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240Z rear brake upgrade


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I have a '73 240Z that I would like to add rear disc brakes to. I have found this kit on ebay:


My question is if I go with this option, do I need to also upgrade my master cylinder to the larger 280Z bore and or do I need to add a new proportioning valve? I have tried to do some research on this and can't find a definite answer. My feeling for this kit, since it is just using maxima calipers and 280Z rotors, is no. But, I would rather have a consensus before I start this and find that I should have.

The car is just about ready to come out of it's winter hibernation, body restoration, and custom paint job. It's been about 7 months in the making and I can barely wait. Once I get more time, I'll post pics of the process and the final results.

Thanks for the help!!

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I did ask about the e-brake and his response was that it should just hook up fine. What bothers me is the word should. As far as the benefit gained, not really an issue. I'm going a little more for my asthetics and some performance. This is why I also don't want to spend around $800 that I have seen some kits go for. I would like something reasonable in price, looks and performance. Haven't decided what to get yet. The question still remains though. Do I need the other parts or not?

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First go over to hybridz.org and look under their "brakes, wheels and suspension" forum. There is a very large "sticky" on brakes which you should read before deciding what to do next.

In deciding you need to consider what you be using your Z for. My 240 has the Wilwood fronts and the 240sx rear disks with a prop valve (OEM valve gutted) and race pads in the rear. It has a 280 booster w/a 15/16 master. It stops the 2400 lb car very well and the e-brake is operational.

Even the prop valve and the rear race pads can not direct enough braking effort to the rear wheels. The fronts are just over powering and if I had to do it all over again I'd likely go with the Z31 front calipers/rotors with the 240sx disks.

We run a 240 on the track and have the Z31 front set-up and the original rear drums with Porterfield shoes. The shoes are at least 3 yrs old and they look like they could go for another 3 yrs.

The kit being sold (say it goes for $100.) will also need the following:

1) rotors -$100.

2) calipers - $100.

3) pads - $40.

4) SS brake hoses - $120 (if you don't already have them)

5) misc brake lines - $35.

6) optional booster - $150.

7) optional MC - $120.

8) optional front brake upgrade ($150-$800)

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I'll third, what's been said. I was on the path of rear disc conversion myself. After upgrading the fronts, I found that there's plenty of braking power. It's not really neccesary to put discs on the rear, except for the "cool" factor.

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  • 2 years later...

i installed rear disc on my 73 ....my calipers i bought of some guy who machines them they have the engraving ke engineering ...my set up uses a 86 maxima caliper and 300 zx non turbo rear rotors ......yes 300zx i made the mistake and thought they needed the 280zx ones when i installed them the pads only got about 3/8ths of the disc ....i haven't tried them out yet since i am very busy to even bleed them so im having my mechanic finish it off .....looks aggressive with the way bigger 300 rotor ....best part is my my parking brake actualy worked before i sent it to the shop ive had my z for 7 years and it never worked ....the conversion ran me about 300

bracket set $100

calipers (salvage yard) $23

rotors $23 each

pads $25 bucks

all new brake hardware $25

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  • 1 year later...

Wait so the upgrade makes you lose the e-brake useage? I thought it was still able to be used and wouldn't mind the better brakeing. I currently have the drums and I probably need to adjust them cause when I was on a hill, small, I pulled the e-brake and it still rolled. Not good. However thats' right after I changed the pads and I had to move the adjuster quite a bit so thats probably why. But still better e-brake braking with disc. Going to check out hybridz now.

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