Brakes Revisited

[ArizonaBOSS]

Good to know, I never ran the DTC 70's just guessing there. The 01 is harder on the rotors then the new 08, so that is saying a lot. Are you still running the PFC 01 up front?

Yes, I am sticking with the 01/97 combo for the forseeable future.

 

[Jimmy Pribble]

So, speaking of split friction pad compounds and excessive weight transfer...has anyone used higher friction pads on the rear brakes and lower friction on the front? I have (not on a Mustang) and I rather enjoyed the results.

No matter what, the fronts will always be doing most of the work, but with excessive weight transfer to the front, the rears are just along for the ride. If weight transfer can be kept to a minimum (through static weight balance, suspension settings, driving style, and brake balance), the rears do more work and the car is more stable.

Or not. 8) Discuss.

 

[VoodooBoss]

So, speaking of split friction pad compounds and excessive weight transfer...has anyone used higher friction pads on the rear brakes and lower friction on the front? I have (not on a Mustang) and I rather enjoyed the results.

No matter what, the fronts will always be doing most of the work, but with excessive weight transfer to the front, the rears are just along for the ride. If weight transfer can be kept to a minimum (through static weight balance, suspension settings, driving style, and brake balance), the rears do more work and the car is more stable.

Or not. 8) Discuss.

Simple answer? Porsche 911.

 

[Sesshomurai]

So, speaking of split friction pad compounds and excessive weight transfer...has anyone used higher friction pads on the rear brakes and lower friction on the front? I have (not on a Mustang) and I rather enjoyed the results.

No matter what, the fronts will always be doing most of the work, but with excessive weight transfer to the front, the rears are just along for the ride. If weight transfer can be kept to a minimum (through static weight balance, suspension settings, driving style, and brake balance), the rears do more work and the car is more stable.

Or not. 8) Discuss.

I'm actually thinking of running DTC60 in the front and DTC70's in the rear for the reasons you mentioned.

 

[cloud9]

I'm actually thinking of running DTC60 in the front and DTC70's in the rear for the reasons you mentioned.

They don't make a DTC70 for the rear. Front fitment only.

 

[VoodooBoss]

Won't putting more aggressive pads in the rear unbalance the braking more? It's the weight distribution and transfer that effects the braking efficiency. Hence my 911 comment.

 

[Sesshomurai]

They don't make a DTC70 for the rear. Front fitment only.

Good to know. Ill have to review the compounds again and find a set that achieves this.

 

[pufferfish]

a higher compound in the rear does nothing to help and may hurt the situation. the range of pad compounds are not based on grip level. they are based on heat range for a given grip level. mustangs use lower pad compounds in the rear because their heat range is lower than the fronts. this is because they are used less. they are used less because of the suspension allowing all the weight to be thrown forward under braking (which induces the nose dive). the real way to make the rear brakes carry more of the load is to change the suspension to limit the dive.

 

[Jimmy Pribble]

Won't putting more aggressive pads in the rear unbalance the braking more? It's the weight distribution and transfer that effects the braking efficiency. Hence my 911 comment.

Right, so the statically unbalanced 911, transfers it's weight forward during heavy braking, suddenly becoming a beautifully balanced machine that can utilize big brakes (and big tires) at all four corners to slow the car. I'm saying a very nose heavy car with big brakes up front, little brakes out back, and sproingy suspension out of the box gets us this:

Note: photo might not be of a car. Maybe very good slowing/stopping power, but I can promise you that vehicle is unstable. So, I'm debating the idea that a net reduction in braking force up front, COULD mean added stability, which improves driver confidence, slows goofy inputs at corner entries when the car wants to flip-flop, and maybe adds some tire and brake life to the fronts. I'm also saying there are many ways to do this (weight distribution, driving style) and pad compounds are only one (possibly small) part of that. I have done it and liked it, but it was also before I had any way to collect data about my driving. If I can start going to the track more regularly, I'll put it to the test.

 

[Jimmy Pribble]

a higher compound in the rear does nothing to help and may hurt the situation. the range of pad compounds are not based on grip level. they are based on heat range for a given grip level. mustangs use lower pad compounds in the rear because their heat range is lower than the fronts. this is because they are used less. they are used less because of the suspension allowing all the weight to be thrown forward under braking (which induces the nose dive). the real way to make the rear brakes carry more of the load is to change the suspension to limit the dive.

Thanks, Puffer. Pads are sold with friction coefficients stated on them. If there are different friction levels, does that not mean that more weight is transfered when using high coefficient pads vs. Sears Roadhandler pads? It's just another factor of total brake force, which includes pedal pressure, etc. Low brake force (driving mom to church) has less weight transfer than high brake force (at the track). Changing any aspect of total brake force should change total weight transfer. Right? I'm totally open to misunderstanding something.

Also, I totally agree that there are better ways to address this desired balance.

 

[pufferfish]

Thanks, Puffer. Pads are sold with friction coefficients stated on them. If there are different friction levels, does that not mean that more weight is transfered when using high coefficient pads vs. Sears Roadhandler pads? It's just another factor of total brake force, which includes pedal pressure, etc. Low brake force (driving mom to church) has less weight transfer than high brake force (at the track). Changing any aspect of total brake force should change total weight transfer. Right? I'm totally open to misunderstanding something.

