Brake Advise Needed...
 

I need to upgrade my brakes. I just switched to 11" GM Metric brakes and they are not much better than what I had. I need to go to a 4 piston caliper that will bolt on to the Mustang II front suspension. Can anyone offer up some suggestions on the best setup available for under $1500?

Roscoe if you see this I know you have probably crossed this bridge and I would appreciate any input you may have. This weekend I could have knocked a good 10 or 15 seconds off my times (14 turns and corners / 1.8 miles) if I could have waited to 300 or 400 foot marks to get on my brakes.

Thanks again everyone.

Clois Harlan

P.S. The new engine was great!

Wilwood makes a 4 piston kit for the mustang II front end. I'm using them on my EM and they work great. Did all 4 corners for (drilled and slotted) for not much more than $1500.00.

Gene

What brake pads are you using? If you're using OEM pads, that's your problem. Hawk black pads work well.
Good Luck,

Dan

You are right I am using the stock brake pads with the GM Metric front brakes. At the meet this weekend I had Scott Stephens (the track owner and former GT racer) drive my car and make suggestions as to what I needed to improve my performance and safety. After about 15 minutes on the track his suggestions were to relocate my brake pedal to the right for easier heal toe braking and to upgrade my brakes to reduce fade and stopping. He thought my handling and power was very good.

My brake pedal fix is a simple one. He suggested removing my straight vertical pedal with a "Z" pedal to move it over a couple of inches toward my gas pedal. However, when I move the brake pedal I will also move my clutch pedal to the right for easier use.

Gene, I just was looking at the Wilwood brakes in the summitt catalogue but I didn't see any drilled and slotted rotors, do you know the part numbers you used?

Thanks,


Clois

Clois,

Go to Wilwoods web site and you will find other distributors. I am working with Precision, (OR) and so far found them to be reasonably knowledgeable. The Mustang 11 setup, (fronts only) 12.19" Dia. slotted and drilled with 4 piston Dynalite calipers are about $750.00. The base kit is same price as Summit, $612.00. I have not yet ordered from them, as I am still designing my plumbing requirements, so cannot vouch for their busisness ethics.

BTW, 12.19" Rotors require min 16" wheels. If you have 17" wheels you could move up to the 6 piston, 13" rotors.
Steve

Before you dive into the major modifications you may want to try the Porterfield R4-S Carbon Kevlar pads.

Anyway, I have the Outlaw 4 piston (basically a Wilwood) setup. All you need is the bracket and caliper. The fronts are really the most important and you may not need to change the rears. Are you running two master cyl's? If so, you will probably have to change the master cyl for the fronts.

No matter which way you go, use the Porterfield R4-S pads.

Roscoe

Roscoe,
What model Outlaws are you using front and rear? I have 2000's on front and GM metric single piston on rear. I am not happy with this setup and plan on putting 3000's on front and moving 2000's to rear. I am using Wilwood .810 rotors all around and think part of problem is that GM metrics are made for 1" rotors. I may need pad spacers to make up difference.
My builder just sent me a pair of US Brake oversize GM metrics to try along with Wilwood "Tan pads" before I give up and tear everything apart. The idea of changing caliper brackets does NOT appeal to me because I don't know how to weld so if I go the route of complete changeover I will probably bring car to HRE shop and have Bill do it.

Tom S.

Clois,

The Wilwood 'Heavy Duty Front Brake Kit' for the Mustang II is 140-2129-B. The slotted/drilled rotors are a special order from Summit. The Wilwood instructions say to add a 'D' to the end of the kit number to specify drilled (no mention of slotted).

Since Wilwood is local to me, I actually bought the non-drilled/non-slotted kit from Summit and then went directly to Wilwood and exchanged them for drilled/slotted rotors. Wilwood charged me full SRP for the upgrade so this actually cost me a bit more than if I would have special ordered them form Summit. At the time, I needed them asap so it was worth it to me.

Here's an exploded diagram of the Mustang II kit. BTW, this is a 'bolt-on' kit with no welding needed and, except for the spindle nut & washer, it includes everything you see in the diagram (even the hub).

http://www.wilwood.com/products/kits/hdfbk/hdfbkdwg.gif

Hope this helps.

