Fix my brakes

[CRaSHnBuRN]

Losing my brakes this weekend was not a fun occurrence, and something I would like to avoid happening again. At this point I have some ideas on what may be part of the problem, but I would like some other input.

First let me describe my current setup. On the front I have new D60 calipers and pads, with the stock rotors (like new). On the rear I have new K20 calipers, pads and rotors. My master cylinder is from a late 70s 3/4 ton chevy (new), connected to the stock toy brake booster by way of a home made adapter. I'm using 36" stainless steel soft lines from the frame to the calipers in the front. For the rear I have a SS soft line from the frame a T on the axle, then a 36" SS soft line to each caliper. Most of the SS lines are from speedway motors. I also have line locks plumbed in for the front and rear, as well as a proportioning valve and residual valve for the rear.

From talking with others with a similar setup, I should be able to lock up the tires, but my brakes have never worked well, going from mushy to outright failing. I have bench bled the MC, but plan on doing it again. I've bled the brakes many times, but that does not seem to help the problem. One odd thing that has happened several times while bleeding the brakes is a stream of fluid will flow back into the MC when no one is touching the brakes. Its hard to describe, but imagine holding a running water hose under the surface of a pool of water, facing up so that the water coming out of the hose breaks the surface of the pond. I have no clue what it means, and neither has anyone else who has seen it.

[CRaSHnBuRN]

I know a common problem is when people mount their rear calipers wrong, so that the bleeder isn't facing up. I don't think that is a problem with mine, but here is a picture of it anyway

http://tamor.us/members-rigs/albums/Build-up/caliper.sized.jpg

[CRaSHnBuRN]

I also think I'm going to try to cut out the amount of softline in my system. My plan is to replace the long soft lines in the back with hardlines going from the T connected to much shorter soft lines going to the calipers. For the front I want to ditch the two long softlines at each wheel, and run only one soft line down to a T similar to the rear axle,

[AggieTJ2007]

if you lock both linelocks and push on the brakes is it soft or mushy?

[CRaSHnBuRN]

I haven't finished wiring in the line locks yet.

[robertf03]

that caliper looks a little too parallel. Aren't they normally at a 45 degree angle?

did you reuse any of the 4 runner brakes? theres not a load proportioning thing on the back or a drum brake valve up front is there?

[CRaSHnBuRN]

that caliper looks a little too parallel. Aren't they normally at a 45 degree angle?

did you reuse any of the 4 runner brakes? theres not a load proportioning thing on the back or a drum brake valve up front is there?

I don't know on the first part. Everyone says to put the bleeder at the top, so I did. Maybe I went to far

The only thing kept from the 4runner brakes was the booster and the hardlines. The stock prop valve was ditched in favor of a adjustable prop valve

[robertf03]

is the pushrod travel long enough for that master cylinder?

Don't toyotas use 4 piston calipers up front? I think I'd put the toyota master cylinder back on there and give it a whirl.

[robertf03]

hell, just put toyota brakes back on there. Sounds like you have access to a machine shop if you made adapters for the booster. split the calipers in half and add a spacer to make it work with 60 brakes. Motorcars ltd in Houston sells the o ring that seals the two halves.

[sasquatch]

hydroboost

[Doug Krebs]

First off, I thought residual valves were for drum brakes. The purpose is to keep a certain amount of pressure on the wheel cylinders to keep the shoes close to the drum. Without this the pedal would have to travel too far and the front would engage before the rear.

Are there any odd spots in the lines where bubbles could get trapped? Have you tried reverse bleeding it from the calipers to the master cylinder?

Was the pedal ever hard?

[mudtoy67]

They have different rate residual valves. Normally a 2 psi for disks and a 10 psi? for drums.

[robertf03]

On discs I think its to keep the pressure lower in the rear, but to make it recieve a higher pressure at first. Not for residual pressure

[CRaSHnBuRN]

is the pushrod travel long enough for that master cylinder?

Don't toyotas use 4 piston calipers up front? I think I'd put the toyota master cylinder back on there and give it a whirl.

The toy MC needs to be upgraded when you run toy axles with disc brakes front and rear. With brakes the size of mine its overwhelmed. The chevy MC swap is a common swap. As for the pushrod, supposedly if you make you adapter a certian thickness the pushrod does not need to be modified, but this is one of the things I am checking into as a potential problem

[CRaSHnBuRN]

hell, just put toyota brakes back on there. Sounds like you have access to a machine shop if you made adapters for the booster. split the calipers in half and add a spacer to make it work with 60 brakes. Motorcars ltd in Houston sells the o ring that seals the two halves.


Thats funny, but no, I think I'll stick with the brakes I have now. As for the adapter, its a simple plate that took 30 minutes to build

[JeepPhisherman]

I don't understand the residual valve, so I bet it's that!

You should post a pic of that adapter, it's ****ing sweet!

[CRaSHnBuRN]

First off, I thought residual valves were for drum brakes. The purpose is to keep a certain amount of pressure on the wheel cylinders to keep the shoes close to the drum. Without this the pedal would have to travel too far and the front would engage before the rear.

Are there any odd spots in the lines where bubbles could get trapped? Have you tried reverse bleeding it from the calipers to the master cylinder?

Was the pedal ever hard?


There are residual valves for discs. Supposedly it keeps a little pressure in the lines so that the calipers do no open completely and pull away from the rotor, requiring more pedal travel to get it back. Does it work, or do I need it? I don't know. I put in on in an attempt to find something to make my brakes work better before last weekends trip. It was discussed alot on pirate when brake problems arose, so I figured I would give it a shot to see if it helped.


As for places air could get trapped, most of the hardlines are still in the stock locations, and I have never had problems bleeding a toy before. I might try reverse bleeding it, but how do I do this?

[CRaSHnBuRN]

I don't understand the residual valve, so I bet it's that!

You should post a pic of that adapter, it's ****ing sweet!

but the brake problems existed before the residual valve was added. Remember it was a quick fix I slapped on the weekend before the trip.


As for my adapter, here is an example of one

http://www.rockstomper.com/images/products/brakes/mckit02.jpg

Mine doesn't look as nice (hell, I didn't even paint mine), but its pretty similar