450Z brake bias tuning

[JMortensen]

bj, i had been told that there is a 'transfer' of pad [something] to the rotor during the bedding in process and that if i changed pads from track to street i'd either need a set of rotors for my street pads or have to 'cut' the rotors prior to swapping pads. not being an engineer myself [or much skill in that area] i tend to listen to those who are experienced. one of the reasons that i do much reading and little posting here-to learn and benefit.

That sounds like a load of bull to me. I used to run street pads and then swap in R4's when I went to the track. Never had any problems. I did bed in the R4's the first time, but after that I swapped back and forth multiple times with no issues.

 

On my ex-boss's racecar we'd just keep throwing pads on it until the rotors needed replacing, then we'd swap the rotors and keep the old pads if they were still good and do the same thing again. Again, new pads, bed them in. Once they're bedded in, you can pretty much do what you want.

 

That's been my experience anyway.

[bjhines]

You state that you want similar performance on all four corners yet what you have is diss-similar performance you are trying to fix. I would bet that you don't even need to stay within the same range of materials much less manufacturers. The demands on the rear brakes are entirely different than the fronts.

Think about it...For one... you have vented rotors on the front and pancakes on the rear. Secondly...The fronts are rotors on hats, the rears one one piece cast. Third... fourth, and fithly, etc. There is nothing similar about any part of your braking system except lateral symetry.

 

 

There are nuances to maintaining pad and rotor contact patches and proper bedding in. So... Yes... There are reasons for ~some people to run into problems when swapping between 2 different sets of pads.

 

Think about the typical M3 BMW driver. Many of these cars are regularly tracked(hard) and then driven to work daily for many more miles in between track events. Large differences in the way the rotors and pads wear can adversely affect one or the other when pads are swapped. But keep in mind that race pads do most of the rotor wear.. street pads tend to conform to the shape of the rotor, where race pads shape the rotor to conform to them. You can still get away with lots of street miles and the race pads will still fit when you swap them back in.

 

We are not BMW drivers(for the most part). My car will see less than a thousand street miles, and 6-10 track events in a year. My street pads seem happy to conform to the rotor wear from the track pads. The rotors don't change wear patterns enough between track events for the race pads to need rebedding beyond a few hard stops.

 

As far as the pad material transferred to the rotors... So what? That is a lot of hype about perfectly normal hot brake wear. It is not like you will contaminate one pad material with the other. You see it on race car rotors because they get really freaking hot. You dont see it on street rotors because they never get hot enough.

 

 

 

This is a one day old rotor with Hawk-Black pads at road Atlanta. Notice the nice bluing of the rotor. That is not a track that is hard on brakes either.

 

 

 

 

There is a lot of material transferred onto this rotor. But it is easily wiped clean by my street pads when I slap them on. The street pads polish them up nicely.

[marcg]

i would really prefer to not run track pads on the street. seems that street pads have a nice initial bit and work great unless you're running repeated and higher speed/high effort stops.

Dave, What size rotors are you running on the 1TUFFZ?

I went to a large rotor so that I could run a fairly mild grade pad (ie street) and still be able to run hard on a track event.

When I had my old 240Z I concluded that the brakes were powerful enough to lock up the 225/50-15 autocross tires at speed, but only lasted about 3 corners at Shannonville before they over heated. Yes I tries drilled and/or slotted rotors and ducted. So they were powerful enough, but I needed to address the heat dissipation problem. So I built my own braking system using Wilwood 11.75" dia rotors with PBR Metal Master pads on a stock 240Z caliper with no brake ducting. I ran the car like this on countless track events picking up several class wins in our SOLO1 series with no brake fade. It did not seem to matter what track I went to or how hot it was I never had braking issues.

So I went with the same attitude with the 450Z large rotor with a mild pad and I should be able to keep the temps in the range for the street pads.

Are you getting brake fade with your setup when you run at the Glen?

[johnc]

Pad material does transfer to the rotors and a properly bedded racing pad and rotor combination actually has pad material gripping pad material. For the pad material to transfer properly the pads need to be up to temp.

