Z31 Rear Brake Upgrade, Instructions And Parts.

[pwhitersxs]

This is an upgrade for people wanting to keep stock calipers and have bigger rear rotors (and possibly calipers).

Ok, I wasn't going to make a thread about this, but here it goes. For a complete read and reference, refer to these threads (although all the information needed is in this thread):

http://forums.freshalloy.com/showthread.php?t=176176

http://forums.freshalloy.com/showthread.php?t=171137

http://forums.freshalloy.com/showthr...=maxima+brakes


For 5 lug cars:

-85-86 z31 mounting brackets
-94 q45 rotors (never tried this, just assuming) or 85 turbo z31 rotors (I know these will fit).
-New longer bolts m10x1.25 x 50mm.
-Tons of washers to extend the mounting bracket out to the original position. The z31 bracket is a thinner piece of metal, while the s13 bracket is much thicker.

For 4 lug cars:
-85-86 z31 mounting brackets
-85 non-turbo z31 rotors that are 4 lug (I know these will fit). napa part number NB 4885872. Also 94 q45 rotors redrillled.
-New longer bolts m10x1.25 x 50mm
-Tons of washers to extend the mounting bracket out to the original position. The z31 bracket is a thinner piece of metal, while the s13 bracket is much thicker.

PADS:
The z31 bracket uses the same stock pads as the 240sx and the same shims.

Other notes:
With the z31 4 lug rotor, there will be about a 2 mm overhang.

Rotor notes:
q45 -- 292x9mm
z31 -- 290x10mm
s13 -- 258x9mm

In this pic is the difference in the rotor diameter. It is a z31 non turbo 4 lug 290 x 10mm rotor. Next to it is a stock s13 rotor.




Here is a pic of the z31 rear rotor with the z31 mounting bracket and with a stock s13 caliper.



I forgot to take a picture of it, but basically the mounting bracket is much smaller where the bolt threads in. So a spacer must be used.

CALIPERS:

The z31 calipers are rear mounted where as the 240sx is front mounted on the spindle. These will still work, but with no e-brake. To have an e-brake, a new cable (or extended) is needed along with guides to allow the cable to work properly and mount onto the z31 caliper.

For S13's: A s14 caliper will work and this allows better brake distribution with upgraded front calipers. With q45 front brakes; the 292mm rear rotor with the s14 caliper will provide the same brake bias that is on the q45. This is because the piston diameter on the s14 rear brake caliper is the same as on the q45. For the s13, either the lever for the e-brake must be switch over or s14 cables must be obtained.

s13 piston diameter: 33.96mm
s14 piston diameter: 38.18mm (same as q45)
z31 piston diameter: 42.8mm

As you can see in the pic, the cylinder for the z31 rear brake is much bigger than the stock s13 style. In that pic is a maxima or altima caliper, but it is still the same diameter piston as the stock s13.



My brake setup now is:

front:
q45 mounting bracket with altima calipers
axxis ultimate pads(q45 obviously)
(yes altima calipers will fit on q45 mounting bracket. Just have to be creative with the slider pins)
This gives me a thicker rotor and not so much piston surface area so the brakes don't lock up as bad.

Rear:
z31 mounting bracket with stock s13 rear caliper.
Normal pads

Finished product (bad picture of z31 rotor):



Any more questions? Just ask in this thread.

[SoSideways]

The pic of the mounting bracket and stuff isn't showing up.

[pwhitersxs]

There isn't a picture of the mounting bracket. I will add that later.

[gunluvS14]

great job dude.
how about measure the total thickness of the stack of washers you added.
One of us can machine it out with some aluminum stock.

[pwhitersxs]

Yea, I will take a picture and measure the total thickness.

For those concerned, this upgrade will require 16 inch rims or bigger.

[pwhitersxs]

Ok, here are some more pictures. They are not the greatest. The camera was dead and I wanted to get some pictures. The first picture shows the amount of washers used. Which ended up being 17 mm. This was the amount that centered the mounting bracket onto the rotor.




Ok, the stock s13 mounting caliper is on the left. The extra thick part of metal is where the bolt goes. Now on the z31 bracket, the bolt goes on the bottom. As you can see, big difference in height and in thickness. Again, I took these pictures quickly, so just use your imagination on determing the differences.



