Heavily front brake biased so why....

[99COBRA2881]

run a less aggressive compound on the rear of a mustang? Ive always done it this way because I was told to from the very first set of track pads I bought, but now I'm questioning it.

Why let the back brakes that don't do much to begin with do even less? Im about to fab some brake cooling ducts for the rear and go to a more aggresive pad. I'm almost sure stopping distance and overall feel of the car under braking would improve, nose dive under hard braking may very well lessen too.

A brake proportioning valve is on my list for this winter but for now I like to overthink things to the point of confusion.

Any thoughts? Crack open a cold one and discuss. :beer:

 

[racebronco2]

I too have wondered if i should add a proportioning valve to the front but it would be better to just get a more agreesive rear pad. Sure would be better to have more rear bite. I have never had the rear brakes go into anti-loc even when the fronts were into anti-loc for several seconds when i tried to move my braking zone up too far.

 

[gcassidy]

A few years ago I moved from Hawk Blues to Hawk DTC-70s up front. But I was still running HP+ on the rear, thinking the same as you mention. Then I went to a brake class at an event put on by Jay Andrews of Andrews Racing (brake retailer), and he said the same as Anthony. That a Mustang does better with a more aggressive pad in the rear even though you don't think the rear is doing much.

So I went to Hawk's DTC-60 in the rear, to compliment the 70 up front, and couldn't believe the difference. I could actually feel a little better stability into my heaviest braking zones, and was able to brake a touch deeper and have a more controlled turn-in because of that. Now my rear pads wear out almost as fast as my front, which didn't used to happen.

It's more work when I change the car back into street mode, but I've gotten almost as fast at changing the rears as the fronts now, which is about 30 minutes all around from flat on the floor.

 

[Sirl]

I just went along with the crowd a few years ago,
DTC 70's up front, and 60's in the rear.
Seems to work well. Most of the guys I know run that combination.

 

[Force4.6]

When I was using Carbotechs a fellow mustang driver told me to try using more aggressive pads in the rear to improve turn in and nose dive. I switched to XP12s in front and XP16s for the rear which provided a noticeable improvement in both those areas. Really made a big difference with reducing the nose dive of the 03/04 Cobras.

 

[was here]

Reason why you want more bias to the front is so you don't have a condition where the rear brakes are doing more of the work. When the rear brakes slow the car down more than the front it sets up a possibility of the rear coming around. Most guys you see will have a one step up in pad in the front. If you have hp+ in front then go with hp in the rear and so on.

 

[99COBRA2881]

Yeah I understand the basic reasoning but I really doubt that the tiny stock cobra rear calipers are going to outbrake the front 4 piston brembos even with a more aggressive pad. Preventing rear lockup with a more aggressive pad might be a problem but I see that being where a proportioning valve would be the next needed part.

This is just another step in dialing in an already well setup race car.

 

[David Hester]

On the A/Sedan car I used DTC 70's front (Liked the old HT's better, but my car was 3200 lb with me in it- sometimes 3190), I also had a bias knob...you bias the rears BTW, and brake pressure gauges. Too much rear will make the rear come around. I usually ended up with 900 psi front and 620 or so rear.
The thing is, with the rears not doing as much work..braking does move weight to the fronts.. they never get hot enough to take advantage of using just as agressive a pad as the front. Hence the general rule of -1...or more aggressive pad on the rear. Make sense?

 

[wheelhopper]

Reason why you want more bias to the front is so you don't have a condition where the rear brakes are doing more of the work. When the rear brakes slow the car down more than the front it sets up a possibility of the rear coming around. Most guys you see will have a one step up in pad in the front. If you have hp+ in front then go with hp in the rear and so on.

Isn't that backwards. If the rear is braking better than the front why would the back end come around. The back end should only come around if it is going faster than the front.

I installed a brake bias adjuster on my '90 GT, I am running a factory '03 Cobra brake system on the car. I have the EBC Blues on the rear. When I had EBC Blues on the front I would have the rear bias set to about 75% full open. When I switched to DTC60s in the front, and forgot to reset the bias, it made for some scary tail wagging situations. I now have the bias set full open to the rear my car brakes awesome now.

I do have a friend that uses the DTC 70s front and rear. He seems very happy with it. Maybe he'll chime in here and give us some more detailed input. But as my car makes further progession to track only, I will probably install the DTC 60s in the rear as well.

 

[Force4.6]

I am just guessing but more bias towards the rear with a more aggressive pad would probably increase the probabilty of lockup which would cause the rear slide to out.

