71' F250 Brake Job

FLATBEDFORD · Post by **FLATBEDFORD** » Mon Jan 05, 2009 4:35 pm

I just hammered the studs back in.

willowbilly3 · Post by **willowbilly3** » Tue Jan 06, 2009 8:48 am

Well, it's too late but I never hammer out the studs. Any good shop can resurface the drum with the hub in and it's better that way, more accurate imo.
If the pedal is going low you probably have adjuster issues. When you say you replaced everything do you also get all new springs, hardware AND adjusters? They are fairly expensive. They can be reused but a complete job of restoring the system I would include new ones.
Also consider this, very few people are even aware of it any more. On drum brake jobs it used to be part of the process to arc the shoes in, nowdays most people don't even know what that means.
What it does is this: When you take a cut out of a drum, and especially an old one that has been cut before, even if it is still within specs the shoe now has a very small contact patch because it is a smaller arc that the corresponding contact area of the drum.. In the old days they would address this by bending the shoe (not recommended on bonded shoes) or more likely grind them to fit.
Now to make matters worse, many (most?) parts stores don't even know how to do a good job, just cut until clean, maybe check the spec to see if they went over it, maybe not but very few of them will make sure both of the drums come out the same size, which is very important to proper braking, and even a larger issue when the shoes don't get arced in.
If your drums are cut out to the max, the shoes may actually be wore out by the time they have a full contact patch.

fordman · Post by **fordman** » Tue Jan 06, 2009 9:24 am

i read an article years ago about not turning rotors even if they are rough. because all it does is eat away at the meat fo them. the rough surface will wear into the pads and give the same stopping power. as well as i have done this and the pad actually smoothes out the rotor by itself. i don't know if this would apply to drums or not.

martinarcher · Post by **martinarcher** » Tue Jan 06, 2009 10:27 am

Here's more pics of the job. I pulled the diff cover off and it looks like this might be a rebuilt rear-end. The yoke has some nasty gouges in it from what I'm guessing was old damage. i spun everything slowly and all the gears look really good and I founds no metal traces in the bottom of the diff housing. If you look close at the pic you can see the gouge on the bottom half of the yoke below the diff gears....

fordman · Post by **fordman** » Tue Jan 06, 2009 6:14 pm

those grooves in the yoke are from it rubbing on the seal. if it was rubbing and it was fixed its ok. if it is still rubbing then it needs fixed.

FLATBEDFORD · Post by **FLATBEDFORD** » Tue Jan 06, 2009 7:19 pm

May have been some loose chunks banging around in there. Must have been pretty noisy at the time!

ares360 · Post by **ares360** » Tue Jan 06, 2009 10:38 pm

well thanks to this thread, I have found out my overflow problem. The master cylinder has a large rear chamber, and the lines are backwards.

willowbilly3 · Post by **willowbilly3** » Wed Jan 07, 2009 6:07 am

fordman wrote:those grooves in the yoke are from it rubbing on the seal. if it was rubbing and it was fixed its ok. if it is still rubbing then it needs fixed.

Good info but I think he is talking about the beat up carrier in the picture.

martinarcher · Post by **martinarcher** » Wed Jan 07, 2009 9:36 am

ares360 wrote:well thanks to this thread, I have found out my overflow problem. The master cylinder has a large rear chamber, and the lines are backwards.

My master cylinder would also leak around the top gasket material. I would notice brake fluid on the valve cover every once in a while (we don't usually drive the truck more than once a week) My lines were right though. I'm hoping the correct master cylinder solves my problem. Glad the thread helped!

Hawkrod · Post by **Hawkrod** » Wed Jan 07, 2009 10:52 am

ares360 wrote:well thanks to this thread, I have found out my overflow problem. The master cylinder has a large rear chamber, and the lines are backwards.