On the left is the 87ish maxima bracket, the middle is the z31 bracket, and the right is the stock s13 bracket. I was a little off, the maxima bracket is only about 2mm longer than the z31 bracket.






The final product showing wheel clearance.

[gunluvS14]

great job. I'll go ahead get the 17mm spacer machine, and maybe soon I will buy the Z31 bracket from you. I'll make the Q45 rear rotor works on the S14.

[pwhitersxs]

Just to let you know, the reason I used the bigger washers closer to the spindle and smaller ones closer to the mounting bracket is because I wanted to make sure that there was enough material closer to the spindle. On the mounting bracket, there is a circular area for where the bolt goes through. I made sure I got a washer that would fit into that area so the mounting bracket sits flush.

I wonder what the price difference would be between a spacer and just getting a bracket machined? Might want to look into that as well. Because getting a spacer machined might not be cost effective when washers would do the trick. Those were standard washers and the cost was around 9 cents a peice.

I will call the junkyard tomorrow and get a price so I can send these out to you. I am excited for more pics!

Also, I wonder if the q45 rotors share the same hat offset as the z31 rotors? This could also cause the spacing on the z31 bracket to change.

[drunkmunky]

Where did you get the z31 mounting brackets from?
I heard that the Nissan Quest also has 11.4" rear rotors and that you could retrofit those mounting brackets and their piston as well. Someone also told me that the nissan quest has a dual piston rear caliper, but I was not able to confirm this with my research on FAST or ALLDATAPRO.

[pwhitersxs]

I got the brackets from the junkyard. At a u-pull-it style yard.

The quest might have the same size rotors, but the spindle location could be different. Nissan uses different length spindles causing the lengths of the mounting brackets to vary. Try it out though, maybe that will enable another brake option.

I tried maxima(94 and 97) calipers, and 95 altima calipers with a sentra spec v rotor. The best option is the z31 or q45 rotor with the z31 bracket.

[pwhitersxs]

Where did you see that the quest has 11.4" rotors? I couldn't find anything like that.

The quest had rear drum brakes up to the current model. The current model has 308x16 vented disc brakes. I think who ever told you that information needs to start reading and learning.

There are definitely more options out there or bigger brakes. This is what I found with what I had to work with at the junkyard I was at.

[drunkmunky]

I've actually been knowledgable about these types of swaps since I have been doing research for my own build. If you look online, the quest has 11.4" rotors available for the rears. Certain quests do have rear disc setups. There is extensive servicing and rebuilding information on the rear calipers and pistons. The only information I couldn't find was this so called "dual piston rear caliper", which I believe not to be true.

[pwhitersxs]

I just looked in the fsm's for years 96,99, and 2004. The only one with disc brakes is the 04 and above. Those come with 308x16 mm rotors.

[drunkmunky]

There are 2 Versions of the Quest, the V40 and the V41. Up here in Canada, we have Quests with abs, and rear disc.

[pwhitersxs]

Maybe the quest is different up there. I don't know. If you find anything, report back.

[pwhitersxs]

Just an update. I have fitted 5 lug 92 Q45 rotors in the rear. They are an absolute perfect fit. The hat is really big so it looks a little weird, other than that it is good. I took off the heat shield as well because they sit really far back.

I am pretty sure the stock mounting bolts can be used. I lost mine so I just went out and bought some m10x1.25 x 30mm bolts. I used 1 locking washer on the outside of the spindle and one washer on the inside of the spindle to properly space out the mounting bracket so it was centered on the rotor.

I will post pictures sometime soon.

[lookbot]

Which caliper bracket and caliper did u use with the q45 rotors? S13 brackets with s13/s14 calipers? i hope so!

[Caithness]

This is friggin awesome. You've just filled in the final piece of the puzzle in a weeks-long search for the perfect brake setup. I've spent dozens of hours searching, looking at parts from multiple retailers, calculating brake biases, and considering pros/cons of the usual setups. Thank you very much for your hard work testing all of these combinations of parts and trying something new. This gets rid of the only problem with the Z31 rear bracket setup.

I was slightly concerned about the forces put on the washer shim stack needed with the z31 rotor and was considering welding the washers together for better strength and load distribution from the caliper into the bracket. I was going to go ahead and try the Q45 rotors myself first to see if they had a better rotor hat spacing for our cars but now I know for sure they'll work.

