Can Combination Valve cause abnormal pad wear?
- Thread starter DaveP
- Start date
SY2455
70's Veteran
Re: Can Combination Valve cause abnormal pad wear?
Dave, I have never seen the proportioning valve cause this.
1. What I have found is the brake fluid absorbing water causing corrosion in the caliper piston and as a results the piston does not release all the way.
2. The only other cause was the makeup of the brake pad. Which one are you using ?
Side note do you nave a plate that has NCRSP on it ?
Dave, I have never seen the proportioning valve cause this.
1. What I have found is the brake fluid absorbing water causing corrosion in the caliper piston and as a results the piston does not release all the way.
2. The only other cause was the makeup of the brake pad. Which one are you using ?
Side note do you nave a plate that has NCRSP on it ?
Last edited:
sly dvl
Ya, it's got a Turbo
Re: Can Combination Valve cause abnormal pad wear?
I have seen this, but on a late 80's Chev K1500 with RWAL. Customer was doing front pads every 5-8K KM. Rear brakes (shoes) were hardly wearing at all. Truck didn't stop very well either.
I removed the rear brake hose and screwed in a solid fitting, test drove the truck and found almost NO difference in braking. This told me that the rears were doing very little.
Replaced the master, no difference. Replaced the proportioning/combination valve and that cured it.
I have seen this, but on a late 80's Chev K1500 with RWAL. Customer was doing front pads every 5-8K KM. Rear brakes (shoes) were hardly wearing at all. Truck didn't stop very well either.
I removed the rear brake hose and screwed in a solid fitting, test drove the truck and found almost NO difference in braking. This told me that the rears were doing very little.
Replaced the master, no difference. Replaced the proportioning/combination valve and that cured it.
DaveP
Active member
Re: Can Combination Valve cause abnormal pad wear?
Thank you Lloyd and Kevin for the replies and input.
I don't think it's the front brakes dragging. They never smell, get hot, rotors aren't blue, etc. No real signs of dragging. The calipers were replaced a few years ago; I don't drive it in deep water, the brake fluid gets changed about every 3-4 years on all my vehicles.
I use organic pads. I don't use metallic, because I don't like the performance when cold. Ie, they don't stop very well the first couple of times in the morning. But these are the same pads (Bendix D154) I've been using for quite some time now on all (3) my S-series. They usually last over 15,000 miles on the truck.
Kevin's response was what I was looking for. He is able to associate my conditions with his experience, and suggest that it is the combination valve. While I feel it still stops pretty well, I could be mistaken. Loss of brake performance is very subtle. I have noticed that it doesn't seem to lock the rear brakes, or engage the RWAL like it has in the past. I also compared the rear drum surface temprature of the truck to the temp on the Typhoon after about the same trip and braking endurance, by touching it with my finger. The Ty is much warmer. The truck's rear brakes aren't doing much.
So based on this input, I'll go ahead and replace the combination valve. It's a $195.00 part, (The SyTy valve is $89.00, and the only difference appears to be the mounting bracket) and that's a big enough expenditure that I want to have some confidence that the problem will be solved.
And no Lloyd, I no longer have any personal plates on any of my cars. A quick Google came up with North Carolina Retired School Personnel. Nope, not me.
Thanks guys.
Dave
Thank you Lloyd and Kevin for the replies and input.
I don't think it's the front brakes dragging. They never smell, get hot, rotors aren't blue, etc. No real signs of dragging. The calipers were replaced a few years ago; I don't drive it in deep water, the brake fluid gets changed about every 3-4 years on all my vehicles.
I use organic pads. I don't use metallic, because I don't like the performance when cold. Ie, they don't stop very well the first couple of times in the morning. But these are the same pads (Bendix D154) I've been using for quite some time now on all (3) my S-series. They usually last over 15,000 miles on the truck.
