hey all, I run HP+'s in the front, and still have the OEM's in the rear. I have been having an issue where the pad is overheating and I'm getting bad material transfer, which causes varying degrees of vibration under hard braking. These pads will not have to be good on the street, because they will be solely TRACK pads.

I was also thinking of doing some ducting to the front rotors to help out with the temperature problems as well.

Advice/recommendations?

THANKS!

Blue

 

I assume you are having problems with the fronts...or you would change out the rears as well.

What type of rotors are you running?

I have ben running HP+ pads this year....and haven't had a problem, except that I have been through two sets since the start of May. There are a few on here that don't like the HP+..but I have used them cause that's what the rotor manufacturer suggests.

I have been looking at running some ducting as well....and am making some intake vents for the radiator intake area out of FG.....

 

Brake Cooling Duct DIY https://www.rx8club.com/series-i-do-yourself-forum-73/diy-brake-cooling-ducts-track-use-83801/

I also use HP+ for track days and ran into that vibration issue once. Next time I went to the track I lightly sanded the rotors & the pads and made sure I bedded them in well and the vibration was not an issue.

 

I was going to sand the pads due to some glazing issues that I had that same day. What bed in procedure did you use?

 

Hawk HT14's Front
Hawk Blues Rear

 

The one from Hawk's site

1. After installing new brake pads, make 6 to 10 stops from approximately 30-35 mph applying moderate pressure.
2. Make an additional 2 to 3 hard stops from approximately 40 to 45 mph.
3. DO NOT DRAG BRAKES!
4. Allow 15 minutes for brake system to cool down.
5. After step 4 your new pads are ready for use.

 

I am still running the OEM rotors. I used to be a big fan of the HP+'s, but it seems as I develop my skills as a driver, that I am outdriving the pads. Well, at least the temp seems to be getting too high for them to work effectivly.

Anyone using Carbotech's or EBC or anything else?

 

I always liked how the brake cooler was stock on vettes!

 

thread on topic please

 

I use the carbotech pather xp 8's for the front and the bobcats on the rear for track days/ tires are shaved ra-1's. I have used the xp's for about 10-12 track days at r/a and roebling.Each day is about 100-125 miles of track use. i only swap out the fronts. i dont bed them in. an old expert told me that was not required when you put the pads on a few days before your event and just do normal driving. i have found that to be true.
i still have over 75% of my xp 8's left and they are absoulutely great pads. Great braking transition--much better than hawks(hawks are good --not flaming them at all) and if you like to trail brake then these are the best I have found. But then again pads are like tires--everyone has their favorites.
On ducts--dont bother unless you have a backing plate. So much turbulance in the wheelwell any directed air will not reach the disc itself unless you have a backing plate. It can a LOW speed and it will help cool them on the cool down lap--but during the event when you need it--it will not happen.
olddragger

 

Thanks for the advice OD! So far it looks like the XP8's are on my shopping list for the next track weekend.

 

Expo1, Can you tell me more about your sanding process? -- how you did it, grit sand paper, emory cloth etc.?

I ended my last track sessions early because of seriously bad vibration. On the street, I can still feel it just not as bad since I have changed back to my Bobcats on the front and the brakes are never as hot. I can also feel it when just coasting to a stop with light brake pressure. Feels like an on and off sensation with very light braking. They feel fine under 'normal braking' which tells me it is not warping but uneven deposits.

Part of me wants to go ahead and get new rotors that don't look like crap as well but the other part of me says if I can get through the summer\fall track season with these rotors, why not?

TIA

 

From what I understand on the sanding process, its just sandpaper. What grit or whatever, i have no idea, so it would be nice to hear someone chime in with that info.

 

Medium grain Emery Cloth with a sanding block. I lightly sand the rotors and the pads to remove any build up of brake material. I guess the key thing is I bed in the pads right after? I usually do this 2-3 days before a track weekend.

 

Well, after reading reviews and spec's it looks like I will be going for the XP8's in front, and regular bobcats in the rear. Also it looks like sanding my rotors will be a good idea to make sure I don't have any problems with the install.

Thanks guys!

 

I think you will be very satisfied Blue. Dont forget the good braking fluid to go along with them. Use brake cleaning fluid to clean the rotors also when you change. I know you probaly know already but I have to mention it--never pull up the parking brake when you get back in the pits-- I still catch myself wanting to do that! Dang habits.
Also when you install the xp's do not use the spacer plates that go on the stock pads. Let them rattle a little--wont hurt nothing--but it does help with cooling a little.
ENjoy and let us know how you like them.
olddragger

 

I must disagree with you olddragger. I have empirical evidence to say that this mod helps... and not just a little. I measure my four brake temps each and every time (yes!) that I come back in from a track session and have been for two years. That's quite a few sessions! The brake ducts lowered the temps dramatically. Although I don't have in-session data, the drastic drop in as-read temperature w/ducts vs. wo/ducts can't be all attributed to the cool down lap, some cool downs are only 25 or 30 sec max on track for heavens sake!

Not knocking your good advice, but on this I have the temperature data to know that this mod provides some worthwhile brake temp relief. Beside it's easy, looks cool (!), and is so inexpensive to do any track junkie should take advantage of it. For street use only, of course, the brakes need no help, regardless of what you are doing.

