ok everybody this is gonna be a long one...

ever since last year my brake pedal was low and no matter what i did (bled the hell out of them and adjust the push rod) the pedal was still low. So i replaced it with another m/c from napa and it was the samething...i then ordered a chevy mastercylinder from rockstomper with the 1 1/8 bore and i finally got an "ok" pedal but it wasnt the best. i settled for this for about 6months.

Until 1 day i went wheelin with friends and came across a water hole. went to go through it and it came just about over my hood. After i made it through the brakes just sucked and went straight to the floor. I was able to pump the brakes and get a little bit of a pedal but as soon as i stopped pumping, id go to hit the brakes agian and they would go straight to the floor unless i kept pumping the heck out of them. The next i day i took the m/c off took the piston out honed the cylinder threw it back together and it worked fine...

couple of weeks later i went through the same water hole again but i just idled threw it and made it. The brakes craped out on me again. So i then open the hood and the water level was no where near the m/c so i knew the master was in good shape. I then blew out all the lines with compressed air and bled the heck out of it and the pedal still goes to the floor. If i pump the brakes i get a little bit of a pedal but nothing to help if i need to make a quick stop.

so after a week of going back and forth to work pumping brakes i ordered a line lock and a manual proportioning valve figuring my stock proportioning valve was shot and i needed the line lock for an e-brake anyways.

well i installed it and still the same thing!!!

then headed down the napa parts store and picked up a new chevy m/c and still the same thing!!!!

WTF i dont know what it could be, its starting to piss me off

i probably used just about a gallon a dot 3 brake fluid bleeding and bleeding and bleeding and still nothing

heres the set up im running now.

 

when i was having a problem getting mine to bleed i ended up having the truck running and did them, it helped and i now have a solid peddle. also make sure u do it the way the book tells u to from the farthest to closet.

 

and use a 1 man bleed kit. or another person to close the bleed valve while your still stepping on the pedal. Othewise you just suck more air back into the line. Don't forget about the LSPV if you have one. By the looks of it, you don't. Maybe put a bleed valve somewhere on those lines inside the cab.

 

Yup i did farthest to closest and i had someone help me bleed the brakes and i also adjust the drum brakes(forgot to mention that above). I tryed to bleed the truck while it was running like once but i was told it didnt really matter so i gave up on bleeding it while it was running but ill try that and see how it goes

 

you could have a crack in 1 of your lines that could be sucking air when u let off the brake

 

Ya im not losing any fluid though

 

You can draw in air but not leak fluid.

Have you checked if your drums and rotors are within spec??

Have you replaced the rubber brake hoses over time they do get weak and tired and swell when pressure is applied using the pressure to expand the hose not move the brakes.

You do use your emergency brake to keep the rear brakes adjusted

 

Sorry i havent posted in a while just been busy! Anyhow the rotors in the front are new with pads. The rear is about 2 years old with new shoes and drums.

As for replacing the rubber hoses there all stainless steal braided lines that are 1 year old.

No i dont use my e brake because the cable snapped a whileeeee ago but every so often ill adjust them with a flat head screw driver.

I also tryedbleeding the truck while it was running and that was a major fail

Whatever. I just purchased the rear disk brake conversion from trail gear should be in next week by friday well see if that fixxes it cause i have a feeling its one of the wheel cylinders but i refuse to dump money into drum brakes that dont even work. So rear disk brakes here we come!!!!

 

Im thinking of buying this 1985 xtra cab pickup with the 22r from this guy. He brought it over to my house for me to look at it and while I was test driving it he said I had to pump the brakes a couple of times to stop it and that scared the crap out of me. He said he replaced the MC about a month ago and it seem to help for a while and now its doing it again. I just would feel better about buying it if I knew what the problem was. So...... if you figure anything out let us know. cause i would really love to buy this truck. I have been searching on here about and it seems like alot of people have had this problem but nobody ever finsh the post up with some kind of fix for the problem or if they ever did fix it. I will try anything I would just like to know if something actually works before i start throwing parts at it..

 

Mine just started doing this as well. Yes it can be the MC, but if the truck brakes fine ok at low pedal and catches a little higher after pumping the brake and/or pedal gets hard if the truck is off and the brake pedal is pumped then it's not the MC. Check the rear brakes. Shoes/drums might either need to be replaced or re-adjusted at the adjuster wheel.

 

I had the same problem i went through 3 master cylinders and one thing that helped was the wheel cylinders in the rear were leaky and so after replacing them same problem....after further examination i had a big vaccum leak after that was fixed with a new intake manifold gasket it harnded right up

 

Wouldn't the lack of vacuum cause a hard pedal? Because removing the vacuum from the booster or a bad booster for that matter will cause a rock hard pedal and the feel of manual brakes.

 

Ya ill let you guys know how i make out. Just trying to find time too do everything. So far i bought 2 front loaded calipers and the rear disk conversion. Hopefully this weekend!!!

 

Well I went ahead and got the truck. So.... I guess im in the same boat as yall now. Im going to do a brake flush and get all the dirty fluid out and air out of the system and the machine we use will also let me know if there is any leaks in the sytem. So hopefully that helps.

 

Ya well i did my rear disk conversion and the brakes still suck! Idk what the deal is???? But anyways the rear disk went real nice putting them on my t100! Well i got front loaded calipers i will me throwing on today after work. Ill put up some pictures

 

when you lifted your truck did you relocate the LSPV bracket? Maybe the LSPV is not sending enough pressure to the rear because it thinks it's unloaded.

 

i did a manual proportioning valve and a line lock. the rear brakes are deff working cause if i adjust the proportioning valve i can lock the rear brakes no problem but i still dont have a pedal and i dont know why. only thing left to do is front calipers which im doing today, replace the braided steal lines in front, or do another master cylinder for the 6th time....

 

only reason i did the rear disk conversion on a week day was because of this so i mind as well do it if im replacing the axle shaft. snapped right at the c clip too


trail gear was having a sale on the pocket bearings and bearings and seals so i just bought those too

all together



i was surprised i had enough line to reach the calipers seeing as my t100 axle is much wider then the mini trucks but i was able to just pull it off!!!

 

WOOOO finally fixxed my brakes!!!! I replaced my front calipers with napa loaded calipers and the thing stops on a dime!!!!

Yesss im so happy right now

 

Gongrats! I hope i will be able to fix mine soon. By the way the rear disc conversion looks awesome. I think i may go ahead and just upgrade my whole brake system. Why not right? Since im already having problems. Thanks for finishing your post and not just leave us hanging.