Forums/Z31P/z31-performance-upgrade-forums suspension-chassis-and-brakes/Brakes working too good…
Imported from Z31Performance.com Forums{{#if:boosted300| — original post by boosted300}}{{#if:2015-03-15 00:52:17|, posted 2015-03-15 00:52:17}}{{#if:36| · 36 post{{#ifeq:36|1||s}}}}{{#if:/Z31performance_archive/forum/z31-performance-upgrade-forums/suspension-chassis-and-brakes/24840-brakes-working-too-good.html|
Local archive: view archived thread on dev.z31library.com}}
boosted300: (2015-03-15 00:52:17)
I only upgraded my fronts to the Wilwood 6 piston, rears are stock, and basically the brakes are working too good. Too good for the tires at least as the front wheels lock up under hard braking if I'm not careful.
Overall the brakes work phenomenal but I have to condition myself to not stab the pedal to get optimal braking…and of course that's not always easy to do, especially in an "OH $HIT" moment.
I'm using the stock Z31 BMC…I know that a bigger BMC is needed when there isn't enough hydraulic pressure to work big calipers, and it maintains proper pressure and pedal feel…but that isn't a problem for me at all. Pedal feels good, firm not spongy, and the pressure almost seems to be too much since the fronts lock up under aggressive braking.
I previously had the Z32 Calipers/350Z track rotors setup and don't remember ever really having this issue, although they certainly didn't brake as well as my current setup.
My tires are Nitto NT05 with treadwear 200 so they aren't super soft compound, but not certainly not hard either.
The obvious answer is that there's simply too much front caliper compared to the back?
Should I consider a proportioning valve? Or would Z32 17/16 BMC help address that?
Thanks in Advance
jaqattack02: (2015-03-15 01:55:44)
I would say you should upgrade the rear to get more braking power there to even things up. Going with a 6 piston in front was probably a bit overkill. I haven't read all of it, but this thread may help you. https://dev.z31library.com/extras_archive/www.nissanroadracing.com/
boosted300: (2015-03-15 02:37:16)
Overkill? What's that?? lol
I'm a firm believer in it's always better to have too much than not enough!
But thank you, great info in that thread…good read.
Sounds like my first step should be to change the rear pads to something a little more aggressive…it might just be that simple.
Thanks again much appreciated.
Bremsen: (2015-03-15 14:29:05)
You have too much pressure and probably a long pedal. What was the piston area change from the previous setup?
Most likely going to the larger M/C will improve the issue. It will move more fluid in the stroke but have less line pressure at the caliper. So, your pedal will feel taller/firmer but require more leg effort to lock up the brakes.
boosted300: (2015-03-15 20:14:57)
You have too much pressure and probably a long pedal. What was the piston area change from the previous setup?
Actually the pedal feels fine…just like stock.
The piston area now, according to Wilwood, is 4.04…I'm not sure what the Z32 Caliper area is honestly.
Most likely going to the larger M/C will improve the issue. It will move more fluid in the stroke but have less line pressure at the caliper. So, your pedal will feel taller/firmer but require more leg effort to lock up the brakes.
Interesting…makes sense…however I read in another thread that the Z32 BMC would increase front bias.
NissanEgg: (2015-03-15 22:41:21)
Not really a bias problem, but a pad compound issue. Step up to a more aggressive rear pad.
I have 17/16" BMC, cheapest of the cheap Centric front pads for my front Z32 30mm setup, and more aggressive "ceramic-performance" on stock rears. The rears lock up first on very hard panic stops and moderate trail braking. My more spirited drives I swap out the fronts to more aggressive front pads and the fronts will lock up pretty quickly on moderate-to-heavy braking.
Bremsen: (2015-03-17 12:44:09)
The calipers are what shift the bias in this situation. You've altered the difference between the front piston area and the rear piston area, but kept the hydraulic side, therefore you've altered the brake bias. The master cylinder changes the pedal stroke and the caliper pressure, but since its a single bore master the front and rear circuits are changed equally. The only way to change the brake bias via the master cylinders is to run a dual master setup on a pedal box.
G-E: (2015-03-17 17:38:33)
4.04 square inches of piston area? That would be rather small…
http://brakepower.com/help_abc_27_PAC_t.htm
My BBK calipers come out to 7.8 square inch… (change N to 1)
boosted300: (2015-03-17 18:33:07)
Perhaps I'm reading it wrong?
