Guest zfan Posted April 1, 2005 Share Posted April 1, 2005 I recently completed upgrading my brakes on my 1971 240Z. I had not been able to test it out as my motor was out being replaced. I got the motor back in and whent to check out the brakes and to put it mildly they sucked. My swap consisted of the s12w toyota/300zx front conversion and the 240sx/300zx rear conversion with the 280zx master cylinder. I have no leaks anywhere. I have swapped out 3 master cylinders and still I get the peddle to the floor or close to it. If you start the car up and put it in gear on the lift you can hit the gas and the rear wheels will turn even with your foot hard on the brakes. We bench bleed the master cylinders to get all air out, manually bleed the brakes several times and even power bleed the brakes at my Buddies shop where we have my car now. I tried extending the booster plunger stem and that didn't help as all that did was end up stuck in the master cylinder when I took it apart. It appeard to have just about come out of the booster sleeve. Anyone got any ideas? I am damn near ready to burn this car to the ground. Mike Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 1, 2005 Share Posted April 1, 2005 I hate to start a brake advice post like this but.... 1) Have a beer or more. 2) Relax, don't go Pyro on us all! 3) When you bleed the rear brakes does anything come out? 4) Try getting a vacuum bleeder. Breast pumps are cheaper if you dont mind the embarrasment at Baby's 'R' Us. 5) Do you have the master cylinder with the front and rear lines reversed. It's different from year to year Z. 6)....anyone else got ideas. Quote Link to comment Share on other sites More sharing options...
fl327 Posted April 1, 2005 Share Posted April 1, 2005 Are you 100% sure that you put the calipers on the right sides? If you switch sides, the brakes have been known to do exactly what you are describing. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted April 1, 2005 Share Posted April 1, 2005 The bleeder valves should be on the top of the calipers. Even with air in the lines the pedal should not go to the floor. Maybe the plunger rod is not getting positioned correctly? I would think too long could be as bad as too short. There is also a "reaction disk" that needs to be in the brake booster. Not sure if that is an issue with the 71 booster or later ones. I remember threads with JMortenson posting in them about reaction disks falling out and the brakes not working. Try putting some clear tubing over the ends of the bleeder valves and put the other end in a jar of used brake fluid. Open the bleeders one at a time, but tighten them down to where they are just shy of finger tight. Then pump the brakes. You should see fluid coming out. When the clear tube is full of brake fluid, tighten the bleeder before removing the tube. Might have to work your way around all four wheels a couple of times to get all the air out. Hope I am not telling you anything you don't already know. BTW, if you have not already done so you really should upgrade the 71 MC to a larger 15/16 MC off a ZX. Make sure you swap the brake lines going to the MC so that the front brakes are being fed off the end of the MC with the larger reservior. The ZX and 71 MC's are reversed front to back. You have the same year Z I do, AND I have the exact same brake set up in boxes waiting to be installed. I hope to hear back what a great set up these brakes are. I have been using the ZX MC with the stock brakes for many years now. Good luck and double the number of beers. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted April 1, 2005 Share Posted April 1, 2005 I'm wondering.. is your check valve good? If it's bad or backwards, you'll loose vacum.. But..ah.. with the engine off, does the pedel pump up and go hard? Or is it soft even then? Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted April 1, 2005 Share Posted April 1, 2005 I had a similar problem with the 280zx master cylinder. I bleed the brakes and no air. Went through each wheel several times and all I got was fluid. Brake petal went to the floor and was mushy. Then I saw the bleed on the side of the master cylinder. Bleed it once and all of my problems were solved. I have bleed a lot of brakes before and never had to bleed the master cylinder. Lesson Learned! Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 1, 2005 Share Posted April 1, 2005 Yeah I took a Chill Pill! Lets see, I did reverse the lines on the 280ZX 15/16 master cylinder. Also Calipers(front) are swapped around to put the bleeders up top. Has anyone had a problem with the plunger rod from the booster to the master cylinder. Mine was not extended at all when I took it apart. I know you can turn the smaller inner rod out to lengthen the rod. My friend did that but probably extended it too long close to 5/8" to 3/4". We should have taken a caliper and measured exactly the difference between the 7/8" master cylinder piston depth/seat and the 15/16 depth/seat. We can bleed the brakes and get a good /decent pedal but when you start the car up the pedal goes to crap in a hurry. The booster is a couple of years old and makes no noise like the last one when it crapped out. That one almost whistled when you hit the brakes. Mike Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 1, 2005 Share Posted April 1, 2005 Yeah We tried that as well. Bleed it at the master even after bench bleeding it. Got a good stream of brake fluid. Thats whats got me so pissed. I am running out of ideas. Mike Quote Link to comment Share on other sites More sharing options...