I've been looking for a brake setup with a combination of ease of install, inexpensive price, near-stock brake bias, and improved heat capacity and dissipation after cooking my stock brakes at the track. Ease of install and price concerns dictated a stock rear caliper as every rear caliper swap involved either expensive drum conversions or weird ebrake cable issues. Bias and heat concerns pushed me to look for larger rotors that could dissipate more heat and push the brake bias closer to stock.

Here's my planned brake setup:
===
Front 300zx 30mm aluminum calipers

Front 300zx 280mm x 30mm rotors- redrill 4 lug

Front 300zx aftermarket brake pads- this one needs some research to determine how aggressive I want to go. Assume Porterfield R4S for starters.

Front splparts 300zx conversion stainless lines

Z31 nonturbo (specific years- have list @ home) 15/16 master cylinder stock split point stock reduction ratio.

Rear stock s13 calipers

Rear 1st gen 292mm x 9mm q45 rotors '92 confirmed to work redrill 4 lug, may need small spacing by washer to center

Rear s13 aftermarket brake pads- research. Assume Porterfield R4S for starters.

Rear splparts 240sx stainless lines

Remove dust shields front and rear

Splparts brake cooling deflectors

Valvoline Synpower fluid- best widely available OTS brake fluid I know of
===

I did asad's bias calculations on this setup and came up with:
effective rotor diameter asad style (center of pad)= 292-40= 252mm
stock caliper so asad same = 34^2 x 2= 2312
"brake torque" = 582624
300zx front
"brake torque" = 1505350
1505350 / (1505350 + 582624) = 72.096 ~ 72.1% front brake bias, 27.9% rear brake bias

Not all the way to 70.5/29.5-stock but close enough. Much better than 75/25-300zx front only, and better heat management in the rear.

Now the only things left to do are 1. get a job 2. buy all this stuff 3. see if any of this will work with my 15" aftermarket wheels 4. if not, buy bigger wheels. I'll post a thread with pics and link it here when I dig into the project.

Originally Posted by pwhitersxs

Just an update. I have fitted 5 lug 92 Q45 rotors in the rear. They are an absolute perfect fit. The hat is really big so it looks a little weird, other than that it is good. I took off the heat shield as well because they sit really far back.

I am pretty sure the stock mounting bolts can be used. I lost mine so I just went out and bought some m10x1.25 x 30mm bolts. I used 1 locking washer on the outside of the spindle and one washer on the inside of the spindle to properly space out the mounting bracket so it was centered on the rotor.

I will post pictures sometime soon.

[gunluvS14]

yup, MAD props to pwhitersxs...
now we just need someone to machine us some spacers, so we don't have to use a stack of washers

I need to do this soon, he hooked me up with the bracket, I just never have time to do it yet. Now I know its legal in STX class in SCCA autoX, I will go ahead do it

[Caithness]

Originally Posted by gunluvS14

yup, MAD props to pwhitersxs...
now we just need someone to machine us some spacers, so we don't have to use a stack of washers

I need to do this soon, he hooked me up with the bracket, I just never have time to do it yet. Now I know its legal in STX class in SCCA autoX, I will go ahead do it

He solved the spacer issue- just use a 1st gen Q45 rotor and it fits perfectly. That's why I was so excited. He only had to use one washer to perfectly center the rotor in the caliper. I'd rather redrill 100 rotors to 4 lug before I'd deal with that spacer setup.

[pwhitersxs]

Well here are a couple of pictures of the q45 rotors.

Caithness, This swap is good for 4 or 5 lug. The z31 rotors work good and the stack of washers I had to use were no big deal to me. It worked fine.



[IMG][/IMG]

[Caithness]

I've got the full setup in my bedroom now. I'm going to go redrill the rotors to four lug and then I have to stop by the junkyard to get some brackets so I can test fit them. From holding the rotor up to the wheel it's not looking good- I'm trying to fit these under 15x7 wheels. If I have to I'll buy stock rear rotors until I can upgrade wheels, but only if my front Z brakes fit.

[pwhitersxs]

It was a close fit on 16's, but there was clearance. So, it could possibly work with 15's. Also, I would not cruise around with front Z brakes and stock rear brakes. That will create tons more front bias. Just a tip.

[LigouriRd]

So let me get this combination straight:
•Z31 caliper bracket
•Stock S13/s14 calipers
•1st gen Q45 rotors
A few washers and it all fits right?

