Brake cooling

[akyp]

Would like to ask those running 993 ducts, are there any issues with rubbing at full steering lock? I'm on stock wheels and tires.

[Sleepless]

UPDATE: A friend and I have experience uneven brake pad wear with the GT3 brake "ducts". The outside pads wear at about twice the rate of the inside pads. My friend swaps the pads after each track day to get even wear. I switched to TF brake ducts which worked great until I got a JRSC which does not allow the TF inlet duct placement; so am switching to APR front inlets in the fog lamps.

[Hyper4mance2k]

Originally Posted by akyp

Would like to ask those running 993 ducts, are there any issues with rubbing at full steering lock? I'm on stock wheels and tires.

Not a single rub. I haven't noticed any change in pad wear.

[chonody]

I have some very very minor rubbing issues on the ducts themselves, however, that is on 17x9 +35 wheels with 255 tires. I'd expect no rubbing on stock but then again I'm not sure if brake cooling needs to be addressed if stock wheels and tires are used.

[Tor]

I installed the 993 (964) brake spoiler too (thanks @fstlane). I made a small video after installing them and did a run to see the difference in temperature:

[ame="https://www.youtube.com/watch?v=WEhu1Oae8To"]Brake cooling![/ame]

[CSG Mike]

Originally Posted by Tor

I installed the 993 (964) brake spoiler too (thanks @fstlane). I made a small video after installing them and did a run to see the difference in temperature:

We hit temperatures of 1000C+ on stock brakes...

While the concept of the air guide is absolutely valid, the temps you're seeing are not really indicative of the numbers seen by someone who *really* needs improved brake cooling. The guides, IMO, are supplemental to other cooling mods, but alone, are most likely going to not be enough for the more experienced drivers.

[Tor]

Originally Posted by CSG Mike

We hit temperatures of 1000C+ on stock brakes...

While the concept of the air guide is absolutely valid, the temps you're seeing are not really indicative of the numbers seen by someone who *really* needs improved brake cooling. The guides, IMO, are supplemental to other cooling mods, but alone, are most likely going to not be enough for the more experienced drivers.

I don't get what you mean? I did the equivalent of brake burnish. 10 stops from 60 mph to 5 mph until the brakes started to smell and fade. Then I drove for 5-10 min with out stopping and with minimal braking.

The fact that there is a temperature difference left to right, shows that the side with the duct gets more air. That is the only thing I wanted to show with the video.

Had I stopped earlier and done the measurement, obviously the temperature would have read higher. Maybe it even 1000F, I had no interest in testing that - since "max achievable temperature" was not the point of the experiment.

How does "driver experience" come into the equation? Anyone can stop the car 10x in a straight line. If you mean: "there are other solutions that will produce more cooling for drivers who require even more cooling" - then I agree, but not for the price point and ease of install of these!!

Personally I don't want to spend too much money on the stock brake system, as I want to go bbk down the line. I am limiting it to braided lines, Castrol React SRF fluid (dry boiling point 608F - wet 518F) and CL RC5+ pads. Combined with the above cooling I'll see how far that gets me.

[Pat]

Originally Posted by Tor

How does "driver experience" come into the equation? Anyone can stop the car 10x in a straight line.

You have to drive the car pretty hard on the street to experience fade. Like...to the point you maybe shouldn't be driving that fast.
Put the car on a track and it's another ballgame. Factor in more grip through tires, suspension, aero, brake pads, etc. and all of a sudden the typical driver won't be able to get the most out of the car, including the braking system. In fact, they likely wouldn't be able to get it into the optimal temperature range.

[Tor]

Originally Posted by Pat

You have to drive the car pretty hard on the street to experience fade. Like...to the point you maybe shouldn't be driving that fast.
Put the car on a track and it's another ballgame. Factor in more grip through tires, suspension, aero, brake pads, etc. and all of a sudden the typical driver won't be able to get the most out of the car, including the braking system. In fact, they likely wouldn't be able to get it into the optimal temperature range.

I don't think you guys read my post.

Originally Posted by Tor

I installed the 993 (964) brake spoiler too (thanks @fstlane). I made a small video after installing them and did a run to see the difference in temperature:

The video shows that there is a temperature difference with Porsche 964 cooling on stock brakes compared to no cooling. Nothing more nothing less.

How (or where) the individual might drive the vehicle after installing this, his or her experience level, other mods or if other cooling systems are more effective is not really relevant, is it?

I could let Fernando Alonso (or my mother) make 10 stops from 60 to 5 mph and the results wouldn't really be different, would they?

I'm sure Counter Space Garage can sell you a more expensive (pro-driver ) solution that is more effective, but that's besides the point.

[Pat]

I'm not disputing your findings. Rather, I'm answering your question. A different person doing the same thing you did won't generate different results. Pushing the car harder will demonstrate this is not a sufficient cooling method for a good driver on a track.

[Tor]

Originally Posted by Pat

I'm not disputing your findings. Rather, I'm answering your question. A different person doing the same thing you did won't generate different results. Pushing the car harder will demonstrate this is not a sufficient cooling method for a good driver on a track.

You could let Fernado Alonso drive an F1 car or an AMC Pacer, it wouldn't change his skills. A skilled driver uses the equipment he has available to the max. A less skilled driver never reaches the limits or exceeds them.

I'm not disputing that you can make the brake system better with a BBK, bumper air intake and ducted cooling directly to the brakes. You could also get a more capable car than a Toyota/Subaru to begin with. Still it's beyond the point of my post.

(Such a discussion really discourage the desire to make future contributions).

[CSG Mike]

Originally Posted by Tor

I don't get what you mean? I did the equivalent of brake burnish. 10 stops from 60 mph to 5 mph until the brakes started to smell and fade. Then I drove for 5-10 min with out stopping and with minimal braking.

