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-   -   Need advice, overheating brakes at track (http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/622736-need-advice-overheating-brakes-track.html)

aftermath 08-03-2011 11:32 AM

Need advice, overheating brakes at track
 
Im running about 390 HP. From what I understand I have the smaller turbo brakes and Im running a Hawk Blue pad. I have ducting to the front brakes, but we have a new track and I upgraded to Nitto NT01 275 tires and I was getting a soft pedal so I backed off. Yes I bleed brakes before every track weekend.

With these tires I can brake a lot harder than the 255 used up street tires I had before. Enough of a change that when I really tested out the brakes I had a hard time locking them up and it took a fair bit of pedal pressure, however the braking was way way better than before and I could really go deep into a corner.

The setup does not have enough bite and I would like the bite of the pads to be better. But will better pads just add to the heat problem?

Would a better pad like the dtc-60 or dtc-70 buy me the braking power I need for now or is it really time to spend money on much larger brakes.

Pete R 08-03-2011 12:47 PM

I am using the big reds with pagid orange pads and I have 0 issues. My local track is really hard on brakes too. The "racier" pads are made to operate at the higher temps and they have various compounds effecting initial bite (i don't have any comparisons to reccomend different pads, I'd post this in the racing section) I would also try the castrol srf fluid, it's wicked expensive but has a REAL high boiling point and very resistant to moisture. Maybe you could work on getting even more air to them. If all else fails, buy bigger brakes, I've never heard anyone complain about having too much brake.

RedDragon 08-03-2011 03:17 PM

What fluid are you running? Soft pedal is from a change in the fluid system (fluid, master cylinder, ect) not pads or rotors.

962porsche 08-03-2011 03:21 PM

i would say yuor not taking your brake temps ! thats the 1st thing to seting up your car . tire temps and brake temps . the only pads i will use on my 944 track cars ( i run 6 944's at this time ) are the DTC 60 AND 70 . they like there temps about 800 degrees . at nhms were its one of the hardest tracks on brakes they have never over heated in all the years i have been using them . one of my 944 V8's i still have the stock 8V brakes on the car . i never thought the brakes would last or work all that good with a car that is putting out 428 rwhp but they do work ok . at some point i will change over the calipers but we have to run a 15 inch wheel on that car to stay in class so big brake kits are out . over the last 25 + years i have raced 944's i have tryed almost every brake pad offered i like the DTC's . check your brake system then get your self some DTC's . don't think you can drive a pad like that on the street thow . they need allot of heat to work and street drive will not build enough heat to do that .

Dantilla 08-03-2011 03:37 PM

I race with stock NA brakes using Porterfield R4 pads and Motul fluid.

When I had my 951, I would boil brake fluid on the track until I switched to Motul fluid.

aftermath 08-03-2011 08:27 PM

I was running the Willwood 570 fluid, 4 days old. The pedal got soft when I was really testing out the brakes, I backed off from threshold braking and it got better. Im thinking now that I have R compound rubber the hawk blue pads are my problem. I would normally take tire\brake temps but this was the first outing with these new tires, first practice was rain, second practice was a blown ignition switch, qualifying race was 3 laps green and 30 minutes of full course yellow so I went onto the track without any data for these new tires. Came off with 42 psi which was way higher than the 38 I was shooting for. My crew didnt take rotor temps as they were hustling us of the track as the Indy cars were coming out and they were waving me out of the pits as my guys were trying to get temps and pressures. PS: This is a track only car, and Im leaning to the dtc-60 or a brake upgrade. The pad change is the cheaper way to try to fix the issue.

RedDragon 08-03-2011 09:35 PM

Try Motul RBF 600 (best bang for your buck) or Castrol SRF fluid. As for your tire pressure, my fastest lap time in my time attack evo on R compound (Advan 050s, Kumho V700 or bridgestone RE55s) have allways been 30-32psi hot.
Have you replaces the master cylinder latley?

Fluid change is cheaper than a pad change, get some Motul.

924RACR 08-04-2011 05:13 AM

Usually an upgrade to a proper R-compound tire will improve brake temps, all else being equal, since you can carry more speed through the corners - no need to slow down as much. You sure you're going fast enough???

That said, I would also expect this is something you can address with pad and fluid selection...

aftermath 08-04-2011 11:11 AM

How will r-compound tires improve brake temps? I can brake way harder with these tires as they dont lock up easy like the old ones could. I may be on the brakes for shorter times but Im using a lot ( way more ) pedal pressure now. I would think harder braking introduces more heat.

I think Im going to try the pad upgrade first as I have had many people say try that first and to be safe I will use some of the 600 fluids as opposed to the Willwood 570 I was using.

I found braking way better with the new tires ( until the pedal started getting soft ) and turning only marginially better which makes me wonder more about my suspension. I can see from the photos taken that I have too much squat out of the corners and a fellow racer said I have more body lean than before. But this thread is about my brakes. I wont get to drive that track until July 2012 and anything else around here isnt going to test the brakes like the Airport track that I was on.

emoore924 08-04-2011 11:20 AM

You might consider losing weight (on the car that is).

