Porterfield R4-S versus Brakeman 3's

[Achilles99]

Porterfield R4-S versus Brakeman 3\'s

I'm looking to get new pads. I plan on daily driving my GTS, and doing roughly 10 auto-x events and 1-2 track events a year with it.

I'd like to stay in stock class, which rules out caliper modifications. I'd like to have more pedal modulation, as it is way too easy to lock up the front brakes with stock pads. I've tried EBC Greens, but I don't like them since they don't have great bite. I did like the fact that they were easier to modulate, though.

After talking with a few people, I think that Brakeman 3's or Porterfield R4-S's (the street pad, not the regular R4 track pads) will fill the ticket. My question: for those of you with Brakeman 3's-would you recommend them for daily driving? How about Porterfield's? Has anyone tried both sets?

I'm also planning on adding an adjustable prop valve, which should still keep me in stock class, if that makes any difference with pad selection...

Thanks for the input!

 

[Tom F&L GoR]

Re: Porterfield R4-S versus Brakeman 3\'s

I've run all three (B#3, R4-S, and R4.) The B#3 and R4 seem similar in most characteristics, for AX, street, and track. R4S is a street only pad; I toasted a new set down to the backing plate in 30 min of track time. I've used R4 and B#3 on the street, R4 seem more rotor hungry... I like the B#3 enough to keep them on the car all the time.

Ummm... where you gonna put the prop valve with OEM calipers?

 

[Achilles99]

Re: Porterfield R4-S versus Brakeman 3\'s

Tom,

I can always count on you for brake advice Did the Brakeman 3's have enough initial cold bite? I only drive 1.5 miles to get to the office...

What do you mean about the prop valve with OEM calipers? Doesn't it go under the hood? I found a place that will make me a bolt-in setup with two Wilwood prop valves (front and rear) and the correct brake lines. I should be able to just drop it in with having to cut or flare any lines...

 

[Tom F&L GoR]

Re: Porterfield R4-S versus Brakeman 3\'s

B#3 will be better cold than R4 pads. It's been ~15F here on some mornings and I worry more about the tires being too cold, pads are fine.

If you don't have enough rear braking, a prop valve won't help. They are designed to reduce rear braking further. It sounds unsafe to put a prop valve on the front lines since a panic stop may allow rear lock-up (because you would have dialed down the front line pressure increase rate.) Search the archives, I think there's an emotional, logical post by Woodhouse about this.

Here's a long one :
http://vca2.viperclub.org/forums/showflat.php?Cat=&Board=UBB14&Number=70341&page=&view=&sb=5&o=&fpart=1&vc=1

 

[Marv S]

Re: Porterfield R4-S versus Brakeman 3\'s

Same observations as Tom gave. I've had the R4-S melt away in track use and seen the R4 split/crack a stock rotor at the track.

The Brakeman 3 is fine for me with it's initial cold bite.

 

[Achilles99]

Re: Porterfield R4-S versus Brakeman 3\'s

Tom,

From what I gather, an adjustable prop valve would allow you to control how much rear bias is available. The stock valve reduces rear bias at a certain pressure, right?

From Ted May's shop in LA (Vprvenm may chime in here, as he has a similar setup), which does a lot of the Speedvision cars and does a lot of prepping, I gathered (don't quote me) that an adjustable prop valve for BOTH the front and rear would allow you to adjust both the front and rear bias. I'm guessing that, to tune it, you would adjust the rear bias as high as possible (since in stock configuration, the rears don't lock up). Then, you would dial down the front until both front and rear would be doing maximum braking without locking up.

Another way to look at it would be to set the system so that the fronts lock up just before the rears do, but also have it set so that the rears NEVER lock up before the front.

I'm not sure why Woodhouse doesn't like prop valves in our cars... I'm going to check and see why not. Perhaps he means you shouldn't put in an adjustable prop valve in line with the stock one, which already reduces pressure?

Keep the input coming... I'm trying to find the best way to get a decent street braking setup (I don't want to lay down the change for StopTechs, as I won't be tracking the car THAT often). Thanks!

 

[Tom F&L GoR]

Re: Porterfield R4-S versus Brakeman 3\'s

A proportioning valve limits the brake line pressure relative to further application of brake pedal. Typically, it's used on the rears to make sure you hit the oncoming barrier with the front end of the vehicle, because the occupant protection is designed for frontal impact.

An adjustable proportioning valve:

1) changes the pressure at which the proportioning begins
2) changes the rate of pressure rise decrease
3) both 1 and 2
4) and maybe you don't know if it's 1, 2, or 3

Your risk situation is if you reduce the fronts to match the rear lock-up and then find yourself in a stickier situation, meaning the fronts are sticking more than you ever expected. The weight transfer, road condition, or sticky tire will then keep the front wheel rolling instead of locking up. However, once you engage the prop valve function you've dialed into the front, and you keep pushing harder (because you don't see any flat-spotting tire smoke yet!) you are now applying a greater amount of rear brake than front brake. Depending on conditions and the prop valve, a little more front brake means a lot more rear brake and you hit the cone/guardrail/tree rear end first.

With a rear prop valve, you always have the comfort of hitting the cone/guardrail/tree front end first.

Someone correct my logic, please.

 

[jcaspar1]

Re: Porterfield R4-S versus Brakeman 3\'s

Has anyone tried the StopTech Club Race pads? StopTech says they use the same friction material as the #3's.

 

[VPRVENM97]

Re: Porterfield R4-S versus Brakeman 3\'s

Achilles,

I have the stock calipers on the front and Wilwood 4 piston calipers on the rear. The stock rear caliper is now the parking brake only. The proportioning valve I have is for the rear brake only. The proportioning valve allows me to adjust the bias to the rears appropriately for conditions. Without the proportioning valve the rears will lock up before the fronts.

The reason I chose this combination is because the stock front brakes are actually pretty good. The problem, as I've been told is the rear brakes are useless for stopping. It serves a more useful purpose as a parking brake. The Wilwoods can be installed without cutting or grinding any part of the car. It can be returned back to stock if desired.

As for proportioning valves on the front and rear, I'll leave that for the experts. I know you wanted to stay with the stock brakes for your autocrossing, maybe that's why Ted recommeded it. Are you still going with the rear brake modification by Tom?

 

[Achilles99]

Re: Porterfield R4-S versus Brakeman 3\'s

Vprvenm,

I told Ted my goals, and the valves would keep me in stock class. I was going to do Tom's mod, but then found out that it was not allowed. I wonder why? The ABS Vipers had larger rear pistons. I guess the reasoning is that ABS Vipers came with them, and my non-ABS Viper did not.

As a side note... are the ABS Viper rear pads larger than the non-ABS? I was thinking that might be another reason why ABS Vipers brake better...

Out of curiosity, how much are the Wilwood rear calipers?