The fact that there is a temperature difference left to right, shows that the side with the duct gets more air. That is the only thing I wanted to show with the video.

Had I stopped earlier and done the measurement, obviously the temperature would have read higher. Maybe it even 1000F, I had no interest in testing that - since "max achievable temperature" was not the point of the experiment.

How does "driver experience" come into the equation? Anyone can stop the car 10x in a straight line. If you mean: "there are other solutions that will produce more cooling for drivers who require even more cooling" - then I agree, but not for the price point and ease of install of these!!

Personally I don't want to spend too much money on the stock brake system, as I want to go bbk down the line. I am limiting it to braided lines, Castrol React SRF fluid (dry boiling point 608F - wet 518F) and CL RC5+ pads. Combined with the above cooling I'll see how far that gets me.

It took you 10, relatively hard stops, to get your pads to 650C, and then another 5-10 minutes to get your pads down to about 100C with the air guide.

Here's my issue with your data.

- Did you do 10 stops, regardless of smell, or did you back off right when they started smelling?
- Did you cool them for 5 minutes or 10 minutes? a 100% variance is a huge range.

- I agree that the duct provides more air, but if it took 10 minutes to get from a 650C surface temperature spike to 100C surface/core temperature, that's a strong indicator that you need more surface area and mass for the temperature spike, not more airflow to lower the temperature equilibrium point.

How does "driver experience" come into the equation? Anyone can stop the car 10x in a straight line. If you mean: "there are other solutions that will produce more cooling for drivers who require even more cooling" - then I agree, but not for the price point and ease of install of these!!

You say nothing of how hard you stopped, or what tires you're using. I can stop at full ABS with stock tires and get less heat into the brakes than braking at threshold with 200TW RE71R. We have no idea if you're braking at 20%, 80%, or 110%.

If you want to take driver experience out of the equation, you need to be doing your stops at full ABS, because the ABS can function identically every time. Can you?

[infinity21]

What does any of that matter? He stopped in a straight line with only one side that has a brake duct. Unless you're suggesting that his straight line braking technique is significantly stressing one side more than the other, I'm not sure what your point is.

[Tor]

Originally Posted by CSG Mike

Here's my issue with your data.

It's wasn't meant to be a highly precise scientific experiment.

I was only test fitting the spoiler (seeing what holes needed to be drilled) and as I finished one side I got curious and took it for a drive. When I got back, I cut the zip tie and took it off again. They will be installed again (both sides), when I finish changing the brake lines as it will be easier to clean up fluid spill without them installed.

Anyway the purpose was to see if the cooling made any difference at all, which I think is crudely demonstrated.

If you think the info is helpful I'll provide as much detail as I recall:

- I use Pirelli Zero Nero GT 225x40R18 (not the best I know, probably not the worst either).
- Stock brakes and pads with 26,000 km / 16,000 miles. No tracking.
- Fluid changed to "unspecified Toyota" DOT4 fluid 1 year ago.
- The outside air temperature was around 15 C / 59 F

- I braked threshold braking all 10 stops (just below ABS would kick in). ABS kicked in very briefly twice during the 10 stops, where I would immediate back off back to threshold again. I believe I have a pretty good feel for the limit, someone might do it even more accurately.
- At either stop 3 or 4, I couldn't brake max, because of a curve in the road, maybe I braked 60-80% that one stop.
- Between stop 4 or 5 (thereafter still in the same curve), I had to delay the next braking application, and probably drove 5 seconds with 60 mph before being able to brake again (it felt forever, because I wanted to brake, so in reality it was probably a very short time).
- The brake felt mushy the last 2 or 3 stops. Probably gradually getting worse. On the last stop I though it was enough on public road and I was approaching build up area anyway where 60mph would be irresponsible.
- I picked up a slight smell on the 9th stop and on stop 10 it was noticeable.
- I checked google maps. From the last stop to the place I pulled over is 7 mins according to google maps. I drove fairly slow, to avoid having to come to a complete stop if catching up with cars that in the meantime had come in front of me. So I guess when factoring in getting out of the car too, it was likely 9-10 min.
- During the 9-10 mins I practically didn't apply any braking at all (see above, keeping distance to cars ahead).
- I came to a stop uphill and didn't brake at all for stopping (braked with the gears and let it roll to a stop and set the e-brake).

- I don't know the max disc temperature. I assume you deduct the 650C from the fade of the stock pads?

If you want to take driver experience out of the equation, you need to be doing your stops at full ABS, because the ABS can function identically every time. Can you?

Doing ABS stops is not recommended for brake burnish, as I am sure you are aware. I'm not sure I would want to do that to my brakes. Besides I took the spoiler off again as mentioned. And I don't see the point in redoing ABS stops rather than threshold braking.

For me personally it is irrelevant anyway:
This is the best it's going to get on the budget I allocated for now. I want to track it with the mentioned setup (braided lined, RC5+ pads and Castrol fluid) before I decide on anything else. This is a discount upgrade on purpose. I don't want to rush to buy anything and finding out later I needed to have gotten something better. Or finding out I overkilled it and wasted money that could have gone into other upgrades.

What I oppose to is that driver experience having to do with what to buy. Chances are that a newbie would task the brakes harder than someone with experience (wrong braking technique, braking too much etc). Plenty of people drive these cars stock or lightly modified on track. People here thrash these cars around Nürburgring with just tire and pad upgrades. Your ambient conditions may dictate something else, if you plan to track this car in Arizona. Here normal summer temperatures are around 25 C / 77 F. Also I don't plan to run 1 hour stint at Spa Francorchamps (although it's not far from me).