 

Thanks. I will try this.

 

Hey Spin
I figued you would post! You did a fine job on that DIY--I like folks that fabrocate(sic) and dont just rush out and buy the laetest greatest bolt on dang the cost!
I respectfully disagree on the cooling affect of non backing plate brake ducts. At speed the directional flow of that air coming from the duct itself is lost in the turbulance in the wheelwell. Low speed cooling--yep I too will think it will have an affect
There is nothing wrong with them at all. I also believe that before you can get back to the pits and do a reading , that cool down lap has done it's job--helped by those ducts. 200degree lost on a cool down lap?--yep --sure will. But while on the track doing the speeds and the hard braking--you would be MUCH better off with backing plates and spreading that air all over the disc and not just into the wheelwell toward the disc. There is a LOT of turbulance in the wheelwells at speed
olddragger

 

Ok oldragger, perhaps do this next time you're at the track. That is if you have an infrared pyrometer, which is what I use, good to about 600+ degrees F plus/minus 2%. Measure your brake temps at the point shown (it's generally the hottest spot) after each session. Let me know your front readings for a few sessions and the track length and cool down time. We'll compare.

I'll try and remember to do the same, as I have covers for my ducts. I can compare directly session to session.

Generally I have had hotter readings on short twistie technical tracks (1-1.5mile) vs long (2.5-3.5mile). Basically I believe the brakes cool naturally alot more between brakings events, and the cool down period is generally longer.

BTW, how have you measured the "ALOT of turbulence" in the wheel area? Or is this a theory, a reasonable assumption, based on other cars you have measured, etc.? You can guess I'm the scientific type, can't you? For me emperical data rules in the face of conjecture.

I've personally never measured for turbulence in the wheelwell, but based on my tempurature results, I'll wager a theory. A ~70-100mph blast of air out of a 4" tube in the wheel well area pointing at the rotor probably has a fairly decent chance of going where its pointed (at the rotor) compared to summizing that some caotic buffeting turbulance eddes will deflect it. After all they would be far less coherent and likely nulified and overcome by the hose blast. Think of a leaf blower. Takes a lot to deflect that air current. Same applies here IMO.

 

well, this is what my drivers side front rotor looks like. Any suggestions?

 

Certainly looks like a case of the pad ickies on your rotors! I'd say a good sanding and a rebedding could help, but this has never happened to me, so I'm not the expert on removing pad deposits. Time for some brake cooling ducts perhaps (my personal opinion)?

Here's a bit of interesting reading. Esp. if you go thru the links to the forum discussions. These sound pretty familiar to those similar topics here, yes?

http://www.racingbrake.com/main/pad_warning.asp

 

Now, if I understand what most links have been telling me, since I am switching compounds on both the front and rears, even if the rotor looks good I should still sand it down to prepare it for the new compound?

 

wont hurt--looks exactly like what spin lead you too. But if the rotors look good and no shimmy shake--then dont sand. do use good brake cleaner on the disc. Wash it down well.
Remember to cool your brakes better compress the braking zone as much as possible. That gives you more time OFF the brakes therefore more time to cool.
Spin-- like what you say, (and sorry for thread highjacking here Blue but our subject kinds of fits in), and I agree with evidence based results. I will always listen.
With an infrared pyro you do have to set your sensitivity for differant types of reflective surfaces. You are probably aware of that. If not then the surface temps of the area you point too will be either the baseline and the disc reading etc will be wrong or vice versa.( By the way what temp caliper paint are you using)?
The point you are showing will not ever be directly cooled by a duct, wrong side of the disc, plus the wheel hides it etc
But to directly answer your questions-- have I measured any wheelwell turbulance ----no i have not--wouldnt know how--so many differant influences, angle of wheel, wheel size, height of chassis, etc
true--you have a 4 inch blast of air going through your duct BUT it is trying to exit into another blast of air therefore the anology with the leafblower would not be one to really use. Do this instead-- ride in the back of a pickup truck doing say 60mph .Do this carefully please. crank up the leaf blower at half throttle point it toward the rear gate(its up of course) and see how much air you feel. You may be surprised.
also do not forget we have the dust shield on the back of the disc therefor blocking any airflow hitting it. The factory "scoop" has to deliver whatever air to the disc itself. It does so in a general fashion.
You have a great DIY going on Spin with your method of routing air through the chad etc--now finish it with some proper ducting and a backplate so all that mega air can really get to all of that part you are trying to get cool
Keep up the good work dude--hope to see you on the track someday. My group is running Road Atlanta this w/e and it is hard on brakes
olddragger.

 

It doesn't matter if it's turbulent in the wheel. You're introducing a volume of air that is coming from outside the car and is at a cooler temperature than the brakes, so this addition of cooler air will help cool the brakes.

Just because air is turbulent doesn't mean it isn't stagnant in position in a given area. The air in the wheel well could be super turbulent but it may never pull in new air from outside and exhaust it's own air. Often turbulent air is a signal of a self-contained "loop" of air. Laminair flow is what actually tells you that an air molecule is moving only in one direction.