[pwhitersxs]

Like a glove. FYI I did post it all right above.

[Caithness]

The fit is totally wheel specific but it can work with 15's. I bolted up the redrilled Q45 rear rotors, 85 nonturbo Z brackets, and the stock calipers with some ~75% life pads and it barely fit. In fact I'm concerned about the clearance with brand new pads in there- I might have to grind the outer face of the caliper a bit. These were 15x7 mystery wheels and we eyeballed the offset somewhere between +25 and +38, with a 3mm spacer so probably somewhere in the low-mid 3x range. There was a good couple millimeters clearance between the caliper and the main inner hoop of the rim; where the wheel got thicker right behind the face of the rim the caliper was a tight fit just on the basis of offset and wheel inner hoop thickness. So I might have to grind just a tiny bit off the caliper with new pads but overall I'm pretty happy that it fits at all. I'll take a few pics when I do the install next week.

[nissanfanatic]

The only stock car I have found to have near perfect brake bias is my 1995 Impreza L with no ABS fuse. I never thought the S13 stock brake bias was anywhere close to optimal. I haven't driven many cars or anything, so my opinion isn't very open. I would get in the neighborhood of 120ft(best of 118ft) for 60-0 tests, with consistent ETs of 3.0 seconds. I run stock rotors, Benix ceramic pads, and ATE super blue brake fluid, and it is on MXs on 17" stock WRX rims. Most stock cars are nowhere close to optimal because the general public would oversteer into oblivion while slamming on the brakes and trying to steer away from whatever obstacle they are trying to avoid.

I'm not sure I would trust that giant stack of washers.

[pwhitersxs]

I can see your issue with the washers. Although all they act as is a big spacer. If anything the extended bolt is the issue. I ran a grade 5 bolt with those washers and I had no worries at all. I did think of it, but it was a non issue for me and i would replace the bolts with the same bolts everytime I did a pad replacement just for the sake of fatigue. Again, that is being over precautious. Of course this is use/do at your own risk, but I did it and had no fears from it at all.

As far as optimal braking goes, I love my car's bias and braking.

[Caithness]

Did you put new pads in with the swap? I started the install and found that the ebrake cable bracket that bolts to the calipers interfered with the sway bar mount. The Z brake bracket places the caliper a lot farther back than the stock bracket. With new pads the caliper was pushed into the swaybar mount. As a temporary measure just to get everything back together I had to cut the metal cap over the swaybar bushing and the caliper was touching the rubber bushing. I'm hoping that when I bleed the system the calipers will clamp down and pull off of the bushing, but I might have to cut the bushing in half to reduce its height and stop it from interfering with the caliper.

I'll take pics when I work on it to show you what I mean.

[Caithness]

Originally Posted by nissanfanatic

The only stock car I have found to have near perfect brake bias is my 1995 Impreza L with no ABS fuse. I never thought the S13 stock brake bias was anywhere close to optimal. I haven't driven many cars or anything, so my opinion isn't very open. I would get in the neighborhood of 120ft(best of 118ft) for 60-0 tests, with consistent ETs of 3.0 seconds. I run stock rotors, Benix ceramic pads, and ATE super blue brake fluid, and it is on MXs on 17" stock WRX rims. Most stock cars are nowhere close to optimal because the general public would oversteer into oblivion while slamming on the brakes and trying to steer away from whatever obstacle they are trying to avoid.

I'm not sure I would trust that giant stack of washers.

Well, the only way to go lower than stock front bias would be to run a full front/rear z32 brake setup with the 85 Z master cylinder or stock. That would get you down to 67/33. After that you're talking about upgrading the rears, doing a bunch of testing and using a proportioning valve on the rear lines to get 100% perfect bias. Too much time and effort and money for my liking.

[pwhitersxs]

I have ST sway bars. So I didn't run into that problem. Although, I have tons of room. I reused the pads I had on, but they only have 5k miles on them. Well if the Q45 rotor doesn't work for you because of space issues, I will dig and find another rotor with less backspacing. You will have to use washers...which I don't see as a big deal, but atleast you will clear the sway bar.

[pwhitersxs]

Ok, an 2003 Altima or a 2005 Maxima (Same rotor) has 2 mm less of backspace. Therefore, you would have 2mm of more clearance to your sway bar link. Not sure if this will work for you now since you redrilled your current rotors, but it is an option.

