ITR Mustang

[RedMisted]

Bill:

What happens with the PBR calipers is that they splay out, so that the brake pads begin to wear cock-eyed. This problem is very commonplace in the left front, and occasionally an issue on the other side unless racing at tracks with an abundance of left turns.

It's also common for the piston sleeves to burn up. No, I've never had fluid boil to the point where I was literally hitting the floor. (Sorry if I exaggerated a bit.) But I've had to throw heel-and-toe downshifting out the window a few times because the pivot point would change enough to compromise throttle-blipping.

The solution? Get as much air as you can to the rotors. Cut off the dust shields, mount the bigger wheels and run tubes no smaller than 3" in diameter. Use super hi-temp fluids and remember to bleed the fronts halfway through an event if racing at a brake-killer like Beaverun.

Pads can make a difference with cooling. Unfortunately, I only have experience with Hawk Blues. I'm told that other companies, such as Carbotech (which I will be trying in '10), may have superior offerings.

Brakes are the big operational weakness with these cars. I learned alot this past year about the need to baby my brakes, and to plan my race strategies accordingly.

And although the bigger wheels hurt weight, you can mount wider rubber. A tradeoff, just like anything in racing.

Hope this helps.

Chris,

I'm interested in the brake problems you experienced with the aluminum calipers. Did you see caliper deformation? Brake pads welded to the pistons? Was there evidence of boiled fluid (pedal to the floor, etc)? Did the seals turn to carbon? (I'm trying to think of all the brake-related problems we had with the 2.3 Liter ITB car.)

Thanks for the input about the brakes. Your answers will make me reconsider the choices I have.

Jethro is, of course, planning on ITS, which has mandated smaller wheel sizes, and lower weight. Also, supposedly, the engine has somewhat lower power potential in typical IT tune. All of which, may lower his threshhold of brake problems.

Thanks,

Bill

[Ron Earp]

What happens with the PBR calipers is that they splay out, so that the brake pads begin to wear cock-eyed. This problem is very commonplace in the left front, and occasionally an issue on the other side unless racing at tracks with an abundance of left turns.

It's also common for the piston sleeves to burn up. No, I've never had fluid boil to the point where I was literally hitting the floor. (Sorry if I exaggerated a bit.) But I've had to throw heel-and-toe downshifting out the window a few times because the pivot point would change enough to compromise throttle-blipping.

Very interesting discussion.

I'm not sure I'm following everything though. You mentioned that you have heat problems and that the heat is deforming the calipers, but, then you say that you're not boiling the fluid. I'm assuming what you're experiencing is some fatigue and thermally induced stress relief, but, you'd need to get some pretty serious heat into it to do that. And that would boil your fluid.

What you've described with your pedal feel is pretty much SOP for Z cars and many other ITS cars. And, it can typically be fixed with a serious analysis of brake ducting and cooling. You might have to switch to a new piston seal of that is having problems but the dust shield on the outside, well, those are going to get hard crumbly and fall away.

What sort of rotor and caliper cooling do you have now? I assume you're using a air hat on the rotor that feeds air to both sides of the rotor and you've got a similar device mounted on the caliper itself. Since these are slotted rotors you might want to feed air into the center hub and skip the rotor hat.

Anyhow, you should be able to make these brakes work and not experience heat problems. I've collected a lot of brake cooling setups over the years. Once I pick this Mustang up I'll have a look at the front area and might be able to offer some suggestions.

[RedMisted]

Ron:

Serious, the combination of brake torque plus whatever heat does cause these calipers to deform. They are soft, crappy pieces. Lightweight as heck, but still soft and crappy. They splay out where the outer pad retaining "fingers" are located. Once this happens, the pads take a serious beating in localized areas.

My cooling set-up is pretty basic: run a 3" tube to the inside of each rotor. I bought some brake spindle connections from Quantum Motorsports that allow me to run that size tube to the rotor, aimed not at the rotor center but just above. Perhaps not optimal, but after experiencing the limitations of the Mustang's brakes at Beaverun and Gingerman for the first time this past year, I'm thinking that some special pieces will need to be fabbed to get the air to a better location. And while using larger tubes...And more tubes... BTW, My intakes use the faux foglight locations to the max.

You mentioned something about slotted rotors. I assume you meant vented unless I'm mistaken and the GCR now allows the use of true aftermarket racing rotors with surface cooling slots. The Mustang OE rotors are simple bald-faced bits, but vented.

Yeah, when you have any ideas on this topic, I'd be eager to hear them!

Happy holidays to all!

[Ron Earp]

You mentioned something about slotted rotors. I assume you meant vented unless I'm mistaken and the GCR now allows the use of true aftermarket racing rotors with surface cooling slots. The Mustang OE rotors are simple bald-faced bits, but vented.

Yeah, when you have any ideas on this topic, I'd be eager to hear them!

Happy holidays to all!

Yep, I meant vented.

So there is no duct to the caliper itself? If not you'll need to correct that.

I'm actually concerned that the caliper lacks the mechanical strength to handle repetitive braking forces that may not be heat related at all. But, with a modern OEM design and all the liability a manufacturer is burdened with I find that a bit hard to believe. I bet it'll be possible to figure out a solution for the problem.

