J Ritt

iTrader: (4)

Droid is 100% correct on this one. The % increase in swept area doesn't mean squat if the setup is not put togehter and tested to work as a system on the 350Z...and the argument is not whether Wilwood makes quality components or not. It's whether or not the pieces work in harmony with the 350Z master cylinder, abs, ebfd, and have the proper bias, etc. to reduce heat, fade, and consistently increase stopping ability under heavy use, and in day to day street driving. I could put Porsche's ceramic composite brake setup on my Z (which is made of extremely high quality components), but that doesn't mean it will work properly...we're talking about the same exact thing here. How is the pedal feel with this system? Is there reasonable pedal travel? Do the brakes bite too much initially for comfortable street driving? You don't know! Most of the people on this board are putting these brakes on street cars that will occasionally see track use (if at all). Saving $500 on an untested, unproven system is insane. We're talking about safety here! Think about how you'll feel when you sell someone a kit that doesn't work properly when they're barreling down the back straight at Watkins Glen at 135mph...or maybe it will work properly? But until you know it will...I'd just make sure you can answer all of the questions that need to be answered. Personally, I wouldn't want to unleash a group of guinea pigs on a track with something I sold them unless I was sure it worked at the very least as good as stock.

Numbers and tests are all well and good but it doesn't take a genius to see that a 4 piston system is better than 2 piston stock!
- that statement is absolutely ridiculous, and depends entirely on what you want out of a brake system...and there is definitely no gaurantee that this system would be better than stock. I would go so far as to say you can gaurantee that the first setup you slap on the Z will NOT be as good as either stock system. As droid said, if you want some pizza dishes under your rims for sex appeal, sure, bolting anything on there will work. If you want performance and safety, you need to be sure about what you're putting on your car. I'd rather save my @ss than $500.

DZeckhausen

I'm almost afraid to jump in here because the discussion has become so heated, but perhaps I can help. There are a few misconceptions floating around that I can try to clear up and a few cautions I would like to give to the group.

First, let me say that I understand the feelings of the group buy coordinator. He's trying to do something to help the community and willing to invest his own time and, perhaps even use his car as a test mule. And he's being challenged by folks for data that he can't deliver and beginning to wonder if the effort is worth it. Been there, done that. In early 1998, I brought Mov'it to the USA and installed several of their $3000 Porsche-based kits for Chevy Impala SS, including on my own. I soon realized there was demand for a lower priced brake system that offered the advantages of a fixed, 4-piston caliper and bigger rotors without the astronomical price. I worked with TCE in Phoenix (does much of the machining for Bondurant School of High Performance Driving) to develop a Wilwood-based kit that sold for around $1400.

We had to go through several iterations of caliper selections in order to get the brake pedal feel and balance correct. We also went to differential piston bores in order to prevent tapered pad wear. After several false starts, the kit sold well and made TCE a bunch of money. I was a hobbyist at the time and my day job was telecommunications, so I didn't have any interest in the financial aspects of the project.

Although it was a success, there were several compromises that resulted from our selection of Wilwood calipers. First, the Wilwood calipers are designed for the track, not the street. So they do not come with any weather boots on the caliper pistons. There is some extra work required when changing pads. You need to scrub the exposed caliper pistons with a brush and solvent to remove road grime BEFORE you retract the pistons. Otherwise the cars equipped with these calipers will suffer from sticking pistons and then overheating rotors and boiling brake fluid. This is not the sort of kit that works well in the northeast, where roads are salted.

Now let's move on to the design you've proposed. You mentioned that overall piston area will increase and you also mentioned that the stock master cylinder will be retained. This means that your pedal travel will INCREASE after the installation of this kit. This is exactly the opposite behavior that most buyers will expect and want. Since you are installing larger diameter rotors, you have the luxury of using smaller caliper pistons while maintaining factory brake torque levels. I urge you to reconsider your caliper piston sizing and select something with LESS surface area than stock in order to reduce pedal travel. (Let me be clear that I'm talking about caliper piston area and not pad area.)

Wilwood calipers exhibit much more flex than most other calipers due to their featherweight design. This means that it is even more critical that you REDUCE overall piston area because a flexible caliper will also increase pedal travel. You need to compensate by going smaller, not larger with your pistons.

And finally, you do need to work on a single prototype and get it tested and sorted out before you go around and get people to commit to a group buy. It's impossible to properly set customer expectations if you don't have a working prototype. As someone else pointed out, just because you have good rotors and good calipers doesn't mean you will end up with a good system.

It's a long and frustrating process, but if you stick it out you will be rewarded with a much greater knowledge of brake systems. You may or may not end up with a cost-effective product, but I encourage you to try. Good luck and if there's anything else I can do to help, let me know.

TheLex

THANK YOU Dave!!! Well written.

And thank you, group buy coordinator for investing your time and effort. It is people like you that make the hobby of modding our cars fun. I would heed Dave's advise though.

DZeckhausen

I'm afraid you've misinterpreted the data in the summary table of my braking article. It's true that the rear rotors ran hotter on the cars with larger front rotors. But there isn't a causal relationship between front rotor size and rear rotor temperatures. There's more going on behind the scenes that has influenced the test data and I'll try to explain it.

First, the car used in the last two columns had a modified suspension and was slightly lowered. As a result, there was less forward weight transfer and the rear brakes did more work before they started to lock up. Thus they ran hotter.

Second, the front calipers used in the 355mm front kit may have had piston sizing that slightly changed the bias more rearward. I don't know this for sure, I'm just theorizing another possible factor that could influence rear rotor temperature.

Third, the contact pyrometers used during the test are not accurate to the nearest degree. I'm not sure what the error bars would be, but I would give much less weight to the temperature data than to the stopping distance data. Just based on the variation of readings from run to run, I would guess the error could be as high as +/- 10 degrees F for each reading whereas the variance in stopping distance was measured in inches.

I hope this helps put the temperature data into its proper perspective.

nwind21

hey guys, I think some of us need to cool down a bit...

In any case Droid, I think your point of seeing test data is valid.

I think as DZ pointed out (kinda?)... if Precision Braking is willing to manufacture the product, then they should be willing to do some testing to verify their product works. It won't cost us buyers anything and if results look good, P. Braking could grab a good market share of the brake kits...

I am concerned about the dust boots lacking on the Wilwood pistons. I was reading about Wilwood on the net and this came up on several forums. Sounds like if an average Joe mechanic was servicing your brakes, he probably will goof things up.

If Jak or M. Mole can talk to P. Braking to get them to do the dev. testing... it doesn't hurt to ask and they have everything to gain from a few days of testing. If they require a Z, I'm sure someone on this board would be willing to donate their car for testing given they receive some kick-back.

Anyways, I'm still interested to hear about the kit/gb and I don't mind waiting for results.

EnthuZ

iTrader: (2)

Interesting thread.

I bought my 13" StopTechs partially because of DZ's article, But mainly because I felt comfortable knowing that StopTech Tests!

So far I'm very happy with the results. I can't wait to try them at Blackhawk next month.

While I was installing, I grabbed the bathroom scale and got some weights......far from exact I know, but interesting:

OEM 11.65" rotor: 16 lbs
StopTech 13" rotor: 20 lbs

OEM Caliper: 13 lbs (with pads)
StopTech caliper: 11 lbs (with pads)

I'll take the 2 lb weight penalty, knowing the increased rotor mass will help the heat issue.