srgunz Posted April 1, 2005 Share Posted April 1, 2005 Your symptoms are your booster reaction disc has fallen out of place. Trust me. I have been there myself and there was no posts about this problem several years ago when it happened to me. You must return the push rod length to its origional position when you put the disc back. If not you will have a big problem of brake lock up. http://forums.hybridz.org/showthread.php?t=70511&highlight=reaction+disc Quote Link to comment Share on other sites More sharing options...
DaleMX Posted April 1, 2005 Share Posted April 1, 2005 I agree with this, had the same problem and chased my tail for a month before replacing the booster. If you pull the rod on the booster out while the master cylinder is off then the reaction disk will fall and walla, no brakes. New boosters come with a holder on the rod (piece of paper) to keep it secure. When you remove it do not pull on the rod or the disk will fall. Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 2, 2005 Share Posted April 2, 2005 Well we tried to measure the distance differences in the depth of the master cylinders 7/8" vs 15/16. Did you know that the 280zx master is 5/8" deeper thus you have to lengthen the rod from the booster to make up for the depth differences. That said my brakes still suck. My friend did a swap on his 74 Jenson Healy and used a 1988 Dodge truck master cylinder 1 1/16" in size and loves it. His brakes are very stoute. He has Wilwood 4 pots up front with Toyota Supra rotors. He is an Engineer by trade and loves Math. He seems to think the problem with the soft non responsive brakes is due to not enough master cylinder. He said to take the size of the stock pistons in the stock calipers and the puny rear drum brakes and now compare the area of piston size on the s12W's and the 240sx rear calipers and you will find going from a 7/8" to a 15/16 is not enough. Only a 15% gain. He thinks it should be 1" minumum and better to go 1 1/16" Has anyone else had a bad pedal and tried a larger master cylinder? Mike Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted April 2, 2005 Share Posted April 2, 2005 Would like to hear the answer to that question myself. BUT the 15/16 MC is the one Arizonia Z car recommends for their 4 wheel disk brake kit. Maybe the Toyo calipers are larger and maybe that would make the 15/16 MC marginal, but it is hard for me to believe it would be totally inadequate. Who else is running the Toyo 4x4 brakes and what size MC is working for you? Quote Link to comment Share on other sites More sharing options...
waynekarnes Posted April 2, 2005 Share Posted April 2, 2005 i copied this a while back, when i was considering the swap i have swapped the toyota calipers .. am using the original 1972 master cylinder, did not move to the larger master ... have no problems ... any way here's some old posts ... hope this doesn't just add to the confusion ... jgkurz Donating Member Joined: Oct 15, 2002 Posts: 340 Location: Portland, Oregon Status: Offline Posted: Jun 15, 2004 - 09:49 PM OK folks I give up. I know when I've been beat. I refuse to put anymore time or money into this futile upgrade. So far it has cost me 85.00 for a new 15/16 master cylinder, 49.00 for the Motive Produts Power Bleeder and 18.00 for my wasted Ate Blue brake fluid. I've done everything except replace the booster and I don't think the 15/16 is worth the trouble if that's what I have to do. I will be putting my 7/8 MC back on. The 15/16 upgrade on a 280z without the 280ZX booster does NOT work. Does anyone want to buy a slightly used 15/16 MC and a Motive Produts Power Bleeder? I won't be needing them. Seriously, I'm done. _________________ - John 77 280Z 3.0L L28ET 12.82 @ 114.97 mph Pop N Wood Member Joined: Mar 18, 2002 Posts: 1326 Status: Offline Posted: Jun 16, 2004 - 04:54 AM I hate to say it but you could have a bad MC. If you are bottoming out the MC then it is not the rod, and it sounds like you should have the bleed process down by now. The only other possibility is a leaky fitting, but I assume you checked all connections for leaking fluid. Also the rod I was talking about goes between the booster and MC. DaleMX Donating Member Joined: Mar 20, 2004 Posts: 206 Location: Atlanta, Ga. Status: Offline Posted: Jun 16, 2004 - 09:11 AM I could be wrong, but I think that too much rod will cause this too. If the M/C cannot return to the home position then it wont operate properly and you wont be able to bleed it correctly. This is what I think is wrong with mine, but I wont know until the monsoon season gives me a good dry break. Dale _________________ 78 280Z gramercyjam Member Joined: May 20, 2002 Posts: 403 Location: San Antonio, TX Status: Offline Posted: Jun 16, 2004 - 09:18 AM A couple things to