Just installed C6 RS6 rear rotors
04-20-2009, 12:56 PM
#11
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Curious about how you modified the caliper carriers...
and what you did with pads.
How did you modify the rear caliper carriers? Also did you use RS6 pads, claiming they just have less pad material on them out of the box?
A customer running the RS4 Ceramic Front Brake Package has inquired before about doing a larger rear setup, though this is the first I've seen anyone attempt or fit a larger rear rotor. I will price these parts out and if major modifications aren't needed for modification I'd be happy to build a kit price for interested folks here too, even a group purchase if people are interested even.
My only concern is if you see the rears locking up too early or even before the fronts causing ABS activation and too rearwards bias. However a lot of Audi owners go to larger rear brakes with OE equipment quite often, even big brake manufacturers tend to offer rear brake upgrades which upsize the rotor.
Good work!
Cheers,
How did you modify the rear caliper carriers? Also did you use RS6 pads, claiming they just have less pad material on them out of the box?
A customer running the RS4 Ceramic Front Brake Package has inquired before about doing a larger rear setup, though this is the first I've seen anyone attempt or fit a larger rear rotor. I will price these parts out and if major modifications aren't needed for modification I'd be happy to build a kit price for interested folks here too, even a group purchase if people are interested even.
My only concern is if you see the rears locking up too early or even before the fronts causing ABS activation and too rearwards bias. However a lot of Audi owners go to larger rear brakes with OE equipment quite often, even big brake manufacturers tend to offer rear brake upgrades which upsize the rotor.
Good work!
Cheers,
04-20-2009, 02:21 PM
#12
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you used the stock RS4 calipers, correct?
front brake pad? you mean inner or outter pad?
are you saying the RS6 pad material ad/or backing plate is thinner than the RS4's?
I could see that: make the pad backing plate a bit thinner in addition to making the pad material a bit thinner...6mm is a good bit though...
are these the stock pad thickness's
RS4 F 16.5/R 15 mm
04-20-2009, 02:27 PM
#13
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Have you considered what this does to your brake bias? This may making stopping distances worse than stock if you trigger ABS sooner and the computer doesn't do a good job of redistributing the braking duties.
This is more of an appearance mod than a performance mod. With the weight distribtion that Audis have, they tend to punish front brakes. I've never seen a tracked Audi with distressed or overly worn rear brakes.
This is more of an appearance mod than a performance mod. With the weight distribtion that Audis have, they tend to punish front brakes. I've never seen a tracked Audi with distressed or overly worn rear brakes.
the car is front heavy taxing the front brakes, and under-loading the rear...
also, the swept area is larger, which shouldn't affect brake force, but help temps...
the larger radius will allow more braking torque...which may prematurely lock the rears up (if not for the ABS engaging)...
some of this can be mitigated by pad material choice, then again, this probably negates any advantage the larger rotor may give...
regardless, it does look cool
04-20-2009, 02:57 PM
#14
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The points about brake bias are true, but this doesn't even increase the radius of the disc 10%. You are going to change the bias of the brakes MUCH more by lowering the car (reduces weight shift forward) adding higher grip pads (increases weight transfer forward) or even changing tires. And I don't see everybody getting all crazy about that.
Subtle changes that may make a difference to the driver of an R15 will probably go unnoticed by the driver of an RS4.
Subtle changes that may make a difference to the driver of an R15 will probably go unnoticed by the driver of an RS4.
04-20-2009, 03:12 PM
#15
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The points about brake bias are true, but this doesn't even increase the radius of the disc 10%. You are going to change the bias of the brakes MUCH more by lowering the car (reduces weight shift forward) adding higher grip pads (increases weight transfer forward) or even changing tires. And I don't see everybody getting all crazy about that.
Subtle changes that may make a difference to the driver of an R15 will probably go unnoticed by the driver of an RS4.
