Got a track related question? I'll try to answer.

[kch]

Originally Posted by 1Cor10:23

@kch I'd skip the ds2500 if your track has heavy breaking zones - I got uneven deposits and crazy rotor vibrations. Essex recommended that they only be used for autox or very light tracking. I guess it also depends on what tires you're running.

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That's the impression I got as well. I'll be on 255/40/17 Maxxis VR-1s, which are probably sticky enough to warrant much better pads. Thanks.

[CSG Mike]

Originally Posted by kch

Brake pads: I'm used to tracking on stock calipers with Cobalt Friction XR2s. I just purchased the AP sprint kit, and it came with a set of both Fedoro DS2500 and Carbotech XP10. I also purchased some 1521s for daily driving.

Several questions:
1) Should I even bother with the DS2500s? It seems they're too noisy for DD and not enough for track use.
2) Is there any problem with using Carbotech XP10 front and Cobalt XR2 rear? The XP10 compound is a little less aggressive than the XR2s, but I'd rather not have to purchase new rear pads when I have tons of life left on the Cobalts.

Thanks!

You'll have a slight rear bias with the XP10/XR2 rear. Are you pedal dancing?

That's the closest combo, but ideally you want front and rear pads to be the same. Did you purchase brzaapi's kit?

[kch]

Originally Posted by CSG Mike

You'll have a slight rear bias with the XP10/XR2 rear. Are you pedal dancing?

That's the closest combo, but ideally you want front and rear pads to be the same. Did you purchase brzaapi's kit?

Yep, brzaapi's kit. Haven't pedal danced in the past (just 3sec TC hold), but will next time.

[infinity21]

This is more of a theoretical question but figured I'll ask here since it's been bugging me for a while.
If you're taking a corner in isolation (no worries about what happens before or after), is it faster to take it with a slight understeer or slight oversteer? Assuming the driving is perfect and the you can adjust damper settings to induce the desired behaviour in the car. Looking to understand the best way to maximize the available grip in the tires.

[DocWalt]

Ideally you don't want understeer or oversteer. Realistically, line choice and driving style contribute a lot.

edit: figured I'd clarify. The ideal car is one that never slides at the front or rear (ignoring slip angle and all of that fun stuff) but the driver's comfort plays in. Is the driver smooth enough to make a car that's 100% neutral work? Is the driver more comfortable with understeer or oversteer? A small line choice change can compensate for most car behaviors and if the driver is more comfortable they will be faster. Pro drivers are as fast as they are because they can very quickly adapt to a car by changing their cornering a little bit ir tweaking the car to their liking.

It's really interesting to have two people drive the same car and see how differently they approach the goal of going fast. I recently shared my car with a friend of mine that normally drives much faster cars and it was very revealing how differently we drive, some of it habit from different cars, some of it purely preference.

[CSG Mike]

Originally Posted by infinity21

This is more of a theoretical question but figured I'll ask here since it's been bugging me for a while.
If you're taking a corner in isolation (no worries about what happens before or after), is it faster to take it with a slight understeer or slight oversteer? Assuming the driving is perfect and the you can adjust damper settings to induce the desired behaviour in the car. Looking to understand the best way to maximize the available grip in the tires.

Faster in what regard? Faster average speed through the corner? Faster entry speed? Faster exit speed?

Assuming it's a perfect 90 degree bend, for the highest average speed through the corner, slight oversteer.

However, using the damper to induce the desired behavior means you're reducing grip to get that desired behavior.

[CSG Mike]

Originally Posted by DocWalt

Ideally you don't want understeer or oversteer. Realistically, line choice and driving style contribute a lot.

edit: figured I'd clarify. The ideal car is one that never slides at the front or rear (ignoring slip angle and all of that fun stuff) but the driver's comfort plays in. Is the driver smooth enough to make a car that's 100% neutral work? Is the driver more comfortable with understeer or oversteer? A small line choice change can compensate for most car behaviors and if the driver is more comfortable they will be faster. Pro drivers are as fast as they are because they can very quickly adapt to a car by changing their cornering a little bit ir tweaking the car to their liking.

It's really interesting to have two people drive the same car and see how differently they approach the goal of going fast. I recently shared my car with a friend of mine that normally drives much faster cars and it was very revealing how differently we drive, some of it habit from different cars, some of it purely preference.

In a purely theoretical context, draw a force vector diagram, of the rear wheels pushing the car forward for acceleration, and the front wheels exerting a tangential force for cornering. Now, tilt the drawing to simulate "oversteer" by tilting it in the force of the tangential force from the front wheels. Notice how the lateral tangential force is additive with the components of the rear force vector. Now, tilt it the other way to simulate understeer, and note how the vectors are now subtractive.

Oversteer is always faster, in a theoretical context. In a real world context, you have to be able to manage it, and most drivers will be faster with an understeery car, because they fear oversteer, and avoid it, instead of seeking to exploit it.

