Eddie

The sound is definitely not the rear brakes themselves. I definitely got it now. There must have been a tiny amount of air left that I finally got out. What ended up working to get it out is a bit different than a bench bleed. Here are my theories.... A) why manufacturers say not bench bleeding voids the warranty: brake fluid lubricates the internals, so where there's a chance air may still be trapped, that spot in the master may see sub-par lubrication. Also, air has oxygen, and oxygen oxidizes, and can accelerate internal corrosion vs. parts fully immersed in fluid. B) why bleeding from the bleeders on top of the master may be inadequate: Bubbles travel up a sloped pipe, but will stay put if the pipe is flat. If the master is not compressed, each chamber (for a dual master) is a horizontal cylinder. Unless the master is sloped towards the bleeder side for each chamber, you may be left with a small bubble pocket still trapped. Here's what ended up finally getting out the last bit of air (I should mention almost all air was already out and the pedal still felt pretty good before doing the below. Pedal feel is a just a tad more firm and essentially feels rock hard now. Hmmm... it feels rock hard now....what a description. Now it sounds nearly exactly like I remember, only slightly different because I've got a custom pushrod which fits in the 260 master and must be adjusted with SLIGHT preload, vs. the previous 510 pushrod which I had adjusted with SLIGHT play. Note that step (1) did NOT work and should be skipped, but I'm including it as something worth NOT doing...... 1) Disconnect lines from master to hook up bench bleed tubes - this ended up just making a mess as fluid was slowly dripping (about one drop/sec) while I tried to get the tube fitting screwed in and the reservoir return tubes on. I finally said screw this and reattached the hard lines. This is also where I paused and started thinking of the why's and theories mentioned above. 2) E-brake on. Find something to press on pedal continuously (wedged between pedal and seat edge). Bleed via master bleeders by relieving pressure and simultaneous Mitty vac vacuum draw. Alternate front-rear-front-rear as you're bleeding, topping of reservoirs, and adjusting the pedal-to-seat wedge, so the pedal's always being depressed (do not let it slip in the process). 3) Continue per step (2) above until pedal bottoms out (assuming you adjusted your pedal height and pushrod length before any of this). Top off fluid and then release pedal. This is where using a Mitty vac is better than a buddy - just before the pedal is released any remaining air is under vacuum, so when you release the pedal, fluid is drawn in from atmospheric pressure. 4). Repeat steps (2) and (3) until it seems like you've gotten nearly all air from the master. 5). Mitty vac bleed from each wheel, furthest first, periodically topping off the reservoirs. 6). Repeat step (2) this many times....f/r/f/r/f/r, followed by step 3. All air should be out of the master by now, and if you don't have a firm pedal feel by now, you either have air still in the lines/calipers/slaves, or a leaking fitting.

Thanks for checking and posting what yours sounds, or doesn't sound like. I did bench bleed first with clear hoses recirculating back into the reservoirs, but with the master out of the car and not installed. I think un-evacuable air must have gotten back in as I was angling the master to get it back in position AFTER the out-of-car bench bleed. Looks like it's time to crack open another quart and try again...in-car bench bleed, followed by bleeding to the wheels. This whole thing kind of makes the bleeder valves which are located on top of the master seem useless if they can't get all the air out. Oh and yes I bled with the e-brake on to reduce the chance of air going back from shoe spring kick-back pushing the piston back in and fluid back up.

Anyone? It takes 5 seconds...

mklotz70... I'm curious, does yours make a sound, or is it super quiet? Anyone else mind listening while pedal stomping fast (with car off and everything quiet around you) to see if you've got a hydraulic noise, too?

Thanks for the replies. I'm not using a booster. The clunking sound is just pedal pressing sound. The squirt sound is definitely coming from the body of the master, not from the pushrod dust boot. It only says "ffssssst" when pressing the pedal down fast, not when slow, and not when being released. Maybe my old master did the same thing, I don't know, but now it does and I have no other non-boosted Datsun to compare it do. I did try bench bleeding it first, but from the time I did that to the time I turned it, angled it, and got it into position, some fluid dripped out, so who knows if that did any justice for it. After I got it installed I bled it again, then all the lines to the wheels. It still felt spongy so then I bled the master again (installed) and saw bubbles come up/out, then the wheels again. Now the pedal feel is good, but I'm not sure if the noise is normal or not. Anyone else's non-boosted master make that same "ffssssst" sound (when pressed fast)?

