Toyota 4X4 Calipers

[Mpower280z]

Just finishing up the final touches on the 78 when I ran into a problem installing the Toyota brakes. I had them plated and rebuilt. I always use DOT 4 brake fluids and assembled the brakes correctly. After installation, Bleeding went very easy, the pedal became stiff only when the car was off. When the vaccum assist came on with the engine, the pressure went to zero and pedal to the floor. At this point I realized it might be better to go with a slightly larger master cylinder. I then purchased a master cylinder made for a 1981 280zx. I installed the master cylinder and made progress. The pressure remained the same even with the vaccum assist on. But now the brakes feel as though you really need to give it your all to stop the car. Its as though there is grease or WD40 between the rotor and pad. Feels as though there is no friction. Any ideas?

[turbo 260]

Make sure that the calipers are on the right side, if backwards the bleeder screw won't be high enough to bleed all the air out, thus the soft pedal. Also rebleed the back cylinders and the master cylinder. i use the stock 260z master cylinder in my car without problems.

Jim

[Mpower280z]

Its not that the pedal is soft, there is plenty of pressure. There just seems to be a lack of friction between the rotor and the pad. I know for sure the calipers are installed correctly (Bleeder screw on top). My stock calipers did the same thing so Im starting to wonder if I should buy another set of Brembo rotors or have them turned. I dont see how that can help, there is no heat marks or imperfections on the surface of contact. Just for shits and grins, Monday I'll go have the rotors turned and see if that helps. Might as well, couldnt hurt.

[biddljj]

"I know for sure the calipers are installed correctly (Bleeder screw on top)"

Bleeder valve should be on the bottom of the Caliper.

Jay

[Mat M]

Bleeder valve should be on the bottom of the Caliper.

Jay

Umm...How does all the air get out of the caliper if the bleeder is on the bottom?

MPower280z, what kind of pads are you using? Some (like Hawk) pads need to warm up in order to grab more efficiently. Also, with the larger MC, hopefully you have the correct amount of fluid. Bench bleeding the MC may help.

Did you start the bleed cycle with the DRIVER side rear brake, then go around the car counter clock-wise? The DRIVER side brake line is longer than the PASSENGER side, and needs to be bled before the rest.

[Mpower280z]

Mat, the pads are Duralast Semi-M. I know that the MC is providing enough fluid because there is plenty of pressure at the pedal. I did the bench bleeding process before installation.

I dont think your supposed to start the bleeding at the drivers side rear. Your supposed to start from the furthest corner of the MC. The brake line separates in the rear at the center of the car. Right? Thats what my tech always told me.

[Mpower280z]

biddljj,

Air bubbles rise therefore the bleeder screw must be on top. If you have your calipers installed with the bleeder screw on bottom then I suggest you change them and rebleed your cars system.

[Mat M]

I know that the MC is providing enough fluid because there is plenty of pressure at the pedal. I did the bench bleeding process before installation.

IME, pedal feel doesn't always translate to brake pressure. I was trying to relay that I hope the reservior stays full with the larger MC using that much more fluid.

It almost sounds as if the pads aren't getting the squeezing force from the pistons. Did you check the free play (in and out ability) of the pistons after you plated the calipers? <*scratches head*>

...snip...

I dont think your supposed to start the bleeding at the drivers side rear. Your supposed to start from the furthest corner of the MC. The brake line separates in the rear at the center of the car. Right? Thats what my tech always told me.

That would probably be true for other makes of car, but the S30s brake lines are actually longer on the driver side rear, then passenger rear, then pass. front, then driver front. Strange, but true.

[Marty Rogan]

I had a real hard time getting the 4x4 calipers bled correctly on my car. The only way I could get the last bit of air out of the lines was to do the normal beeding procedures, as you have already done. You did get it right by the way.

1) Bleed the brakes.

2) Go to the passenger side, and remove the outer brake pad.

3) Get 2 pairs of vice grips, with padded jaws.

4) Open the bleeder. Use the vice grips to push the pistons in. Be careful not to rip the seals.

5) Close the bleed screw and pump the brakes a couple of times to get the pistons out again.

6) Repeat until all the bubble are out of the caliper.

7) Replace the outer pad and then do the same with the inner pad.

8) Repeat on the drivers side.

I hope this helps.

Marty

[=Enigma=]

Marty, what is the logic behind of removing the pads? I see no reason to do this. Please explain.

[Mpower280z]

Mat M, Thanks for the tip on the brake lines. I had no idea that the lines on the drivers side were longer. That comes to me as quite a suprise.

Marty R, I can see the point in bleeding the calipers in that manner. Alsmost like how you bleed the master cylinder, but instead with the calipers. I'll give it a try and then bleed the system out again the way Mat M has informed me. I'll try round three tomorrow night and get back to you then. Thanks!

[Marty Rogan]

Marty, what is the logic behind of removing the pads? I see no reason to do this. Please explain.

By removing the pads, you are able to get the pistons to travel farther than when the pads are installed. That little extra travel squeezes out the last little air bubbles. This is an old racers trick. This is the ONLY way I was able to correctly bleed my brakes.

Marty