check - I didn't see them mentioned so I will - Bleeders on MC good an tight? I've had problems with some rebuilds where the bleeders couldn't be torqued down enough to seal and I couldn't get a good bleed. Proportioning valve, all the way out (counter clockwise)? I don't know if you wilwood is like mine, but with mine when the adjuster is all the way in, the pedal feels soft and goes down a lot further than when it is all the way out. _________________ John B 73 FP 240Z 1900 Lb, L24, E31, Quarter Master/Tilton , 3X2 Weber 45's, 4.44 R190, ZX 5 Speed, 16X10 slicks, Coilovers, etc. Owen Hybridz God Father Joined: Feb 08, 2000 Posts: 2005 Location: Huntington Beach, CA Status: Offline Posted: Jun 16, 2004 - 09:50 AM On the pressure bleeder...I used a similar product, DIY. A garden sprayer (plastic bottle with a hand pump and a hose to spray the liquid-used for spraying pesticides on roses, I guess). A master cyl. cap with a brass fitting, and some clear hose. Total cost was $12. The universal caps sound interesting tho. maybe I'll get one to adapt to my system so that I can do other cars like the Motive does. Owen _________________ http://v8zcar.com fastzcars Member Joined: Sep 06, 2001 Posts: 252 Location: San Gabriel,CA Status: Offline Posted: Jun 16, 2004 - 10:46 PM JG, I'm sorry to hear that the power bleeder didn't cure your problem. But I have to concure with Pop N Wood. You probably have a bad M/C. Have you taken apart the M/C. It's not that hard to do. There are only 4 internal parts. I found this out when I was going through the same ordeal. Take a day or 2 off from the project. to clear your mind. I've had to do this quite a few times myself just to keep me from running my car off a cliff. Don't give up. _________________ Keep the rubber side down. TOMAHAWKZ New Member Joined: Jul 01, 2003 Posts: 17 Location: QUEEN CREEK ARIZONA Status: Offline Posted: Jun 17, 2004 - 01:19 AM John this might sound wierd but the rod may be too long. If the m/c pushrod does not allow the piston in the m/c to come all the way back some of the passages will not be uncovered allowing the fluid to get behind the seal that builds the pressure when the pedal is depressed. for some good info on brake set up try the wilwood brakes or tilton web sites. they have some good info on proportioning valves also. Alot of people have them when they dont need them others have them and dont know how to adjust them. let us know what you find.. Tomahawk Z 77 280z with a rebody and reverse mount wilwood mastercylinders....... jgkurz Donating Member Joined: Oct 15, 2002 Posts: 340 Location: Portland, Oregon Status: Offline Posted: Jun 17, 2004 - 12:49 PM Everyone, Thank you for the advice and encouragement. I have tried all the recommendations in this thread without success. What's strange is this is the same experience I had on my 78z years ago. I just could not get any pedal pressure built up. The car was stolen before I could resolve the problem. I chalked the problem up to a bad master cylinder but could never prove it. That's one of the reasons I was willing to try the 15/16 MC on my current 77z. The only fact vs opinion based fix I know of is to put a ZX booster on my 77 with the 15/16 MC. Since I don't feel like going through the trouble so I'm going to give the 7/8 MC a try. For some reason the 240z folks don't have a problem with the 15/16 MC. So far no one has come forward that has a 15/16 on a 77 or 78 280z without the ZX booster. I'll keep everyone posted with my progress. P.S. I'll probably keep the Power Bleeder. Regarding the M/C Shucks will let me swap the slightly used 15/16 for a new 7/8. Later, _________________ - John 77 280Z 3.0L L28ET 12.82 @ 114.97 mph Last edited by jgkurz on Jun 17, 2004 - 02:43 PM; edited 1 time in total Phantom Donating Member Joined: Feb 26, 2002 Posts: 1662 Location: Arlington, TX Status: Offline Posted: Jun 17, 2004 - 02:17 PM This has been a very interesting thread - especially since I'm about to do a brake upgrade, like what Z-ya has, on my '77 280Z. I had already decided to forego the proportioning valve until after the conversion to see what the balance was like first. I think I'll also wait on the 15/16" MC too and just stick with the 7/8 for now. _________________ '77 280Z with LS1/T56, 311 rwhp, 326 rwtq, 12.9@110 http://www.zcar.com/month/2003/08/ wheelman Donating Member Joined: Sep 26, 2003 Posts: 225 Location: Southeastern Washington State Posted: Jun 17, 2004 - 02:51 PM I'm glad I read this thread as well. I was also going to do an "upgrade" to a 15/16 MC along with the Toyota caliper swap but now I'm going to stick with the 7/8 MC and the stock 7" booster. I will use a proportioning valve because I'm eventually going to put disks on the rear. Wheelman _________________ 73 240Z, LT1, T-5 jmortensen Donating Member Joined: Jul 07, 2003 Posts: 1818 Location: Seattle, WA Status: Offline Posted: Jun 17, 2004 - 04:00 PM This installation should not be a problem. I can't figure out what has gone wrong here, but this is a fairly simple operation. My only thoughts on why it isn't working are: 1. The disc inside the booster that sits between the back of the master and the pin fell out (usually falls into the booster). 