[Ron Earp]

Hey Chris,

What year is your car? I'll check around and see if there happen to be some casting differences or running part order changes. I know the books show the same part number for all years, but if you've messed with Fords any you'll often times find changes that didn't result in a part number of suffix change.

Ron

[Marcus Miller]

Ron- talk to the T1 corvette guys, they have this problem all the time on the C5, which are similar calipers, no?

[Ron Earp]

Ron- talk to the T1 corvette guys, they have this problem all the time on the C5, which are similar calipers, no?

As Chris mentioned they are PBR calipers and I think a similar caliper was used on the fronts of C4s if I'm not mistaken.

I think this is the OEM sales sheet on those:

http://www.pbr.com.au/downloads/broc...r_Brochure.pdf

I imagine some discussion with PBR directly would result in some insight to the problem if it is indeed non-cooling related. I know that these same calipers are used on the front of Australian Roaring Forties GT40 replicas of which a few are used in sanctioned racing there. I know one of the guys really well and I don't recall them indicating they had caliper flex or failures, but I'll quiz him more directly about that.

[RedMisted]

The Quantum pieces only have a connection for a single tube to the rotor. So nothing for the caliper. I've known that it's critical to cool the binders as well. But let me ask, how might this be done given space limitations inside the wheel? I'm not that well-versed in brake cooling setups.

You raise an interesting point, that the real problem with caliper splay may be more a function of material weakness under load, and not really a question of heat.

My car was built in May, 1999. I put the month because there apparently are some differences, I don't know what, between early '99s and Mustangs manufactured later that year.

Yep, I meant vented.

So there is no duct to the caliper itself? If not you'll need to correct that.

I'm actually concerned that the caliper lacks the mechanical strength to handle repetitive braking forces that may not be heat related at all. But, with a modern OEM design and all the liability a manufacturer is burdened with I find that a bit hard to believe. I bet it'll be possible to figure out a solution for the problem.

[Ron Earp]

I've known that it's critical to cool the binders as well. But let me ask, how might this be done given space limitations inside the wheel? I'm not that well-versed in brake cooling setups.

Probably need to fabricate a manifold that will bolt onto the caliper and get air into the pad area as well as the outside housing. I made some for Jeff's TR8 and have seen others of similar design for the Z. Think about making it from sheet metal, or fiberglass as Mike M did for the Z, and having a 3" duct on the backside for the hose. The part that wraps around the housing will need to be thin if you're using stock wheels.

One of the big reasons that folks got away from the smaller wheels on the Z was to get more brake cooling. Just having the wheel further away from the caliper assembly helped with airflow and also helps with packaging of cooling hardware. If you're sticking with the 15" wheels it may not be possible to get enough cooling in there and that might be part of the problem.

You raise an interesting point, that the real problem with caliper splay may be more a function of material weakness under load, and not really a question of heat.

My car was built in May, 1999. I put the month because there apparently are some differences, I don't know what, between early '99s and Mustangs manufactured later that year.

And PBR might be able to help here as they should definitely have the data on what sorts of loads the caliper can handle. Something tells me that for a company like PBR that supplies damn near about everyone that the caliper itself can handle the load. And if it didn't at some point it time it was re-designed.

And lastly, this might not mean anything but AutoZone lists two different part numbers for the driver's side front caliper depending on the year:

1999 is this one and had a picture
Part Number:
C466

2004 is this one and didn't have a picture
Part Number:
C898

For the real story you'd have to go to Ford but in theory the 99-04 cars are the same car.

[RedMisted]

Ron:

Thanks for checking on the calipers. The two part numbers at AutoZone probably doesn't mean a thing.

If the calipers eventually show themselves to be truly substandard from a material/design standpoint, would we have any recourse with the powers that be to run anything else? For example, 13" Mustang Cobra brakes? (Geez, I wish!) Sure would help with durability (and heat).

Interestingly, I hear that the A Sedan Mustangs were given allowances with their brakes because of severe overheating. Of course, those are much heavier cars travelling at much higher speeds.

Probably need to fabricate a manifold that will bolt onto the caliper and get air into the pad area as well as the outside housing. I made some for Jeff's TR8 and have seen others of similar design for the Z. Think about making it from sheet metal, or fiberglass as Mike M did for the Z, and having a 3" duct on the backside for the hose. The part that wraps around the housing will need to be thin if you're using stock wheels.

One of the big reasons that folks got away from the smaller wheels on the Z was to get more brake cooling. Just having the wheel further away from the caliper assembly helped with airflow and also helps with packaging of cooling hardware. If you're sticking with the 15" wheels it may not be possible to get enough cooling in there and that might be part of the problem.



And PBR might be able to help here as they should definitely have the data on what sorts of loads the caliper can handle. Something tells me that for a company like PBR that supplies damn near about everyone that the caliper itself can handle the load. And if it didn't at some point it time it was re-designed.

And lastly, this might not mean anything but AutoZone lists two different part numbers for the driver's side front caliper depending on the year:

1999 is this one and had a picture
Part Number:
C466

2004 is this one and didn't have a picture
Part Number:
C898

For the real story you'd have to go to Ford but in theory the 99-04 cars are the same car.