I replaced my working original master cylinder with a new 7/8ths master (260z), bled the brakes, the pedal feels rock hard, total pedal travel is good at about 1.75", but when I press it down fast I hear a "ffsssssst" squirt sound, kind of the same sound the fluid makes when it squirts out a suddenly released bleeder when bleeding brakes. When I press the pedal slow there is no noise at all. There are no leaks on any nipples, fittings, or anywhere else, and the pedal feel is good. Is this just the sound of fluid traveling at high speed through an orifice (or similar normal restricted viscous flow) and others have this same sound, or is mine the only one that sounds like this when it's not supposed to? Here's a video of the sound... http://m.youtube.com/watch?v=41fGC9Sv6Ok&feature=youtu.be&desktop_uri=%2Fwatch%3Fv%3D41fGC9Sv6Ok%26feature%3Dyoutu.be

I just dealt with your same pushrod issue...posted this earlier on "General Discussion - How long does a Datsun live?"... "Who needs a lathe when you have a drill press and an angle grinder. It was a little bit of trial and error to get the bolt centered perfectly in a drill chuck since I was clamping on the threads, but once I got it, it had minimal wobble and ground up great.... http://i557.photobuc...gleGrinder.jpeg Result - new master cylinder pushrod for Z master conversion.... http://i557.photobuc...CylPushrod.jpeg Rust protection. Ooops! I guess I shook the can too many times..... http://i557.photobuc...ledtoohard.jpeg" I also added a dust boot just like the stock setup made from one of these EDPM rubber boots from McMaster Carr (trim to length with scissors and cut center hole for rod pass-through with an Exacto knife). It's a perfect fit on a 260z master... http://www.mcmaster.com/#6448k38/=qp8pi9

Stupid!!!! Okay I found out about the photobucket thing for photo posting.... My Ride.... http://i557.photobucket.com/albums/ss19/eeeaooo/Datsun%20510%20Uploads%20for%20Ratsun/Ride1.jpeg http://i557.photobucket.com/albums/ss19/eeeaooo/Datsun%20510%20Uploads%20for%20Ratsun/Ride2.jpeg Rebuilding caliper pistons is easier than I thought. Not sure why someone thinks rebuilding pistons is getto. I trust myself in rebuilding components more so than a third world wage earner putting together a "remanufactured" part who only cares about getting paid, rather than having any kind of motivation that the whole thing is assembled for reliability and longevity.... 1) Pump pistons just short of all the way out (check against length of new ones so you know how far to go). Check BOTH sides are almost out. 2) Open bleed screw and wiggle piston while pulling until it comes out. Let the mess spill all over in an oil pan! 3) Pop out metal ring wiper seal retainer and wiper seal (keep ring - the original fits better than aftermarket and can be reused if preferred). 4) Pull out pressure seal. 5) Clean, inspect, clean again, let dry thoroughly (brake parts cleaner). 6) Wet bore pressure seal groove and wiper seal recess with new brake fluid. 7) Wet new piston (not worth reusing the old one unless it's mirror smooth - doubtfull), insert in bore, and press in (may need to use C-clamp). 8) Put new wiper seal (wetted with fluid) in retaining ring, slide over piston end and check that the lips are properly seated and not folding over. 9) Press in wiper seal/retaining ring home. I used a PVC pipe coupler slightly smaller than the piston, split it down the side, spread it apart with some old bolts, slid it over the piston and pounded on the end of it with a dead-blow hammer carefully until the wiper seal retaining ring went in evenly and all the way. http://i557.photobucket.com/albums/ss19/eeeaooo/Datsun%20510%20Uploads%20for%20Ratsun/CaliperPistonRebuildingeasierthanIthought.jpeg Who needs a lathe when you have a drill press and an angle grinder. It was a little bit of trial and error to get the bolt centered perfectly in a drill chuck since I was clamping on the threads, but once I got it, it had minimal wobble and ground up great.... http://i557.photobucket.com/albums/ss19/eeeaooo/Datsun%20510%20Uploads%20for%20Ratsun/DrillPressampAngleGrinder.jpeg Result - new master cylinder pushrod for Z master conversion.... http://i557.photobucket.com/albums/ss19/eeeaooo/Datsun%20510%20Uploads%20for%20Ratsun/FinishedZMasterCylPushrod.jpeg Rust protection. Ooops! I guess I shook the can too many times..... http://i557.photobucket.com/albums/ss19/eeeaooo/Datsun%20510%20Uploads%20for%20Ratsun/Rattledtoohard.jpeg