Gene

Tom,
I've got 2000's on the front with 11" Granada vented rotors. The rears are all 11" Explorer rotors and calipers.
Roscoe

Clois, are you trying to stay in the 11" arena?

12 or 13s will allow more surface area and a greater coefficient of friction. They will, however restrick your rim and tire size.

I do not think you can put 15" wheel on a 13" brake system.

BTW, drilling is primarily used to vent gasses emitted by the pads, it is not a coefficient improver. It will improve the pads performance.

If you are going to increase tires/wheels, the 13" with draft venting to keep them cool. drilled and vented will improve the stopping ability of the brakes.

If the car is too light, the car will just skid. Tires and contact area rule when the brake system is no longer a factor.

Hope this helps.

Roscoe,

I am running a basic stock factory master cylinder set up. One master cylinder with a proportioning valve that I removed and replaced with a brass "T". I am running 4 wheel discs' with the 11" GM metric fronts and Mark VII Lincoln rear disc brakes.

Are the Porterfield R4-S pads available only at speed shops?

Clois

Porterfied are available from Porterfield.

http://www.porterfield-brakes.com/

Roscoe

Roscoe,

Just ordered a set of Kevlar RS-4 pads from Porterfied in California, $79.00. They should be here in a couple of days.

Thanks for the advise.

Clois

Clois

I do not remember if you are running a stock style master cylinder or a double master cylinder system with a balance bar between them.
If you are using the stock style master cylinder. You can run into a problem of not using the rear brakes enough. Say you use the complete stock brake system of a donor car. The english roadster style kits have the motor set back lots farther than most stock cars so your percentage of total vehicle weight has been changed with a higher rear weight percent than the donor vehicle had. Meaning that the front brakes will be easier to lock up and the rear brakes harder to lock up. Meaning your front brakes are getting way to much pressure and your rear brakes not enough pressure.

To cure this problem and to use your rear brakes to their full potential you need to add brake line pressure to the rear and take some away from the front at the same time and the only way to do this is with the double master cylinder system with the balance bar between them. Other wise the more you improve the front brakes the less you are using the rear brakes.

You want the front brakes to lock up slightly before the rear so adjust your balance bar so the rear brakes lock up first then adjust back just enough that the fronts lock up first this way you know you are using your rear brakes to there full potential and not over working your front brakes. Be sure not to have much fuel load on when doing this because if you do this with a full fuel load when the tank is almost empty the rear might lock up first. Unless you have a remote adjusting knob so you can adjust the brake bias as you are driving.


Roger

Feel like spending a bunch of money?
 

Lets start at the begining.

Lots of ways to modify the peddle or just move the whole assembly. Just make it so sturdy that no matter how hard you press it does not deflect in any way. Then make it a little stronger!

Your 'test' driver mentioned better stopping and less fade.

Better stopping. Can you lock all four wheels? If so, maybe he was talking about feel.

If can not lock all four, you need more brake torque. Do you drive this car on the street as well? Larger rotors or higher coeficient of friction pads.

With a single master cylinder put a adjustable proportioning valve back on the car so that you can adjust it from the cockpit. They do more than just cut down the rear pressure by a fixed amount. Rear brakes obviously.

Fade. Pad or fluid? Heck, could be both! Peddle get soft and spongy on you or does it stay high and firm just the car won't stop? The first is fluid the second, pad.

Ideally you would measure your pad and caliper/fluid temps and go from there. If it is the fluid, change to a high temp fluid, like wilwood 570 or better, bleed before EVERY event. If it is pad, determine the operating tempature range and CF of your current pads. Go to higher temp pad. More CF if you don't want to push as hard to stop at the same rate, less CF if you want to harder to stop at the same rate. If you have stock pads, or most of them for that matter and are unable to determine the CF for that pad then look at the edge codes, if they are still there!

If fade is still present, hopefully you tested the tempatures (both) that first time out and you will know where to go from there.