[Caithness]

Thanks for going and doing the measuring for me. I'll only resort to a rotor swap if I absolutely have to since as you said I already have these rotors and they are so doggone close to fitting as is. I'm sure I can make them fit with something on this list:
1. Bleed the brakes and get the calipers to clamp down. This alone probably won't make it clear.
2. Pull the swaybar bushing and chop a few mm off the top, get new top hat and clamp it back down. This could easily work but I have to consider the implications for proper swaybar functionality.
3. Grind or cut the ebrake bracket. Not keen on doing this as I think I'd have to remove too much material and possibly compromise the strength of the part.
4. Spacers on the caliper mount (hearing that they hold up in dirt track racing makes me feel a LOT better about the washer trick).
5. New rotor.

Just have to see what I can do when I get back in town.

[gunluvS14]

Is there anything else you would like to add into this thread?
I am fixing to move this thread to the Best of 240sx section

[Caithness]

I hate to leave it without having resolved the fitment issue with the swaybar which might dissuade people from trying it. If you want to move it right now, maybe I could PM you with the info when I get it working and you can add it to the thread?

Originally Posted by pwhitersxs

Caithness...You will have to use one washer or so to space out the Z31 caliper bracket to center the caliper on the Q45 rotor.

My driver side caliper seems perfectly centered without any washers. My passenger side caliper might be ever so slightly offset such that a washer would perfectly center it. At this point I'm not sure why that is, some small difference in the brackets, not really sure. With a sliding caliper as long as the pad didn't drag I wasn't going to worry about it until the setup was up and running when I was going to look into it more.

[pwhitersxs]

Originally Posted by gunluvS14

To be honest with you, I was going to read your entire post, but after I saw the wikipedia link, I lost all of the interested....

Stacking washers between the caliper bracket and the upright has little to do with coefficient of friction. Argue about normal force will reduce under braking is totally incorrect since the force doesnt even act on the same plane.

What you have to worry about its the bearing load. Thats why theres diff. bolt diameter and grade for different torque application

From my limited knowledge...gunluvS14 is correct. I wouldn't even worry about any form of bending moments because of Nissans design. The only negative affect I can see the washers having is spacing out the bracket causing more stress on the bolt which in turn can cause it to bend and eventually break. Of course I highly doubt the bolts would see that kind of force. I have had some classes in ME, but I am an EE, so my knowledge is very limited. It just seems that on forums one person says one thing and everybody tends to run with it. As far as losing anti-corrosion material is concerned, better tell all of the coilover manufacturers to stop making their products. This can be extended to companies making pretty much anything, since over time paint and other protective coatings do disappear. I just want these stupid arguments about washers to stop. I would like to stay focused on the subject matter.

gunluvS14 if you want to move this to "best of" you can, but I hope Caithness can resolve his issue. I would hate to leave him hanging.

[pwhitersxs]

Ok, I am going to update this because of the problems Caithness ran into with the Q45 rotor with the stock sway bar.

For 5 lug cars:

-85-86 z31 mounting brackets
-92 Q45 rotors (Works with ST sway bar setup) OR 2003 Altima rotor (Should work with stock sway bar setup)
-Maybe a few washers to center the bracket in between the rotor.

For 4 lug cars:
-85-86 z31 mounting brackets
-85 non-turbo z31 rotors that are 4 lug (I know these will fit). napa part number NB 4885872. Also 94 q45 rotors redrillled (for Q45 rotors follow 5 lug instructions).
-New longer bolts m10x1.25 x 50mm
-Washers to extend the mounting bracket out to the original position. The z31 bracket is a thinner piece of metal, while the s13 bracket is much thicker.


Thanks to Brakewarehouse.com:
Q45 Rotor:
Outer Diameter: 291.6mm
Height: 64 mm
Nominal Thickness: 9mm
Hub Reg: 68.04mm
Bolt Size: 12.7mm
5x114.3
Weight: 12lbs

2003 Altima rear rotor:
Outer Diameter: 291.7mm
Height: 62 mm
Nominal Thickness: 9mm
Hub Reg: 68mm
Bolt Size: 12.9mm
5x114.3
Weight: 10.5lbs

As you can see, basically the only real difference is the 2mm in height. This should be enough if the e brake bracket barely doesn't clear.

[gunluvS14]

Nicely done.
I did some clean up and I'm moving it in 3.........2...