Brake woes

The_Josh_Bear

Full Access Member
Joined
Jun 1, 2016
Posts
1,916
Reaction score
1,498
Location
Western WA
BTW, if you have oil contamination in your rear brake shoes, they are /less/ likely to grab, because the oil acts as, well, a lubricant.


One idea is that perhaps the rear brakes aren't adjusted properly. Make sure to adjust the star wheel out as far as you can(pumping the brakes a couple times to even stuff up), then back in until it stops dragging. I've been told that you can get grabby brakes if they aren't adjusted properly.

You'd think that, and I'm sure that at first they slide better, but I've had my shoes oil contaminated 4-5 times over the years with axle lube or brake fluid and can say for sure that 3 of the times caused a wheel to lock up easily. The other two I must have caught before I noticed poor braking either way.

Yep the rears are adjusted properly. E brake cables return correctly as well and are not dragging.
 

Thewespaul

Supporting Member
Supporting Member
Joined
Jul 27, 2015
Posts
8,796
Reaction score
8,058
Location
Bulverde, Texas
You can pick up ultrasonic cleaners for less than $100, it will pay for itself very quick if you’re doing a lot of wrenching, but for now just soaking in some diesel and rinsing in brake clean will work.
 

Thewespaul

Supporting Member
Supporting Member
Joined
Jul 27, 2015
Posts
8,796
Reaction score
8,058
Location
Bulverde, Texas
The oil contamination causes grabby shoes because it causes the shoe material to swell, not really related to it having actual oil on them which gets burnt off pretty quick.
 

franklin2

Full Access Member
Joined
Feb 24, 2009
Posts
5,161
Reaction score
1,385
Location
Va
I will verify oil/brake fluid will make them grab. If they are totally soaked and dripping, I agree they do not brake very well. But if it's a small leak or if you have tried to clean them off after a leaking episode, they will start grabbing. Nothing to do but buy new shoes.

Sorry I haven't gone back and read the beginning of the thread lately, but what is all this talk of a proportioning valve? I see in his signature he has a 89 like mine. It did not come with a proportioning valve from the factory, it came with RABS system. That's all it came with on my truck, no proportioning valve.
 

The_Josh_Bear

Full Access Member
Joined
Jun 1, 2016
Posts
1,916
Reaction score
1,498
Location
Western WA
You must be registered for see images attach

This here that my gloved finger is pointing to is called a proportioning valve by Ford. Dunno why as it's a pressure limiting valve but that's what people call it. Sits between the MC and rear brake lines. Keeps the rear end from seeing over some amount of PSI as shoes are self-exciting and don't need a lot of pressure.
 

hacked89

Full Access Member
Joined
May 30, 2018
Posts
1,739
Reaction score
2,330
Location
Bucks County PA
1989 f250 had proportioning valve and rabs from factory

Since we are discussing language...
A pressure limiting valve has a binary value set that if that set value is exceeded it cuts off the pressure.

A metering valve in brakes is very similar to that. But some of them work where since the shoes need X distance to engage versus the pads on the calipers the rear brakes are metered to engage first until X pressure is reached and then the front pressure begans.

A proportioning valve only let's a certain % of pressure to the rear brakes. This % depends on weight over the axle in the calculation. Since the part calls it a proporting valve, and has notes regarding GVW..its a proportioning valve IMO but we would need pictures of it taken apart.


Btw pull the PV out and use an adapter if needed and reconnect it to the master cylinder. If the truck brakes no different than with the valve it's not working properly.


Sent from my SM-G955U using Tapatalk
 

The_Josh_Bear

Full Access Member
Joined
Jun 1, 2016
Posts
1,916
Reaction score
1,498
Location
Western WA
1989 f250 had proportioning valve and rabs from factory

Since we are discussing language...
A pressure limiting valve has a binary value set that if that set value is exceeded it cuts off the pressure.

A metering valve in brakes is very similar to that. But some of them work where since the shoes need X distance to engage versus the pads on the calipers the rear brakes are metered to engage first until X pressure is reached and then the front pressure begans.

A proportioning valve only let's a certain % of pressure to the rear brakes. This % depends on weight over the axle in the calculation. Since the part calls it a proporting valve, and has notes regarding GVW..its a proportioning valve IMO but we would need pictures of it taken apart.


Btw pull the PV out and use an adapter if needed and reconnect it to the master cylinder. If the truck brakes no different than with the valve it's not working properly.


Sent from my SM-G955U using Tapatalk
Any idea on how to get said adapter? Sounds like I might be throwing parts at this anyway just to test the darn thing.

Pulled it and cleaned it out and re-installed. If there was a difference it's not much, still locks up the rears easily. BUT at least it's consistent and predictable and I can deal with that for the little bit I need to drive in the next week or two.
 

The_Josh_Bear

Full Access Member
Joined
Jun 1, 2016
Posts
1,916
Reaction score
1,498
Location
Western WA
So it finally occured to me that I could take the guts out of the prop valve and reinstall to do the same thing as the superduty's but without having to source the part. Guess I'll give that a shot this week and if it doesn't help I'll swap out the shoes. I didn't see any bits inside when I went to clean it or broken spring or anything that looked very odd. But it's probably the OEM prop valve and had little bits of stuff and a touch of rust inside. Cleaned it best I could in the few mins I had.

Thanks for all the help guys!
 

hacked89

Full Access Member
Joined
May 30, 2018
Posts
1,739
Reaction score
2,330
Location
Bucks County PA
So it finally occured to me that I could take the guts out of the prop valve and reinstall to do the same thing as the superduty's but without having to source the part. Guess I'll give that a shot this week and if it doesn't help I'll swap out the shoes. I didn't see any bits inside when I went to clean it or broken spring or anything that looked very odd. But it's probably the OEM prop valve and had little bits of stuff and a touch of rust inside. Cleaned it best I could in the few mins I had.

Thanks for all the help guys!
No problem. Just remember we expect it to be worse than before, that would mean the pv is atleast somewhat working. If its no different than before or barely different, something is wrong with the pv.

Sent from my SM-G955U using Tapatalk
 

franklin2

Full Access Member
Joined
Feb 24, 2009
Posts
5,161
Reaction score
1,385
Location
Va
So it finally occured to me that I could take the guts out of the prop valve and reinstall to do the same thing as the superduty's but without having to source the part. Guess I'll give that a shot this week and if it doesn't help I'll swap out the shoes. I didn't see any bits inside when I went to clean it or broken spring or anything that looked very odd. But it's probably the OEM prop valve and had little bits of stuff and a touch of rust inside. Cleaned it best I could in the few mins I had.

Thanks for all the help guys!

I will look and see if I have that little brass fitting. If you go back and check your shoes, it should be dusty and dry back there. If it's black and greasy looking, and the shoes have a shine to them, I would suspect they are contaminated.
 

Forum statistics

Threads
91,217
Posts
1,128,517
Members
24,045
Latest member
Ramtough01

Members online

Top