ITR Mustang

[RedMisted]

Early Z brakes didn't work well either until racers had done years of development to reach a tried and true formula.

Really? Seems to me that the Z cars I've seen run basic cooling setups like mine. I thought that these cars were able to handle the heat and loads because of their radically low weight.

[Ron Earp]

Really? Seems to me that the Z cars I've seen run basic cooling setups like mine. I thought that these cars were able to handle the heat and loads because of their radically low weight.

Maybe they do in the Midwest, not sure. In the SE with CMP in he racing mix, fluid, cooling hat, caliper duct, pad selection, and lots of brake maintenance are required to make the solid disc Z brakes work well from 2450 to 2575 lbs (240z to 280z).

All I'm saying is there is a lot more to do before you should worry too much.

[Z3_GoCar]

Another reason to optimize brake cooling: The ITR Mustang is equipped with PBR aluminum front calipers, unlike the earlier SN-95 cars that came with cast iron bits. This is great for weight, but these calipers deform like crazy in the heat, even at the easy tracks. It's normal for me to replace the front calipers (at about $65 a pop)about every other event. If I don't, I'll be wasting box after box of $200 brake pads. So running the larger wheels helps me to minimize an economic issue.

Just my $.02

You should go to a welding supply shop and pick up a temperature crayon. Aluminum looses much of it's strength when heated up to 195*F - 250*F. It's no suprise that you're getting creap if you're getting close to this temperature.

...Also, you could add a water spray system to keep your calipers cooler too... It'd be a good use for the windshiled washer bottle and pump.

[RedMisted]

...Also, you could add a water spray system to keep your calipers cooler too... It'd be a good use for the windshiled washer bottle and pump.

I have heard of water cooling systems on pro cars, but is such a thing legal in IT? I have never heard of water-cooled brakes on an IT car.
If I know the GCR, if it does not mention something, you can't have it. And I don't recall the IT chapter allowing for water-cooling of much of anything except the engine.

[Ron Earp]

Aluminum looses much of it's strength when heated up to 195*F - 250*F. .

Somehow I don't think that is the case. Pure aluminum melts at over 1200F, most alloys slightly less. Given the fact most modern engines have blocks and heads made out of aluminum and operate at 180F to 250F as standard fare, it doesn't reason that the aluminum would give up much of its strength at that temp. Hell, I suspect the the brakes on the street cars are hitting 180-190F in stop and go traffic. They don't fail there.I can check with a fellow I know who has extensive casting experience with aluminum if interested.

You'll definitely want to use temperature crayons or paint to check temps, or, a pyrometer. Back in the dark days of TR8 brake work we were getting some obscene 475-500F temperatures, bona fide verified with temp probes, on the calipers. Bad things happened to lines,seals, and even tires/wheels when that was going on.

[Jethro]

245/50x15 wow that seems really wide, do you know if the fenders will need to be rolled to clear that. What width rim would be required? 8"?

Thanks for the advice guys.

[Z3_GoCar]

Somehow I don't think that is the case. Pure aluminum melts at over 1200F, most alloys slightly less. Given the fact most modern engines have blocks and heads made out of aluminum and operate at 180F to 250F as standard fare, it doesn't reason that the aluminum would give up much of its strength at that temp. Hell, I suspect the the brakes on the street cars are hitting 180-190F in stop and go traffic. They don't fail there.I can check with a fellow I know who has extensive casting experience with aluminum if interested.

You'll definitely want to use temperature crayons or paint to check temps, or, a pyrometer. Back in the dark days of TR8 brake work we were getting some obscene 475-500F temperatures, bona fide verified with temp probes, on the calipers. Bad things happened to lines,seals, and even tires/wheels when that was going on.

Ron, this is based on something I read about aircraft structures, it's the difference between a Mach 1.5 plane like the Concorde and a Mach 2.0 or more plane. In a motor block they can over design the casting thickness to compensate for the loss of strength. A caliper on the other hand usually doesn't have that much extra space for more material.

[Z3_GoCar]

245/50x15 wow that seems really wide, do you know if the fenders will need to be rolled to clear that. What width rim would be required? 8"?

Thanks for the advice guys.

The 8" rim is a recommended width. I run 245/45's on a 7" rim no problem.

[RedMisted]

Ron, this is based on something I read about aircraft structures, it's the difference between a Mach 1.5 plane like the Concorde and a Mach 2.0 or more plane. In a motor block they can over design the casting thickness to compensate for the loss of strength. A caliper on the other hand usually doesn't have that much extra space for more material.

The brake pad retaining "fingers" on the 11" brake calipers of the '99-'04 Mustang V6 and GT are very thin indeed. I know the torque is a culprit with the caliper splay on our cars, but the heat can't help. Not when the material is so thin. Just check a Mustang caliper against something off, say, a Corvette and anybody will see that Mustang brake systems were not developed with road racing in mind.

Among the latter SN-95 cars, I've always believed that the Cobra (made with larger brakes plus IRS) was meant for road racing, the GT was designed to be a drag racer and the V6 was built for, well, looking cool while getting the groceries...

[billf]

Ron,

Keep me in the loop if you are able to get the information.

Thanks all,

Bill

[Ron Earp]

Ron,

Keep me in the loop if you are able to get the information.

Thanks all,

Bill

Will do, I sent out feelers already

I got your PM too, thanks and I'll respond back.

[Ron Earp]

The brake pad retaining "fingers" on the 11" brake calipers of the '99-'04 Mustang V6 and GT are very thin indeed. I know the torque is a culprit with the caliper splay on our cars, but the heat can't help. Not when the material is so thin.

Hey Chris,

How thick are the fingers on your calipers? I measured mine and they are right at 0.700" on the nose from the outside of the finger to the back of the pad. That is at the "thick" area. You saying the little finger right there on say the middle one is what is flexing?



Also, the backs of these calipers are nicely done. Twin piston with some fairly decent cooling fins cast into them. Those cooling fins will make a great perch for a manifold for brake cooling.

[RedMisted]

All three fingers will flex outward. Not just the middle one.

Rear calipers are terrific. I've had mine on my car for several years of aggressive abuse. No cooling tubes to the rear brakes, and I use Hawk HP-Plus street pads. I change these pads about every 6-7 race weekends, minimum.

[JeffYoung]

Chris how have you observed this? Someone in the car hitting the pedal while you watch?

On the rears, how hard do you use them? Can you lock the rears? Do you have the stock proportioning valve, or an adjustable?

ONe of the tricks to getting a Z car or the TR8 to stop is to make sure you are actually using the drums in the rear, but taking out the stock proportioning valve, putting in an adjustable, and dialing in rear brake.

[RedMisted]

Chris how have you observed this? Someone in the car hitting the pedal while you watch?

On the rears, how hard do you use them? Can you lock the rears? Do you have the stock proportioning valve, or an adjustable?

ONe of the tricks to getting a Z car or the TR8 to stop is to make sure you are actually using the drums in the rear, but taking out the stock proportioning valve, putting in an adjustable, and dialing in rear brake.

The front calipers gradually distort as they are exposed to repeated brake torque and high operating temperatures. I make it a habit to check pad wear after every track event, and eyeball the caliper fingers. When the pads are cock-eyed and the fingers are splayed out, there's no need to measure anything, as you can see the caliper distortion in plain sight.

So the caliper doesn't really flex like a rubber band and then regain original shape. It changes shape permanently. It distorts. Sorry if I had anyone confused on that one--- I was using too loose of an interpretation of "flex"

Car has a stock proportioning valve. I never notice rear lockup. I usually am a moderately gentle braker for the very reason that the Mustang brakes are crap.