Billet Narrow Superlite 6 Lug Mount
Piston: 6 Piston Area: 4.04 Pad Volume: 3.8 Mount Description: 3.50" Lug Mount Rotor Width: 1.1 Billet Narrow Superlite 6 Lug Mount
PISTONS: Type: Stainless Finish Red Powder Coat Piston 1 Dia. 1.62 Piston 2 Dia. 1.12 Piston 3 Dia. 1.12 Piston 4 Dia. - MATERIAL: Aluminum FIT: Maximum Rotor Dia. 14
I plugged the numbers into the calculator and got the same - 4.04
http://www.wilwood.com/Calipers/Cali…dth=&pistarea=
mtherkamp: (2015-03-17 20:21:17)
looks like Wilwood only calculates the 3 piston areas, I think you need to multiply that 4.04 by 2 for full-floating calipers, resulting in 8.08.
NissanEgg: (2015-03-17 20:38:20)
Wilwood does use some pretty small pistons, and unequal size pistons for the 6-piston setups.
jaqattack02: (2015-03-17 20:55:49)
I've got the Wilwood 4 pistons, and doing the math myself I get 8.24, and Wilwood lists it as 4.12, so it does seem like they are only calculating half. That said, if yours really is only an area of 8.04, your issue isn't really with the BMC. I'm running a stock BMC on mine as well and under normal driving I don't have issues. If I really get on the brakes hard the front locks first, but that is expected since it has larger brakes and also a lot less traction than the rear (235 profile tires vs 275).
Also, I did some research prior to buying my calipers and my piston size is only a touch larger than a Z32. So at least as far as hydraulics go, it shouldn't operate much different than Z32 calipers.
boosted300: (2015-03-18 03:40:28)
I would say you should upgrade the rear to get more braking power there to even things up.
I've got the Wilwood 4 pistons, and doing the math myself I get 8.24, and Wilwood lists it as 4.12, so it does seem like they are only calculating half. That said, if yours really is only an area of 8.04, your issue isn't really with the BMC. I'm running a stock BMC on mine as well and under normal driving I don't have issues. If I really get on the brakes hard the front locks first, but that is expected since it has larger brakes and also a lot less traction than the rear (235 profile tires vs 275).
Also, I did some research prior to buying my calipers and my piston size is only a touch larger than a Z32. So at least as far as hydraulics go, it shouldn't operate much different than Z32 calipers.
The Wilwood 4 pistons have more area than the 6 pistons…go figure! Your experience sounds pretty similar to mine in regards to braking reaction. I also have a similar tire disparity with 245's in the front and 275's in the rear.
I gave Dave at Arizona Z a call today to get his perspective and he echoed much of what you and some of the others here are saying.
Passing along his take:
- from the sound of it that the brakes are actually working just as they should and that, simply put, the front brakes are disproportionately powerful compared to the back and that, like Bremsen mentioned, that in and of itself has increased the front bias.
- upgrading the BMC would increase front bias
- He suggested upgrading the rear calipers/discs, disabling the proportioning valve built into the BMC (mentioned in the thread jaq posted link to), and implementing an external proportioning valve
- He asked which size BMC I had currently have. I wasnât sure off the top of my head but I told him it was the stock Z31 and I guessed 15/16. He said thatâs the size he recommends for his full front/rear BBK.
I started perusing proportioning valves. Google brought me to StopTechâs site where they have a technical write up on proportioning valves and list items that will increase front or rear bias:
Factors that will increase front bias
⢠Increased front rotor diameter
⢠Increased front brake pad coefficient of friction
⢠Increased front caliper piston diameter(s)
⢠Decreased rear rotor diameter
⢠Decreased rear brake pad coefficient of friction
⢠Decreased rear caliper piston diameter(s)
⢠Lower center of gravity (i.e. lowered vehicle)
⢠More weight on rear axle (i.e. loaded)
⢠Less weight on front axle
⢠Less sticky tires (lower deceleration limit)
Factors that will increase rear bias
⢠Increased rear rotor diameter
⢠Increased rear brake pad coefficient of friction
⢠Increased rear caliper piston diameter(s)
⢠Decreased front rotor diameter
⢠Decreased front brake pad coefficient of friction
⢠Decreased front caliper piston diameter(s)
⢠Higher center of gravity (i.e. raised vehicle)
⢠Less weight on rear axle (i.e. unloaded)
⢠More weight on front axle
⢠More sticky tires (higher deceleration limit)
Taking all of your valuable input into account, my thought process is
- Upgrading the rear pads to a more aggressive compound
- Upgrading my tires to a softer compoundâ¦currently my NT05âs have 200 treadwear. Iâm looking at NT01âs (treadwear 100 and feel much stickier than that) or Toyo Proxess 888âs (treadwear 100 with a more uni-directional pattern).
This should be a good start in improving the bias balance by themselves until I can tackle the rear brake upgrade and proportioning valve.