 

I run Hawk DTC70/60 pads on my 350Z all the time. When driving on the street the pads act as grinders cleaning and polishing the surface of the rotors. When I take the 350Z to the track and get the pads up to temp there is a noticable increase in initial bite and overall torque. At the end of the day there is a definate layer of pad material built up on the rotors.

 

For the next day of street driving I need to be careful because the pads bite a lot harder into the rotors. That hard bite goes away once the cold pads have a chance to grind the pad material off the rotors.

[Zmanco]

FWIW, I'll share my own experience in tuning the F/R brake bias. On my 73 I have the later Toyota 4x4 calipers that can take 300ZX pads and the 240SX calipers in the rear. I am running 84 300ZX Raybestos PG Plus rotors all around and have an adjustable prop valve for the rears. I initially used PBR Metal Master at all 4 corners and while I had no fade issues, even with the prop valve all the way open the fronts always locked first.

 

After getting some advice on pads with a higher coefficient of friction http://forums.hybridz.org/showthread.php?t=121024 I tried the Hawk HP Plus in the rear and solved the problem. I now can fine tune F/R balance with the prop valve and was quite surprised how much of an improvement I felt from just getting the rears to do their share of the job.

 

I know some here are not fans of the Metal Masters, but my own experience with them has been very good. While this is definitely not my daily driver, I do drive it just about every chance I get when the weather is good (~5k miles per year) and find these pads to quite acceptable for street use as well, even when cold. The 2 tracks I have used this combination on do have some tough braking points, one track where I was dropping from 115 mph to 70, and the other where I was going from 100 to 35. I have not felt any fade with this setup.

 

I'm not saying that these pads are the right ones for you, just pointing out, as others have, that a little experimentation with pad materials can have a big impact on your braking performance. I'm often surprised to see members here put so much effort into bolting on big brakes, but using generic pads. Same thing with suspensions and wheels, and then choosing tires based on size, not the brand/type of compound etc, but that's a topic for another day ...

[1 tuff z]

Dave, What size rotors are you running on the 1TUFFZ?

I went to a large rotor so that I could run a fairly mild grade pad (ie street) and still be able to run hard on a track event.

When I had my old 240Z I concluded that the brakes were powerful enough to lock up the 225/50-15 autocross tires at speed, but only lasted about 3 corners at Shannonville before they over heated. Yes I tries drilled and/or slotted rotors and ducted. So they were powerful enough, but I needed to address the heat dissipation problem. So I built my own braking system using Wilwood 11.75" dia rotors with PBR Metal Master pads on a stock 240Z caliper with no brake ducting. I ran the car like this on countless track events picking up several class wins in our SOLO1 series with no brake fade. It did not seem to matter what track I went to or how hot it was I never had braking issues.

So I went with the same attitude with the 450Z large rotor with a mild pad and I should be able to keep the temps in the range for the street pads.

Are you getting brake fade with your setup when you run at the Glen?

 

 

brake fade, what's that? [lol]. no brake fade at all, in fact the brakes-once up to temp work very well. repeated reduction from 150 to ~80 before entering the bus stop [back straight at wgi] is no problem. i'm confident there is more available [ie, brake later/deeper] but i don't have the guts to push it further.

 

i'm running 13" front rotors, 11" in the rear.

[marcg]

brake fade, what's that? [lol]. no brake fade at all, in fact the brakes-once up to temp work very well.

 

David,

Have you tried a softer pad on the front? It would give you better bite when cold and depending on how well the rotors control temps you might get away running at the Glen without brake fade. After all the Glen is not that hard on brakes, unlike Shannonville and Calabogie Motorsport park where you have several fast straights (~ 120 mph) followed by some ~55mph corners. The Glen like Mosport and Mont Tremblant have very fast corners so scrubbing off speed is not as intense.

I'd be curious how your setup would respond to such a combo. We'll have to meet up next year and compare notes..........