Possible Brake Issue

[blazing816]

My 86 1/2ton truck is not my DD, I drive 08 sports car. So yesterday when I drove my truck because we had crazy snow storm here in Michigan the brakes did some different and I just wanting any input if someone thinks something might be wrong.

I drove all the way to work and didn't notice anything (25miles) however I am used to the brakes being more "squishy" then my sports car and they did not seem that way. The truck has set for the last probably 4 month with only a couple of drives up the neighbor gas station. Anyways on the way home from work when some #$%&#$% car cut me off I had to step on the brakes hard (nothing like locking up for my life hard...but hard then normally) When doing this after a few seconds it felt like the brakes gave out and I had to push the pedal down farther to stop. I drove the rest of the way home (15 miles) and I could stop and what not, but the pedal was needing to be pressed about half way down. I did not want to step on them really hard, because I wanted to make it closer to home.

so I am curious if you think that maybe one of my brakes were "frozen" its been about 2-6 degrees F with out the wind chill here, and it just finally broke free, or if you guys think something is wrong. I looked around the ruck (as best as I could with 2ft of snow) and did not see any brake fluid leaking...and the reservoir was full. Also my two front calipers and pads are brand new with full ceramic pads and one new hub and rotor, the back brakes were rebuilt about 2.5-3 years ago.

Any input would be helpful so I may be able to pin point it easier, with it being cold and snowy out. Or if I am just being paranoid and everything is okay. Thanks in advance!!!!

[79gmc15]

With it being that cold I wonder if it affected the rubber brake lines. I have a simi similar problem too. Brakes work fine except when I do stop harder there seems to be a little bit more of a delay. So I'll be watching this thread.

[bake74]

     On these older trucks the rubber brake hoses if original are know to become more " flexible ", meaning they will expand and contract with the action of a heavy brake pedal.
     So by pressing hard on the pedal, the rubber brake hoses are expanding instead of pushing all available fluid to the brake calipers.
     This might not be your problem, or it might be part of it.  You should bled your brakes and pay attention to the rubber lines, especially in the rear.

[Blazin]

When we have deep snow after a few hours of plowing my brakes aren't as good as they should be. I have always figured they are just caked up with snow and ice. They always seem to come out of it when the truck is melted off.

[VileZambonie]

You blew a line, wheel cylinder or something. Fill the master up with brake fluid and have an assistant pump the brake - where there's brake fluid, there's a leak.

[blazing816]

I have not lost any brake fluid and there is no puddles under it as of now. I feel that it may be the rubber lines expanding and or something, because I still can stop, the brakes are working and the lines do not look the best. I think I may just change the rubber lines as it seems to be a good thing to do anyways. But I like your idea Vile, have someone pump the brakes and check for leaks (even though I do not notice any fluid leaking) I will have to pull it in the garage so I can lay under to watch leaks.

I will let you know if I find anything, since I am sure other people have had this issue also.

[79gmc15]

What about steel braided flex hoses?

[VileZambonie]

Check your wheel cylinders too

[DanInMichigan]

No missing brake fluid, the pedal goes halfway before getting pressure...could be the master cylinder?

[Smarttravis1511]

What about master cylinder? I've seen where the cylinder can bypass! The one I had when the brakes were pushed you could see bubbles come back into the resivoir

[travh123]

i also would suspect master cylinder. because you have no missing fluid and you have braking at about half way through your pedal. it seems like one of your primary seals on one of the pistons in the mc have failed. when either one fails it takes about half way through your pedal for the brakes to start working. either the primary piston has to travel forward far enough to meachanically push the secondary piston so it can build pressure. or the secondary piston has to be pushed to the end of its bore by hydraulic pressure in the primary system, and when the secondary piston reaches the end of its bore the primary system can build the pressure it needs to apply the brakes. either way you only have 2 brakes working...

idk how clear that was but heres a picture

[blazing816]

Thanks....pictures always help. So are master cylinders rebuildable or do I just need to find a new one and if so should I replace the brake booster also, or is that unnecessary?? and if I need to replace it, is there anyone that has done a conversion to get better braking out of these trucks, like something better then vacum assist (but nothing too major as it is in my beater truck).

Please let me know your ideas, because I am always up for bettering things if I have to replace them anyways.

[Smarttravis1511]

Parts are cheap for these.... I wouldn't rebuild or buy a rebuilt one IMO! I bought a new one at oriellys for under 50 bucks

[81_Chevy]

same happened to me. just go buy one at O'Reilly's. simple, its new, and not that bad on price. that way you dont have to worry about it anymore. and if it goes bad theres like a 1 or 2 year warranty on them so u just take them back and the replace it for free. oh and when you buy it make sure to paint it with something or seal it somehow. they get nasty surface rust on them because its bear metal.