240z S12W+280zx disc conversion

[superduner]

Hey guys. I swapped in all the brake lines and components from my donor 82 zxt over to my 70z. And wondering if swapping over the, zxt brake system will help with the loss of brake power in the rear that comes from adding the Toyota S12W vented 4 piston front calipers? Current set up is as follows.

280z booster, 15/16 MC, 280zx fuel lines and proportioning valve, S12W front calipers, 82 zxt rear disk conversion. You guys think I'll still have weak breaking in the rear? Would like a more even break feel. Read that 4 piston fronts cause front wheels locking up on hard breaking. Just looking for people's opinions in my set up.

[tim.d]

I have the same intended setup as you, but my build is still a long ways from being complete. Somewhere I came across where user mtnickel said he was also using the same setup, here are his responses to some questions I had via PM:

 

"I'm honestly just on econo semi metallic pads for the street. Excellent initial bite. For the street I think it'd be hard to fade them, at least the way I drive. If I were to track, id get a different set, but for street and autocross they are likely fine. Centric cheapo. sorry that's not more help. May help that I rebuilt rears and greased them all nicely. I wondered if those that complained of bias were on an old crusty set that may be ceased."

 

Then a couple months later....

 

"Now that my brakes have bed in a bit more, I seem to have lost a little rear balance  . Even all the way rear the front's lock up first. Perhaps the front pads had more glazing, or the fact that they are a much larger pad area means they broke in slower.

Braking is still very good, but i'm a little disappointed i don't have enough bias to lock to the rears."

 

I think if some specialty pads are found and used it can be a pretty well biased setup... just sourcing those pads, if at all possible, is going to be the biggest challenge.

 

Edit: '82 rear brakes are different than the '81 rears mtnickel and I were discussing - looks like there are plenty of pad options for you.

Edited December 11, 2016 by tim.d

[superduner]

I have the same intended setup as you, but my build is still a long ways from being complete. Somewhere I came across where user mtnickel said he was also using the same setup, here are his responses to some questions I had via PM:

 

"I'm honestly just on econo semi metallic pads for the street. Excellent initial bite. For the street I think it'd be hard to fade them, at least the way I drive. If I were to track, id get a different set, but for street and autocross they are likely fine. Centric cheapo. sorry that's not more help. May help that I rebuilt rears and greased them all nicely. I wondered if those that complained of bias were on an old crusty set that may be ceased."

 

Then a couple months later....

 

"Now that my brakes have bed in a bit more, I seem to have lost a little rear balance . Even all the way rear the front's lock up first. Perhaps the front pads had more glazing, or the fact that they are a much larger pad area means they broke in slower.

Braking is still very good, but i'm a little disappointed i don't have enough bias to lock to the rears."

I think if some specialty pads are found and used it can be a pretty well biased setup... just sourcing those pads, if at all possible, is going to be the biggest challenge.

Hey thanks for sharing the feedback man. Under what conditions are the fronts locking up though. Under track hard braking,emergency hard breaking or just lighly pressing on the brakes. It'll be an "aggressive" street driver for me but turned off about the thought of the car locking up on me on smooth breaking to be honest

[Miles]

Note brake bias problems here:

 

http://forums.hybridz.org/topic/113398-toyota-truck-calipers-ventilated-brake-rotors-mm-rear-disc-brakes/

[Roberto260Z]

All those people who say that have too much front bias with that setup (and mostly with a wilwood PV), but has no one actually removed the wilwood PV and had full brake load to the rears and see what happens?

 

The wilwood PV dialled to max (57%), is still is less than not having it all (100%).

[Miles]

Many of these Toyota/280ZX or Toyota/240SX or Toyota/Maxima installations have been done with  no after market PV and the stock PV gutted out and still experienced front brake bias (typically .60 front - .40 rear or worse).

 

The bias issue derives from unbalanced front-rear brake torque. 

 

If you search the brake forum there will be many people who tried mixing front - rear  brake pads to achieve better front - rear bias with marginal results (some of the racers do report using aggressive pads on the rear plus PV adjustments worked ok).

 

Read all of the brake FAQs and spend some time in the Brake forum looking at these so called brake upgrades.

