Baer PRO + brakes issues

[ocpony]

New Baer Brakes installed 2 weeks prior in prep for Texas Mile back in March. I bedded them in three times before going to the mile. After the mile they are grabby and look like this. I have have been driving them for a month off and on (not my DD) and they are a little less grabby but the hot spots are bothering me. I would not have thought these would have done this. I also have Agent forty-seven brake ducts. I know I was stopping from 180mph in a half mile but thought these could handle that on one stop at a time. I made 3 runs 171.5mph then several hours later 173.7mph. Then the next day in am 180.3 mph then my son made his virgin run in my car and ran 145.7 mph about 2 hours later.
Do these need to go back to Baer? Can they be resurfaced being a slot and drilled rotor?
I really heated and hot spotted my stock rotor at the mile in 08 when I was shutting down from 160mph which is why I upgraded to these.
The grabbyness is not bad until you are under 15mph coming to a stop. Mostly just noticeable but not affecting the stopping or anything.

Any thoughts?

 

[SoundGuyDave]

A few things come to mind when I'm looking at those rotors...

1) Drilled/slotted = bling. Replace the friction rings with plain surface, and you'll have a LOT more even heat dissipation. The cross-drills only really create heat risers, and the slots haven't been proven to do anything except reduce mass, and mass equals thermal reserve.

2) They do appear cooked. I would try to cut them down, and see what you get, but when you get them that hot, it tends to change the properties of the rotor ring, so it may come right back.

3) What are you using for a cooling duct outlet at the knuckle? The closer the seal between the outlet and the rotor hub, the more efficient the cooling.

4) What pads are you using? With single, long stops from high speed, I'm not sure exactly what you'd want, but the "standard" street and race pads wouldn't be it, I wouldn't think.

5) Remember that once you've done your run, do NOT put on the parking brake, or come to a complete stop using the brakes... With everything so hot, you can get pad deposits on the rotor that can create all kinds of weird brake "feel" issues.

 

[pieperz06]

i would say that race pads would not be what you want because you would be putting them through weird heat cycles and you would be brakeing hard while they are still cold

did you make sure to break in the pads before you went to the mile.

i know that when i had my hps's and stock rotors and calipers i hot lapped it hitting 140-148 all day with about 20 min between runs and i had no brake fade or discoloring

 

[ocpony]

QUOTE=SoundGuyDave;522159]A few things come to mind when I'm looking at those rotors...

1) Drilled/slotted = bling. Replace the friction rings with plain surface, and you'll have a LOT more even heat dissipation. The cross-drills only really create heat risers, and the slots haven't been proven to do anything except reduce mass, and mass equals thermal reserve.
I understand about the solid rotors over cross-drilled advantages. My understanding on the slotted is that they help with the outgassing but that may all be hype. I was on a time issue and that is what I was told that I could get in in-time before the event. They arrived in 3 weeks even when they told me at least 4. 6 weeks or more for different rotors. I do take it to shows and 1/4 races too so the weight is an issue depending on the event.


2) They do appear cooked. I would try to cut them down, and see what you get, but when you get them that hot, it tends to change the properties of the rotor ring, so it may come right back. I cooked my stockers in 08 shutting down from 160mph on three runs. I resurfaced them and they are much better but some of the hotspots returned. Metallurgy definately was affected. Hell they looked like a rainbow in places! Can you just replace the friction disk and bolt it to the hat?

3) What are you using for a cooling duct outlet at the knuckle? The closer the seal between the outlet and the rotor hub, the more efficient the cooling. I run the Agent 47 setup which is the same as I had on the stockers when they cooked. It puts the air directly into the center of the hub. I am not sure just how close but I thought Agent 47 stuff was designed to be effective?

4) What pads are you using? With single, long stops from high speed, I'm not sure exactly what you'd want, but the "standard" street and race pads wouldn't be it, I wouldn't think. I agree.
I just used what they sent in the kit and it was not specified. I assume a street/track pad. Again it was a time issue and I only got the kit installed about 12 days before the event. I guess I can call Baer and see what they say the pads are. Any ideas on what type of pad. Needs to go from cold 90 degrees or so to 700+ (?) in matter of seconds.

5) Remember that once you've done your run, do NOT put on the parking brake, or come to a complete stop using the brakes... With everything so hot, you can get pad deposits on the rotor that can create all kinds of weird brake "feel" issues.[/QUOTE]
I know not to use the parking brake and never do. I shut it down on the first two (171.5 then 173.7mph) runs noticing that the brakes seems to go soft about halfway into the braking sequence (outgassing I assume) as they didn't looked glazed after those runs. I actually pressed harder near the end of the run to make the turnin. On the third run (180mph) it did the best and felt solid the entire time. I even let up a little bit and coasted a bit before turning in at around 45mph. Of coarse I have to stop to get the time slip which is after returning 1/2 mile at about 30mph. Then 10 mph slow zone for over a mile going past the spectators and other racers in the pit area.

Both side of both rotors looked like the pictures. The hot spots don't seam to correspond to the cross-drilled holes or the slots. They isn't any decernable pattern to me.

@ pieper, Yes I heat cycled them as per the instructions on three occasions before the event . I only had maybe a total of 120 miles on them though as I spend the last week before the mile working on the full belly pan.

 

[SoundGuyDave]

QUOTE=SoundGuyDave;522159]A few things come to mind when I'm looking at those rotors...

1) Drilled/slotted = bling. Replace the friction rings with plain surface, and you'll have a LOT more even heat dissipation. The cross-drills only really create heat risers, and the slots haven't been proven to do anything except reduce mass, and mass equals thermal reserve.
I understand about the solid rotors over cross-drilled advantages. My understanding on the slotted is that they help with the outgassing but that may all be hype. I was on a time issue and that is what I was told that I could get in in-time before the event. They arrived in 3 weeks even when they told me at least 4. 6 weeks or more for different rotors. I do take it to shows and 1/4 races too so the weight is an issue depending on the event.

