Tester… that may have been a little hit and run. But it doesn’t work on cars that are old enough to have corrosion build up on the adjuster wheel, especially cars that drive salted roads and end up with more than normal rust. . But you are right, most of the time it works.
But when you live in rust belt, and do a rear brake job, you make sure the self -adjust mechanism works.
I did . . . I don’t appreciate it when somebody insinuates I’m being untruthful
You would be mistaken
That is evident. And I will.
Congratulations on alienating one of the more experienced members on this forum. One who may just have more professional experience than YOU.
You may now proceed without me
I’m going to go go out on a limb.
Since i’s happening on the two opposing corners, it appears to be tied into whatever ties them together.
Since it builds pressure as you drive, it must be something that can do so AND is connected to both lines.
Have you tried disconnecting the booster line?
If the booster isn’t functioning properly such that the valve system in the center of the diaphragm never fully relieves the vacuum on the front of the diaphragm constantly has vacuum, it’ll slowly build the brake pressure by constantly pushing the MC center rod. Perhaps the two opposing brakes that are slowly applying themselves are on the shorter line perhaps they’re slowly closing in advance of the other side. And once the fluid in those calipers gets hot, it’ll expand and exacerbate the problem.
Like I said, the theory is a wild idea. But clamping off the booster vacuum line is free and easy, so why not try it?
keith . I think all cars have crossover brakes and have for a long time. Even ones with drum rears. I was looking at the master yesterday before I posted an it has 4 lines coming out of it, and it’s 2001.chev prizm with drum rears. I think the crossover brakes have been mandated. It would make sense. You can bust a brake line and stil get stopped. That doesn’t mean you can keep driving it because once you’ve lost what’s in the reservoir you can’t stop but an initial rupture will just lose 2 brakes, not all fo them.
@Carboncrank 1. Stopping a vehicle with the parking brake is nonsense , you have real brakes for that purpose 2. Putting the transmission in neutral at stop lights is not wise 3. Not repairing brakes properly is a danger to you and all people around you so do it right .
LOL, once many years ago I was coming off an exit ramp from a divided highway to a stoplight at a busy cross street when I lost my main brakes. The pedal hit the floor. Trust me, stopping the vehicle with the parking brake was not nonsense. It saved my bloated buns.
Manufacturers today call them “parking brakes”, but if you ever lose your brakes like I did you’ll learn to appreciate their unwritten function as “emergency brakes”. Yeah, they take longer to stop the vehicle… but hey, that’s far, far better than nothing.
I showed this image before.
This is Lake Avenue in Duluth.
I was a passenger in a vehicle on this hill when the vehicle lost its brakes.
The image here is from seventh street.
The brakes were lost on sixth street.
As soon as the brakes were lost, the driver shifted into lower gear and at the same time applied the parking brake.
The parking was of no use because of the speed the vehicle had gained.
The transmission screamed to slow the vehicle down.
I looked at him and said, “Turn left at 4Th street because it’s bus stop, and there won’t be any vehicles parked at the corner”.
We took that corner on two wheels, barely missing the parked cars ahead of the bus stop, hit the ground and swerved between two parked vehicles into a vacant lot.
Now that’s excitement!
Thank God you’re still with us!
My 2007 Silverado does not have diagonal lines. Only one line to the rear that splits over the rear end.
I go to Toyotanation forum for laughs. I have yet to see experts there . The real mechanics that post here could work circles around the ones who reply at Toyotanation . Now granted I have seen some of the regulars here and at Toyotanation and they give reasonable replies.
I did a little research on diagonal brake systems and found this. Just an FYI.
(For typical light duty automotive braking systems)
In a four-wheel car, the FMVSS Standard 105, 1976; requires that the master cylinder be divided internally into two sections, each of which pressurizes a separate hydraulic circuit. Each section supplies pressure to one circuit. The combination is known as a dual master cylinder. Passenger vehicles typically have either a front/rear split brake system or a diagonal split brake system (the master cylinder in a motorcycle or scooter may only pressurize a single unit, which will be the front brake).
A front/rear split system uses one master cylinder section to pressurize the front caliper pistons and the other section to pressurize the rear caliper pistons. A split circuit braking system is now required by law in most countries for safety reasons; if one circuit fails, the other circuit can still stop the vehicle.
I don’t think it does, my RPMs actually go higher when I shift to neutral from drive by a few hundred; regardless, even if it does the fuel savings are minuscule at best…I actually have a bigger concern with this “method” you use…if you don’t have your foot on the brake pedal, your rear brake lights don’t light up at all causing a safety hazard…if your lights aren’t on, I think the person that actually rear-ends you could have a legitimate case to put cause on you…also if you use your hand break when you park, you’ll never have to worry about it not being used and getting stuck
I don’t know about any legal liability, but I keep my foot on the brakes whenever I’m stopped for any reason, regardless of where the shifter is (neutral or gear) for the very reason you mention. I don’t want to get hit I the rear end no matter who’ll be liable.
