Hydratech vs ABS Electric vs Manual brakes

[wmhjr]

Guys, looking for some advice. My ride is 3720lbs empty. Weight distribution is actually very good (50.6% front, 49.4% rear) considering. Running Wilwood 12.2" 4 piston brakes with 7/8" manual master cylinder. Brakes modulate pretty well, and car is very comfortable to drive.

However..... I'm hoping to get to some events like MMCC, Motor State, and RTTH this year. Even after switching to BP20 pads, I'm not all that satisfied that I'm yet delivering enough pressure for panic and threshhold braking. The car is a completed project and appearance is also important. The engine compartment is very finished, smoothed firewall, etc. I think I have a few options. In no particular order:

1) More aggressive pads, and check my line pressure. Advantage is low cost, no real fabrication or modifications. I could use the really aggressive pads only for the HPDE type events. Disadvantage: No real help during normal driving.

2) Hydroboost. Advantage: Only need to modify plumbing in the engine compartment, assuming I don't need major changes in my steering pump/reservoir setup. I will need to modify my setup which has the line lock and clutch fluid reservoir mounted to the master, as there will be insufficient clearance against the inner fender with the master moving forward toward the front of the car. Disadvantage is more cost than manual, but probably less than ABS electric. Also, that I'm hearing mixed reviews as to "frothing of fluid" and steering/brake feedback during spirited driving - as well as increased steering noise. Also, lots of hydraulic lines in an otherwise very clean engine compartment.

3) Electric ABS. Advantage: Apparently highest power assist pressures. I could possible mount the pump and accumulator back in the void in front of my trunk. That would keep the engine compartment relatively clean from a plumbing perspective. Disadvantage: No means to mount clutch/linelock with the master used by ABS. ABS master is totally proprietary - only one company makes it, so long term? Need to run two lines all the way from the master back to the trunk area.

Does anybody have any good advice concerning this? Here's a pic of the engine compartment

[parsonsj]

Me: I'd try dual manual masters, but most importantly, I'd upgrade to 14" rotors. You'll have lots more braking leverage that way, though it will cost you some acceleration due to the cost MOI will impose.

jp

[Payton King]

Went through this with may project for about a year and I am running manual brakes. Not to get into a long story, but you need to ditch the BP20's. I had about 1200 psi at the caliper and could not get my car to stop like I wanted and that was with the BP10s (BP20's need more heat). 1200 psi is about the max Wilwood reccommends for their stuff. Anyway, the pads did not have enough cold bite. We could talk about heat ranges and Cof and the like, but I will tell you what I am running and I am very pleased. Carbotech AX6's on all 4 corners for street and autocross. High bite cold, easy on rotors, almost no noise but they are a little dusty but it is easy to wash off and it is not corrosive like some pads. Running on a big track I swap out the front pads for Carbotech XP10's and leave the AX6's in the rear. This is running street tires. If I go up to an R coupound I will go more agressive front and rear. That is the short answer and the cheapest route to try before you start spending big money. I almost changed my system to power until I tried the Carbotechs from a rec from Tobin at Core3. I did try a set of Wilwood "B" compound for about 10 miles. Stopped the car like crazy but were very loud and you could see the wear on the rotors. I am sure they would work great on the track but way to harsh for the street...they are sitting in my tool box, let me know if you want to give them a go.

[wmhjr]

John and Payton,

Thanks. This is some of the feedback I'm looking for. John, do you think larger hats will really help that much? I know they'll help with preventing too much heat and warping. I'm just not sure about the actual panic/threshhold braking. I'm not too worried about the effect of MOI. Let's face it - the car is big and heavy. I've got plenty of well behaved power (call it 600hp/600tq) but the goal here isn't something that will be able to really challenge something like Penny, Mark or Mary. It's more to just prove that a well balanced big old "show looking" car can perform surprisingly well. I have seriously considered the 13" rotors with 6 piston fronts - hadn't really thought about 14" up front. Payton, a couple questions: Do you have any idea what your car weighs? The Carbotech pads seem like magic from how you're describing them. Right now, I have REAL difficulty locking the brakes at any speed. I know the NT05s are soft for a street compound, but still.

[Apogee]

Increasing your rotor diameters actually achieves less than you might think in terms of the overall brake torque. Moving from a 12" to a 13" rotor only nets you about a 8% in brake torque per inch while moving to a 14" will be almost double that. The larger rotors increase your braking capacity by a much more significant margin due to the additional thermal mass, but the the torque is merely a function of the effective radius where the pad centerline contacts the rotor. Changing your pads to a more aggressive compound (like "FF" to "GG") with a higher coefficient of friction can easily increase your brake torque by up to 30% or more.

Hydraulic solutions are nice if you want to run a lower CoF pad with low-dust, low-noise, low-rotor wear characteristics. The greater the system pressures, the more forgiving the system since rotor diameters, pad CoF's, etc can be overcome with sheer brute force.

Tobin
KORE3

[parsonsj]

Bill,
I'd guess the 14" rotor will give you around 15% better braking torque, just based on effective radius. They'll also help reduce brake fade significantly if you spend any time on a big track, but you didn't really ask about that.

I'd give the other pads a try since they are easy to install. If that gets you in your brake-happy zone, good enough. If not, then I'd look into the larger rotors. Both of these things will make a bigger difference in braking torque than messing with the masters.

