NO Brakes

[dat240z71]

I replaced my whole brake system (calipers, wheel cylinders booster and master cylinder) and now I have no breaks. When I apply the beaks the peddle goes all the way to the floor and barely function. I have bled the system more time than I care to remember. I have searched and read that sometimes the reaction disk in the booster falls out so today I took the old unit in and got another and still no beaks. When I replaced all the beaks components I up grade to the 280zx master, as someday I would like to do the Toyota four piston calipers swap. What I wonder is would the master cylinder be the problem because I’m still running the stock 240z calipers? Any idea would be greatly appreciated, as I would like to get my 240zt back on the road.

P.S when the car is off I have a fairly good peddle but when the car is running it fades.

[Ricklandia]

P.S when the car is off I have a fairly good peddle but when the car is running it fades.

Vacuum leak? Is the car idling normally? might be something as simple as the integrity of the booster vacuum hose.

[g72s20]

I dunno Rick...the fact the pedal is able to be pushed to the floor when the booster is effectivly "in circuit", but the pedal won't go to the floor without this assistance suggests to me the problem is beyond the booster and in the hydraulics path. Remember everything is set up to work properly with the booster "boosting " your effort at the pedal. I suspect air in the hydraulic path somewhere, most likely something amiss at the master cylinder. Any chance of having the system pressure bled? Generally a brake shop job

Kent Hughes of 240K forums fame is having the very same problem.

Good luck with it.

Jim.

[george71z]

Are the calipers on the correct sides? If they are reversed, the bleed screws will be at the bottom, and you will never get all the air out. Did you bench-bleed the M/C before you installed it? Just a thought.

[dat240z71]

I just checked and the calipers are on the correct way, and yes I did bench bleed the MC. what I have notice is when the breaks are applied the car pulls the right very hard.

[Ed]

Dude, breaks not beaks.

[kinfish]

If you have mixed components you may have created a problem. Prime suspect is the adjustable rod between the brake booster and the master cylinder. In the free state it needs to be set so that it is .010 to .040 loose. If there is a big gap, you are consuming brake pedal movement just to get the rod to touch the piston in the master cylinder. Decreased movement of the piston could mean no brakes. You need to take accurate measurements with a depth micrometer to calculate what length the rod should be set at.

The next headache is that there are at least two different rods depending on model year. They are different lengths. Make sure you have one that can be adjusted to achieve the desired gap.

[240ZX]

If you have mixed components you may have created a problem. Prime suspect is the adjustable rod between the brake booster and the master cylinder. In the free state it needs to be set so that it is .010 to .040 loose. If there is a big gap, you are consuming brake pedal movement just to get the rod to touch the piston in the master cylinder. Decreased movement of the piston could mean no brakes. You need to take accurate measurements with a depth micrometer to calculate what length the rod should be set at.

The next headache is that there are at least two different rods depending on model year. They are different lengths. Make sure you have one that can be adjusted to achieve the desired gap.

I concur! This is good advise. Had the same issue when I changed over my brake system. Adjusted the rod and had brakes!!!

[dat240z71]

I have adjusted the rod out almost all the way still nothing

[Bambikiller240]

Dude, breaks not beaks.

Dudes, BRAKES not beaks or breaks :lick:

[Marty Rogan]

First of all, make sure that rod is adjusted properly.

Second, I would re-bleed the master on the car, then RR, LR, RF AND LF. If that still does not do it, try this: Start with the RF caliper, take out the outer brake pad, open the bleeder and carefully push in the piston with a pair of channel locks or pliers that will reach in there. I put rubber grippers over the pliers so that I don't scratch the pistons. Step on the pedal to push the piston out again. Push it back in. Do that a few times. Replace the outer pad, and remove the inner pad. Repeat the procedure, then replace both pads. Move over to the driver's side and repeat.

I had one hell of a time bleeding my brakes after I installed the Toyota conversion. This procedure was the only way I could get all of the air out.

Good luck!

Marty

[kinfish]

Did you take the detail measurements as suggested in previous post? Adjusting the rod to max length is a shotgun approach and will not lead you to a solution that will fix the problem, especially if you forgot to bleed the system after removing the master cylinder. Your "rod" may be too long or too short and it will never yield the desired gap dimension.