Stock Brakes vs. Upgrades

[JMortensen]

Just as an example of why NOT to "upgrade" the brakes, I'll tell you about my first attempt, which was using 4x4 calipers on solid rotors and 79-81 280ZX rear disks. I went to a driving school and was informed that my car was not locking up the rear brakes in the "drive through this puddle and slam on the brakes to see what it feels like when you lock all 4" exercise. I had an adjustable prop valve at the time and it was already all the way open. Ended up taking it out completely, still couldn't get the rears to lock before the fronts. Finally went back to the stock front calipers and was able to get the rears locking fist, and then was able to reinstall the prop valve and cut down the rears so that they locked up just after the fronts. When the brakes were tuned like this, I was able to really dive into corners on the brakes a lot harder.

 

I think that most people don't really know what proper brake bias is. I'm as guilty as any: if you asked me if I thought my upgrade was better than stock before I went to that driving school, I would have said "HELL YES!!!" but I would have been WRONG. At that time I had been autocrossing for probably 4 years, and thought I knew which was my ass and which was a hole in the ground. I really didn't. A lot of guys go put some shiny new brakes on their car, and with no other experience than having driven around the block a couple times, come home and snap a few pictures and jump on the internet to say how great the new brakes are and how their eyeballs popped out of their head or they were hanging in mid air on the seatbelt, etc. Maybe the guy had brakes that hadn't been bled in 15 years and the pedal was spongy, or they had the cheapest Autozone pads you could buy or warped rotors, etc. The guy puts on his new Wilwood front brakes with stock rears and is amazed at how bitchin the thing feels, but the information he gives is pretty useless without any context. The internet is a wonderful thing because people who know better (who often times have learned by failing in the exact same way) will help keep the guy with the new Wilwood fronts on the right track. It's much better to learn from others' mistakes.

 

It is entirely possible to put much larger brakes on and increase the amount of heat you can put into the brakes and improve the balance over the factory. But if you don't get the bias right, you are probably making the brakes less effective (in the short run) than they would have been if left stock and properly maintained. I say in the short run because as others have noted, the stock Z brakes just don't have a lot of heat capacity, so it is pretty easy to push them beyond their limits. The stickier the tires and the better the car handles (note I didn't say the more hp you have) the quicker you can burn the brake pads off the car or boil the brake fluid.

[cygnusx1]

     An aside about brake bias.  I use the base Wilwood package from AZC with the bias valve in the center console.  Playing with the bias has been very interesting and revealing to Jon's point.  I have set the bias so that the front locks before the rears in a maximum braking situation.  Then I will get the brakes hot, and need to dial rear bias out because the rears seem to bite harder when they are hot, with the pads I run.  In the rain, you can run a ton more rear bias because you are not able to get as much weight off the rear tires due to the limited grip.  That is a reason alone to upgrade the set in a balanced way.  In reality, there is no "perfect" bias setting that works all of the time.  On the street, it only matters that the rears don't lock first in a panic stop.  Stock brakes are UNDOUBTEDLY designed that way.  ABS is king.    

Edited October 4, 2010 by cygnusx1

[bjhines]

Thats a great example of what kinds of things you learn at a High Performance Driver's Education Event. Running your car at a few events will shed new light on to the careful considerations the factory made for all the systems on the car.

 

BTW, I still think the stock brakes are too scary for me.

[kce]

I think that most people don't really know what proper brake bias is.

 

It is entirely possible to put much larger brakes on and increase the amount of heat you can put into the brakes and improve the balance over the factory. But if you don't get the bias right, you are probably making the brakes less effective (in the short run) than they would have been if left stock and properly maintained. I say in the short run because as others have noted, the stock Z brakes just don't have a lot of heat capacity, so it is pretty easy to push them beyond their limits. The stickier the tires and the better the car handles (note I didn't say the more hp you have) the quicker you can burn the brake pads off the car or boil the brake fluid.

 

At the risk of sounding like a complete newbie (which I am)... the 240 has separate braking circuits and a bias value located on the firewall next to the brake master cylinder right? I would check but the car is being stored in another state.

[cygnusx1]

I believe all the S30's have bias valves of some sort.  Some on the firewall and some at the rear.  All of them are set safely for street driving and will work at the track.  We assume the rest of the system is in good working order and uses appropriate pad/shoe selection.  None of the factory ones are adjustable.  Adjustable setups are generally reserved for track cars and for people who like to pretend they have a track car like me.   I did a few track days and I am glad I went with the Wilwood setup from AZC.  It fills in where I lack specific performance driving skills.  Besides, who doesn't like gadgets? 

