Opinions/Thoughts on this brake setup?

[nusevad]

Ok, so i searched and read for the last 3 hours on different brake "upgrades"

 

Seems like general consensus is that toyo 4x4 with any rear brake calipers will give too much bias to the front and throw off brake balance.  Not much of a solution was found after reading through the threads of resoling that issue than "leave the rear drums alone" 

 

Here is my situation.  I bought a complete suspension+brake setup from an enthusiast.  Basically I have a 2nd suspension setup separate from the stock suspension on my Z.  

 

The fronts are toyota 4x4 with coilovers, "power" slotted rotors, new bears, new poly bush, powercoated control arms, etc.  

 

The rears are early 280zx calipers with Jim Cook brackets with "power" slotted rotors on coilovers and new everything like the front.

 

My current stock suspension has some issues as it pulls to the left when I brake, i suspect a seized front passenger caliper  and my stock 7/8 brake master cylinder COULD be bad as the reservoir closet to booster is almost dry and dirty.  

 

My question is, has anyone used stock front calipers with either a 280zx rear calipers, 240zx, etc? If so, how do you like it?  I would really like to use the rear setup I bought as the install is super easy, all i have to do is drop my stock suspension and bolt in the one i just bought.  

 

If one of my stock calipers is FUBAR or MC is fubar, I am considering installing a 15/16 MC and use the 4x4 toyota calipers. 

 

What do you guys think?? 

[SRRTz]

I ran stock fronts with late 280zx rears for a while. The performance really wasn't any different from the stock drums but maintenance was far easier. If I wouldn't have decided to start running HPDEs I would probably still be running this combo

[nusevad]

I ran stock fronts with late 280zx rears for a while. The performance really wasn't any different from the stock drums but maintenance was far easier. If I wouldn't have decided to start running HPDEs I would probably still be running this combo

 

Oh ok, the late 280zx rear is similar to 79-81 zx rear? Either way as long as it makes maintenance easier and not give me really bad bias with stock fronts I might just leave the stock fronts. 

 

Do i need to upgrade to a 15/16 MC for the 280zx rear calipers? 

Edited May 7, 2015 by nusevad

[JMortensen]

I did both. I ran 4x4 fronts with early ZX rears and couldn't get enough rear braking out of them, so I ended up running the stock fronts, and then I could dial in the bias with an adjustable prop valve. 

 

You would want the larger master for the fronts more than the rears. If you're going back to stock fronts, then the larger master isn't necessary. The other issue is that some drum masters have a little check valve to keep a small amount of residual pressure in the lines. You don't want that on a disk system. Check to see if there is a check valve in the rear circuit on the 7/8 master.

[Miles]

I have done the following so called brake upgrades to get a real world idea of how effective they are and what the unintended consequences are for each brake swap:

 

• Toyota solid rotor front with stock drums. Basically like stock stopping performance,  but less fade in panic stops.  The stock 7/8 MC allowed too much pedal travel so I installed a 79 280ZX 15/16 MC. Pedal then became stiff and required more effort which could have been offset by installing an 8 inch diameter 280Z booster (more on that later).
• Toyota vented front using Modern Motors kit with stock drums. Same as above only vented and more weight.
• Toyota vented front and Modern Motor Sports 280ZX rear kit. No better stopping than stock. Calculated brake bias was 70% front and 30% rear.  After about four years the rear brakes started overheating. A long story short, I discovered that the flanges (where the wheel bolts to) on the new OEM Nissan stub axles I had installed with the 280ZX rear brake kit had become warped. The thin soft flanges can become warped easily just bumping into things. For drum brakes having warped stub axle flanges isn't a big deal, but for disk brakes it can cause the calipers to rub on the rotors causing overheating. Finding the problem surfaced when I checked the flange run out with a dial indicator. New OEM stub axles are NLA so I replace the warped stub axles with steel alloy units from Chequered Flag Racing. Brakes are no longer overheating.
• Toyota vented front with Maxima rear calipers. Much worse that the 240ZX rear set up.  The rotors used with the Maxima calipers are smaller that the 300ZX rotors used on the 240ZX so  there is less brake torque.

At some point the 280ZX MC failed  and was NLA so I installed the Wilwood 1 inch MC and a 280Z 8 inch booster to offset the pedal stiffness anticipated with using a 1 inch MC.

 

 

 

After all that, my current set up is Toyota solid front with 280ZX rear, 1 inch Wilwood MC, 280Z 8 inch booster and Axis Ultimate brake pads. The brakes work well for a daily driver.  The brake pedal feel is a bit soft the first 1 inch of travel, but becomes firm and linear. They are like the ABS brakes in my Frontier pickup.

