Do you need upgraded brakes for a Stage2 ?

[Ceveman73]

...You're right about piston area and brake bias etc, though you don't take into account the increased leverage of the larger front discs, and it could be that 68% front bias isn't enough.

Nick

The front/rear bias of 68% is with STOCK front and rear discs. Increasing the leverage at the front by installing a larger front disc will increase the front bias even more. A 410mm disc pushes the leverage out by 4%, so presumably will increase the front bias by the same amount, giving an immense 72% forward bias. I guess you can dial that back by fitting rear pad with a 4% higher COF than the stock pads?

Anyone know what options are available for the rear, apart form simply fitting more aggressive pads?

M.

[welwynnick]

The brake bias has to be set for worst case, which is an emergency stop (about 1g). The RS6 has a static weight distribution of about 60/40, and the wheelbase is 112 inches, so the CG is 112 x 0.6 = 67 inches ahead of the rear wheels, but it moves forwards a lot in 1g braking. The CG height is about 20 inches, so the projected CG moves forwards 20 inches. 67 + 20 = 87 inches from the rear axle, so the dynamic weight distribution becomes 87 / 112 = 77% on the front.

So the front brakes really do the lion's share of the work, and comparing the swept area of the front and rear discs in any car (it's a good measure of their ability to dissipate heat) you normally find that though the front brakes are larger, they're generally not large enough.

Having said that, I think the 430mm brakes that I linked above might be too much. The calipers have large pistons: 38, 38, 36 & 32 mm, which would push the bias too far forwards. 410mm on stock calipers sound like a great idea to me. The mod I did before was to upgrade my Merc brakes from 360 single piece to 390mm floating, and it was a great move (and balance was no problem). Because the leverage is better, the calipers don't have to work as hard. Subjectively the car feels lighter - better than feeling that the car's too heavy for it's brakes.

The two companies I linked did actually offer rear brake upgrades as well.

Nick

[zex]

Since I have carbon ceramics on my C6, I didn't have to upgrade but I'm using this brand on my track car (Focus ST mk3) and it does what they advertise. You can customize your big brake kit.
https://ceika-store.com/products/cbk77? ... udi~md_rs6

[julianmalc]

I Have a stage 2 MRC tune and found the standards brakes struggling, went to BG engineering and had the AP calipers and 410mm AP discs conversion for the front, this is the largest disc AP racing make, I had ferodo 2500 front and rear pads, I had a lot of nose dive and the rear discs were marking up, so bought standard size floating AP rear discs, because they have higher cof than standard and matches the front disc material the car brakes a lot flatter and more balanced, best value mod I have done after the ARB.

[welwynnick]

Are you saying that upgrading your rear brakes gave you less noise drive?

Did you have your front and rear brakes upgraded at the same time?

Cheers, Nick

[julianmalc]

Hi Nick,
yes, she was braking better with the front set up and just rear pads, Hel lines front and rear plus Castrol SRF brake fluid, but was more on the front end biased, as they got hot you could feel the rear losing retardation and making it even more nose heavy, the AP discs are lighter on the rear than standard and floating,slotted as well, the braking had less weight transfer to the front and less change as the brakes got hot. In general more braking with a balanced feel that does not change when the brakes get hot.

[julianmalc]

NB; I changed the front set up first and all the lines plus brake fluid, drove for a couple of months and had the above, then fitted the AP rear discs and noticed an immediate improvement in balance

[don0301]

Can anyone tell me if HEL lines for standard setup will fit ok with 410 AP discs?

Or do I need to get new ones?

TIA

[IanH755]

HEL lines fit with AP 410mm discs which are using the OEM caliper but NOT with AP Calipers (different connections).

[don0301]

Ta

[don0301]

Just pulled the trigger on AP discs all round, 410mm fronts with standard calipers.

Can anyone point me to where I can get good quality caliper service kits?

TIA