Topic: brake binding and fluid return issue

[Royota]

so I'm having an issue after I replaced the master cylinder, brake booster, and 100" of line. I bled the lines like crazy to get the air and foreign material out of the system. I drove to the gas station 3 miles away and filled up, but on the way back home it felt like I was loosing power and something was dragging. at the last stop light I let off the clutch and it was dragging a lot. I got up the 40 foot hill into my driveway and it would barely move. I was spinning the tires and it wouldn't go forward. the brake pedal became very stiff and when I investigated, the front calipers were locking up. after putting it in 4lo and dropping the clutch it still wouldn't move, so I opened the front bleeder screws and drained some fluid, and the calipers loosened up so I could move it 20 feet to my spot.

after that lengthy explanation, my question is:
what is causing my brakes to lock up? it isn't immediate, it was over the 3-mile test drive to the gas station and back. did I bleed the MC and lines improperly? or did I pump fluid into the lines and fill the cylinder with too much fluid so it's pressurizing? I have NO idea what's going on and if anyone can provide any help I would be very grateful.

new master cylinder
new booster
new (replaced all "slightly" corroded and rusted sections) brake line
new pads and wheel cylinders in the rear

so what did I mess up?

thanks fellas

[Rocksurfer]

If you didn't bench bleed the new master the pistion inside will jam forward and cause the front calipers to lock since the fluid cannot return to the reservoir. I learned this the hard way, but a word of caution for you do not expect it to remain locked the fluid will slowly return to the reservoir releasing the calipers, I also found this out the hard way when I was test driving my truck. I hit the brakes at a stop sign and they would not release so not thinking about it I hopped out to check it out, I even left it in drive all of a sudden I heard them release and barely made it back inside my truck. Not being a big problem normally but I lived at the top of the foothills and this was the 1st downhill stop of a very long hill straight down for about 2 miles.

[Royota [OP]]

I *thought* I bench bled the master cylinder properly but from your experience it sounds like I left air in it. Thank you that's exactly what happened to me and I.will redo the entire system... again... haha

[Rocksurfer]

I had to get a replacement the piston jammed and I was never able to make it return to a working position.

[bleakhorizon]

i had almost the same issue, but with the rear brakes, could drive and after bumps would seem to start dragging, after letting some fluid out it would release. ended up replacing the LSPV...  put a bias adjuster in there and never had a problem again..

[Royota [OP]]

That sounds like my issue. Do you have instructions? I could pay Midas an arm and a leg or I could just do it myself. My fronts lock but the rear brakes have a hard time bleeding if at all so I think its a proportioning valve issue or I put the lines from front to rear in the wrong place... but I checked that about 12 times and every time it looks ok... but something isn't right. Whenever I work on my truck I drink a bit so double checking is required haha lspv? Didn't bleed properly?
Its still doing it. I bleed them, and a few miles in it drags and makes me powerbrake into a parking spot like an and everyone looks at me like some kid doing donuts.

[Rocksurfer]

I just bolted my LSPV arm to the bottom of my bed which leaves it it the open position, and yes I did a thread on how to do it. lemme see if I can find it, might even be in my trucks thread.

[Rocksurfer]

Here you go, this is my LSPV elimination....

http://board.marlincrawler.com/index.php?topic=85642.30;msg=993006

[NorCalPR]

Here's if you want to truly get rid of the lspv. I had to when I went to rear discs

http://www.ttora.com/forum/showpost.php?p=2251306

The prop valve is from "Flyin Miata". It comes with the 10mm adapter. Like I said, one will have to be reflared. Your local auto shop should have a reflaring tool and bender that you can rent for free.

Sounds to me though like a bleeding issue. Make sure to bleed the brakes then the lspv last. Using a mittyvac will ensure you will get all the air out the master, even without a bench bleed.

[bleakhorizon]

Here you go, this is my LSPV elimination....

http://board.marlincrawler.com/index.php?topic=85642.30;msg=993006

ohh   prettier than mine, i just looped my current one over the exhaust lol....

[Royota [OP]]

So... not really any work to update, but some observations
during regular driving the pedal travel is very short and firm and the brakes work free and fine for about 4 stops. After that, it feels the same if not slightly stiffer and shorter, and it just simply locks the front calipers. Sometimes I don't even press the pedal and they progressively get tighter and tighter... driving up a hill they seem to apply themselves... what the hell... opening the bleeder valve relieves it until it happens again

Someone said the rubber hoses can fail and with suction they collapse in and prevent fluid return. I'm seriously pissed at this truck haha if I remove the LSPV will it help the front?

[NorCalPR]

Sounds more like a booster issue to me

[OOPS]

Do you have the free play adjusted right on your brake pedal?

[OOPS]

And the pedal height is correct?

[Royota [OP]]

That's awesome thank you I will check tomorrow. I just put a new booster in but neither of them have vacuum leaks and I adjusted them as close as I could. I did something wrong so I will be more accurate this time and thorough

[Royota [OP]]

Replaced the rubber brake hoses (there are 3) and removed the LSPV, plugging the T from the front lines and routing the rear straight into the rubber line to the axle. Then I bled the system and it.felt like a brand new truck.. apparently it was the LSPV or hoses.. awesome.. haha thanks for all your help guys I really appreciate it. I adjusted the pedal per your citation as well and it feels awesome. And I had no idea that my rear brakes never worked until I felt them today haha

Anyone want a 1988 xtracab LSPV? No idea if it works, but Toyota wants $280 for them and this ones free so it can be rebuilt.

[Rocksurfer]

Once you put larger tires on the LSPV is worthless.

[zorak]

I switched to the V6 calipers and V6 master and had to ajust the rod between the booster and master and made it to long. as the brake fluid heated up the brakes started to drag. the hotter it got the more preasure was applied. Adjusted the rod and all is good now.