I've been upgrading and refreshing the entire brake system and I got the 1" wilwood MC since the 280zx MC wasnt available. I also have 4 piston front calipers.

I bench bled it and then installed and bleed everything, but I think something is up. I dont feel like I get any pressure until its almost to the floor. I've flushed quite a bit of fluid through it and it doesnt feel any better.

I'm wondering if anyone else has installed this MC and had any issues. I feel like maybe the booster rod may not be adjust right? I left it at the stock depth. I also noticed that the pedal feels the same weather the car is running or not. I read that if the booster was bad the pedal would be really stiff.

Did you install new calipers? If so, make sure the bleed screws are at the top of the caliper. It wouldn't be the first time someone swapped left and right calipers.

yea, the bleeders are at the top. I replaced all the hoses and wheel cylinders as well. the system was completely drained.

Drums in the back? Are the front calipers the Toyota units?

I've read past reports about needing to unbolt calipers and orient the bleed screw to the very top, sometimes even using a piece of wood to take the place of the discs. But I think that was for a rear disc conversion.

One way I learned to determine if you have a large air bubble is to watch the fluid leave and return to the reservoir after pressing the pedal. If a lot moves it means the MC is pushing it out to somewhere and the bubble pressure is returning it. It was the clue that told me I had the fronts reversed. Big air pockets.

Yea it’s still rear drums. I think the calipers are Toyota units, I bought them used here on the forum.

I concern I have is that I’m not sure if I bled the master cylinder correctly. I did one bleeder at a time since all I had was a one man bleeder bottle with a check valve.

I also have one of those cheap handheld vacuum pump, but I never got that to work when I originally bled the brakes before the rebuild. I had good solid flow near as I could tell. I could only watch the driver side.

Worth a shot to orient the calipers.

Take a depth gauge and compare the Wilwood MC to the factory MC for comparison.

finally got out and measured. from the mounting face, they both have a depth of 10mm+- I rebled all the brakes again and it didnt really feel much better. I decided to actually put the tires back on and see what it feels like on the ground. Seems like they are meh. They do work, but I think it needs more bleeding. They work well enough that I can take it down the road and have them professionally bled.

Hopefully the reaction disc is still in place inside the booster.

@nowak1981 Search reaction disc threads on this site and you will understand what @Terrapin Z means. Very common problem. Has a direct correlation with the problem you’re experiencing.

thank you for this! I think you’re absolutely right. I was considering asking a while back about whether or not the booster rod should be flopping around. Reseating the rod wasn’t an issue, but it makes sense if there is suppose to be pad back there.

It’s a round disk. Unfortunately the only way to find out is to remove the booster. Probably find it in the bottom of the booster. Ask me how I know🤦‍♂️🤦‍♂️

I found mine the same way @yarb did when I replaced my booster. I glued it back on for ease of reassembly.

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