 

The stock brakes were designed as a system with all of the parts working together.  Altering one thing can have a domino effect that results in poor performance and added cost.

 

None of the above brake combinations improve street performance.  Racing may be another matter where people can use different front and rear pads and a proportioning valve to dial in brake balance.

Edited May 7, 2015 by Miles

[JMortensen]

You shouldn't have a soft pedal for the first inch. With 15/16" master and 4x4 and 280ZX I had a rock hard pedal. Probably need to lengthen the pushrod. I recall doing that when I installed the ZX 15/16" master.

[NewZed]

Has there ever been a better brake shoe to consider for the Z system?  Tens of race pads to choose from, but you don't see much on shoes.  I've also found that the aftermarket shoes seem to be designed for already turned, oversize, drums.  The diameter of the shoe is greater than the diameter of the drum, so a new shoe only contacts on the ends.  Lowers the contact area, making weaker brakes.

 

This is likely, although it may not be seizing - " it pulls to the left when I brake, i suspect a seized front passenger caliper".  I had a newer caliper on one side with an older one on the other.  Just the mismatch in seals, either age or quality, or design, caused a pull.  One set of pads hit sooner than the other.  The rubber seals in the calipers are what determine pull-back of the pistons in the cylinders, and pads from the rotors.

 

.

Edited May 7, 2015 by NewZed

[nusevad]

interesting...well should I at least try thee toyota 4x4 front with early 280zx rear + 15/16 MC? I have all the parts, i just dont have a porportioning valve. 

 

By the way, what rear rotors works with the early 280zx rear caliper? I suspect the one that came with could be warped...it got a bit scratched up during shipping too.

[RebekahsZ]

Having gone thru this, not quite as extensively as Miles, there are only two brake systems for the S30: stock, and AZC. Anything else and you are kinda wasting your time. Take the time you waste on Toyota swaps and go mow yards. By the fall, you will have the money for the AZC kit and you can install it over the winter. And you will thank me. I didn't believe it either, but Im a believer now.

[nusevad]

Thanks for the input everyone, especially Miles for going through so many setups so we have this knowledge!

 

I apologize but I forgot to mention that my Z will not be participating in autoX or tracking this year, I would like to next year but this year is mainly for maintenance (just bought Z last November) and improve/replace old or obsolete components, basically resto-mod this summer and by next summer I would have enough saved up for the AZcar brakes and participate in events.  

 

In that respect, for boulevard cruising and driving to local meets to meet with other enthusists, would Toyota Calipers + 280zx + 15/16 MC be sufficient and safe for highway cruising? No canyon carving, no drag racing, just semi-spirited drives and cruising

 

I searched and found this post by Seattlejester, can anyone confirm these bias #s?  Looks like the 4x4 + 280zx isnt THAT bad....

 

So to calculate ratio Moments...

 

Front Bias = (Moment of Front / (Moment of Front + Moment of Rear)) x 100.

Rear Bias = (Moment of Rear/ (Moment of Front + Moment of Rear)) x 100.

 

Moment Toyota 4x4 front caliper = 2360mm^2 x Line pressure x (135.5mm-21.5mm) = 269040mm^3 x line pressure (in kg/mm^2)

Moment Toyota 4-runner = 2904mm^2 x Line pressure x (135.5mm-21.5mm) = 331056mm^3 x line pressure

 

Moment Nissan 280zx = 1452mm^2 x Line pressure x (142.5mm - 21.5mm) = 175692mm^3 x line pressure

Moment Nissan 240sx = 1134mm^2 x Line pressure x (142.5mm - 19mm) = 140049mm^3 x line pressure

 

The ratio removes line pressure from the equation assuming same line pressure goes to front and back (for our very simple calculation)

 

So we end up with biases of:

Toyota vented 4-runner and Nissan 240sx rear caliper setup

70%:30%

Toyota vented 4-runner and Nissan 280zx rear caliper setup

65%:35%

Toyota solid 4x4 and Nissan 240sx rear caliper setup

66%:34%

Toyota solid 4x4 and Nissan 280zx rear caliper setup

60.5%/39.5%

Edited May 8, 2015 by nusevad

[Miles]

Her are my numbers:

 

• Stock front - 240SX rear                   65% : 35%  I tried this combination and had to reduce pressure to the rear brakes with a proportioning valve.
• Toyota Solid Front - 240SX rear       66% : 34%
• Toyota Vented  Front - 240SX rear   70% : 30%

Many other numbers like these in the brake forum.