[DocWalt]

I was trying to avoid the purely theoretical context for a reason It is definitely worth thinking about and knowing that a truly neutral car is slower than a car with slight oversteer, so hurray physics.

Mathematically neutral and real world neutral are two different things, in my experience. For example, I consider my BRZ neutral, but everybody that's ridden with me comments on how "active" (aka tail happy) I like my car to be. Someone that prefers that little bit of understeer is likely driving a car that's actually mathematically neutral

[CSG Mike]

Originally Posted by DocWalt

I was trying to avoid the purely theoretical context for a reason It is definitely worth thinking about and knowing that a truly neutral car is slower than a car with slight oversteer, so hurray physics.

Mathematically neutral and real world neutral are two different things, in my experience. For example, I consider my BRZ neutral, but everybody that's ridden with me comments on how "active" (aka tail happy) I like my car to be. Someone that prefers that little bit of understeer is likely driving a car that's actually mathematically neutral

neutrality can change with throttle application

If you can't spin your rear tires at a given speed, then you want a looser car. If you can spin your tires at a given speed, then you want to make sure you know which way the rear will go when they spin. Neutral is relative, but loose is fast.

[infinity21]

Thanks for the input guys. I feel pretty comfortable with slight understeer (as with many others) but wanted to explore the other side of slip angles to see if it's worth mastering. My bouts with oversteer is one that aims to immediately correct it. I have no reservations going WOT out of corners and applying corrective steering as necessary but I'm not very good at sustaining slight oversteer so it's something I will work towards in future track days

Back to real life, I currently run RCE T2 which slightly understeers with 400/400 springs (at least that's my perception of the car's behaviour). Would it be faster to get the car to oversteer through appropriate brake/throttle/steering application or should I just stick to what I'm doing until I get stiffer springs in the rear? Perhaps the first step is to approach the apex smoothly and try to oversteer out of the corner?

A good example of my current driving style can be seen in the last minute or so of this video
[ame="https://www.youtube.com/watch?v=PSI--VO6oZY"]2016-06-11 SPDA DDT lapping - YouTube[/ame]

[CSG Mike]

Originally Posted by infinity21

Thanks for the input guys. I feel pretty comfortable with slight understeer (as with many others) but wanted to explore the other side of slip angles to see if it's worth mastering. My bouts with oversteer is one that aims to immediately correct it. I have no reservations going WOT out of corners and applying corrective steering as necessary but I'm not very good at sustaining slight oversteer so it's something I will work towards in future track days

Back to real life, I currently run RCE T2 which slightly understeers with 400/400 springs (at least that's my perception of the car's behaviour). Would it be faster to get the car to oversteer through appropriate brake/throttle/steering application or should I just stick to what I'm doing until I get stiffer springs in the rear? Perhaps the first step is to approach the apex smoothly and try to oversteer out of the corner?

A good example of my current driving style can be seen in the last minute or so of this video

Your car is faster in a state of heavy understeer. You can learn to throttle steer with your car, but it'll be slower than just letting it plow.

[Takumi788]

I am looking to change the pads in my almost track only car. (I drive to some car shows and to the track only.) I want to go with the Hawk DTC-60 pads. I hear rumors of blank rotors being 100% good to track with. Is this true? or is slotted the way to go? My car is NA with DOT slicks.

[ka-t_240]

Originally Posted by Takumi788

I am looking to change the pads in my almost track only car. (I drive to some car shows and to the track only.) I want to go with the Hawk DTC-60 pads. I hear rumors of blank rotors being 100% good to track with. Is this true? or is slotted the way to go? My car is NA with DOT slicks.

They are fine, I've ran a couple sets of HP+ and DTC60s on my car, no interest in spending more than amazon prime pricing on rotors.




***Just Remember the DTC 60 dust is corrosive and a bitch to get off after it gets wet and then hot again.

[Yanbags]

Hi guys,

Question about wheel hub rings on track. I've read and was told mixed things from seemingly credible sources about whether or not to use them. On track, I'm running 17x9 Enkei RPF1 wheels w/ RE71R tires.

From what I'm gathering for the BRZ on the forums - the wheels are centered by the lugs since they're conical, and after proper star-pattern torquing, there is no load on the studs/lugs. My alignment/race shop and a customer of theirs this weekend claimed metal (aluminum?) hub rings are very much recommended because they've seen broken studs when not used. I tend to trust them because they have several years of track experience and STI/BRZ specific setups but I'm a sitting duck on this one.

What gives?

Originally Posted by infinity21

Back to real life, I currently run RCE T2 which slightly understeers with 400/400 springs (at least that's my perception of the car's behaviour).

FYI - I also run the RCE T2 400/400 with their out of the box recommended settings for damper clicks and I wouldn't say it understeers at all on track. It could very well likely be your alignment setup; what are your alignment specs?