Also, pads are going to have an operating range and torque rating. Some will operate better only once they get into in the right temperature range. There is temperature paint you can put on your rotors that changes color at certain temps so you can see how hot the rotors are getting.

Last, different compounds have different "torque", or as you've put it, "bite". If you get a high-torque pad and you're operating in the right temperature range and you're still not getting the stopping you want, get bigger brakes or lose weight...

aftermath 08-04-2011 12:38 PM

I can lose 10lb :). I gutted the car but there is a bit more I can remove. Fiberglass is on my wish list. There is maybe 50lb of easy weight to still remove without getting fiberglass\lexan parts.

aftermath 08-04-2011 12:45 PM

http://forums.pelicanparts.com/uploa...1312487105.jpg

962porsche 08-04-2011 03:21 PM

all you have to do is use a good brake fluid i use wynn's dot 4 super heavy duty . if it states its dot 4 super heavy duty its realy a dot 5.1 fluid stated by the temp rating . so if your using a dot 4 or higher your fluid should have a high enough temp rating so your not cooking your fluid no matter what tires your using . i run either a R tire or a full slick on all my cars but my 944 loaner . you stated your using cooling ducts . so my thinking is that your cooling ducts may not be set up right ? if the duct size is to big it will not push enough air throw the ducting to cool the brakes . the same will hold true if the ducting is to small . also many racer remove the backing plates from there brakes . this in fact will increase your brake temps . when i removed the ones on my car the brake temps went up from an average of 841 F to an average of 906 F . what i found is that the air geting pushed throw the ducting was hitting the rotor and bonceing back off . were if the backing plate is on the car the air has to move across the rotor . `

aftermath 08-04-2011 09:17 PM

Good point on the ducting. Its 2.5 inch hose. I added a front splitter and it covers under the car a fair bit, it might have altered air flow in the wheel well.

Rasta Monsta 08-04-2011 09:53 PM

Quote:

Originally Posted by aftermath (Post 6176892)
But this thread is about my brakes.

(whispers) More rear ARB!

aftermath 08-04-2011 10:08 PM

ARB? Whats that?.

I spent some time getting the front\rear bias set right with a proportioning valve I put in previously. Due to the basically zero track time before the race I never got to try to adjust the brakes bias valve with the new tires....so I left it at the setting that worked for the other tires.

So Im at rotors and calipers are fine, I feel that the willwood 570 fluid is probably ok also. The pads are a issue ( hawk blue ), the cooling could be thrown off by my splitter and of course I need to get some track time to work on the brake bias setting. This is great stuff, Im pretty sure now I dont need a brake upgrade like I thought I needed when I started this thread.

962porsche 08-05-2011 02:08 PM

i have splitters on most of my 944's . they should not stop any air from getting to the wheel houses . the splitters i build go to the center axle line and cover the hole front under side if the car . the cooling ducts i offer start at a 3 inch and taper down to a 2.5 inch so you should be ok with just using a 2.5 duct . your brake bias could be set wrong ? but you should feal that under braking ! when i install bias ajusters i install them in the car so you can ajust it from the drivers seat . over the course of the days racing you can ajust it for your braking needs as the track changes . the temps that the hawk blues should be running at is about 600 degrees F . there ok for street and DE but there in no way a full race pad . if your only racing the car then get race only pads .

333pg333 08-06-2011 11:21 PM

Going up to larger rubber will put more stress on the brakes as you will be travelling faster into your braking points. I don't know these DTC pads but I can certainly recommend PFC pads. Best bite I've had on any pads so far. (EBC Reds, Pagid Blues and Blacks). Castrol SRF and s/s lines. Big Reds front, Mo30 Rears. Full floating slotted rotors on front. I found that the drilled and slots definitely help reducing soft pedal but the X drilled ones crack too fast.
The PFCs worked well enough on the street too. The only downside is that they throw a lot of Carbon metallic dust and you want to get that cleaned off pretty quickly. We take a bucket and sponge to the track and wash them down between sessions, after they have cooled of course. You could also try the 5/33 brake proportioning valve. Many guys use these with good results. Fits straight in.

924RACR 08-08-2011 07:50 AM

Actually the point about better rubber means (assuming you do it right, your suspension balance is good, and you are using the extra grip) you can carry more speed THROUGH the corners.

Since you can go THROUGH the corner faster, you can enter the corner faster... which means LESS braking.

So, I understand the desire for better brakes, and nothing wrong with that - but I'm wondering if you're not getting the full benefit of the fresh rubber (or is it too old to stick well, if used?).

aftermath 08-08-2011 08:07 AM

Brand new rubber, nt01 275's on all corners. I had so little seat time this race due to rain\mechanical that maybe Im still slowing to speeds I expect from the old tires. All I know for certain is I need way more seat time, but I was getting a soft pedal and when I backed off the pedal feel was good. I do believe my car doesnt handle as well as it should and I know the tire pressure was way off this first time out. The car brakes way better with the tires but turning was only margially better.


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