Kevin's response was what I was looking for. He is able to associate my conditions with his experience, and suggest that it is the combination valve. While I feel it still stops pretty well, I could be mistaken. Loss of brake performance is very subtle. I have noticed that it doesn't seem to lock the rear brakes, or engage the RWAL like it has in the past. I also compared the rear drum surface temprature of the truck to the temp on the Typhoon after about the same trip and braking endurance, by touching it with my finger. The Ty is much warmer. The truck's rear brakes aren't doing much.
So based on this input, I'll go ahead and replace the combination valve. It's a $195.00 part, (The SyTy valve is $89.00, and the only difference appears to be the mounting bracket) and that's a big enough expenditure that I want to have some confidence that the problem will be solved.
And no Lloyd, I no longer have any personal plates on any of my cars. A quick Google came up with North Carolina Retired School Personnel. Nope, not me.
Thanks guys.
Dave
It's just a six
Super Member
Re: Can Combination Valve cause abnormal pad wear?
Rotors do not need to get blue or smell when the pistons do not release all the way.
Also the caliper pin (caliper floats on it) has to be clean,no rust,& lube on them.:2cents:
Rotors do not need to get blue or smell when the pistons do not release all the way.
Also the caliper pin (caliper floats on it) has to be clean,no rust,& lube on them.:2cents:
NecroWolf
lost marbles member
Re: Can Combination Valve cause abnormal pad wear?
i have seen the prop valve do wierd stuff on other trucks. we had a humvee that went through 3 rear pumpkins because the rear brakes were dragging and heating it up. i have also seen different brake fluids mixed and react to each other causing brake issues. but on s-serires if i have front brake issues i swap out the front lines. seems to be a regular issue for them
i have seen the prop valve do wierd stuff on other trucks. we had a humvee that went through 3 rear pumpkins because the rear brakes were dragging and heating it up. i have also seen different brake fluids mixed and react to each other causing brake issues. but on s-serires if i have front brake issues i swap out the front lines. seems to be a regular issue for them
RMcCourt
More Miles by Boat
Re: Can Combination Valve cause abnormal pad wear?
This on my Daily Driver 91 S-series 4X4 pick-up truck. By "abnormal" I mean the last 2 sets of pads lasted less than 2,000 miles. I usually get about 12-15K from a set of pads in this truck the way I drive/use it.
I had an issue with the RWAL awhile back. I replaced the RWAL solenoid/valve ($175!) and the codes went away. I also replaced the Master Cyl at the same time. The pedal is hard, firm, and reasonably 'normal'. The truck seems to stop OK, but it may be a little biased towards the fronts, with not a lot of rear-brake action. It's really hard to tell for sure.
The truck has 271K on it. I have driven it 160K of those miles. I know something is not right for this short of a pad life. The combination valve (proportioning valve) is origional to the truck. I am suspicious that this valve is malfunctioning in the proportioning action.
Has anyone else ever found the combination [proportioning] valve to be malfunctioning, and causing abnormal brake balance that shows up as rapid front-pad wear? Or am I even on the right track, here? I'm open to suggestions.
Thanks,
Dave
This on my Daily Driver 91 S-series 4X4 pick-up truck. By "abnormal" I mean the last 2 sets of pads lasted less than 2,000 miles. I usually get about 12-15K from a set of pads in this truck the way I drive/use it.
I had an issue with the RWAL awhile back. I replaced the RWAL solenoid/valve ($175!) and the codes went away. I also replaced the Master Cyl at the same time. The pedal is hard, firm, and reasonably 'normal'. The truck seems to stop OK, but it may be a little biased towards the fronts, with not a lot of rear-brake action. It's really hard to tell for sure.
The truck has 271K on it. I have driven it 160K of those miles. I know something is not right for this short of a pad life. The combination valve (proportioning valve) is origional to the truck. I am suspicious that this valve is malfunctioning in the proportioning action.
Has anyone else ever found the combination [proportioning] valve to be malfunctioning, and causing abnormal brake balance that shows up as rapid front-pad wear? Or am I even on the right track, here? I'm open to suggestions.
Thanks,
Dave