[superduner]

Many of these Toyota/280ZX or Toyota/240SX or Toyota/Maxima installations have been done with no after market PV and the stock PV gutted out and still experienced front brake bias (typically .60 front - .40 rear or worse).

 

The bias issue derives from unbalanced front-rear brake torque.

 

If you search the brake forum there will be many people who tried mixing front - rear brake pads to achieve better front - rear bias with marginal results (some of the racers do report using aggressive pads on the rear plus PV adjustments worked ok).

 

Read all of the brake FAQs and spend some time in the Brake forum looking at these so called brake upgrades.

Right!? At this point I'm beginning to think this 4 piston upgrade is going to end up being more of a downgrade of the car isn't stopping better than if I had the stock 240z set up. Granted the huge caliper and rotors look stand point is cool and all I'm at the point in life where functionality and reliability outweigh looks and bragging rights. Might have to start to looking into actually bigger rear brakes to even things out maybe? Any "real" personal experience recommendations for the rears with the toyo front set up?

[Miles]

Over the last 15 years I have done the following brake mods on two daily driver SBC 72 240Zs:

 

• Stock front - Maxima rear, 15/16 MC, stock booster:  no better than stock and eliminated drum maintenance issues
• Toyota solid - stock drums, 15/16 MC, stock booster : no better than stock
• Toyota vented -stock drums, 15/16 MC, stock booster : no better than stock
• Toyota Vented - 240SX, 15/16 MC, stock booster: no better than stock
• Toyota solid - Maxima, 15/16 MC, stock booster: worse than stock
• Toyota solid - 240SX, 1 inch MC, 280Z booster: 280Z booster eliminated stiffness caused by the 1 in. MC. Bias = .66 front .34 rear. Average street brakes. Currently on my 240Z  since 2009.

 

I also experimented with different pads and found that all of the "street performance pads" were worthless. For street we want a pad with good cold bite, but every  "street performance pad" I tried  (Hawk, Porterfield etc) required some heat before they had a decent bite - not what I wanted in rush hour traffic.

 

The only reason I never went with the big Wilwood kits is that I would have to buy new larger  wheels and the Wilwood kits did not have a parking brake that I liked.

[grannyknot]

• Stock front - Maxima rear, 15/16 MC, stock booster:  no better than stock and eliminated drum maintenance issues
• Toyota solid - stock drums, 15/16 MC, stock booster : no better than stock
• Toyota vented -stock drums, 15/16 MC, stock booster : no better than stock
• Toyota Vented - 240SX, 15/16 MC, stock booster: no better than stock
• Toyota solid - Maxima, 15/16 MC, stock booster: worse than stock
• Toyota solid - 240SX, 1 inch MC, 280Z booster: 280Z booster eliminated stiffness caused by the 1 in. MC. Bias = .66 front .34 rear. Average street brakes. Currently on my 240Z  since 2009.

Miles, did you measure the stopping distance with any or all of these combos or are you reporting what you felt?

[Miles]

Grannyknot

 

I have a test area that I marked off in 100' increments in the 70s. It is where I bed in pads and "test"  my brake work.

 

When I bought my two 240Zs in 2001  I replaced all of the brake components with OEM parts and drove the cars for several years before trying different brake setups.

 

My biggest complaint with the stock brakes was fading in stop and go traffic and having to adjust the rear drums.

 

Fading was never an issue with any of the Toyota - 240SX set ups I installed. 

 

None of the above setups hauled the car down faster then the stock brakes or would throw you into the straps.

 

The advantage of these swaps, from my experience, is I have seen no brake fade and they have been low maintenance once dialed in.

 

For track use several members report good results using more aggressive pads in the rear in conjunction with  PV adjustments during the race.

 

For daily driving the above brake swaps are ok.

 

The problem with  all of these brake modifications is there is no one place that records comparative brake performance data for popular Z car brake swaps. Developing comparative data has been brought up many times here and other Z websites, but has not happened.  So you are left with trusting what others say or doing your own tests.  Consequently, it is not unusual to find in old posts members going through several brake swaps until they  get the performance they seek.

[seattlejester]

The root of the problem is that while everyone knows of the toyota front brake and rear disk swap, there are a lot of actual combinations. This is even more complicated by the fact depending on how you do the rear swap you can end up with a variety of diameters for the rear disk which can affect the ratio.