Also, if I come to an unusual/abnormal stopped line of traffic on the highway, I not only keep my foot on the brakes but I also turn on my flashers. I prefer to do everything possible to prevent getting hit.
The hand brake use sort of depends. In cold, icy weather I avoid using it for fear of it freezing up. In normal weather, it gets used a few times a week just in normal daily driving. That to me is sufficient to keep it from getting stuck due to lack of use.
Just my two cents and without reading all the posts, but I did see the comment that hoses are only $12 and masters are expensive. A master is anywhere from $30 to $100 depending on the brand etc. from Rockauto. True hoses are less than $10 but how many more years would you think the master is going to last anyway. It’s not like it hasn’t done its job for 15 years. So you go to the work of replacing the hoses and bleeding the system only to find out it is the master, and do it all again? Just seems like for $100 or so you can make sure and just do the job once. Theory is nice and its nice to understand what’s happening but the bottom line is understanding or not, the object is to fix the brakes, not understand them.
Wow, long post I just joined. My 2002 Chrysler minivan was acting just like the OPs Prisim but it was at random, sometimes not happening for a week or more. Diagnosing it was made difficult by the fact that I live in rust belt central and my van had never had those little rubber caps over the bleeder valves. Trying to open the bleeders would have meant removing the calipers and wheel cylinders and getting them down on my workbench to take out the rubber parts so I could use enough heat to free the bleeders. This also would result in broken brake k\lines at the wheel cylinders because nuts rust more tightly to the lines than they do to the wheel cylinder.
My brake fluid was dark and had black chunks floating in it. A restricted hose or sticking caliper would not explain the left rear and right front always sticking at the same time. Before I replaced the master cylinder I decided to try something. I used a turkey baster to empty the master cylinder and refill with fresh fluid. I did that 4 weeks in a row. It worked! The problem didn’t occur again. My belief is that the crud in my brake fluid plugged one of the return ports in the master cylinder.
I know this wasn’t a “proper” repair but bear in mind that this van was less that 2 years away from the junkyard because of terminal rust.
I replaced rear brakes on my 2012 Camry about 2 months ago, the little rubber caps on the bleeders plus the fact that I don’t commute through the salt 5 days a week made all the difference. No problem bleeding the brakes.
I hope I read you right and that you have already replaced the master? So now the culprits are the hoses and/or the caliper or wheel cylinder. So change those both out, and the hoses along with it, why not since you have to bleed the brakes anyway. Although I have to say, collapsed brake hoses are not all that common, especially not two at the same time, but why not change them, since it’s your brakes. If THAT doesn’t fix it, find whatever else effects the brakes in your car (it could even be the proportioning valve, but I think that’s built into the master on most cars).
If I had this problem I might just take it into the shop. To keep the bill lower, I’d get the parts myself and bring it all to the shop (the markup if the shop buys your parts, tend to be ridiculously high). And have them do a fluid flush too, sounds like it could use one.
Providing your own parts means you will not have a warranty on the repair .
In addition, the shop may refuse to install them. Many shops won’t.
If you’re going to have a shop do work for you, let them get their fair markup. You wouldn’t bring a bag of food into a restaurant and ask them to cook it for you, would you?
the_same_mountainbike… That’s and interesting idea from someone that obviously knows more than I do about how a booster works than i do. Brakes at the firewall are not something I know alot about so I’ll have to look at it to even figure out how to do what you are suggesting.
As I’ve tried to work this our and the discovery the opposite rear was dragging to, a wild idea was just the kind of thing I was looking for. I wish I understood the inner workings you describe better but for now I think I’ll see if I can just figure out how to try that and save educating myself about how the booster works until later. Which is actually kind of not like me.
but sometimes I drive all over town before it starts. I’m not sure at all what trigger it.
How will it drive without the booster?
After reading here about adjusting the back brakes bike driving backwards and pulling on the handbrake lever a couple of times I did that last night. It made the problem worse. The right rear started dragging a almost right away and the left front was getting hot too. So much for my theory of water in the brake fluid near the caliper boiling and pressurizing the whole system front to rear. But for whatever reason I’m beginning to think the problem starts with the right rear. Why it’s compensating at the left front I don’t know. I just want to be sure the car is safe to drive without the booster. It may be time for me to put the rear on Jack’ Stan’s and crawl underneath and see where that cable comes out into the rear brake. I’ll also get a chance to see if that break or the left front is dragging while cold.