G-E: (2015-03-18 09:08:54)
The easiest/free upgrade you can try is shimming the rear bias spring in the master cylinder until it binds, it can be a pain to do…
It will eliminate the regular split point that stops the rears getting additional clamping above a certain pressure
It's very likely that's _all_ you need to do
jaqattack02: (2015-03-18 13:18:14)
My plan is to upgrade both my rear calipers and rear pad compound. I just haven't actually gotten around to doing that. Need to swap my rear control arms first, along with getting the M30 ebrake drums installed.
boosted300: (2015-03-18 15:19:40)
My plan is to upgrade both my rear calipers and rear pad compound. I just haven't actually gotten around to doing that. Need to swap my rear control arms first, along with getting the M30 ebrake drums installed.
On a side note, for those that have seen the suspension Arizona Z makes for S30's…he's actually finalizing a similar setup for Z31's. Apparently it eliminates the crossmember and swing arms and utilizes a strut …can't wait to see that. Its gonna be interesting to see something that beautiful underneath a Z31.
boosted300: (2015-03-18 15:21:18)
The easiest/free upgrade you can try is shimming the rear bias spring in the master cylinder until it binds, it can be a pain to do…
It will eliminate the regular split point that stops the rears getting additional clamping above a certain pressure
It's very likely that's _all_ you need to do
Thanks good tip, that was also discussed in jaq's link and it sounded interesting…
Wait, did you say "easiest" and "it can be a pain" in the same sentence?!
jaqattack02: (2015-03-18 15:52:02)
If I were you, I would start with the pad compound and see where that gets you. I don't find mine all that bad, as it only does it when you seriously crank down on the brakes hard. The way the car stops, I can't imagine hitting them that hard unless it was a super panic stop, I've only done it when testing the brakes.
boosted300: (2015-03-18 16:26:24)
If I were you, I would start with the pad compound and see where that gets you. I don't find mine all that bad, as it only does it when you seriously crank down on the brakes hard. The way the car stops, I can't imagine hitting them that hard unless it was a super panic stop, I've only done it when testing the brakes.
Will definitely be my first step, thanks very much.
Rick88ss: (2015-03-18 19:49:52)
What pads do you have in the front and back now? What rear pads are you gonna switch to?
frostvectron: (2015-03-18 20:01:29)
FYI, NT01 and R888's are not meant for street use.
boosted300: (2015-03-18 20:15:18)
What pads do you have in the front and back now? What rear pads are you gonna switch to?
I think I'm gonna go with hawk hp plus in the rear
Fronts are something called BP-20 I believe.
boosted300: (2015-03-18 20:20:30)
FYI, NT01 and R888's are not meant for street use.
Don't tell that to the GTR crowd down here!
But technically, yes you're right…but it won't be a problem.
It's not a daily driver and I don't plan on driving it in the rain anyway.
I have several friends with GTR's and Supras that run one of those two on their daily drivers with no problem.
I have Advan A048's on my 240Z which is also a competition tire not for street use and no issues.
jaqattack02: (2015-03-18 20:24:15)
I think I'm gonna go with hawk hp plus in the rear
Fronts are something called BP-20 I believe.
You may also look at going to a Wilwood BP-10 in the front. From what I remember the BP-20 is the more aggressive track oriented pad, while the BP-10 is designed to be for street use with occasional track time.
G-E: (2015-03-18 22:38:37)
Wait, did you say "easiest" and "it can be a pain" in the same sentence?!
It can be a pain to do the surgery on the master, some use a 5-point allen head screw, others are locktited, but it's "easy" in the sense that you don't have to touch the car's dirty bits [archived image: smile.png]
NissanEgg: (2015-03-19 19:10:58)
You may also look at going to a Wilwood BP-10 in the front. From what I remember the BP-20 is the more aggressive track oriented pad, while the BP-10 is designed to be for street use with occasional track time.
^ THIS!
On my Wilwood Dynalite 4-piston setup on my B13 I use the BP-10 as the street pads for the front. It stops the same as stock and I can lock up the tiny rear drums slightly before the fronts. My track pads are the Poly-Q compound, which is basically a dirt track compound and several grades higher than the BP-20. The BP-20s I used before the BP-10s had more bite and kind of sensitive to initial input for a street pad, which made it kind of jerky/grabby and annoying.
boosted300: (2015-03-19 22:54:53)
To be honest, I'm not positive which pads I have, I forgot! I have to pull one out and look at the number…
however, they feel very streetable for the most part…after some aggressive braking they feel a little "grindy" almost like metal on metal…which I've always found a little unusual.
I'll let you guys know as soon as I get a chance to look at them.