My ride....

By no means is mine all bone stock and original...I was always looking for an excuse to replace a part and upgrade. I'm just amazed that the "bad" caliper piston has lasted this long, and that the other good one and the master cylinder are still functioning well. And yes the brake cleaner dries fast but just to be sure absolutely all traces are gone I figured I might as well take a break for 30 minutes. I rubbed the seal grooves and the bore clean with Never-Dull, and I sprayed the crap out of them to be sure all traces of lint and micro-metal flakes are gone. I needed a break from the fumes!

Wholly cow Datsuns last a long time!!! One of my front brake calipers finally decided to show very slight leakage...I mean SLIGHT, after 42 years and over 340,000 miles. For piece of mind I'm rebuilding both (just finished cleanup and waiting for brake cleaner to dry off before assembly), and replacing the original and still completely functioning master cylinder. That is a damn long time!!!

Laecaon - thanks for the measurements, but are those of your wheel holes, or the actual 280ZX lug nuts? Oh - and thanks for the ebay link......yeah those are the ones I've seen that look like they will work (18.5mm x 14mm deep). I'd like to solve this mystery of why 280ZX lug nuts are so dimensionally special ONCE AND FOR ALL by getting the actual dimensions of somebody's nuts (ha ha). Are you measuring your hole or your nuts? If hole, does anyone have the right nut they can measure? See the below image link of what to look for... http://community.rat...g-nut-specsjpg/

LOTS of research all over the place has led to one conclusion.....for Datsun factory mags, in my case '81 280zx Turbo 15x6 "snowflake" wheels, you must use Nissan lugs nuts. I find it hard to believe Nissan invested in special fabrication equipment just to make custom lug nuts. I'll bet they bought them from a handful of vendors specializing in fasteners. This make far more economic sense. I think I found new ones (non-Nissan) that fit, but I want to make sure. Does anyone have a pair of calipers and a Nissan factory lug nut for an '81 280zx Turbo that fits the "snowflake" rims, that can provide some dimensions? See dimensions on the attached image.... Thanks! D (shank ∅) = __________? Dw (washer ∅) = __________? L1 (shank length from washer face to chamfer) = __________? L2 (shank length from washer face to end) = __________? t (washer thickness) = __________? http://community.ratsun.net/gallery/image/3597-280zx-lug-nut-specsjpg/

Feb 6th – last time I showed up :(because the next day I discovered bearings on both front wheels went bad…explains why it felt like white-knuckle driving coming back from Fairfield four days prior. So two choices…. 1) Bad bearings = buy new bearings and seals, remove hubs, clean, regrease and reinstall = drive and smile with no glee because it’s the same as before 2) Bad bearings = excuse to finally put on the used front coilovers I bought at least nine month prior and the new strut brace I bought over three years ago = raise and lower the car every hour and smile with glee knowing that I can Second option OF COURSE! Stripping strut tube paint, removing rust, 600-grit sanding rust off spindles, mirror polishing grease seal races on spindles, stripping and repainting coils (what a pain)….strut gland nuts didn’t fit tight – modify….NEW strut bar didn’t fit right – fab up custom bronze bushings and slightly shorten bar, and strip and repaint brackets to a better color…assembly, all various weeknights only in between family time and got the ride rolling on May 10th by coincidence! I couldn’t make it in June, but I’m coming this time – yeay! Dibbs on fondling the orange 2-door’s hood struts (I need to do mine to negate interference with my strut brace)! Please, orange dime, can I fondle your hood struts?