Cross drilled rotors or slotted rotors, aside from reducing mass which can INCREASE the heat of the rotor (talking small amounts here), do the same thing as having slots or groves in your pads. Much cheaper to put some in the pads! If bigger rotors are not needed, otherwise, why not, besides they look cool.

Check you pads for taper (leading edge thinner than the trailing) if that happens, post again, whole 'nother ball of wax!

You can go out and drop a bunch of money and still not be happy! Granted, if you are going to race it a lot, very, very few stock parts will be up to snuff. But you can get after market parts and have them still not do the trick.

Have fun!

Rick

Clois

Rdorman is correct on the things he has mentioned here, except that I do not know about the adjustable proportioning valve that does more than take pressure away from which ever line you but it in depending on how far you turn it. But there may be one out there. Would not be the first thing that I have not heard of. If not and you are using more front brakes than rear this is not the answer.
What we have to remember here is we are dealing with kits that most of them weigh less than 2,400 lbs. And the track time at the event Clois is talking about was only 15 minute sessions. We are not dealing with 3600 lbs stock cars that race for 2-5 hrs. Are SCCA cars that race from 2-24 hrs. I was at the same event as Clois running Granada front rotors with GM metric calipers with stock pads on front and Pontiac Trans Am rotor with GM metric calipers with stock pads on the rear. With absolutely no brake fade and I ran two consecutive sessions. I was also running with the Group one guys (which is the fastest Group at this show) and so it was not that I was not running hard enough to fade my brakes.

Thanks for posting all the info rdorman. That will be very helpful to a lot of people.

Good luck on solving your problem Clois.

Roger

proportioning valve
 

Thanks for the kind words Roger! What works for one person and car combination may not for someone else. A lot can be done on paper but beyond that the only way is testing time.

For those who are looking to work out brake issues, find and buy Fred Puhn's Brake Handbook. None better that I have seen ever written. Even Carroll Smith said he would not right a brake book because he couldn't top Fred's book. Now THAT is saying something.

A proportioning valve, not to be confused with a metering valve, transmits full pressure to the rear brakes up to a certain point, the split point. After that point it reduces the amount of pressure to the rear brakes by a certain, and in the case of an adjustable proportioning valve, adjustable ratio.

The idea being the harder you are on the brakes the more weight transfer you have to the front wheels the less pressure the rear brakes can tolerate with out locking up. For street driven cars this is an advantage over a balance bar assembly that works on the assumption you are always braking at the max.

Rick

rdorman

Thanks for the information on the metering valve. I will have to remember that one in case I ever need it.

Roger

Your welcome!
 

Not to bad for a 'waxer' am i?:LOL:

Proportioning valve. If you get a metering valve with four wheel disc brakes you won't like it!

I can't recommend Fred's book enough. I think it is out of press but you can always find it on places like Amazon. It has every formula you need to design and and play with different components all on paper.

I have concidered whipping up a program based on the formulas. If I ever get some spare time and do so, I will make it available to everyone here at CC. As I recall, the math was within the capacity of the various spreadsheets packages. You could plug your numbers and specifications and out come everything you ever wanted to know (to be verified by testing of course!).

Any one know at what rate steel and aluminum transfers heat to air and fluids? Making the assumption that there is no air flow, or a minimum amount, I could even estimate max brake temperatures. This would be a even bigger leap but it is not hard to convert kenetic energy into temperature rise for the brake mass(the reason bigger brakes, all else being equal, are more resistant to fade)

Rick

I finally got back to read everyones reply on this subject. I am told Freds book is available at one of our older book stores here in Tulsa (Steves Sundry) and I am going to check at noon otherwise I will try Amazon.com. This weekend I had the chance to put some heat in my brakes and try a few things (heal - toe, deep stops and quick stops at speed. I still don't have the feel I want so I am going to try and find Freds book and then determine where I am at and where I need to be. The one thing I am not satisfied with is my pedals positioning, and that should be an easy fix.

Roger I would like to drop by your shop this Friday after lunch or possibly on Saturday if you are going to be open. By the way I got your message last week but was unable to contact you at that time.

Clois