 

That is why you get some people suggesting that the fronts lock up way before the rear (insufficient rear bias), and others that say that they have to turn in their proportioning valve quite a bit before the rears stop locking up. I worked out just the bias not factoring in a lot of factors on the second page of the link miles provided 

http://forums.hybridz.org/topic/113398-toyota-truck-calipers-ventilated-brake-rotors-mm-rear-disc-brakes/?p=1064030

 

From the math on the rotors and piston sizes, all the 4 runner options place you in the higher 60s to 70 percent front bias. Your specific setup assuming you used the rear 280zx 258mm rotor is 68/32. My guess is that stock brakes in good working order are about 63/37 give or take a % or two. 

 

The best feel is going to come where the rears are doing the absolute most work they can without locking up or locking up shortly after the fronts lock up and where the fluid displaced feels like it engages quickly enough with good pedal feel. Another consideration is that given that our rotors at least for the fronts sit attached to our hub the pistons most likely have more to push out, with bigger pistons or more pistons combined with a stock size master this can feel like the brakes don't really engage till the bottom 1/2 of the travel.

 

It would be nice if someone had a bias bar and could test the actual % where the locking shifts, but alas...

 

Interestingly enough miles experience puts his % as follows.

 

• Stock front - Maxima rear, 15/16 MC, stock booster:  no better than stock and eliminated drum maintenance issues (64/36)
• Toyota solid - stock drums, 15/16 MC, stock booster : no better than stock (?)
• Toyota vented -stock drums, 15/16 MC, stock booster : no better than stock (?)
• Toyota Vented - 240SX, 15/16 MC, stock booster: no better than stock (70/30)
• Toyota solid - Maxima, 15/16 MC, stock booster: worse than stock (66/34)
• Toyota solid - 240SX, 1 inch MC, 280Z booster: 280Z booster eliminated stiffness caused by the 1 in. MC. Bias = .66 front .34 rear. Average street brakes. Currently on my 240Z  since 2009. (65/35)

The last setup is about 2% different from my personally assumed stock bias point and in addition it has better booster assistance due to the larger most likely newer booster and the larger bore in the master cylinder able to displace more fluid with less effort which combined brings this to a pretty ideal setup using OEM parts. It would be interesting to see if a slightly more aggressive compound in the rear would make it feel even better. 

[Miles]

Seattlejester

 

I have considered trying a more aggressive pad with the 240SX rear calipers, but avoided doing that because of how road conditions change in daily driving. Also, my experience with performance pads is that they feel like blocks of wood until they heat up - again the need for cold bite in traffic.  I spent several months researching brake pads with a higher "cold coefficient of friction", but found none for a 240SX caliper. The Bimmer/Vett people have more friction code choices EE, FF, GG etc pads.  See atch picture  for DOT friction codes.

 

With my current set up Toyota solid - 240SX, 1 inch Wilwood MC and 280Z booster pedal travel is about 1/2" to engage brakes with a  light/normal feel on the pedal.  I had the280Z  booster rebuilt by a company in Sacramento that rebuilds boosters and master cylinders.

Edited December 13, 2016 by Miles

[seattlejester]

I agree semi-metalics have terrible characteristics in the cold, I'm running a standard parts store ceramic both front and back, but I imagine I could step up to like an EBC pad or something more performance oriented like a Hawk pad if I wanted more bias. I want to say there was a thread somewhere where people were listing the codes on the variety of parts store pads and common performance pads. Granted in reality I am not sure it is really worth chasing that slight improvement as the harsher the pad the more likely it will be to eat into the rotor. 

 

I will say that half inch of travel before the brakes do anything is kind of disconcerting moving from a modern car to the Z, always a moments panic before I realize the the brakes are there just a bit further down. 

 

I am very interested in the 280z booster, wilwood 1 inch combo, does it feel good enough for the investment? I have rebuilt 240z booster and the 15/16th master and it works, but I definitely get on the brakes earlier. I will say though that I have been thrown forward enough in my harness to regret having an anti sub belt. You really have to lay into it, which actually raises an observation when my friend was bleeding the brakes where I can see the firewall flex from the brake pressure. Our cars would probably merit from a master cylinder brace.

