Wheels vs front caliper size, any options?

[lifespeed]

After 9,300 miles it is time for new brakes again. The rotors were resurfaced and Porterfield R4S pads sanded at 5,000 miles due to pulsing. They went another 4,300 miles pretty smoothly before completely wearing through the front pads.

So two brake jobs in 10K miles. That is a LOT of maintenance, which is my second biggest complaint. The first is pulsing which when bad enough kills the braking performance and is annoying to boot.

Here is what they looked like in the front. You can see the pads are completely gone, although not metal-to-metal. The rotor surface looks slightly pitted, as if it has been abused. The pad surfaces had small chunks missing out of them. But they have only been used on the street with occasional hard stops. Not enough to get it real hot.

These R4S were 900 deg F pads, while the BP10 were 800 degree pads. A modest improvement in the pad transfer or pulsing was observed with the switch to higher temp pads. At least a step in the right direction but not good enough.


Front R4S - pads are completely gone



Front R4S rotor surface showing the appearance of hard use , pitting and heat. But the use was normal driving . . .



Front R4S - another view of pad wear



The rear R4S were much better as can be seen by the rotor surface. The pad switch from BP10 to R4S in the rear pretty much eliminated all pad transfer and pulsing issues, and the wear is very good. Probably would go 35K miles. To me this is indication the higher temperature pads are a step in the right direction. But 800F to 900F in the front wasn't enough.


Rear rotor with R4S pads doesn't look so hammered


Rear pads are in much better shape

[lifespeed]

As evidence seems to point to higher temperature pads improving the pulsing problem, I ordered a set of Carbotech XP8 pads. This pad compound seems to straddle the fence between street and race compounds, although is officially listed as a "race" compound for dust and noise reasons. With a temperature range of 200F to 1275F, they are safe to drive on the street, yet have a significant temperature margin over the previous R4S 900F pads.

So far I have been very happy with the performance of these pads. Initial bite is outstanding! They have far more grip than either the BP10 or R4S, which required significant pedal effort to haul the car down from speed. Further, both of these pad compounds would increase their coefficient of friction as the pads heated. So one would have to keep track of the rotor temperature in order to know how much pedal pressure to apply. It wasn't difficult, but definitely not consistent.

The XP8 pads bite hard cold, but don't dramatically increase their CF as they heat up. Which is fine as they already have plenty of grip. This makes them a much better-behaved and predictable pad in my view. So far I am very impressed with their performance and like them a lot. However, I have only driven them a few days so have no long term results yet. I am hoping the pulsing problem (most high-maintenance and irritating) will be cured with these pads. The short service life of the front brake pads in this FNSL6R setup is also problematic, but I don't know that I will see an improvement here. If not, a larger caliper, thicker pad and friendly wheel may still be required to get to an acceptable brake service interval. I will report back on my long term experience with this pad compound one way or the other.

These pads do have some downsides:
1) lots of brake dust, although the claim it is non-corrosive.

2) They have made some noise on occasion, although once thoroughly bedded this appeared to go away. The jury is still out on this, although clearly they have potential to be noisy. I did grease the back of the pads and caliper sliding surfaces.

3) I did start to get some pulsing, although that may be too strong of a word. More like alternating strong/stronger braking forces. I suspect the required smooth pad transfer layer had worn off in spots from mild low-temp street use. I re-bedded the pads with a couple hard stops and they are completely smooth again as I roll to a stop. I will note this procedure was completely ineffective at correcting pulsing problems with BP10 or R4S, and was not likely the same issue although it may have felt similar.

Edit: Here is a picture after break in and some street miles. The pads are clearly aggressive. They felt good and stopped well, but gave up the ghost after only 4K miles. Yikes! Don't use racing pads on the street.

[lifespeed]

After burning up the pads and rotors with a desperate try at Carbotech XP8 racing brake pads (an excellent choice for track use I'm sure, but not street) I slapped a set of inexpensive Hawk HPS on without even resurfacing the rotors. There wasn't enough meat left to machine them anyway.I had to keep the car on the road until the Aero6 kit was delivered and I had modified the correct aftermarket wheels to fit the front at 50mm offset, plus the additional consideration of a new Ford 9" axle being built for the rear.

Surprisingly, the Hawk HPS pads lasted the longest of any pad in this over-stressed combination of FNSL6R caliper and 14" X 1.1" rotor. I got 14K miles out of them and they probably would have gone a couple thousand more. So, if you are already an owner of the FNSL6R kit this may be the best way to mitigate the wear problem. Pedal feel and stopping power were not quite as powerful as the other pads, but the 4K to 9K mile maintenance intervals were ridiculous. Even with the Hawk pads the FNSL6R brakes are far more powerful than stockers.

