Brake cooling ducts
- Thread starter Andy Tims
- Start date
dtunnicliffe
New member
Andy,
Have you looked at the various set ups in the Porsche Performance Handbook? Armed with a good pair of tin snips, some sheet aluminium and I reckon you could easily (and cheaply) knock up a set yourself. One option would be a simple scoop clamped to the lower arm made of sturdy alloy plate. It is on my 'something to do over long winter evenings' list. Not exactly rocket science and I guess very rewarding.
Dave
Have you looked at the various set ups in the Porsche Performance Handbook? Armed with a good pair of tin snips, some sheet aluminium and I reckon you could easily (and cheaply) knock up a set yourself. One option would be a simple scoop clamped to the lower arm made of sturdy alloy plate. It is on my 'something to do over long winter evenings' list. Not exactly rocket science and I guess very rewarding.
Dave
Andy Tims
New member
ORIGINAL: Melv
You don't need 'em Andy! []
Mel
Others may disagree. When I came in after my 1st session at Goodwood a couple of weeks ago, the brakes were smoking so badly I thought the pads were actually on fire.
I have glazed the dics & now need new ones & some extra cooling may help extend their lifespan.
Any sensible comments?
dtunnicliffe
New member
Sounds like you do need them. And besides there are so cool and good pub chat material! Seriously though, what about the disks - standard or 'x'drilled? Pads are also an issue. Been some good threads on pads etc recently, well worth checking it out.
And Melv, forgive me, but arn't those cooling ducts on your 964?
Dave
[]
And Melv, forgive me, but arn't those cooling ducts on your 964?
Dave
[
]
ClubSport 911
New member
I bet that hurts.....
ORIGINAL: dtunnicliffe
And Melv, forgive me, but arn't those cooling ducts on your 964?
Dave
[
Correct my sharp eyed friend, but not connected! I have yet to see a picture of a Cup Car racing in the Carrera Cup without blanks over the brake cooling ducts.
IMNVHO, braking methods on track need to be revised from what is considered normal on the road; also a cooling down lap is vital, without touching the brakes.
Mel
Melv,
You are correct that that a lot of people new to track days cook their brakes by applying them to gently for too long, but jumping to Andy's defence having followed him at goodwood in his Boxster I can assure you he is not in that category, he brakes late and hard.
Regards
You are correct that that a lot of people new to track days cook their brakes by applying them to gently for too long, but jumping to Andy's defence having followed him at goodwood in his Boxster I can assure you he is not in that category, he brakes late and hard.
Regards
Andy Tims
New member
As I was getting used to the car (no ABS, smaller discs & callipers than the Boxster) & suffering from very long pedal (pretty sure the fluid needs changing) I was probably braking earlier & less hard than normal, so this may have caused the glazing.
I'm well aware of the need for a cooling down lap etc, so it wasn't that.
I have also considered getting the discs skimmed, but:-
1) Even genuine Porsche discs are not that expensive for a 3.2.
2) The discs have seen a bit of life anyway.
I will be getting new OE discs, Porterfields & some decent fluid before my next track day, but I thought the cooling ducts might just help.
dtunnicliffe
New member
Mel
[/quote]
Mel, you are of course absolutely correct. J'n Parmer Racing drum in the point about the cooling lap - also, when parking up don't apply the hand brake and never sit with your foot on the brake - induces distortion.
Nice car by the way, with or without extra cooling!
Dave
[/quote]
Mel, you are of course absolutely correct. J'n Parmer Racing drum in the point about the cooling lap - also, when parking up don't apply the hand brake and never sit with your foot on the brake - induces distortion.
Nice car by the way, with or without extra cooling!
Dave
Guest
New member
ORIGINAL: Melv
You don't need 'em Andy! [
Mel
I am going to call you on this Mel (handbags at dawn fella !). Have you actually looked at the discs and calipers on a 3.2 compared with a Cup car? If you had, you would understand that the 3.2 brakes are marginal for track use once you start to approach ten tenths or drive longer sessions.
Just a few facts. The 3.2 (even in CS trim) will weigh more than a Cup car. With 230hp vs 260 (plus) hp it is not a whole lot slower at the end of a straight than the cup car. It won't get round the corner as fast so it needs to brake earlier to slow down more and hence brakes for a for a longer period of time regardless of driver skill. The thermal capacity of a 3.2 front brake is probably about 50-60% of the cup cars (280mm diameter x 24mm thick vs 320mm x 32mm - or something close to that). So it don't take a genius to work out that you get overheating in the 3.2 and may (as you say) need to block the ducts on the cup car to stay at race pad operating temp.
If you don't believe my pseudo maths, do some research. It is well known among 3.2 owners and racers that the brakes are a weakness. Search for Steve Weiner's comments on Pelican (owner of the Rennsport shop and racing/preparing cars for decades). Where the club rules do not allow mods, the racers have to drive around it, but that is no reason to say that the problem does not exist.
So, with that out of the way, what do you do to get a 3.2 to stop (without fire, smoke and brimstone)? The old adage goes: if you can lock the wheels you have maximum braking. But if you can only do it a few times before overheating then you have exceeded the thermal capacity of the brakes. The primary thermal reserve is the disc. The disc is cooled by air. Thus ducting air is the trick. I assume you already have track pads and race fluid which operate at higher temps. If not, there is a recent thread recommending some usual suspects.
To the original question, I have a similar duct setup to the one shown and it does help. You also need to get the hub block off plates which stop the air being spilled thru the hub and ensure it goes thru the disc vanes where it does some good. Buy them from Smart Racing in the US. 9M has them (or can get them) but they were just Smart Racing sourced when I bought them from 9M. If you want any more info re the original question, I would be delighted to help answer any specific question you have. I can take/post pictures if it would be helpful. One comment on the 9M product is that they have a habit of getting knocked off during off track excursions or on kerbs as they hang below the wishbone. They are also inefficient for airflow given the small scoop and the sharp bend immediately thereafter.
One other good option may be the 964/993 air deflectors. Let me know if you want more info and I will find pictures.
BTW, a 2.5 or 2.7 Boxster has brakes that are virtually the same size as the 3.2 - 24mm thick in the front and 20mm thick in the rear (ie smaller). Slightly bigger diameters and 4 pot calipers with bigger pads, but ultimately the pads and calipers do not help much with cooling. I don't entirely understand why we don't see more Boxsters with brake issues at track days (particularly as they are heavier than 3.2s and similar hp) but my guess is that the components are just so much newer that they all work nearly perfectly unlike the majority of 3.2s. It has been suggested that there are not many Boxsters used on track days or driven all that hard at track days but while that may have been true a couple of years ago I don't think that is the case anymore.
HTH
Richard
Guest
New member
This picture shows the ideal way to duct, running from the foglight openings in the valence and with a nifty little arrangement to get by the A-arm, but there is a lot of "stuff" in front of the wheel that makes this a non-starter on a fairly std car. My hose is tied to the A-arm and dips a little below it and in front of it. It should pick up "some" air and "some" air seems to be enough.
BTW, make sure you have removed the dust sheilds aka brake heaters. This is first step before even thinking of ducting.
BTW, make sure you have removed the dust sheilds aka brake heaters. This is first step before even thinking of ducting.
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