240Z Brake Master Cylinder Problem . Ray writes:. Hi ZDoc, I have a 1971 240z and my master cylinder recently decided to start leaking out the rear seal rather badly. I went to my local parts store to get a replacement and they show the same part for 70-79 Z's. The brand they carry is Bendix and the master cylinder looked like an OEM part (I'm guessing Bendix bought out Tokico's brake stuff) it had Tokico and 7/8 on the side of it just like the original. The only problem was the circuits for the front and rear brakes are switched. I took it back to the parts place to tell them they must have given me the 260 master cylinder by mistake and thats when they informed me of the one number from 70 to 79 thing.. So my question is did Nissan update the part at some point or does Bendix just feel it's not cost effective to carry the older part. I saw a post on the 240z list the other day saying that someone tried to get a older rebuild kit from Nissan (Courtesy, I believe) and they told him there was only one kit for 70 to 79. And if Nissan did update the part, how do they compensate for the fact that the later master cylinder has a deeper contact point for the booster's pushrod.. Thats the other half of my problem. I had no problem re-routing the brake lines for the master cylinder but according to my Hanes manual (maybe thats part of my problem!) the booster and the pushrod adjustment is the same for the 240's and 260's. I adjusted the pushrod out to where I think it should work (after lots of measuring of the old and new master cylinders) and my brake pedal still seems to go way to far down. The car seems to stop ok, as a matter of fact the brakes grab even and hard before I feel any resistance to the pedal but it still doesn't seem right. They grab hard but there is no "feel" to them. They grab all at once but wont grab any harder with more pressure. For general info most of the brake system just had a major overhaul, new calipers, wheel cylinders, stainless flex lines, new hard lines at each wheel, new pads and shoes, and rotors and drums turned. The brakes seem to be bled ok, there is no spongyness in the pedal at all.. Thanks ZDoc !. Ray Brown 71 240Z. Doc replies:. Hi Ray,. Doc here, it sounds like you have the one thing fits all syndrome. There are different master cylinders for the "Z's". The earlier 240's had a different size bore from the 280's. On the 71 240Z that I have here at the house I checked it and it has a 7/8" bore with the rear reservoir the front brake side. Also the larger reservoir is for the disc brakes on the front of the car. You may want to call Rod's Discount Datsun Parts at: 408-448-3277. I believe that he is in your area and can help out with your situation. I don't trust some of the after market stuff and he possibly has the right stuff in stock.. Tell him that Doc sent you.. You need to be careful with the booster push rod adjustment! Too short a distance will give you too much pedal travel and too short will have the brakes lock up. Watch out! It may be that the master cylinder was the wrong one and that you have the brake lines reversed. Brakes are nothing to get switched around and it sounds like the rear section is switched from your description of lack of more pressure when the pedal is applied more. I hope that this helps........ ZDOC OUT.