Two things I would add, not all drum brake master cylinders have equal sized chambers, they can be a large and small one just like disc brakes. They are not the same as a disc brake master cylider because they do have a residual pressure valve in both ports and a disc brake master cylinder usually only has a valve in the front half for the rear drum brakes. The front brakes do the vast majority of breaking on a vehicle and the front brakes are larger. This usually means the front wheel cylinders are larger as well which brings us to the second point, when you have two different sized chambers the larger one is the rear and that is the one the front brakes connect to. Front brakes to rear chamber, rear brakes to front chamber. Hope this helps, Hawkrod

martinarcher · Post by **martinarcher** » Wed Jan 07, 2009 11:31 am

Hawkrod wrote:
ares360 wrote:well thanks to this thread, I have found out my overflow problem. The master cylinder has a large rear chamber, and the lines are backwards.
Two things I would add, not all drum brake master cylinders have equal sized chambers, they can be a large and small one just like disc brakes. They are not the same as a disc brake master cylider because they do have a residual pressure valve in both ports and a disc brake master cylinder usually only has a valve in the front half for the rear drum brakes. The front brakes do the vast majority of breaking on a vehicle and the front brakes are larger. This usually means the front wheel cylinders are larger as well which brings us to the second point, when you have two different sized chambers the larger one is the rear and that is the one the front brakes connect to. Front brakes to rear chamber, rear brakes to front chamber. Hope this helps, Hawkrod

Right On. I do believe the front wheel cylinders on my truck are different that the rears. So I guess it is possible that the master cylinder on the truck right now if fine, but I am still going to swap it out. It looks original and after 37 years there is no shame for a master cylinder to be replaced during a full brake overhaul.

ares360 - your problem could purely be related to the front lines being hooked to the front chamber. Might be worth just swapping the lines.

martinarcher · Post by **martinarcher** » Wed Jan 07, 2009 11:39 am

willowbilly3 wrote:
fordman wrote:those grooves in the yoke are from it rubbing on the seal. if it was rubbing and it was fixed its ok. if it is still rubbing then it needs fixed.
Good info but I think he is talking about the beat up carrier in the picture.

You might be right....I'm not sure what it is called. Please correct me if I'm wrong - I'm certainly not up on differential terminology. I guess it is the carrier since the diff gears are inside it and the pinion is bolted to it. What is a yoke? Here's some more pics of it rotated to see the grooves better. Hopefully it clears up any confusion. I don't think it was caused by a seal, it looks like old damage caused by loose parts (possibly a past blown rear end??). I just want to make sure it's nothing I need to fix, and if it is - what need done.

Got the rear brakes on last night....

Thanks guys!

fordman · Post by **fordman** » Wed Jan 07, 2009 11:54 am

the yoke is where the driveshaft connects.

ares360 · Post by **ares360** » Wed Jan 07, 2009 12:54 pm

martinarcher wrote:
Hawkrod wrote:
ares360 wrote:well thanks to this thread, I have found out my overflow problem. The master cylinder has a large rear chamber, and the lines are backwards.
Two things I would add, not all drum brake master cylinders have equal sized chambers, they can be a large and small one just like disc brakes. They are not the same as a disc brake master cylider because they do have a residual pressure valve in both ports and a disc brake master cylinder usually only has a valve in the front half for the rear drum brakes. The front brakes do the vast majority of breaking on a vehicle and the front brakes are larger. This usually means the front wheel cylinders are larger as well which brings us to the second point, when you have two different sized chambers the larger one is the rear and that is the one the front brakes connect to. Front brakes to rear chamber, rear brakes to front chamber. Hope this helps, Hawkrod
Right On. I do believe the front wheel cylinders on my truck are different that the rears. So I guess it is possible that the master cylinder on the truck right now if fine, but I am still going to swap it out. It looks original and after 37 years there is no shame for a master cylinder to be replaced during a full brake overhaul.

ares360 - your problem could purely be related to the front lines being hooked to the front chamber. Might be worth just swapping the lines.

I will definitely swap the lines first but its no big deal if it doesn't work. I have about 50 dollars credit at autozone so either way, THEY WILL WORK once again.

martinarcher · Post by **martinarcher** » Wed Jan 07, 2009 11:21 pm

Cool. You'll have them working in no time!

Anyone have the trick to getting the master cylinder off the brake booster. I removed both brake lines, and both stud nuts that hold it on the firewall. I pulled until I was blue and it will not come off. I found the Bendix diagram for their master cylinder and it looks like the manual cylinder has a pushrod that bolts to the petal, but mine are power brakes. Do I just need to pull harder? How do I get my master cylinder off the power booster?

Thanks!

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