[cobalt327]

Bleeders:

Pressure
Vacuum

[Oilyrascal]

Originally Posted by cobalt327

Bleeders:

Pressure
Vacuum

Thanks, I have the vacuum already, I may make a go at making the pressure bleeder

[vinniekq2]

the wheel cylinder system? is it homemade? are the bottom wheel cylinders mounted upsidedown? what do you use to split fluid flow on the rear cylinders? do what cobalt said about adjusting shoes. Are the shoes correct?how many adjusters are on the rear wheel systems? Is there an emergency system on the rear brakes. can you take a picture front and backing plate and post it?

[1Gary]

Kind of a guess.Modern day systems have a proportioning valve mainly because of a disc/drum mixture.With the extra wheel cylinders in the rear,you might not be moving enough pressure/volume to the rear brakes.Certainly it is going to require more than the fronts.You might find that you need to get a adjustable proportioning valve to correct that.You have to be careful with them because the brake requirements do change when in a panic stop vs normal braking.

[Oilyrascal]

Originally Posted by vinniekq2

the wheel cylinder system? is it homemade? are the bottom wheel cylinders mounted upsidedown? what do you use to split fluid flow on the rear cylinders? do what cobalt said about adjusting shoes. Are the shoes correct?how many adjusters are on the rear wheel systems? Is there an emergency system on the rear brakes. can you take a picture front and backing plate and post it?

Hello, no its not home made, here is a picture of the front front view, sorry I do not think I have a picture of the backing plate for the front ......and here are the rear brakes



The bleered are on top.

Two adjustors on the front and rear top and bottom

I use the factory splitter located on the top of the housing and then there are factory split lines between cylinders

[Oilyrascal]

Originally Posted by 1Gary

Kind of a guess.Modern day systems have a proportioning valve mainly because of a disc/drum mixture.With the extra wheel cylinders in the rear,you might not be moving enough pressure/volume to the rear brakes.Certainly it is going to require more than the fronts.You might find that you need to get a adjustable proportioning valve to correct that.You have to be careful with them because the brake requirements do change when in a panic stop vs normal braking.

You may be right about the proportioning valve, I was doing a little digging on-line and I thought that there was a strong possibility that there would be something aftermarket that would increase my brake volume.

I guess I was wrong, thanks

[vinniekq2]

It may be the picture? It looks like the shoes were wearing in the middle on the dual wheel cylinder system.This indicates the drums are way oversize/wrong shoes.The reason I say this,it appears the middle of the shoes appear worn and the outside edges appear thicker.You may have to get the shoes custom refit and get them arced to the drum size.
The other idea would be to fabricate an adjuster that fits inside of the return springs(if there is room).If you run out of travel in the wheel cylinders then you would have to fabricate longer engagement pins.The original hold down pins could still be used.
NOTE: when you take the shoes off of the backing plates make sure the bearing surface for the shoes are flat(fill in any groves that are worn in the backing plate) The shoes need to run true to get proper adjustment.

[MARTINSR]

Man that is wild, what a MONSTER! Interesting, but it WILL work just as it did from the factory.

Brian

[Oilyrascal]

Originally Posted by vinniekq2

It may be the picture? It looks like the shoes were wearing in the middle on the dual wheel cylinder system.This indicates the drums are way oversize/wrong shoes.The reason I say this,it appears the middle of the shoes appear worn and the outside edges appear thicker.You may have to get the shoes custom refit and get them arced to the drum size.
The other idea would be to fabricate an adjuster that fits inside of the return springs(if there is room).If you run out of travel in the wheel cylinders then you would have to fabricate longer engagement pins.The original hold down pins could still be used.
NOTE: when you take the shoes off of the backing plates make sure the bearing surface for the shoes are flat(fill in any groves that are worn in the backing plate) The shoes need to run true to get proper adjustment.

Thanks for the info, I may have to check this out, it may come down to getting another rear for the truck, something more part friendly but thanks

[1971BB427]

If you look at the pivot point on the shoes you can see the shoes don't travel straight out, they travel at a 45 degree angle, so they will always wear differently than a lighter car/truck system that pivots on the lower adjuster. Even if the shoes fit the drum perfectly when new, they will still have an uneven wear pattern with dual cylinders and angled pivot points.