One thing you might do to get a better idea of what's going on is to measure the brake line pressure. You can get a gauge that screws into your caliper bleed port, and then push the pedal while a friend or reluctant wife reads the gauge. If you can put 1200 psi to the caliper without giving yourself a hernia, then pads and/or rotors is the thing to try first. If you can only get 800 psi, then you might need some master cylinder boost.

jp

[wmhjr]

Thanks again, guys! John, I will actually be measuring line pressure tomorrow or sunday. I had lent my gauge out and just got it back. The other thing that Wilwood mentioned to me was that I'm runing 3/16" hard (stainless) lines everywhere - except for between my prop valve and the "T" above my rear diff where the 3/16" hard lines go directly to the rear calipers (no flex lines back there). Wilwood mentioned that this might cause an issue with the rear brakes, but not the front obviously. I'll also mention that I've been tossing around the idea of Superlite 6R 14" brakes up front. I am a little concerned that at an HPDE, the 12.2" narrower rotor might get a little toasty and be more prone to warping. Thoughts?

[parsonsj]

I am a little concerned that at an HPDE, the 12.2" narrower rotor might get a little toasty and be more prone to warping. Thoughts?

It's a good question, and I don't know the answer. All I can say is that my Wilwood 14x1.10 front rotors took all the HPDEs I could throw at 'em, and never ever had a warping problem. Perhaps somebody else has some direct knowledge of swapping between 12.2 and 14" rotors...

jp

ps. When you do get on the track, and they tell you to do a warmup lap and a cool-down lap, do it. It will help reduce spikes in the temps of all your running gear, and could reduce rotor warping.

[chr2002ca]

I'm running the same 7/8" Wilwood Master cylinder and 3/16 brake lines throughout. I have the Baer Track 2 piston calipers up front and single piston in the back with 13" slotted and drilled rotors on all four corners. So a similar setup to yours with slightly larger rotors. I'm seeing nearly the same braking behavior as you. Overall driving is pretty good, however it takes an extreme amount of pedal pressure to lock up the brakes or stop quickly in an emergency situation. Normal stopping requires a little more pedal pressure than I would like, but that's to be expected from a manual setup. I like the fact that the brakes can at least can lock up now because my previous setup wouldn't even lock-up the brakes(1" MC with a 9" dual-diaphragm power brake booster and plenty of vacuum). I'm now just looking for something to slightly improve my braking power, especially initial bite. I only need a slight improvement at this point and I'd prefer to keep extra equipment off my car, so I have been considering the Carbotech AX6 pads. From what I've heard and read, the pads can make a huge difference, but at the same time, they can have some unwanted side effects(dust and noise). Like you, I really don't want to go through the trouble of hooking up a Hydraboost system due to the worries related to the power steering system and fluid. The ABS electric system looks great on paper, but then you have the added weight and the amp draw on your electrical system, and I haven't seen too many real-world reviews on that system to be comfortable with it for my application.

If you go with Carbotech AX6's please let me know how they work out, and I'll be sure to do the same if I go that route also. I've read in some reviews online that it's extremely important to prep your rotors for the AX6 pads and bed them in properly or else they can be a bit noisy. If the Carbotechs don't work out, I may just have to consider the ABS electric system.

Payton, thank you for sharing your experiences with the Carbotech pads. That goes a long way in helping me decide to try out these pads.

[wmhjr]

Guys, thanks again for the advice and experience here. Here is some more info...

I measured line pressure front and rear today. For the front, I can easily generate 1000lbs with almost no effort. 1400lbs is not a problem - takes some effort but you probably don't want to make 1400lbs without some, right? For the rear, I learned something. I had assumed that "opening" or counterclockwise turning of the valve handle on my prop valve would "open" or "increase pressure" to the rear. Whoops. It was originally pretty much "unscrewed". I was making 400-600lbs. So, I started screwing the valve in. Before long, it was 1100lbs. I left it where the same effort to make 1400 in front made 1100 in the rear for now.

I'm thinking my master and all my lines are perfectly fine. As the wilwood gauge only goes to 1500, I'm thinking they don't want more than what I'm generating. So, I'll concentrate on rotor/caliper/pad changes.

I think I'm going to go for the Superlite 6R 14" in front. Keep the 12.2" Dynalite Forged 4 piston in the back.

For pads, I talked to Carbotech. For my application, they recommended AX6 in the back for all use. For the front, they recommended XP8 in front for street/autox use - possibly AX6. For road course, they recommended XP10 or RP2. One thing they mentioned that I liked was that if you buy directly from them, you can get the pads pre-bedded.

Thoughts?

[parsonsj]

Good stuff! It's always better dealing with data!!!

If you can generate 1400 psi you don't need any master cylinder help. At all. I think it's that big car and show car pads. If you go with the SL6s and keep the Dynalites on the back, you'll have almost exactly the same setup as II Much. 1200 psi on the front was a good harness test.

jp

[wmhjr]

Thanks John. I was relieved to see the numbers myself. I really appreciate the advice.

[Payton King]

Sorry, I was not on the boards this weekend. Looks like you got taken care of. My car weighs about 3500 lbs. I am running a twin master set-up with a 7/10 front and 3/4 rear master. Runing 13 inch rotors front and rear with the Wilwood 6 piston front and 4 piston rear. I was able to stop by Carbotech because they are a local company just outside of Charlotte. Adam spec'd me out on my pads. I have run my track pads from Carbotech on the street XP10 when I went to Motor State last year (or maybe they are 8's, I will look tonight) but I can tell you the AX6's all the way around are better on the street and autocross. I would say zero noise. The dust is not terrible, a lot less than my wife's BMW. I think Adam told me the AX6's are around .52 or .54 CoF cold. Rotor prep consistes of taking a small abrasive disc and scuffing the rotors to get the old brake layer off before putting on the new pads. They bedded easily.