[kce]

I believe all the S30's have bias valves of some sort.  Some on the firewall and some at the rear.  All of them are set safely for street driving and will work at the track.  We assume the rest of the system is in good working order and uses appropriate pad/shoe selection.  None of the factory ones are adjustable.  Adjustable setups are generally reserved for track cars and for people who like to pretend they have a track car like me.   I did a few track days and I am glad I went with the Wilwood setup from AZC.  It fills in where I lack specific performance driving skills.  Besides, who doesn't like gadgets? 

 

Awesome. Thanks everyone for all the great info and time put into this thread.

[dsommer]

If you've ever driven or have the chance to drive a Z with the upgraded AZZC Wilwood brake set up you'd understand, there is stopping power and there is STOPPING power. On my first V8 Z car I installed the Wilwood kit and WOW talk about bang for your buck I'd recomend it to anybody wanting to make their Z STOP.

 

Is it money well spent? Again yes.

[bjhines]

I totally agree with the AZC ultimate upgrade. The cost of the AZC kit is close to the other options. I own a BMW M3 E36 and it has ~slightly~ larger brakes than the AZC/Wilwood kit. I have always been impressed with how well the M3 performs on track with nothing more than a track pad swap. The M3 is a lot heavier than the 240Z and it stops consistently at the limits of traction during 30 minute sessions.

 

The 240sx rear calipers are overly complex and too flexible. The Toyota front calipers are overweight for a car(they were for trucks). The front 300ZX disks are notorious for shimmying until they are turned while mounted on the hubs.

 

The Wilwood calipers are simple, light, and VERY easy to maintain. The Wilwood Ultralight disks are cheaper than the 300ZX disks. The Wilwood pads are cheaper than performance pads to fit factory calipers. The aluminum hats make the entire assembly lighter than stock. Bonus; the Wilwoods will easily stop a car that is 1000# heavier than the 240Z.

Edited October 7, 2010 by bjhines

[zgeezer]

Exactly.

 

I've swapped a few S30's over to modest rear discs, purely for consistency. Most of my activities are street and autocross (where repeatability wins races). Stock fronts, appropriately sized rear discs, prop valve, and a proper set of pads have served me well... even with V8 power.

 

I glean that those who did the Maxima rear disc brakes, stock fronts, and a Proportioning Valve are likely to have a balanced set up. What about those of use who have the MM 240sx rear discs? Given the MM240 zx rear discs, what would be a better front set up: the stock rotors and calipers with quality pads or stock rotors with the Toyota solid disc calipers?

 

I understand that "better" is a four letter word, but my choices are limited. Today, I must build around the MM mount and rotors and it appears I will forgo the Toyota vented rotor calipers. What are the realistic options? Arizona Z and Silvermine are priced waaaay beyond my current budget.

 

g

 

[Miles]

I glean that those who did the Maxima rear disc brakes, stock fronts, and a Proportioning Valve are likely to have a balanced set up. What about those of use who have the MM 240sx rear discs? Given the MM240 zx rear discs, what would be a better front set up: the stock rotors and calipers with quality pads or stock rotors with the Toyota solid disc calipers?

 

I understand that "better" is a four letter word, but my choices are limited. Today, I must build around the MM mount and rotors and it appears I will forgo the Toyota vented rotor calipers. What are the realistic options? Arizona Z and Silvermine are priced waaaay beyond my current budget.

 

g

 

 

 

Did you look at the Brake FAQ? Also, recently discussed here: http://forums.hybridz.org/index.php/topic/107891-questions-about-front-rear-brake-upgrades-for-73-240z/

[RebekahsZ]

Is the guy who started this thread still listening as we bench race this into oblivion? Chuck, you still out there? Bueller? Chuck, what style of driving do you plan to do with the car in the next few years? Obviously from this discussion, it matters. For example, my NEXT Z will be a total performance car, stripped of ALL creature comforts, back half-ed for 9" axle with a supercharged LSx. It will not be a street car. I'll probably go with the AZZC Wilwood setup. My current car is FULL of COMPROMISES so that it does pretty well in most driving situations, but it is at best a fun, hobby car; the greatest challenge to the brakes will be autocross (I've boiled the brakes once when I first got the car, and it was scary because of where spectators were allowed to sit at the end of the straight away, one of which was my infant daughter, Rebekah, in a stroller - so I appreciate everything the bigtime road racers have contributed). But, it is mostly a street driven, noisy car that I'm driving to work and drag racing on Saturday night. I live on a hill, ie. I need an e-brake. Do either the Silvermine or the AZZC Wilwood kits have allowances for an emergency brake? I'm running the Maxima setup because it does, and it works great. I'm actually going to change my current pad setup to help it stop better when the brakes are COLD. That's how I need them for drag racing, the slowdown areas of the local tracks are short and even shorter with the LS2, I need the brakes to work when I first get on them.

