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I think my sd abs/master is failing, stupid questions.

total newb

senior jerk ass
Joined
May 19, 2020
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283
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Loc
trinity center ca
12/99 f350

So one of my front calipers "locked up". Compressed the pistons and cleaned the pin holes out, greased them up and put it back together. Pedal felt good to take up slack, 1 psi pump and check the wheel, stuck again.



So what are the odds that its the abs or the master? Any obvious ways to verify 1 or the other? Since it is only 1 front cal i suspect the abs.

Im about done fucking with this poor thing anyhow but its 1 more thing thats gona drive the price down and be shitty to drive till i do sell it.
 
I replaced front lines with the calipers either last summer or the one before, but they were napa lines so maybe. Thats why i didnt go with soft line option because "theyre new so theyre good right?"
 
Does that mean new calipers as well?

Are you running phenolic piston calipers? If it got hot and stuck once, I'd be highly suspect they deformed and are susceptible to stocking again
 
I replaced front lines with the calipers either last summer or the one before, but they were napa lines so maybe. Thats why i didnt go with soft line option because "theyre new so theyre good right?"
Manufacture defects comes to mind, so not necessarily. Myself due to issues with OEM lines and the like over the years, if I'm replacing the flexible line it's going to be braided.
 
Yes they were both done at that time. The thing is though, it didnt stick, it compressed down just fine, cycled out just fine.

So like trikekid said, its not releasing psi/return flow. Which is why im thinking up stream.
 
Yes they were both done at that time. The thing is though, it didnt stick, it compressed down just fine, cycled out just fine.

So like trikekid said, its not releasing psi/return flow. Which is why im thinking up stream.
If you crack the bleeder does it return/back off?
 
Didnt try but ive never had a caliper auto retract with open line. Unless you mean just crack the bleeder and see if it lets off to allow it to roll.

Caliper crompressed with normal resistance with clamps like ive done for 20y.
 
Yes they were both done at that time. The thing is though, it didnt stick, it compressed down just fine, cycled out just fine.

So like trikekid said, its not releasing psi/return flow. Which is why im thinking up stream.
I've pushed pistons back in with a c clamp that had a internal collapse in the soft line.
 
So what are the odds that its the abs or the master
Slim to none.
When the wheel is locked up crack the bleeder and see if these any pressure. When I do a brake job on disc brakes with brackets I'll sandblast all the critical points so the pads and caliper will floats like it's supposed too. Then use brake grease on the bare metal and under the shims.
 
Didnt try but ive never had a caliper auto retract with open line. Unless you mean just crack the bleeder and see if it lets off to allow it to roll.

Caliper crompressed with normal resistance with clamps like ive done for 20y.
Crack bleeder and see if it will roll or if the tire can be moved. That'd highlight pressure being held or still applied by abs if it comes out under pressure, and if the tire still can't be worked enough to roll then back into the caliper

If it went back in about the same, it'd be more odd for it to be a stuck caliper, but hell it shouldn't have happened in the 1st place
 
After replacing two front calipers on an F150 and still having issues I discovered that an internally collapsed soft line was the root culprit of all my woes. I couldn't crack the bleeder on either one, which is why I jut put new calipers on it.
 
When I do a brake job on disc brakes with brackets I'll sandblast all the critical points so the pads and caliper will floats like it's supposed too. Then use brake grease on the bare metal and under the shims.
I just omit the stamped stainless things and let the pads chatter around. :laughing:
 
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