Outgassing, or more specifically, the pad "floating" on a gas layer was indeed a problem, but the compounds (specifically the binding agents) we've been using for the last 30 years or so cured that issue, so the drill/slot thing is just a hold-over from that era.


2) They do appear cooked. I would try to cut them down, and see what you get, but when you get them that hot, it tends to change the properties of the rotor ring, so it may come right back. I cooked my stockers in 08 shutting down from 160mph on three runs. I resurfaced them and they are much better but some of the hotspots returned. Metallurgy definately was affected. Hell they looked like a rainbow in places! Can you just replace the friction disk and bolt it to the hat?

You absolutely should be able to get solid rings, without having to buy new hats, and it will be considerably cheaper than the whole assembly. Make sure you get new hardware, though!

3) What are you using for a cooling duct outlet at the knuckle? The closer the seal between the outlet and the rotor hub, the more efficient the cooling. I run the Agent 47 setup which is the same as I had on the stockers when they cooked. It puts the air directly into the center of the hub. I am not sure just how close but I thought Agent 47 stuff was designed to be effective?

Generally speaking, their stuff certainly seems that way! Something about your pic is bugging me, but I just can't put my finger on it... After I converted mine over to the FullTiltBoogie backing plates, I'm a lot less enthused about the A47/QMS style outlets, that don't seal the airflow to the hub. The FTB actually covers the entire hub, which forces the air through the vanes, not just "suggests" that the air head that way... Not saying that's the root of your problem but...

4) What pads are you using? With single, long stops from high speed, I'm not sure exactly what you'd want, but the "standard" street and race pads wouldn't be it, I wouldn't think. I agree.
I just used what they sent in the kit and it was not specified. I assume a street/track pad. Again it was a time issue and I only got the kit installed about 12 days before the event. I guess I can call Baer and see what they say the pads are. Any ideas on what type of pad. Needs to go from cold 90 degrees or so to 700+ (?) in matter of seconds.

I've got no specific advice on pad compound, but you might try giving Jay Andrew (Andrew-Racing.com) a shout (tell him I sent you!), the man seriously knows brakes! I would find out from Baer exactly what compound you got, what the MOT is, etc. Something is telling me that you are on a race compound, see my next response for details.

5) Remember that once you've done your run, do NOT put on the parking brake, or come to a complete stop using the brakes... With everything so hot, you can get pad deposits on the rotor that can create all kinds of weird brake "feel" issues.

I know not to use the parking brake and never do. I shut it down on the first two (171.5 then 173.7mph) runs noticing that the brakes seems to go soft about halfway into the braking sequence (outgassing I assume) as they didn't looked glazed after those runs. I actually pressed harder near the end of the run to make the turnin. On the third run (180mph) it did the best and felt solid the entire time. I even let up a little bit and coasted a bit before turning in at around 45mph. Of coarse I have to stop to get the time slip which is after returning 1/2 mile at about 30mph. Then 10 mph slow zone for over a mile going past the spectators and other racers in the pit area.

Actually, that "soft" feeling to me sounds like a bedding issue. It's actually pretty tough to properly bed brakes on the street, but the basic idea is to get them hot enough to get a solid transfer layer down on the rotor, and then park the car to let them cure. You'll know when you have the layer down, since the pads will feel "soft" under braking... The race compounds that I run are so hard, that I feel like I have to re-bed them every track outing... On the street, they just seem to grind the transfer layer off the rotor. I get blotchy dark areas on the rotor on the way to the track, but after the first (short!) session, I have a nice, even, "black-chrome" coating all across the rotor. Lasts until I head home, then it's blotchy again when I park the car.

Both side of both rotors looked like the pictures. The hot spots don't seam to correspond to the cross-drilled holes or the slots. They isn't any decernable pattern to me.

To my eye, the patterns seems concentrated around the drilled areas, and I would bet that if you pulled the rotor and looked at the construction, you would find that they're centered on the internal vanes. When they're drilled, you remove mass from the rotor ring, honestly only a few grams, but that mass is critical in the rotor's ability to absorb and radiate heat.

That's all I've got on this one... Honestly, mostly gut reactions and supposition, but I would make a few phone calls, over to Jay, and to Baer, and see what they have to say.

@ pieper, Yes I heat cycled them as per the instructions on three occasions before the event . I only had maybe a total of 120 miles on them though as I spend the last week before the mile working on the full belly pan.[/QUOTE]

 

[ocpony]

Thanks for the comments Dave.
These calipers use C5 style pads so there should be lots of different compounds available.
I will find out what they came with and order some different compounds and try them out for differnent applications. Maybe I just don't have full layer of transfer down? They do brake well but on the street with ducts I am sure it is difficult to keep them at optimum temp if not impossible. As I do make a lot of testing/tuning runs on the street with them "cold" but I need them to work good on the street too since my tuning runs in fourth gear are to 130mph+. I then usually hit the brakes hards to get back to 60mph. When I would do this with the stockers they would start fading in about 3 or 4 runs. With 650+ to the wheels 60 to 130 mph is just seconds at wot and then shut down hard. Don't need any tickets and I don't like to be at highspeed near any traffic.
Just need to get some info on the pads and some street compounds on it for now then change them for the high speed runs.

 

[JeremyH]

I have the same brakes when cold at least in the winter they were grabby at slow slow speeds. I also give them a few good warm up cycles everytime i drive the car.
Probably took a good month of easy braking and bedding to get them good.