 

[gcassidy]

Doug, Rick's right. The reason you went full open with your rear bias when you put 70's up front is because they're EBC Blues in back. When you forgot and had it closed some, you were doing more braking with the front, and the car was probably hunting with the fronts doing most of the work. Once you put more bias to the rear, it settled it down, the rear was doing more work, the front wasn't hunting, and the car was more stable. That's just what happened to me when I put the 60's in back in place of the HP+. You may not notice much difference between the 60's and the Blues in the rear, and we got lots of Blues to burn through. :lol1:
The reason Chris can run 70s front and rear is his car weighs even more than mine.

 

[wheelhopper]

That's what I said.

 

[LargeOrangeFont]

Yeah I understand the basic reasoning but I really doubt that the tiny stock cobra rear calipers are going to outbrake the front 4 piston brembos even with a more aggressive pad. Preventing rear lockup with a more aggressive pad might be a problem but I see that being where a proportioning valve would be the next needed part.

This is just another step in dialing in an already well setup race car.

You could get the rears to lock up before the fronts due to weight transfer under braking, which is probably how the practice of using a less agressive pad in the rear got started.

I generally use the same or a more agressive pad in the rear and use the adjustable prop valve in the rear to dial out rear brake as needed.

 

[LargeOrangeFont]

I am just guessing but more bias towards the rear with a more aggressive pad would probably increase the probabilty of lockup which would cause the rear slide to out.

The car will feel beter and better as you add more rear brake and approach rear lockup. That is why you use the prop valve on the rear to dial out a bit of braking to keep the rears from locking.

 

[gcassidy]

That's what I said.

You're assuming I actually read your post. oke:

 

[ac427cobra]

This is precisely the reason why I developed the SN-95 13" rear brake conversion kit.

My 2000 Cobra R with the OEM 13" Brembo four pots on the front did approximately 70% of the braking on the car. Initially I ran Hawk Blue pads front and rear. Rear pads were lasting me 2-3 times as long as the front pads.

As I got more comfortable in the car and got it up to speed, I felt I needed a front brake upgrade. After much research I decided on the Brembo SN-95 14" front brakes.

After the front brake upgrade, the rear pads were then lasting 4-5 times as long as front pads and knew the rear brakes were no longer holding up their end of the bargain. I estimate the rear brakes were down to doing approximately 15% of the braking at that point and I could hardly feel any braking coming from the rear.

So I decided to come up with a solution. I knew a lot of people like myself that wanted to keep the OEM rear caliper because they probably have a stock of brake pads and the E-brake feature was something many people didn't want to give up. I liked having the E-brake for loading the car in the hauler. By increasing the leverage point on the rotor, you'll increase brake torque proportionately. The rear rotor diameter went from 11.66" to 12.9" There's really no need for a brake bias adjuster, brake bias can easily be adjusted with front and rear pad compounds.

I also wanted to reduce rotating mass in the drivetrain so I wanted to make sure the rotor I designed for the kit weighed LESS than the OEM rotor.

Weight of OEM rotor:

Weight of 13" conversion rotor:

Here is what the 13" rear brake conversion kit looks like:

and installed on the car:

The kit, FT 7000A sells for $749 and if you take advantage of our order form and send a check in with your order, you can save 5% off the purchase price. More info can be found on our SN-95 brake page:

FTBR Brake Parts

and our order page:

Full Tilt Boogie Racing Shopping Cart

I'll be glad to answer any questions anyone may have.

:thumbsup::coolman::beer:

 

[wheelhopper]

Look at those small calipers on that big rotor. Next project, convert a Cobra PBR 2 piston caliper to work on the rear.

 

[ac427cobra]

Look at those small calipers on that big rotor.

It may 'look' small to the untrained eye, but it's the perfect amount of brake torque! ;-) oke: This mod shaved more than a second a lap at Road America for me. :-D

Next project, convert a Cobra PBR 2 piston caliper to work on the rear.

That would be adding FAAAR too much brake torque. Think about it, front brakes on the rear of a car!??! You will then for sure be installing a brake bias adjuster to take out most of that excessive brake bias out of the rear. :read: Oh, and let's not forget to mention the horsepower killing addition of rotating mass (and unsprung weight) with a 13" diameter x 1.100" thick rotor!!! The rotors for the PBR calipers weigh over 19# in stock form. :idea:

And losing your e-brake in the process. Not sure how many people would find that attractive?!?? :dw:

But hey, if you have those calipers hanging around the shop and the curiosity factor is getting to you, put them on your car and get back to us with the results!! op:

 

[99COBRA2881]

I welded in a nice delete panel where the parking brake used to be.

 

[wheelhopper]

I have been running with no parking brake for over a year. I thought I was really going to miss it, but I don't. When I swapped to the IRS the factory brake cable was about 2" short.

After all this info, which makes sense and I never really bothered thinking about, I am going to order some better pads for the rear and see what happens.