2. The rod is the wrong length. 3. The master is bad. I wouldn't be afraid to do this swap, I'm sure it has been done hundreds of times by lots of different people sucessfully (including me). The drum master has a check valve built in for the rear brakes IIRC. If you put rear discs on a drum master, then the rear could potentially drag, just a bit, all the time. I think I read somewhere that someone had removed the check valve, but I can't remember where or who said that. _________________ Autox and track day '70 Z jgkurz Donating Member Joined: Oct 15, 2002 Posts: 340 Location: Portland, Oregon Status: Offline Posted: Jun 17, 2004 - 04:59 PM jmortensen wrote: The drum master has a check valve built in for the rear brakes IIRC. If you put rear discs on a drum master, then the rear could potentially drag, just a bit, all the time. I think I read somewhere that someone had removed the check valve, but I can't remember where or who said that. jmortensen, I appreciate your thoughts. The above comment concerns me a great deal. I definatley don't want my brakes to drag even a tiny bit. I will be trying the 7/8 MC when I get a chance to work on the car next week. As I understand it, the check valve in question is for protection against significant pressure (as much as 1000psi) coming back into the M/C once the brakes are released. I'm not sure how this could lead to brakes draging unless the M/C was failing. In my situation I believe 1) the M/C has been bled as good as it possibly can be. 2) The M/C is functioning correctly (for a 1980 280ZX) because I've tried this upgrade with three seperate 15/16 M/C's with the same results and 3) I've adjusted the rod and tested almost infinitely, again without success. In my opinion the next step would be to try 1980 280ZX booster which I will not be doing. For some reason the 240z guys seem to have no problem with this upgrade. _________________ - John 77 280Z 3.0L L28ET 12.82 @ 114.97 mph jmortensen Donating Member Joined: Jul 07, 2003 Posts: 1818 Location: Seattle, WA Status: Offline Posted: Jun 17, 2004 - 05:38 PM Quote: 1. The disc inside the booster that sits between the back of the master and the pin fell out (usually falls into the booster). What about that one, have you checked for that? You could put on 100 masters and none will work if that disc isn't in there. I think it's called a "reaction disc". My understanding of the check valve is limited for sure (a while back I talked at great length about how I thought the drums were affected by wheel cylinder size on the IZCC list and was totally wrong so don't believe everything I say when it comes to drums), but I believe it holds a bit of pressure in the wheel cylinders to keep the seals against the bores. I also believe that this valve is in the m/c itself. _________________ Autox and track day '70 Z Phantom Donating Member Joined: Feb 26, 2002 Posts: 1662 Location: Arlington, TX Status: Offline Posted: Jun 17, 2004 - 06:11 PM FWIW - I did the Toyota 4x4 upgrade on my front brakes (drums on the rear) and kept the 7/8" MC. Toyo brakes work great but you may want the proportioning vavle because now the rears don't do much, if anything. It may be a different problem than just the upgrade becuase I've been running it for years and it initially seemed OK but I'm not going to worry about it because of the big upgrade all around coning this summer. ALSO - I pulled out my '77 280Z Factory Service Manual and checked out the 7/8" Master cylinder - BOTH front and rear lines have check valves in them. Hope that helps a bit. _________________ '77 280Z with LS1/T56, 311 rwhp, 326 rwtq, 12.9@110 http://www.zcar.com/month/2003/08/ TOMAHAWKZ New Member Joined: Jul 01, 2003 Posts: 17 Location: QUEEN CREEK ARIZONA Status: Offline Posted: Jun 17, 2004 - 07:02 PM The little check valve you are all talking about is a residual pressure valve. They are installed to keep the fluid in the lines instead of making its way back to the master cylinder this prevents you from having to double pump the pedal to build pressure. They are usually installed in both rear drum and rear disk brake set ups but the amount of pressure they keep in the lines is different. I believe the drum brakes use a 10 lb valve and the disk set ups use a 2 lb vlv. If you convert to disk in the rear and dont change the residual pressure your