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brake booster swap/upgrade s30/z31/z32

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Ok so I'm about to go into the process of doing the toyota 4x4 front caliper swap on my 73 240z with a Ka24de swap. But I was curious would it be possible to use the z32 master brake cylinder and booster? I now have a cable trottle so all the linkage components on the firewall are gone giving me more room. I know that the stock 73 booster is 8-1/2" diameter, and the z32 has a 9.7" diameter booster. Using the booster will let me use a 15/16" MBC while having a bigger booster. The only thing is that the booster it self may not fit because of the MCC. I also looked at the z31 booster witch is a dual diagraph at 8.7" its a little bit bigger that the stock one on diameter, I'M guessing the dual diagraph will make a different that and the fact that the z31 is a heavy little thing. The only problem I'm seeing is that with the MBC and the booster it's self it may be too long to fit. Unfortunately I can't find any information regarding the length of the booster online. The good new is that I work at Oreillys. I'm planing on ordering in both, try doing some messurements. I should probably mention that Im planing to make a bracket to mount my stock 2 piston front brakes onto the rear (yes yes yes i know). The car is used for drifting (like it or not). Theres also going to be a modified hand brake out of a s14 (240sx) witch I welded a plate together, and attached a s14 MCC to. Meaning I will be able to use it as a parking brake. Plans are to use the rear z31 brake rotors as well. I would really appreciate any feed back on your opinions towards any of this. Its always nice to have a second (or more) opinion. 

 

Thanks in advance 

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Now, what everyone is going to tell you is just get a 15/16 master from a '79-'81 ZX. But as those are nearly impossible to find now for cheap, you have a few options. 

 

I'm not sure about the 240Z's (I think the master cylinders for brake and clutch are closer than the later model S30's?), but you said '73 and I think this is only an issue on the earlier models. 

 

You can get a Wilwood (forget the part number. It's in the sticky'd thread about brake upgrades) that only needs the holes oval-ed out a little and the fittings swapped from standard to metric threads off your stock master. 

 

But what I'm doing with my disc swap (4x4 front calipers and rear maxima disc) is swapping a '82-'83 280ZX master cylinder and booster. The reason you need to swap the booster is because the master cylinder on the later model ZX's mounts 90 degrees from the stock master. With the booster swap, all you do is remove the spacer and flip it 180 degrees and it bolts on and allows you to use the later master cylinder. These can be found a whole lot easier than the early model master cylinders these days.

Picture is courtesy of a thread on Zdriver.

post-11862-0-57678700-1403393861_thumb.jpg

 

If you're set on Z31/Z32 stuff, there are a few members on here and other Z forums that have done the swap. I remember seeing a writeup on a Z32 master and booster swap, but can't remember where. You have to make new hard lines for it.

Edited by R3VO 3VOM

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But you see where I'm going with all this right? 

 

Bending new hard lines are not that hard of a task. the only thing that worrys me is clearance of the booster (with) with the master clutch cylinder. And the clearance of the master brake cylinder (length) to the strut tower. The main reason this accrued to me was with the fact of easier to find parts, and the fact that they have a better design to them. Also sence I'm using the stock fronts as rears I'm gonna need more fluid pushed to the caliper. ( the 280zx has floating rear calipers, with a one piston design. Another down side is that you have to have a mechanical hand/parking brake to tighten the rear brakes with the mechanism. A fixed caliper will fix that with 2 pistons pushing evenly-ish to the rotor. Theres a small difference in size between the two different brake pads for each caliper. 

 

I'm going to try to find that writeup you mentioned.

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Now, what everyone is going to tell you is just get a 15/16 master from a '79-'81 ZX. But as those are nearly impossible to find now for cheap, you have a few options. 

 

Not true.

 

I just bought a brand new re-man'd 15/16" early 280ZX brake master cylinder a couple weeks ago. It is from Cardone. Regular Canadian retail on it is $80 (or so) I paid a little less due to club discounts where I bought it. I just installed it last night, and it is correct for a bolt on to the S30. 

 

The Z31 brake booster will not be a bolt on to a '73 and later S30, the studs that pass through the firewall are a different pattern. IIRC the spots where the holes would need to be drilled for the Z31 master interfere with the bracing and such of the pedal box in that area. It MAY fit on an earlier S30 a little easier because the booster mounting pattern was a little closer to the Z31 pattern IIRC.

 

Another option would be to make an adapter. I was sent a link a while ago to an adapter offered by a Japanese supplier that allowed for an S13 booster to be mounted in an (later) S30. It was a two part plate that one plate bolted to the booster, then another plate bolted to this one that had studs for the proper pattern. It looked like a good idea, but was about $380 (using the at the time conversion for Yen to CDN dollars), plus shipping, brokerage, etc.

 

I've honestly never felt that the booster was a weak point in these cars. I have used the stock S30 booster for the Toyo/280ZX brake swap, along with the 7/8" master. I have also used the stock booster and master with my Z31/280ZX brake set-up. I also used a stock, slightly modified (one stud cut shorter) stock S30 booster with a Z31 master cylinder, but had issues with how the brakes actually applied. It acted like the reaction disc was missing, but it wasn't and didn't really have a lot of time to figure out why. It may have been an issue with the master itself. I now have the 15/16" master and it seems to be working well. I've only drove it maybe a mile with some test braking since I put it on last night, but pedal feel is better than when I had the 7/8" master.

