is that. As was said, pulling the drums might be difficult, so check out the other things first.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

ArdWrknTrk

Re: Rear brake leak?

Administrator

This post was updated on .

In reply to this post by old55pete

By '86 all these heavier trucks had the Sterling 10.25" axle.
Edit: Steve, I must have scrolled down to your post that I was replying to and seen "'86". D'oh!

No problem popping the drums off and no left hand threads either!

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

ArdWrknTrk

Re: Rear brake leak?

Administrator

This post was updated on .

In reply to this post by swampedout

Sam,
I got a copper/nickel brake line kit from Amazon.
Had a bunch of fittings too.
I'll link it when I check my purchase history.

The fluid is going somewhere.
I'd check where Bill said, at the hose* junction in the corner of crossmember and frame rail.

Does your truck have one of those load level proportioning valves with an arm attached to the rear axle?

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

ArdWrknTrk

Re: Rear brake leak?

Administrator

Sam, this is the kit I bought:

https://www.amazon.com/dp/B07W2Z8F5X/ref=cm_sw_r_cp_apa_fabc_uecWFb8Q1RRNJ?_encoding=UTF8&psc=1

25' is plenty of line from MC to rear hose, and both sides of the axle.
I have some left over but I'm not sure if it would be enough to complete the front.

I'm also going to suggest that you need to adjust your rear brakes.
Without any emergency brake it's not likely they'll adjust themselves.

That should take a lot of travel and softness out of your pedal.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

85lebaront2

Re: Rear brake leak?

Administrator

In reply to this post by ArdWrknTrk

Jim, he has a 1984, so will have the Dana 60 which uses the integral hub and drum.

On Copper for brake lines, not a good idea, it gets brittle with age and if it is soft enough to bend, it is soft enough to expand un der the high pressures used.

Bill AKA "LOBO" Profile

Frank Wyatt

Re: Rear brake leak?

Check the rear drum backing plates for wetness as that would be a sure sign of a leak, either brake fluid from the wheel cylinders or the axle seals. We all know the axle grease has a unmistakable smell and is easy to distinguish the two from each other.

1981 F 150 Custom 300 ci with a fully rebuilt 1968 240 head Carter YFA T-18 3.25 9" rear 2WD
dual gas tanks
1990 Lincoln Town Car 5.0 AOD
Home town Mc Kenzie, TN

ArdWrknTrk

Re: Rear brake leak?

Administrator

In reply to this post by 85lebaront2

It's not copper, it's cupronickel.
Exceeds all DOT, TUV, CE, EU standards.
Very easy to flare and won't ever corrode.
Maybe you should check into it.

I'm not sure about how much snow Sam sees in New Mexico but here in the northeast steel lines don't last and stainless is very difficult to properly flare because it work hardens so quickly.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

85lebaront2

Re: Rear brake leak?

Administrator

Jim, copper was tossed out as a possibility, I believe after spending 30+ years in a laboratory (one 4 year stint 1966-1970 and 30 years starting Jan 1982) I know the difference between copper and CUNI alloys. Now begs the question, is it 90/10, 70/30 or something else?

If I need to do any brake lines in the future I may look into that, right now everything including the konvertible has solid, non-rusted lines.

Bill AKA "LOBO" Profile

old55pete

Re: Rear brake leak?

In reply to this post by ArdWrknTrk

Jim............Sam's signiture says that his pickup is an 84. and unless it has the light 3/4 rearend with semi floating axles. Other wise, I am pretty sure that he has a full floater rearend and will have to remove the axle, then the hub and drum as a unit as I am pretty sure an 84 has inboard drums.

Im guessing it really does not matter as they need to come off to do a proper inspection and to replace the parking brake cables.

Steve
86 Bronco, XLT, 5.0 EFI, EEC IV, AOD, IFS, limited slip front and rear, 3.08 gears, Tilt steering, factory AC

ArdWrknTrk

Re: Rear brake leak?

Administrator

Yep.
I don't know where I got '86 from...

But you're right, they have to come off to replace the cables and shoes anyhow.

I hope it is something cheap and easy, like a wheel cylinder or the line at the hose.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

ArdWrknTrk

Re: Rear brake leak?

Administrator

In reply to this post by 85lebaront2

I've seen 90/10 and 88.7/11.3 thrown around.

https://www.copper.org/applications/automotive/brake-tube/brake.html

I don't think the Germans and Nordic countries (where this has become compulsory) haven't done the engineering, or are interested in spending more than necessary, for no gain in safety.

Go ahead and continue to use dead soft steel.
There's just too much sodium and magnesium on the roads up here.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

85lebaront2

Re: Rear brake leak?

Administrator

Ok, Jim, your link goes to a pretty good reference and it says 90/10 is what they use.

Bill AKA "LOBO" Profile

old55pete

Re: Rear brake leak?

In reply to this post by ArdWrknTrk

An intresting read on the copper brake lines, thanks Jim. I may have to rethink that and file it away for furture use.

Steve
86 Bronco, XLT, 5.0 EFI, EEC IV, AOD, IFS, limited slip front and rear, 3.08 gears, Tilt steering, factory AC

swampedout

Re: Rear brake leak?

Thanks for all the tips. I plan on getting this project done btwn Christmas and New Years. Until then, Im probably not going to pull the drums because I know thats a can of worms Ill need to address before the wheels go back on.

What about the proportioning valve? Could I have a leak there?
I guess this is a good excuse to clean all the dirt off the truck, so I can see leaks more easily.

Sam
1984 F250. 460. C6. 4x4.
MSD Ignition. Airbag rear suspension
Whole buncha problems

ArdWrknTrk

Re: Rear brake leak?

Administrator

Some of the heavier trucks have a valve that adjusts rear brake bias depending on ride height.
If laden it gives more brake in the rear.
In a panic stop (where the rear comes up) it lessens the amount of brake pressure applied to the unloaded rear axle, to help them from locking up.

I think Bill has this...

You can have a leak anywhere the lines go.
I'd probably fill the master and pump the brakes on dry ground, then see if there are any drips.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Rear brake leak?

Administrator

Big Blue had that valve, but it was apparently stuck giving very little brake to the rear as I never had good brakes and could slide the front and never the rear. In fact, with my car hauler trailer attached but the brakes on it disconnected I was almost pushed through an intersection with the front tires locked and no sound from the rear. And my trailer's tongue weight is LOTS, so there was plenty of weight on the rear.

Now, after removing that valve, I have good brakes.

Gary, AKA "Gary fellow": Profile