Subtle changes that may make a difference to the driver of an R15 will probably go unnoticed by the driver of an RS4.
but who knows if it will be an issue...
normally no, maybe on occassion the ABS will engage sooner...
it all depends on how fine the ABS is calibrated...
if someone uses the brakes correctly, ABS should never engage...
in a panic stop, the rears MAY lock up and increase braking distance...
but it is a valid topic for discussion...is it a 'problem'? probably not...
04-20-2009, 04:10 PM
#16
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I'm unsure what it would do to ESP function as well. It may become more intrusive in situations where it calls for rear wheel braking.
I'm speaking a bit from experience. I added a 6-piston front brake kit to my S4 which shifted the bias about 3% forward of stock taking just piston size and rotor diameter into account. I didn't see any tangible difference in bias. However, after upgrading to a larger rear rotor (255 mm to 306 mm) which changed bias 6% in the other direction to am overall 3% rearward bias from stock, I could definitely feel a difference in the way the chassis behaved under hard braking. In actuality, I probably shifted the bias more than 6% as I went with pads with higher coef. of friction too.
I'm not saying this mod is a bad idea, I'm just saying I would plan things out carefully. Swapping brake parts doesn't aways equal better results.
I'm speaking a bit from experience. I added a 6-piston front brake kit to my S4 which shifted the bias about 3% forward of stock taking just piston size and rotor diameter into account. I didn't see any tangible difference in bias. However, after upgrading to a larger rear rotor (255 mm to 306 mm) which changed bias 6% in the other direction to am overall 3% rearward bias from stock, I could definitely feel a difference in the way the chassis behaved under hard braking. In actuality, I probably shifted the bias more than 6% as I went with pads with higher coef. of friction too.
I'm not saying this mod is a bad idea, I'm just saying I would plan things out carefully. Swapping brake parts doesn't aways equal better results.
only one way to really know...thrash the car and see what it feels like...
a panic stop is not the time to find out braking distances are increased
<9 minute on the 'ring is a very good effort...nice
04-20-2009, 04:56 PM
#17
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That track is very humbling, definitely something you should check out if you haven't already. You'll never see a larger collection of M3 CSL's parked in one place!
04-21-2009, 06:58 AM
#18
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Good points...
Actually, I have been on a very fast track (the back straightaway at Road Atlanta) and have been found wanting for brakes at the end of the straight. I upgraded to the ceramic rotors and have still been told my rotors were glowing red after braking there, so it is entirely possible to tax the rears. With the stock suspension that is minimised since there is significant nosedive, but with an upgraded system that keeps the rear end more planted meaning more braking would be done by the rear brakes and an upgrade my be entirely rational.
Now as for ESP and ABS kicking in prematurely, well on the track I switch off the ESP and as for ABS, I have had them kick in on many a track braking at the end of a fast section, so I think it would be a moot point. As far as street driving though, neither should be an issue since speeds are slower and the system should correct appropriately even if there is increased rear braking force.
As for mods, how exactly were the calipers and/or brackets and dust shield modified. As a matter of fact is the dust shield really necessary?
Now as for ESP and ABS kicking in prematurely, well on the track I switch off the ESP and as for ABS, I have had them kick in on many a track braking at the end of a fast section, so I think it would be a moot point. As far as street driving though, neither should be an issue since speeds are slower and the system should correct appropriately even if there is increased rear braking force.
As for mods, how exactly were the calipers and/or brackets and dust shield modified. As a matter of fact is the dust shield really necessary?
04-21-2009, 08:44 AM
#19
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I'm no fan of messing with brake bias on any vehicle, yet alone a car with ABS and ESP. For appearances only? That sounds like a discussion I had many times with my wife. Like many women, she's all for looks at the expense of function (take high heel winter boots for example). Function always trumps form in my book but whatever turns your crank.
Well at least the increased weight will help balance out the Audi's front weight bias.
Well at least the increased weight will help balance out the Audi's front weight bias.
Last edited by ELEVENS; 04-21-2009 at 08:49 AM.