Also, I totally agree that there are better ways to address this desired balance.

ok, i hope i can convey a very complicated answer in a way that is easily understood.

pad compounds: some brands may have CF(coefficient of friction) listed in their compound descriptions, but the numbers are for a specific heat range. if your pads are out of the range, they will have less CF than listed. pads should be chosen for the heat range.

brake dive: brakes will not change this. from a one dimensional perspecitve, it makes sense that it would, but from a dynamic prespective, there are too many other factors at work to allow that to happen. remember, tires stop a car, not brakes. if the tires are unloaded, does it matter if you have more brake potential?

understanding the dive is the really complicated bit and it dictates braking potential (or the level of grip the tires offer to stop the car) on each axle. understand this and you understand why no companies offer 6 pot 15" brakes for mustangs rear axles. do the inverse with the less front brake and you end up with less overall braking. i have been trying to come up with a simple way to illustrate what happens under braking, but i have nothing. let me think about it and hopefully come back with something that makes sense.

 

[Grant 302]

So, speaking of split friction pad compounds and excessive weight transfer...has anyone used higher friction pads on the rear brakes and lower friction on the front? I have (not on a Mustang) and I rather enjoyed the results.

No matter what, the fronts will always be doing most of the work, but with excessive weight transfer to the front, the rears are just along for the ride. If weight transfer can be kept to a minimum (through static weight balance, suspension settings, driving style, and brake balance), the rears do more work and the car is more stable.

Or not. 8) Discuss.

Haven't tried it but spent a lot of time thinking about it. The brake bias is set for the stock ride heights which, as we all know, have very high brake dive. So once this is 'fixed' with lower ride heights, or altered front suspension with anti-dive properties...it seems to me that a higher rear brake bias would be very practical and beneficial. And then to see the recent win with the larger rear rotors...

I've considered the rear Roush kit for larger rotors before, but I worry about the sole source nature of the replacement dba rotors.

Changing to a more aggressive rear pad concerns me a bit for lack of cooling ducts for the rear. And that's a problem that could be solved with a little pioneering...but that's more of a project for a dedicated race car.

But maybe a practical solution would be a high early-bite pad in the rear...

And if you try it, I suggest using the lower LCA bracket hole for the highest brake-squat for the rear.

 

[VoodooBoss]

Now that the 2013+ GT500 has 15" rotors and six piston calipers up front and larger rotors for the rear there should be more aftermarket options available.

 

[Teamsketch]

I am interested to hear your review of the 06 and the wear compared to what you were running. If you had run the 01's it would be a better review for me but still like to hear how they compare to the Hawk's. I have not talked with anyone that has run them.

Give the Powerslots a try, I may experiment with other front rotors over time but unless someone else can show me rears rotors that work better and last longer for the money then the Powerslots, they will be the only rear rotors I will buy for the Boss.

I'll report back what I find on the P06. So far I have 15+ days on the current rotors and 'they look great' according to my mechanic so I probably won't have any good data on rotor wear. Apparently that 600+ lbs of additional weight in the boss makes a big difference when it comes to eating rotors and pads.

 

[Teamsketch]

Here are a few pictures of my current front brake rotors. The first is from my E36 M3 track car. This is the type of wear I am used to seeing. It is hard to tell from the pictures but the cracks on the surface of the rotor are very fine, even though there are a ton of them. The next three are of the Boss DBA5000 rotors. On the Boss there are only cracks around the holes but they are much deeper. Is this the type of wear other people are seeing?

Thanks in advance.


First M3 Rotors:


Boss Rotors:

 

[Sesshomurai]

ok, i hope i can convey a very complicated answer in a way that is easily understood.

Yeah, that makes a lot of sense. Appreciate the info.

I guess since I already have a very stiff suspension with little nose dive, I probably will reconsider experimenting with compounds on the rear.
I only got the idea from some people at the track myself but was curious if it would contribute to balance or front pad wear differently.

 

[ArizonaBOSS]

Those M3 rotors are normal, lots of face-checking/cracking...it is unavoidable. The drilled rotors...it's tough to say from those photos if those are only surface cracks or not, but I don't like that there's one at each drill location.

Always avoid drilled rotors, IMO.

 

[Jimmy Pribble]

Always avoid drilled rotors, IMO.

I agree. However, now that I think about it, has anyone ever considered split rotor styles? Heavy OEM blanks up front for max thermal capacity, drilled rotors out back for light weight, since they aren't doing anything anyway?

 

[Teamsketch]

Those M3 rotors are normal, lots of face-checking/cracking...it is unavoidable.

Thanks for the feedback. I have a great shop that works on the M3 here in Seattle and that's what they have confirmed over the years that the surface cracking is OK and like you said unavoidable.

The drilled rotors...it's tough to say from those photos if those are only surface cracks or not, but I don't like that there's one at each drill location.

Always avoid drilled rotors, IMO.

The cracks at every hole concerned me as well. And yes I completely agree, for now on I am officially going to avoid drillled rotors like the plague.

 

[Jimmy Pribble]

I agree. However, now that I think about it, has anyone ever considered split rotor styles? Heavy OEM blanks up front for max thermal capacity, drilled rotors out back for light weight, since they aren't doing anything anyway?

Relax. Them's just jokes.