[240zip]

Having spent a few days at the track (Colorado HPR) I can say the biggest issue with track driving is heat build-up. This is especially true if you run two classes (we have four) back-to-back. I run the 4x4 upgrade with cross drilled rotors in front and stock drums in back with a 280ZX master. We've also run autocross at Goodguys and were competitive (3 place overall). After two back-to-back sessions the brakes started to get spongy. I tended to end the second session a few laps early. I'm going to use a performance brake fluid next time and I'm considering upgraded pads for the drums and front. We used the stock Toyota pads that came with the kit and are investigating better track alternatives.

Edited July 12, 2012 by 240zip

[bjhines]

I would agree that heat buildup is a big problem with the stock setup. There is also the problem of low thermal mass, so the heat builds up quickly. Venting the front disks is a big help on track.

 

Brake fluid is important enough that most organizations require that it be less than 90 days old. I use Ate blue, and flush alternately with Ate gold. The stuff is only $12 a quart and it will work at high temps.

I tried pads from Ferrodo, Carbotech, Performance Friction, Hawk, and others. I decided that they all offer something that will work at high temps. I was never happy with the performance "street" pads, as they do not work when hot(they just have a higher coeff. of friction).

 

You really have to go with the race pad compounds on track, I never needed high coeff. of friction, especially on the fronts. The rear shoes can be custom relined by several companies, Carbotech is a small company and they have experience custom relining 240Z brake shoes. Just send them old shoes and specify the thickness of the material they apply. The biggest problem with race compounds is that they do not have good initial grip when cold, so they can be inconsistent on the streets. Many of the race compounds will wear the disk much faster than street pads, Hawk Blues are especially bad about turning your rotors into glitter if they run cold.

[240zip]

I think the brake fluid upgrade is my first step. Does anyone make an upgraded rear drum brake shoe upgrade. You mentioned sending them off to be 're-shoed'. I'll look into that. Since my car is not 100% track dedicated, I don't want to chew up my rotors with overly aggressive pads.

 

What about cryo treatment of rotors? Any thoughts there? I know my friends who race Porsche seems to like that approach. I also suspect they use 'unicorn tears' in lieu of brake fluid.

[bjhines]

Cryo and unicorn tears. They are trying to use stock fitment parts and make them a tiny little bit better. We are discussing an entire brake system refit in many flavors.

 

You have to reline the rear drum shoes. Grab an old set and get it done.

Edited July 13, 2012 by bjhines

[240zip]

I'm leaning towards this one for the rear shoes.

 

Carbotechâ„¢ 912 Kelated Metallicâ„¢

 

An advance organic-metallic compound specially formulated for drum shoe applications in lighter weight race cars and/or high performance street vehicles. High friction coefficient of 0.46 to 0.48, providing excellent braking without any risk of lock-up. Very good brake modulation throughout the entire brake pedal travel range, with excellent wear characteristics, providing an outstanding value. With a price-point significantly below other compounds offering similar performance, 912 ™ is an excellent choice for the budget-minded racer or high-performance driver. Optimal recommended operating temperature range is from ambient to 650°F.

[240zip]

Question. Which is better? Motul RBF 600 Racing Brake Fluid or ATE Super Blue Brake Fluid? I like the blue / gold alternating flush approach. Are either available at places like Advance Auto or AutoZone?

[30 ounce]

I use Motul RBF 600 and NAPA semi metallic pads for track and have excellent results. I get the Motul at the Kawasaki dealer in Loveland (I-25 between Windsor & Loveland west side). It's a lot less $$ than ATE Super Blue and easier to find.

Edited July 13, 2012 by 30 ounce

[bjhines]

You have to balance/bias the brake system. This is experimental in nature. I think you choice of rear compounds is fine, You might need to try a few different front compounds.

 

The concept of brake biasing is simple;

• You want front and rear brakes working at the limits of tire traction.
• The rear brakes must not lock before the fronts. Dragging the rear wheels will cause a total loss of control. The fronts must lockup first.

The real world of biasing depends on vehicle dynamics, driver technique, track conditions, and carefully considered compromises.

[johnc]

Either brake fluid is fine. What's important is bleeding the brakes (all four wheels) at the very first sign of a soft pedal. Its almost standard practice to bleed the brakes and adjust the rear drums between qualifying and the race in an ITS 240Z with the stock brakes.