[Miles]

Originally I installed a 280ZX 15/16 MC with a 240z booster.  The pedal was heavy and stiff with this combo. When the 15/16 MC failed I decided to try a 280Z booster with  a Wilwood 1 inch MC. The 280Z booster made the pedal feel more normal and less stiff.

 

Actually the 1/2" travel is the slack adjustment in the pedal, but the pedal feedback is immediate.

 

Note: the booster was a tight fit between the throttle pivot and the Tilton clutch MC. When I replaced my clutch last year I used a Wilwood clutch MC which is more compact and just clears the booster. I would have preferred a 10" booster, but there isn't enough space.

 

I'll post a picture of the booster later.

 

swap info:  http://forums.hybridz.org/topic/49295-260z280z-booster-in-a-240z-it-can-be-done/

Edited December 13, 2016 by Miles

[Neverdone]

Now I have a question, according to some guy on Zdriver, the 280zx brake booster can be installed by removing the spacer on the back and flipping it 180 degrees and adjusting the brake pedal link

 

Why not just use that? Is there something else that needs to be modified?

 

Also, is the 280z brake booster different than the later 240z brake booster?

[seattlejester]

Miles:

Well the throttle pivot doesn't apply to me, but my engine is going to be sitting right against the firewall with a longer intake runner setup so maybe the larger diameter may prove troublesome. 

 

That does sound quite nice though, I will attest that 240z + 15/16 MC does feel stiff. Like the brakes are working, but if you want to stop you really have to muscle into it. I am very curious how much of that is the firewall deflection. I think I'll have to whip up a MC brace after all this engine swapping business is done.

 

Neverdone:

Depending on how big it is it may interfere with people who are running side draft carbs with filter boxes? And adjusting the link could mean lengthening, shortening, bending or some other combination of things that people are not really wanting to deal with. Really a modern booster and larger bore master would be nice, but I fear just the sheer size of them nowadays make them problematic.

[Miles]

The constraint for larger boosters on the 240Z is the space between the throttle pivot bracket and the clutch slave on manual transmissions cars.

 

The larger 280ZX booster fits automatic 240Z cars because there is no clutch MC in the way.

 

I used the 8.5 inch 280Z booster.  See picture for fitment.

 

The 280Z booster bolt pattern differs slightly from the 240Z which requires re-drilling the mounting holes in the firewall.

 

On  SBC V8 with T5 transmission  equipped 240Zs you can to get a little more clearance between the throttle pivot bracket and the clutch slave by using  Wilwood clutch MC instead of the Tilton clutch MC.  The Wilwood clutch MC is much more compact.

[superduner]

Now I have a question, according to some guy on Zdriver, the 280zx brake booster can be installed by removing the spacer on the back and flipping it 180 degrees and adjusting the brake pedal link

 

Why not just use that? Is there something else that needs to be modified?

 

Also, is the 280z brake booster different than the later 240z brake booster?

 

Bro I tried that like crazy and I'll share thst k order to get the zx booster in there BOTH the throttle linkage part Woodhaven to be moved and the clutch MC would also have to be moved about an inch to the right to make room. Still lots the zx booster laying in the garage from the z zxt donor car incase I ever pull the trigger... Although highly unlikely. Unless the 280z booster/15/16 Mc set up feels too much of a pain to stop

[Miles]

Information about friction codes:  http://www.bimmerfest.com/forums/showthread.php?t=570124

 

Brake bias: http://www.stoptech.com/technical-support/technical-white-papers/white-paper---brake-bias-and-performance-why-brake-balance-matters

Edited December 14, 2016 by Miles

[grannyknot]

Miles, SJ,  this is great info, I have been through every brake thread on Hybridz a couple times and am still a bit confused.

I have done the stock set up on my last 240, every part was brand new or rebuilt, no air in the system and the braking was just okay. My latest Z which is still all apart I'll be using, Toyota/vented up front, Maxima rear, SS braided lines, 15/16th Master with 280 booster, PV , all new hard lines and NAPA premium pads(hopping for a better cold bite)

 

SJ, I never thought about the firewall flex, that would certainly add a springy feel, well now is the time to address it while the car is apart. I guess it will be easier to work from the engine bay side, there is lots of room next to the clutch master for a simple right angle brace and then a second one might be possible under the dash between the pedal box and the gas pedal linkage.