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Those who track on R compound tires...

fweasel

By fweasel
in Suspension/Brakes

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SBT Grand Master

SBT

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Not being a serious track monster, do the R-comps add that much additional traction that the brakes are seriously overheating? If the answer is yes, and you haven't upgraded your brakes to a BBK, that might be the answer before ducting... dunno...see opening disclaimer.:confused:

SBT

- Pro amore Dei et patriam et populum -
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KartRacerBoy Grand Master

KartRacerBoy

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Racing brakes that don't work for racing :confused::lol:

 

If you duct them then the stock ones will work just as well as the Brembos ;)

 

And stock w/ ducts = much cheaper! And no sticky calipers in the winter. And no idiot installers taking off your front dust shields. :lol:

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Give us some time.....good news about the 08 STi and the Leggy is that you guys will share a lot of parts. :D

 

 

- Andrew

 

I am particularly curious if it means we could upgrade hubs to 5x114.5. Fronts should bolt on I believe, but unsure about the ABS.

 

I looked at underneath 08 STI and rear hubs also look like they could bolt on, but then it's not clear what to do about the backing plate.

 

Could be an interesting thing to look into. Of course this assumes 6spd MT swap. I'd be happy to ditch 5x100 wheels and those crappy small bearings.

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fweasel Grand Master

fweasel

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Give us some time.....good news about the 08 STi and the Leggy is that you guys will share a lot of parts.

- Andrew

It would be better news if Tony had the prototypes on his car yesterday at the track, even better if I could get a set myself.;)

No, but I haven't come close to overheating the XP10s and 8s on the BBKs I have...

 

Are you getting that hot? What pads do you run?

Different track, different driving style/abilities (mine being the lesser). Hawk DTC-70/60

I also would like to know this answer. Are there any brake ducts available for the LGT?
Nothing bolt-on at the moment. See RCE's post about the upcoming 08 STi application.

do the R-comps add that much additional traction that the brakes are seriously overheating? If the answer is yes, and you haven't upgraded your brakes to a BBK, that might be the answer before ducting... dunno...see opening disclaimer.:confused:

SBT

Yes, they do. Ducting is the answer.

If you duct them then the stock ones will work just as well as the Brembos ;)
I have no delusions about what the Brembos do and don't do for me. What they do allow, is a much wider selection of proper track pad compounds and a slightly easier pad swap.
ignore him, he'll go away.
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fweasel Grand Master

fweasel

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prova makes a set of ducts for for legacy but i dnot know if they only fir jdm bumpers.

Yes they do, but they're more like air guides and not the solution I'm looking for. TRS runs them on his car, and my initial response was "those will get knocked off in the winter."

http://www.photodump.org/stored23/provaduct.jpg

ignore him, he'll go away.
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Xenonk Grand Master

Xenonk

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Not being a serious track monster, do the R-comps add that much additional traction that the brakes are seriously overheating? If the answer is yes, and you haven't upgraded your brakes to a BBK, that might be the answer before ducting... dunno...see opening disclaimer.:confused:

SBT

 

if you are setting qualifying lap pace on stock size rotors on a 95F day, then YES.

 

 

Even with a BBK, (a couple of my friends in the STi) still over heat their brakes.. trust me, we MELT stuff. Even with a BBK, the brakes aren't cooling fast enough, especially on a course that doesnt allow enough time to cool between brake zones and if the brake zones are close to each other.

 

Take VIR full course for example. Each major brake zone is about 120+ mph entry speeds down to 45mph just before you let off on the pedal from the trail braking (55 mph if you run r-compounds). Those are at turns 1, 14. The problem is that at turns 4, 5, 10, 11, and 16 you are also using hard stabs to set the car up. I turn in a lap time around 2:18 to 2:20 (which is dog ass slow). at 140 seconds divided by 7 brake zones, that's only 20 seconds between brake zones on average. There's no way the brakes will dispel 1400F fast enough over say a 25 minute session on a hot 95F day. If was around 50F where there's less traction for the R-compounds, you wont have any overheating issues. You have to look at the overall use in time, how often the brakes are used, and how hard. You also have to see how hot your brakes are running and the kind of pace and aggressive braking you need to do. The biggest factor is how you transition off the throttle and onto the brakes. I say biggest due to race-craft. This is the major factor for a driver know how to maintain the peak performance of the car, especially over endurance race situations. We are talking about a rotor setup that can sit there and work with the brake pad to keep up for 3 to 4 hours at a time in temperatures exceeding 1600F. You can't purposely run qualifying pace and expect the brakes to hold up for the next 30 laps or 1 Hour. Point is that if you are still on postive gs accelerating as you are coming off the throttle (basically an over lap of power being transmitted into the motor and the motor hasn't acheived a state of engine braking yet) then you have that force to deal with as well (it might not be much, but at .2gs or even .1gs is still a lot of momentum and force to deal with, remember from high school physics F=MA). A 3600 lbs car at .1g of acceleration, you are still dealing with 360 lbs of force. That's like having 2 other passengers with you in the car!! Tell me if you toss 360 lbs around and see if the brakes heat up or not will make a difference. If you allow the car to settle from the off-throttle situation and let it coast a little before you apply the brakes, then it's easier on the brakes in general. Many times I have to back off the aggressive style of driving for a couple of corners or even a full lap just to get some pedal feedback from the brakes (since they are fading).

 

Let's put it this way: With a brake duct kit, you can really take out some the stored heat that you are building up. I've literally got my stock brakes without some kind of crappy ducting just past 1700F (well over 1250C) on a track day in 95F without it. I just keep using higher temp brake pads until I truly need some ducting. I havent run any real ducting yet, I just keep my track pace in check.

 

Racecomp Engineering does sell brake duct hoses, you just have to come up your own way for now of how to port the brake ducts onto the back of the hub assembly without having the tire hitting it. Racecomp Engineering have made hub duct brake brackets for their STi fitments, but none so far for the GT... although it's not too hard to make if you have some mild steel and want to weld on something for yourself to use for the time being, it's just that there's not as much room behind the hub assembly to mate the duct bracket on there. You can run the hose to the fog light openings and just cut a round 3" hole behind your splash guards to pass the hose through it.. or you can just run it along the steering rack tie-rods as well, but make sure doesnt hang lower than your skid plate.

 

I rather use hose clamps, there's no zip tie in the world that will survive even at 500F before it melts. Even my rear calipers heat up so much that my brake paint that is good up to 800F flakes off. I need engine enamel paint that's good up to 1200F.

Keefe
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SBT Grand Master

SBT

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Keefe,

 

As always - appreciate the detailed (now it makes sense) breakdown. Guess I knew intuitively that R-comps have more traction than a standard HPT, but would not have known that there was a minimum temperature range at which they perform significantly better. I know my MPSes tend to be more grippy when they're heated, but they seem to do well across pretty much all road/air temperature ranges. I presume that the R-comps don't do well until they really are heated to a minimum temp.

 

Given the scenario you outlined above, it only makes sense that you'd want to duct the brakes and I get the "why" now, so thanks for that too.

 

To the OPs question then, if the air/track temps are high enough to really make the R-comps "grippy", and the track has a series of high-speed braking zones, without sufficient cool-down intervals, then brake ducting would be helpful, maybe even necessary, if you wanted to avoid or significantly reduce brake pedal fade.

SBT

- Pro amore Dei et patriam et populum -
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fweasel Grand Master

fweasel

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Did Racecomp have some that someone was testing out on here?

Tony from Turn In Concepts tracks a new 08 STi and is awaiting a prototype set from RCE. That's the only person I know that is expecting them or close to actually using a set.

ignore him, he'll go away.
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