brakes will drag for sure causing 2 things excessive premature wear of the pads and disks and they will get hot and we all know what happes when they get hot they dont work!! They are also used when you mount a master cylinder below the height of the calipers, like on some old hot rods where the stickum below the floor keeps the fluid in the lines. I assume they are installed in one of the valves in the engine compt. but Idid not look for mine as I removed all the stock brake equipment and went with aftermarket stuff srgunz Junior Member Joined: Aug 15, 2001 Posts: 36 Location: Wisconsin, USA Status: Offline Posted: Jun 17, 2004 - 08:39 PM When you put the old cylinder back on, make sure you put the rod adjustment back to where it was. Remember to carefully measure both cylinders like I said in my other reply. If they do measure the same, the rod stay's at its origional length. I went thru similar problem. It was the reaction disc falling out of place. If one plays with the rod at all, the disc falls to bottom of cannister. When it does you will NEVER get any pressure. You will need to get the booster on the work bench and put disc back. See your FSM. _________________ Steve 72 240: L28,mikunis,minilites,5spd.,MSD, headers,koni's,HKSflywheel,4:11lsd Phantom Donating Member Joined: Feb 26, 2002 Posts: 1662 Location: Arlington, TX Status: Offline Posted: Jun 18, 2004 - 05:10 AM TOMAHAWKZ - So I could just replace the rear drum 10 lb. spring with a front disk 2 lb spring and install disk brakes on the rear, right? That way I'm not having to change out the entire MC for one that pushes about 12% more oil? _________________ '77 280Z with LS1/T56, 311 rwhp, 326 rwtq, 12.9@110 http://www.zcar.com/month/2003/08/ jgkurz Donating Member Joined: Oct 15, 2002 Posts: 340 Location: Portland, Oregon Status: Offline Posted: Jun 18, 2004 - 06:59 AM srgunz wrote: It was the reaction disc falling out of place. If one plays with the rod at all, the disc falls to bottom of cannister. When it does you will NEVER get any pressure. You will need to get the booster on the work bench and put disc back. See your FSM. jmortensen and srgunz, I have never heard of a "reaction disk" until this thread. I looked at my 77 Service Manual and it does have a small illustration, but that's about it. If a missing reaction disk could cause my brakes to never pump up then this could be the problem. Is there an easy way to determine if the disk has dropped into the booster? My 15/16 M/C is still installed and fully bled so I could unbolt the M/C and pull it back. Is the "reaction" disk the piston like part that is secured to the back side of the rod? After pulling out the rod and adjusting, I have no problem re-seating the piston back into the booster. _________________ - John 77 280Z 3.0L L28ET 12.82 @ 114.97 mph jmortensen Donating Member Joined: Jul 07, 2003 Posts: 1818 Location: Seattle, WA Status: Offline Posted: Jun 18, 2004 - 08:24 AM Well it looks like Steve has actually dealt with this before, and I've just heard of it, but when I've heard of it the advice was unbolt the master, pull it off the booster, and look in there. If you see the disk put it back in place and reattach the master... _________________ Autox and track day '70 Z Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 2, 2005 Share Posted April 2, 2005 Question number one. If you do not adjust the rod from the booster to the master cylinder how is it going to work? The 15/16" 280 master cylinder is much deeper than the 7/8" s one and to make it reach equally for the same piston travel you have to adjust the rod length. If I remember correctly it is about 1/2" to 5/8" difference from the 7/8 to the 15/16" 280 master. One thought was to put the rod back to where its original position was and make a slug or fitting that I could insert in the 15/16 master cylinder that would shorten the travel and therfor make it the same throw or depth of the smaller 7/8" master. Mike Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted April 2, 2005 Share Posted April 2, 2005 The 15/16 MC worked fine on my 1970. The only problem is the brake pedal didn't catch until it was a half inch from the floor. It just moved without any resistance until it hit that point. I didn't measure anything. I just lenghtened the rod until the brake pedal was catching at a good height for heel and toe driving. BTW, I upgraded to stainless steel brake lines at the same time. So once the brake pedal hits, I only get another 1/4 to 1/2 inch of movment. With SS lines the brake pedal is like stepping on a brick. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 2, 2005 Share Posted April 2, 2005 He said to take the size of the stock pistons in the stock calipers and the puny rear drum brakes and now compare the area of piston size on the s12W's and the 240sx rear calipers and you will find going from a 7/8" to a 15/16 is not enough. Only a 15% gain. He thinks it should be 1" minumum and better to go 1 1/16" Until such measurements are made, you're only guessing. When I replaced the OEM Z calipers with the ZX calipers, the single piston caliper had approximately 12% more piston area than the Z calipers (measured on one side only). This made the move to the 15/16" very attractive. One would assume that any OEM 4 piston caliper (or Cobra for that fact) is going to have an increase in piston area over a typical single piston floater, but I've found very few set-ups actually do. Many high performance vehicles use floating calipers, which do have their own advantages, so I'm not upset by keeping this design on the car verses the 4 piston type. Going to a 1" MC would firm the pedal up even more so than the 15/16", but will require more muscle to produce the same degree of clamping force on the caliper end. This would be a questionable improvement (just a guess at this point), and a 1 1/16" would be way to large. The diameter of the rotor plays into your decision as well. If you increase the rotor size from 11" to 13", you've increased the braking leverage by 18%, which then would make up for the loss of leverage produced by going to a too large of bore MC. My goal was to keep the OEM "feel" in regards to brake pedal pressure, stroke, and moderation. I've found this happy medium with the current set-up that I run ('87 Supra rotors and calipers). I've experimented a bit by putting some 13" Cobra rotors on some Z hubs, but the Cobra caliper's lack of piston area, and the narrow pad pattern (1 5/8") would result a marginal increase in performance (from my analysis) than my 12" rotors with a 2" pad pattern and larger bore calipers. I believe this is so because the Cobra calipers and rotors would have about 12% less swept area (even with the larger diameter rotor than my current 12" rotors), but does have about 11% more leverage (again, due to the larger diameter). But this leverage would be cancelled out by the smaller piston area of the Cobra calipers. In the end, the greater heat dissapation of the Cobra rotors would be better, but I don't need that much extra heat dissapation any more, and the added rotational mass would decrease performance in certain aspects. So in the end, you've got to look at everything if you want to make an intelligent decision on brake parts. Quote Link to comment Share on other sites More sharing options...
srgunz Posted April 3, 2005 Share Posted April 3, 2005 I have read many write ups for this upgrade and nobody has mentioned that the ZX master has a greater piston depth. So I do not get that at all. Perhaps they remove the spacer that is mounted between the master and booster on the 240Z's. It seems to me it is about the difference you are talking about. The later zx master has the single reservoir. Is that the one perhaps you are using? Quote Link to comment Share on other sites More sharing options...
Clifton Posted April 3, 2005 Share Posted April 3, 2005 When I went with the 15/16 MC on my 71' I had to adjust the rod. I didn't on the 73'. Make sure you don't have it out to far. It would be worse than not having it out far enough. Some cars will drag brakes others will not pick up the fluid. If your reaction disk has dropped down you will have more travel but would still be able to stop the rears from turning. I would chebch the rod length again. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 3, 2005 Share Posted April 3, 2005 My personal experience in this realm was that the socket (so to speak) at the end of the ZX MC is different from the Z MC, which does change the depth of insertion of the rod. The piston stroke though should be no different than the Z stroke. Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 3, 2005 Share Posted April 3, 2005 Well I think I got it worked out finally. I had to take and turn the extension out on the rod that goes from the booster into the master cylinder. It was approx. .78" deeper going from the old 7/8 master to the 15/16 280 zx master. We made up some of the difference by using a slug to keep from extending the rod from the booster to the new master cylinder. I have decent brakes but not great. Part of that is because I am running a large roller cam on my 383. I am only making 10 " of vacuum and even with a spare vacuum resavoir it isn't enenough. I am going to install an old vacuum pump like they ran in some of the old Buicks. Thank You Guys for all your help and imput. I think I would go nuts if I didn't have all the imput and idea's this board and its members bring here. Mike Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.