[vinniekq2]

If you dont mind a heavy modification,consider finding a drum brake application that is more modern but has the same diameter shoes and graft the entire backing plate onto the diff in your truck.I was thinking you wanted to keep it as original as possible.
Like posted by 1971BB427 the pivot point on the single cylinder system will wear uneven,,,You can make sleeves of different diameters to fit ovet the pin to adjust the shoes out at the bottom.This is not a simple star wheel but it works if you dont mind taking the brakes apart yearly.Also compensates for drum wear

[Oilyrascal]

I have brakes ! I dont know where I left on here but after I put on the third master cylinder from Autozone ( Napa cordone were all junk ) I have brakes. Let me tell you how it is and maybe I can get some feedback on how to make it better.

Locked up all brakes tight against the drums with the adjustors, I still have yet to adjust the front brakes properly ever, there is evidently a feeler gauge involved to adjust the bottom adjustor and I just havent bothered to check where it is at.

Anyway I locked up all 4 brakes with the adjustors that were simplest to do and bled all 4 wheels, I could tell right away that this new master was reacting differently, things flowed smoother, I was hearing things that I am accustomed to hearing when I bleed brakes.

After done bleeding ( BTW the truck does not run yet so no booster comes into play yet ) I left the front wheels locked up against the drums and un-locked the rear drums and had my wife hit the brake pedal, no movement in the rear, I stuck a 7 foot steel fence pipe inside the spoke on the wheel and tried to move it, no movement.

I went to the front, unlocked them with the adjustors and had my wife step on the brakes, movement still in the front but took some force, readjusted the brakes quickly ( top adjustor only ) and tried again, difficult to move but I could still force it.

I have to have too much drag on the front brakes, and the pedal does go to low when all 4 wheels are loose and spinning but I am getting there.

How will this react with the brake booster helping???? I have a feeling that will make the pedal even lower.

I noticed that if I pumped the pedal a bit the pedal would be higher and I am assmuming ( but did not verify ) that all 4 wheels would have been locked up at this point.

Thinking about re-bleeding, dont know if that will help, I was pretty thorough already with the bleeding, any advice to get more pedal room before it sinks would be helpful.

I guess maybe I am running out of pedal again because of there is just not enough room in the pedal to make up for the volume of fluid I need but I can keep working on that.

[vinniekq2]

if the pedal pumps up the the adjustment is too low.Your brakes need to be square on the backing plate.The bottoms need to be adjusted to just touching.The tops when resting on the stops need to be close to adjusted.The pins need to be long enough that the wheel cylinder does not run out of stroke.The extra 2 wheel cylinders will need a longer stroke master to move enough volume of fluid. The boost does not make a difference to the volume of fluid moved. You might consider using wheel cylinders with a reduced bore to get more movement for the shoes.
If you cannot find smaller bore wheel cylinders,have a machinist sleeve the cylinders.

[Oilyrascal]

Originally Posted by vinniekq2

if the pedal pumps up the the adjustment is too low.Your brakes need to be square on the backing plate.The bottoms need to be adjusted to just touching.The tops when resting on the stops need to be close to adjusted.The pins need to be long enough that the wheel cylinder does not run out of stroke.The extra 2 wheel cylinders will need a longer stroke master to move enough volume of fluid. The boost does not make a difference to the volume of fluid moved. You might consider using wheel cylinders with a reduced bore to get more movement for the shoes.
If you cannot find smaller bore wheel cylinders,have a machinist sleeve the cylinders.

Th truck only has 23,000 miles on it, ex fire water tanker truck, I saw zero wear on the backing plates if thats what you mean, if you mean the back brakes need to be re-adjusted than I can do that.

Longer stroke master with this power brake booster is not going to happen I do not think, I have looked thru catalogs at Napa, on-line ect quite a bit, 1 1/4 bore master was the largest I could find to fit this brake booster but unfortunately stroke is not always listed and its tough to get anyone to answer that question.

I really do not want to get into sleeving wheel cylinders if possible, I just got this all together and dont relish the though of pulling out the axles again and replacing the gaskets ect.

Maybe you know of an aftermarket master cylinder brake booster assy that would work? I can replace these easy enough if need be

[vinniekq2]

No idea exactly what you are working with? I would look at everything from a hydr boost in a new diesel to OE.Consider also calling suppliers like Wilwood,as they specialise in complete after market systems. some after market pedals may incorporate a master that better suits your objective.