Here is a quick phone snapshot of the new Aero 6 setup and widened American Racing AR883 wheels. This is after 2,200 miles of use including the rainy season dirt coating. Although the camera phone shot isn't quite as detailed, I can state with confidence the wear rate is dramatically reduced. The rotor surface is close to mirror smooth, and is clearly much happier. There is no "lip" from wear on the rotor surface where the pads stop making contact towards the inner radius.

Despite the rotor diameter remaining the same, and the basic physics proving that increased pad area doesn't increase the coefficient of friction one must remember these are just fundamental laws that don't take into account the realities of over stressed materials changing properties.

The result is these brakes are significantly more powerful and easily modulated than the FNSL6R kit. Which was a lot more powerful than stock. During some brake bedding activities I applied the brakes as hard as I am likely ever to do, normal street driving just doesn't call for that behavior. The force was so great I thought my eyeballs were going to hit my sunglasses.

I noticed the ABS is very effective if the limit is exceeded, recovering traction quickly and gracefully. I have read some comments the factory ABS is wanting, and I suspect this is the same problem as the factory brakes poor performance, not a deficiency in the electro-hydraulic system.

[lifespeed]

First I want to thank Todd for stepping up and designing the bigger Aero6 kit. It looks like my days of excessive brake maintenance are over, and the performance is race car level.

I can't recommend the FNSL6R setup for the Marauder. It is just to big a car for the smaller brakes that fit under the stock wheel. If you have these calipers, all I can say is try the Hawk pads and upgrade to Aero6 when you can't stand it anymore.

I know we all love our Marauder wheels. They're stylish, distinctive, and offered a level of upgraded performance compared to Grand Marquis wheels. Which probably isn't saying much. I have to say upgrading to 20" wheels was one of the best things I have ever done. The ride and handling were so much improved, as was the braking. One can only stop as fast as grip allows. Cornering is better too. I like to think the style of wheel I chose was in keeping with the Marauder theme, while allowing the basis for much upgraded performance.

[MOTOWN]

My question is how is the brake dust with the pads your using?

[lifespeed]

My question is how is the brake dust with the pads your using?

Brake dust is not bad at all. Not nearly as bad as aggressive pads dust. Carbotech 1521 pads were used with the Aero6 setup.

[MOTOWN]

Brake dust is not bad at all. Not nearly as bad as aggressive pads dust. Carbotech 1521 pads were used with the Aero6 setup.

I'll be ordering a set , i love my Aero 6 setup, but the brake dust from the bp10 pads are killing me!

[daddyusmaximus]

Is there a brake thread or website for beginners? I would like to learn more about the different caliper and pad types you guys are talking about so I could make more sense of threads like this. My new to me Marauder has very slight vibrations/pulsing in the brakes depending on how hard the stop is. Can't really tell if I have slightly warped rotors or it's this "pad transfer" you guys are talking about.

[lifespeed]

Is there a brake thread or website for beginners? I would like to learn more about the different caliper and pad types you guys are talking about so I could make more sense of threads like this. My new to me Marauder has very slight vibrations/pulsing in the brakes depending on how hard the stop is. Can't really tell if I have slightly warped rotors or it's this "pad transfer" you guys are talking about.

Yes, it is pretty much always pad transfer, "warped rotors" is a misnomer. I had the same problem with stock brakes, which started me down the brake upgrade path. The short version is the best solution is the Wilwood Aero6 kit from TCE, but it requires widening and spacing your stock wheels to maintain stock geometry while creating caliper clearance to the spokes, or switching to an appropriate aftermarket wheel.

Given the incredible performance improvement offered by 20" low-profile tires I have to recommend the latter.

[ChiTownMaraud3r]

I'll be ordering a set , i love my Aero 6 setup, but the brake dust from the bp10 pads are killing me!

My mustang with brembo big brakes creates a ton of dust under normal driving conditions.. any thoughts on upgrading to another pad in the future?

[MOTOWN]

My mustang with brembo big brakes creates a ton of dust under normal driving conditions.. any thoughts on upgrading to another pad in the future?

I'll be ordering the Carbotech pads that Lifespeeds running, and see how the brake dust is with those.

[daddyusmaximus]

I'll be ordering the Carbotech pads that Lifespeeds running, and see how the brake dust is with those.

Any updates on pad wear? I may have misunderstood, but read it as the last set he tried was the Hawk HPS, and he liked them.

[lifespeed]

Any updates on pad wear? I may have misunderstood, but read it as the last set he tried was the Hawk HPS, and he liked them.

Hawk HPS were just a keep-the-car-on-the-road pad slap for the fatally-flawed FNSL6R brake kit (fits under the stock wheels with a thin spacer). They worked OK, but the brake kit as a whole is undersized for the Marauder.

I run Carbotech 1521 with the Aero6 calipers with a proper 1.25" thick rotor, which does not (easily) fit under the stock wheels. These have worked well, no doubt helped by the larger pad area and rotor thickness.