Brakes

Ron

Ron

Dum Spiro Spero
Moderator
Joined
Apr 16, 2005
Location
Sharon, SC
Ok one of y'all smarter than me - weigh in here.

Tundra ~ 300k miles.
Brakes stop as good as ever.
Pedal feel is same as always.

At stop - and only at stop - it will try to pull through the brakes. So same pedal pressure I've used forever, when sitting at a red light - it will start to creep forward.
A little extra pressure and it stops and holds fine. To be more precise it isn't hard pressure just more than its ever taken. Historically a foot just resting on the pedal will keep it stopped, now it takes an intentional press.

Pads have been replaced twice in its life and have plenty left o n them visually.
Never replaced a caliper, rotor or any other part of the brake system.

Anyone got any ideas? I'm wondering if a fluid flush - even partial - might be worth a try given 300k miles. (fluid is still full)
I guess the booster could be starting to fail.

Any other thoughts or input?
 
Ron said:
Ok one of y'all smarter than me - weigh in here.
Click to expand...

shawn said:
Torque converter
Click to expand...

Sorry you are disqualified :flipoff2:

In all seriousness I would think a TC would exhibit some other symptom as well. Maybe its just super early symptom...interesting thought I hadnt considered.

Ive never serviced the trans or changed the fluid or filter...so its probably warranted to fail.

Shrug...if that's it drive it til it dies and push it in a hole. If it lays down on the way home tonight Ive got my moneys worth....and I have been side eyeing a new by-GAWD-zilla so I can be like my hero @Jody Treadway
 
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Get somebody to hold the brakes while you spray starting fluid around the booster.
 
LBarr2002 said:
I'd say booster is getting weak or vacuum leak.
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More info? I don't understand the test.

As in it should rev?

I need to check a booster on a old 7.3 diesel. Sounds like a bad idea for that fuel type though.
 
WARRIORWELDING said:
More info? I don't understand the test.

As in it should rev?

I need to check a booster on a old 7.3 diesel. Sounds like a bad idea for that fuel type though.
Click to expand...

Yes, if you have a vacuum leak and introduce a fuel source like starting fluid or propane from an un-lit torch it will draw it in through the leak and rev the engine. Typically won't work on engines with forced induction like turbo diesels since the engine doesn't create the vacuum, but I don’t know anything about old 7.3s.

Duane
 
have your rotor turned, probably slicker than snot on a door knob and flush the fluid.
 
Does that have the DAC? or the "hydroboost" or whatever they call it? I have had issues in the past with them loosing pressure, there is a special procedure to replace the pads where you have to "use up" the pressure reserve by pumping the pedal with the key off.
 
lbyota85 said:
Older 7.3s had vacuum pump. Changed to hydro boost in the super dutys.
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Yes little vac pump. Haven't done any tinkering. Gonna start with that little belt driven pump.

Edit...by memory of the line goes to an electric controlled valve of some sort as well. Tee's into the diaphragm and master cylinder assembly.

Edit number two....it's rattling and sounds like a small bag of hammers. I bet it s bad🤠.
 
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Got any nerve issues in feet/legs? I thought my brakes were slipping until I realized I just wasn’t putting the same pressure - felt the same to me, but neuropathy has gotten so bad now I can’t feel much below the knee. Everything has become needing to be very conscious as compared to years ago.
 
A quick check for the torque converter would be try the same thing on a slight decline with the truck in neutral. If it stops pulling through, then you have root cause, if not, I would follow @Jeff B advice and have the rotors turned, might also be a caliper sticking or a hose that has given up the ghost and is expanding slightly under light pressure.
 
Has this thing never had the brakes bled? I'd definitely try that. Even though it's a sealed system, over a long period of time small amounts of moisture can still seep in.
Moisture in the lines will decrease ability to hold for long periods bc the moisture is compressing.
I suspect your overall stopping has decreased slightly but since it's been really gradual you didn't notice it.
Boil a frog kinda thing
 
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