Still no brakes! (1 Viewer)

[mydogpea]

New complete brake kit, master cylinder(yes, I did bench bleed it first), wheel cylinders, shoes, springs, etc,etc, bled brakes using a pressurized brake bleeder, no air in lines, adjusted wheel cylinders(which by the way, rotate the wrong direction to expand the shoes-in towards axel) wheels drag on the shoes when spun. The only thing I haven't done yet is adjust pedal height.
I have to pump the pedal 3 times to the floor then on the fourth it gets firm about 2 or 3 inches from the floor and starts to slow the truck down ...SLOWLY!
Absolutly zero stopping power whatsoever. Barely stops even at 5mph.
The only 2 things I come up with is, pedal needs adjusting or faulty booster.
If someone has another idea as to why the brakes aren't working properly, lay it on me.

 

[kurtnkegger]

Is it hard to push the peddle after it finally firms? If yes, then there is probably some problem with the booster. It wouldn't be too absurd to suspect a faulty master would it?

 

[igotta40]

My first impression is maybe your booster push rod is set incorrectly. Clearance should be 0.1 - 0.5 mm (0.004 - 0.020 in.) If your clearance is 1 or 2 mm that would cause the problem you have.

That new master cylinder may not be the same as the old one in that the booster rod clearance is no longer in spec.

The Toyota Factory Service Manual (FSM) shows a Special Service Tool (SST) that is used to set that clearance. I had trouble locating that tool so I made one and it worked perfectly. It's very easy to make one.

The boster push rod length is adjustable.

I'm concerned as to why your wheel cylinders adjust the wrong way. Where did you get them?

 

[saryon7]

If you are really sure that you got all the air out of the system, them my bet is that you got a bad master cylinder. It isn't all that uncommon to get a bad one from rebuilders. A simple check for air in the lines is watch the master cylinder for the liquid surge that happens when you press the pedal. A little surge is normal, a more violent one can mean air in the lines. Also, once you pump up the brakes and the pedal gets firm, does it slowly sink to the floor? If so, you have a leak somewhere. If you don't see any fluid anywhere, or the fluid level stays up, then you probably have an internal leak within the master cylinder where it doesn't leak fluid, just leaks it internally past one or both of the seals.

 

[JohnnyC]

Still air

This thread has your answer: https://forum.ih8mud.com/40-55-series-tech/229491-rear-wheel-brake-cylinders.html

 

[pb4ugo]

I think 1st you need to figure out why your adjusters work backwards. Are they the correct 1's? Were they assembled correctly? Are they in the correct location? Figure out that 1st. Then determine if you have the correct master.

 

[mruff]

brake

Subscribed. I have the exact same issue..

 

[mydogpea]

Is it hard to push the peddle after it finally firms? If yes, then there is probably some problem with the booster. It wouldn't be too absurd to suspect a faulty master would it?

Could be the master but it is new. Yes, when the pedal does firm up, I can't push it any further. It stays about 2 to 3 inches from the floor.

 

[mydogpea]

If you are really sure that you got all the air out of the system, them my bet is that you got a bad master cylinder. It isn't all that uncommon to get a bad one from rebuilders. A simple check for air in the lines is watch the master cylinder for the liquid surge that happens when you press the pedal. A little surge is normal, a more violent one can mean air in the lines. Also, once you pump up the brakes and the pedal gets firm, does it slowly sink to the floor? If so, you have a leak somewhere. If you don't see any fluid anywhere, or the fluid level stays up, then you probably have an internal leak within the master cylinder where it doesn't leak fluid, just leaks it internally past one or both of the seals.

Pedal does not sink to the floor when it firms up. Very sure I got all the air out, I left the bleeder open for about 30 seconds after the last tiny bubble I saw on every wheel.

 

[mydogpea]

I think 1st you need to figure out why your adjusters work backwards. Are they the correct 1's? Were they assembled correctly? Are they in the correct location? Figure out that 1st. Then determine if you have the correct master.

Well, I just was going off of what the Haynes manual said, "Using a suitable tool, rotate the adjusters through the backplate holes so that the tool tip moves in a direction from the wheel center towards the rim" This expands the shoes to firmly contact the drum. I've read in other threads that the tool handle moves from the center of the wheel outward towards the rim. Which is how mine turn. So maybe the Haynes manual is incorrect?

 

[JohnnyC]

Did you read the post I linked to?

 

[mydogpea]

Still air

This thread has your answer: https://forum.ih8mud.com/40-55-series-tech/229491-rear-wheel-brake-cylinders.html

I read this thread but it won't help me without pictures. I was lost at "compressing the other cylinder"

 

[mydogpea]

Did you read the post I linked to?

I wish there was a "how to" video or at least some pictures as to what part of the cylinders need to be purged of air.

 

[mydogpea]

I'm assuming that the front ones will have the same issue? Why would CCOT sell something assembled when the purchaser will have to disassemble them upon installation? What a PITA!!!

 

[mydogpea]

Alright, I tore apart one of the old cylinders and now I know what part is trapping the air. So I have a ?
Can the CCOT spring and rubber cup be replaced with the OEM ones that have the metal cap on both ends of the spring? This would eliminate the problem occuring again.

 

[mydogpea]

Okay, so I was able to purge the air out of the wheel cylinders that have the piston facing upwards, Now, how do I do the same thing to the ones with the pistons facing downwards...without losing all the fluid?

I'm guessing I won't need to since the air bubbles float which there shouldn't be any trapped in that piston...Does this sound right?

 

[cjgoode]

Just doing the top of each one should be fine. Also make sure your drums are properly adjusted, You need to adjust both sides of each drum till they are barely rubbing, so that one more click on either side changes the rubbing. Often one side causes the shoe to rub on the drum, but the other side is not even close yet causing you to pump twice to expand the one side that was not adjusted. So that is 8 adjustments.

 

[mydogpea]

pictures

I took some pics of what I did. Hopefully they might be able to help someone else that is going through what I did.
The truck stops better but I still have to double pump so I'm thinking I will have to do it again.

 

[mydogpea]

here's those pics. They're hard to tell but I did what FJROSS described.

 

[Coastline]

From the movie : The Beverly Hill Billies.

[Jethro and Cousin Pearl are driving in the truck to Jed's place]
Cousin Pearl: Jethro, did you take care of those old brakes like I told you to?
Jethro: Yes, Ma, I pulled them off the truck yesterday. The new brakes should be coming in the mail next week.