 

I'm pretty sure the Z32 master is either 1" or 17/16" in size, not 15/16". The Z31 master I tested was a 1" master as well.

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Well I do know that the later s30 boosters a slightly bigger that the earlier model ones. Drillings holes in the fire wall to fit a better booster and MBC isn't a issue for me but if it does interfere with the pedal box. Thats something I hadn't considered. 

 

With that said would anyone happen to know if a z32 MBC would fit on a s30 booster with the boosted put in at a 90 angle turn? Making the mounting bolts horizontal instead of vertical? The picture provided by R3VO 3VOM shows a different booster. I'm being very adamant on using the z32 MBC cylinder because of the fact that it may well be bigger that 15/16 meaning a more fluid will be pushed. My new plan is to get my hands on a s14 MBC or a z32 MBC (sence they are the same in terms of mounting) and do some measurements. 

 

And when we say that you can't find a new 280zx MBC we mean new not reman. A lot of people feel as thou they will be prone to trouble. 

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I just put the huge 2+2 280z booster in my car and went out to the track, made exactly zero difference in braking, as mentioned above.  IMHO the booster swap is worthless.  I then put the 15/16" MC on the car because I am moving to rear disc.  Even on stock calipers and pads braking was improved.  I expected a big difference in pedal travel but that didn't happen.  I wanted go through each step one at a time to see where the big differences were.

 

I have a set of brackets being made up to place 280zx calipers on the rear like guys used to sell here.  I like the idea of keeping the park brake (I also have a street 240 these are going on) and keeping the car "all Z."

 

If anyone is interested pm me.

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Now, what everyone is going to tell you is just get a 15/16 master from a '79-'81 ZX. But as those are nearly impossible to find now for cheap, you have a few options. 

 

I'm not sure about the 240Z's (I think the master cylinders for brake and clutch are closer than the later model S30's?), but you said '73 and I think this is only an issue on the earlier models. 

 

You can get a Wilwood (forget the part number. It's in the sticky'd thread about brake upgrades) that only needs the holes oval-ed out a little and the fittings swapped from standard to metric threads off your stock master. 

 

But what I'm doing with my disc swap (4x4 front calipers and rear maxima disc) is swapping a '82-'83 280ZX master cylinder and booster. The reason you need to swap the booster is because the master cylinder on the later model ZX's mounts 90 degrees from the stock master. With the booster swap, all you do is remove the spacer and flip it 180 degrees and it bolts on and allows you to use the later master cylinder. These can be found a whole lot easier than the early model master cylinders these days.

Picture is courtesy of a thread on Zdriver.

attachicon.gifmaster cylinder.jpg

 

If you're set on Z31/Z32 stuff, there are a few members on here and other Z forums that have done the swap. I remember seeing a writeup on a Z32 master and booster swap, but can't remember where. You have to make new hard lines for it.

 

do you know anything or anyone that used a 83 280zx booster and MC on stock drums and such? im just trying to research and see what the right combo is. i have a 6/73 240z. I seem to see the way to go is the 83 280zx booster and MC.

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I did, and I did it in stages.  I liked the 15/16 MC but didn't feel any improvement with the booster.  Changed the drums to discs last.

 

On my street car (bone stock '71) fresh, stock, well adjusted brakes are perfect.

Edited by wesmc

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The only reason for the booster swap with the '82 - '83 master cylinder is to allow it to bolt right up to the car. There is no performance advantage to the booster. It's just like putting a 15/16 master on a stock car more or less. Booster plays no effect other than merely allowing the master cylinder to bolt on.

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i got ya that makes sense, well it seems now that they no longer make s30 boosters. the rebuild kits have been halted and thus auto parts stores dont sell boosters anymore. i even tried to get on off ebay but  my order was canceled. im buying one from someone on here but if and when that one is bad idk what im gonna do, idk what any of us are gonna do. the z32 booster and MC is to touchy. i dont really want to do a booster delete. threre was someone that has done a VH45 booster and MC but ive not herd back on how that felt, and im on all stock brakes for the moment. any ideas?

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Are you sure your booster is bad and not some other issue?

 

Only time I've seen a booster go bad is if the master cylinder leaks brake fluid back in there and it sits in there for a while.

 

Could always find one from a junkyard. There are always a few Z's through my local yards a year. Where I got my '83 booster. Then just ordered a rebuilt master from eBay for $30 something shipped. There's always ZX's through or being parted out on local CL ads.

 

Z32 requires re-bent lines but is nice because the proportioning valve is built in. But without the calipers to match I'm not sure how that works; the bias would be all out of wack.

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Yes, it's Sat for 13 years give or take a year or 2, and when I bled the brakes and I replaced the wheel cylinders the pedal is soft and brakes don't engage till bout 3/4 the way down. I'm buying one from someone on here but like I said, I'm thinking ahead here.

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i had not replaced the MC but it was bleed. Im sure it was good because it was giving good pressure when bleeding the brakes so i know it was functioning corectly, then the booster wasnt holding pressure so i got a pressure check valve and that helped a little but still soft pedal. 

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I'm not sure about it on 240Z's because I think the early early models and the later ones were different? I can't remember if '73 was also different as that was the last year before the 260Z. My car is a '76 280Z and I had no issues. The two boosters were exactly the same size ('76 versus '83). Because I know some year 240Z's can't run certain things because of how everything is positioned. But I just don't know enough to be of any help with those. Someone with better knowledge of the earlier chassis' would have to chime in.

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