240playtoy

Common problems include reaction disks. Replaced master cylinders can sometimes have different depths in the plunger, making your booster move before actuating the master cylinder. Here's some literature for you, I believe both problems are mentioned in it. http://forums.hybridz.org/showthread.php?t=113240&highlight=reaction+disk

Got most of my stuff from rockauto.com. Including my brake swap equipment....

I made the split gauges from 4 Norskog digital gauges. Removed the LED's, wired them up back on with wire extensions then put the whole setup back into the slightly modified gauge cluster.

My original parts are my sets of dual combo gauges. (Off and on) Now I've also installed Speedhut electroluminescent green tach and speedo covers and now I've got the dual gauges of volts and fuel level in place of amps and fuel.

As far as I can tell from what it does when it's gone, the reaction disk seems to allow your booster to modulate the force being applied to the MC. All the booster mechanisms still move when the reaction disk is missing, the only thing that's different is that when you press down on your pedal. You'll get essentially no braking power until a point, then nearly full braking power (locked up brakes). If all of your MC's (including your original) appear to "have the same problem" in that the pedal is soft, it's a very good chance it's your RD. Is your brake system stock? No swaps of different year MC's, boosters or anything like that? The one thing that's confusing me is that your brake light comes on, I don't remember that happening when I was having my myriad of brake problems. In my 240 only 2 things turn that light on, my parking brake and that "distribution" block the MC feeds into. I believe it shuts off front or back brakes if there's a loss of pressure on one side?

Gracias, Jon. I thought I'd seen something about that in a thread about how the cylinder works, but I figured I'd stay away from that as I didn't know much about it.

I don't know about pre-loading, if there needs to be some, then I need find a different adjusting screw as mine is out as far as it will go without falling out. I probably have less than a mm between my rod and piston, less than an inch of travel in my pedal before I get resistance.

I had to adjust mine due to using one of the ZX masters. But then, I think I also had an aluminum diamond spacer that went over all four of the bolts on the booster (~1/2" thick). In addition, your MC housing looks like it's got a deeper "shroud" on the back end of it than my original did. Does your MC fit flush against your booster without you having to tighten it down?

Just moving the plunger in and out doesn't mean your reaction disk is still in place. The reaction disk sits in a metal recess and the plunger moves into it as well. Check this for visual (my reaction disk is missing in the pictures). I do immediately notice a difference between your booster and mine (240z). Your adjusting nut in your picture appear to be between 1/4" and 1/2" longer than that on the 240. I now know why massive adjustment of mine was needed to remove my excessive pedal movement.

Here's the VATS bypass I used, a bit bigger. didn't see the other one from LT1350.com back then. Pretty sure it wires to a blue wire off the PCM, that and ground and power. I've got it hooked to a switch for a poor man's antitheft system.

The pedal is rock hard. (I've also got the stainless braided flex lines).

ich.... Which brakes lock up, front, rear or all? Then there's the common question I've seen asked "are you bleeders on the top of your calipers?". I have a feeling I'm not going to be of any further help. I'd recommend starting up a post about it with everything you've learned is not the problem.

If you "upgraded" to the ZX master cylinder, your rod may not actually be touching the back of the piston. I found mine hissed and wasn't firm until I was about 1" from bottoming the pedal on the floor. There was over 1/2" between the rod and the piston when I measured. Here's a quick little writeup that I posted a while back, but it seems you know about it (you were the only one who posted). So what issues are you trying to fix (description of sounds, pedal pressure and braking)?

I looked at my old booster, it seems that either I didn't have any retainer holding in the plunger or I lost it. the area surrounding the plunger was a piece of metal with a rubber gasket covering it. It pulled right out without issue.

after I got my booster off the car and the plunger out, I just shook it for about 10-15 seconds and magically, my reaction disk fell out. I think I was just lucky. Of course, this was after I purchased a rebuilt booster.

Mine pretty much fell out. Just grabbed the plunger out it came w/ my finger strength only. I believe there was some sort of retainer "clip" in it. If I still have it laying around, I'll try to get a picture of it.

there's a piece similar to an acorn nut on the end that threads into the rod. I believe it needs a 7mm wrench. I held the shaft with needle nose pliers and loosened the treaded rod. After it was loosened, you can thread it out with your fingers.

I've noticed recently, now that my car is legal to drive, that my front end just gets beat to hell by small bumps in the road. I found that the tokico spring kit I purchased has ~ 1-2" of travel before they bind completely. Others (Wheelman, Zoldman and the Brit) have had this issue as well. As I have the rears (165 lbs/in) and they are linear, could I move them to the front and get a "front" set of sports springs from ArizonaZCar (180 lbs/in) and have a reasonably comfortable ride? (I'm strapped for cash and would much rather spend only $100 rather than $200) Oh yeah, I've got a 240z with an LT1 mounted JTR style and backed it with a T-56 tranny.

I've still got the oil cooler on my LT1. If you still have the stock radiator, go buy the one recommended by JTR and take them to a radiator shop and have them swap the endcaps. Poof, your stock hoses work and line up and you can even retain your radiator fluid level gauge (if you had one). I was amazed at how well this worked with mine. Then I got the taurus fan. It only needed minor mods (put some metal "shims" on) and I used the plastic hangars on the radiator to mount my fan. Only issue: the radiator cap has clearance issues with the hood, either mount the radiator about half an inch lower than the JTR parts place it, or you can lean the top back a little bit. I'd take some pictures but I put my digital camera thru the washing machine......

A good while ago I swapped my brakes to front toyota 4x4 calipers and 240sx calipers w/ appropriate disks. Also added the 280zx MC. After excessive brake bleeding, I hunted down the fact that my reaction disk fell out in my old booster (thread) and replacing with a new booster, my pedal would drop 3-5" before any resistance. I heard a lot of hissing coming from the booster area. Hours of searching later, I found that several people had had bad rebuilt MC's and they made hissing noises. So I purchased a $30-$40 rebuilt MC for replacement from Autozone (lifetime warrantee for insurance against crappy rebuilds). More searching later, found some people had adjusted the actuating rod (between booster and MC). I check mine out before going thru the trouble of removing and replacing my "defective" MC. Measured up my old MC plunger depth and the 280zx depth. This is what I found. As was done by others, I had to adjust my rod. My hissing is gone and the pedal is rock hard and has <1" of travel before engaging. Evidently my excessive bleeding of my brakes had removed all the bubbles. Time to license my car!!

perhaps it wasn't a good idea looking back at it, but I didn't "clearance" my 240 tunnel when putting my T-56 in. The parts that were in the way on my transmission were mounts for something I didn't need, so I ground them off. BTW, I'm up in Rolla if you ever want to come and look before installing/cussing.

If you removed your M/C from your booster, it's very possible your reaction disk fell out. Reaction disk missing (follow link to see pictures): Sensitive = push it down a long distance with little slowing of the vehicle then poof, wheels lock up. To take the booster apart to find the disk missing was very easy, but maybe my booster was ready to fall apart to begin with. The actuating rod on the M/C side just pulls out along with the "retaining" piece (round piece in front of the plunger in the pics on the link). As for soft, I had that issue as well but it went away after I replace my missing reaction disk.

here are a couple pictures of the parts on either side of the reaction disk, I did not get a picture of the actual disk as it was inside my booster. it is the same diameter as the actuator and ~ an 3 16ths thick and rubber of some sort.

When I replaced my brake system with the 240sx and toyota calipers and the 280zx master, I noticed that my brakes didn't like to activate linearly. I'd press the pedal down and wouldn't get much stopping power then press a little more---front end lockup. It was my reaction disk. It's not that hard to check.