But (assuming I have BP-20's) rather than downgrade the fronts…wouldn't I rather upgrade the rears?
adamvann3: (2015-03-19 23:14:49)
You may also look at going to a Wilwood BP-10 in the front. From what I remember the BP-20 is the more aggressive track oriented pad, while the BP-10 is designed to be for street use with occasional track time.
I run BP-10 on the Wilwood 4 pot fronts and EBC green stuff in the rear. Seems to be a good balance but the fronts will lock up prior to the rears. However the car doesnt dive forward under hard braking which gives it a balanced feel.
z31s could really use a simple solution to adapt z32 rear caliper setup. It would balance out a lot of the front brake upgrades widely available.
A lot of awesome information on here. Quite impressed to see some of the heavy hitters back providing some good insights!
boosted300: (2015-03-19 23:25:01)
I run BP-10 on the Wilwood 4 pot fronts and EBC green stuff in the rear. Seems to be a good balance but the fronts will lock up prior to the rears. However the car doesnt dive forward under hard braking which gives it a balanced feel.
z31s could really use a simple solution to adapt z32 rear caliper setup. It would balance out a lot of the front brake upgrades widely available.
A lot of awesome information on here. Quite impressed to see some of the heavy hitters back providing some good insights!
You know I was thinking the exact same thing…I might have missed it, but it seems that's something no one here has really done?
I have a friend with a pretty radical S130 and he has the Z32 front and rears…I asked him about the rears and he said he just had to make a bracket…
Is it just not that simple for us?
jaqattack02: (2015-03-20 01:26:14)
I have a simple solution for the z32 rears including keeping the ebrake. The issue is that it uses M30 or R31 skyline parts, neither of which are all that easy to come by.
jaqattack02: (2015-03-20 01:28:33)
You know I was thinking the exact same thing…I might have missed it, but it seems that's something no one here has really done?
I have a friend with a pretty radical S130 and he has the Z32 front and rears…I asked him about the rears and he said he just had to make a bracket…
Is it just not that simple for us?
With 87+ RCAs the Z32 calipers are bolt on, but you lose your ebrake, if that matters. For those that care, the STi rear Brembos also bolt on.
boosted300: (2015-03-20 01:54:02)
I have a simple solution for the z32 rears including keeping the ebrake. The issue is that it uses M30 or R31 skyline parts, neither of which are all that easy to come by.
JDM Miami is right by my house and I know the owner…is it anything they might have?
jaqattack02: (2015-03-20 02:13:44)
I'll try to put more info tomorrow when I'm at a computer. I have the parts and am planning to do a write up at some point.
adamvann3: (2015-03-20 18:42:36)
You know I was thinking the exact same thing…I might have missed it, but it seems that's something no one here has really done?
I have a friend with a pretty radical S130 and he has the Z32 front and rears…I asked him about the rears and he said he just had to make a bracket…
Is it just not that simple for us?
Alex made some weld on brackets for a rear setup. I am not saying its hard to do, but just not widely available
With 87+ RCAs the Z32 calipers are bolt on, but you lose your ebrake, if that matters. For those that care, the STi rear Brembos also bolt on.
In the past I would have not cared about this but I have lost brakes twice in vehicles (not the Z) and the ebrake is something I must have. Would be nice to retain the factory caliper for the ebrake and z32 for working brake.
jaqattack02: (2015-03-20 20:21:55)
In the past I would have not cared about this but I have lost brakes twice in vehicles (not the Z) and the ebrake is something I must have. Would be nice to retain the factory caliper for the ebrake and z32 for working brake.
It doesn't keep the factory caliper. It adds a drum style ebrake like the Z32 uses. The M30 has a similar ebrake system to the Z32, and RCAs similar to the Z31. For someone that is running coils already, they could just grab an entire M30/R31 RCA and bolt it in place of the Z31. They would just need to swap hubs as I believe the M30 is 4 lug, but it uses coils very similar to the S13. In my case, since I'm not using coils, you can unbolt the entire backing plate with the ebrake assembly, and bolt it onto the Z31 RCA, as 2 of the 4 bolt holes match up, then you just have to drill and tap the other 2. I haven't actually done it yet, but I have all the parts. Planning to take lots of pictures and do a write up once I have time to actually do it.
Rick88ss: (2017-07-18 05:05:00)
To be honest, I'm not positive which pads I have, I forgot! I have to pull one out and look at the number…
however, they feel very streetable for the most part…after some aggressive braking they feel a little "grindy" almost like metal on metal…which I've always found a little unusual.
I'll let you guys know as soon as I get a chance to look at them.
But (assuming I have BP-20's) rather than downgrade the fronts…wouldn't I rather upgrade the rears?
What's up man....Old post I know....lol
What did you finally do about the front and rear brake pads? I have to get back to my Z. It's been a while since I showed her some love.