RS2 brakes big enough?

[Bowlerwell]

There's an RS2 on pistonheads at the moment that claims, "The car also benefits from having the bigger 993 turbo brake upgrade with bigger calipers and drilled discs front and rear."

Is this really necessary?
Won't it just mean bigger bills when pads or discs need replaced?

Thanks,
JohnB

[alg]

Yes and yes (but not much in it)

[HPmuirt]

Yes, the pads will be more expense, but mainly because the numpty put x-drilled discs on so they will need to be changed more often X-Drilling the fronts is pointless, but the rears too, that is just plain stupidity

Discs were originally drilled because early brake pad materials gave off bubbles of gass when heated to high temps (gassing out). The gasses become trapped between the brake pad and disc, preventing the friction contact required to slow you down. Thus holes were added to allow the gasses to vent away. This was a big advantage, but modern pads release virtually no gas.

Also, contrary to popular belief, X-drilling actually increases the disc temperature (very slightly), but MOST importantly, it creates stress points, making the disc more likely to crack and on top of that it chews brake pads at a phenomenal rate.....think cheese grater Also, drilled discs are noisier and more likely to wear and cause uneven feeling brakes, causing vibration as they age.

Question, F1 uses every technology available to them (until banned) and develops many more besides, so why don't F1, Indy, NASCAR X-drill? Also, why is X-drilling now being banned in more and more motor sports?

The exception to the above is on bikes, where the discs are HUGE. Cracking/temp issues and pad wear remain, although much less due to the weight of the machine, but X-drilling is used to reduce the mass of the rotating parts.

The current wisdom suggested that using grooved discs and pads is potentially worthwhile - certainly for track cars, but doubtful for road cars that only see the track a couple of times a year at best.

Cutting thin, shallow slots across the face of the disc can clean the face of the pads, by reducing the glazed top layer which appears on the pad when heated to very high temps – normally only track temps though (i.e. me at Castle Combe ). The glazed layer does not produce the same friction as the normal pad material and therefore significantly impairs braking efficiency.

Apparently, the likelihood of stress fractures is much lower with grooves compared to drilled, although still greater than standard discs of course.

Cheers n

Si

[alg]

The OEM porsche/audi discs are cast not drilled. But otherwise I agree not needed on road car with modern pads.
I may change my mind about cost given new front pads DS2500 £130/pair with correct shims from audi £110/for four as there does not seem to be a direct porsche range complete alloy shim with 44mm/36mm anti vibration plugs !!!!!!!!!!!!!!!!!!!!!!!!!!!
I know you can get the plugs at £2.50 a piece and reuse the shim before anyone tells me !! but I need to keep it simple for the local audi specialist

[CliveH]

Cross-drilled discs

You make some interesting points Si, which I can't fault (but those of you who know me will vouch for my Grade 1 in "Technically Challenged"... ), but it does raise the question then of what is the wisdom of, for example, Audi continuing to use cross-drilled (well cast) discs on the RS6+, RS4 B7...the list goes on (not to mention Porsche, BMW, Merc, Ferrari...) ???

[Lloyd]

You make some interesting points Si, which I can't fault (but those of you who know me will vouch for my Grade 1 in "Technically Challenged"... ), but it does raise the question then of what is the wisdom of, for example, Audi continuing to use cross-drilled (well cast) discs on the RS6+, RS4 B7...the list goes on (not to mention Porsche, BMW, Merc, Ferrari...) ???

Perhaps, this is more of a cosmetic consideration? Big discs with holes in certainly 'look' sporty... Do they sell better than solid discs? "Go faster discs etc"

Perhaps, one reason for cross-drilled discs reaching higher temperatures (than solid) is simply due to them having less mass? Marginally less metal to store energy, hence marginally higher temperature?

[Fat Audi 80]

.... They look nice?





ETA: Bollocs, beaten to it....

[Smith_S2]

would these fit an S2 with the right carriers?

http://cgi.ebay.co.uk/PORSCHE-993-BR...QQcmdZViewItem

just lost out on a house, money is going elsewhere.....on the S2!

[BRY]

Yes they will, ask about corrosion under the stainless guides before you buy them.
Then ask me for some 996s :mischeif:

[Flat on my back]

Discs

Plain discs, slotted pads, me being tight arsj!

[rs2315]

There's an RS2 on pistonheads at the moment that claims, "The car also benefits from having the bigger 993 turbo brake upgrade with bigger calipers and drilled discs front and rear."

Is this really necessary?
Won't it just mean bigger bills when pads or discs need replaced?

Thanks,
JohnB

Standard calipers just fine.
It's all in the pads, get those right and you'll stop good enough
rs2315.

[dan_b]

Yes, the pads will be more expense, but mainly because the numpty put x-drilled discs on so they will need to be changed more often X-Drilling the fronts is pointless, but the rears too, that is just plain stupidity

Discs were originally drilled because early brake pad materials gave off bubbles of gass when heated to high temps (gassing out). The gasses become trapped between the brake pad and disc, preventing the friction contact required to slow you down. Thus holes were added to allow the gasses to vent away. This was a big advantage, but modern pads release virtually no gas.

Also, contrary to popular belief, X-drilling actually increases the disc temperature (very slightly), but MOST importantly, it creates stress points, making the disc more likely to crack and on top of that it chews brake pads at a phenomenal rate.....think cheese grater Also, drilled discs are noisier and more likely to wear and cause uneven feeling brakes, causing vibration as they age.

Question, F1 uses every technology available to them (until banned) and develops many more besides, so why don't F1, Indy, NASCAR X-drill? Also, why is X-drilling now being banned in more and more motor sports?

The exception to the above is on bikes, where the discs are HUGE. Cracking/temp issues and pad wear remain, although much less due to the weight of the machine, but X-drilling is used to reduce the mass of the rotating parts.

The current wisdom suggested that using grooved discs and pads is potentially worthwhile - certainly for track cars, but doubtful for road cars that only see the track a couple of times a year at best.

Cutting thin, shallow slots across the face of the disc can clean the face of the pads, by reducing the glazed top layer which appears on the pad when heated to very high temps – normally only track temps though (i.e. me at Castle Combe ). The glazed layer does not produce the same friction as the normal pad material and therefore significantly impairs braking efficiency.

Apparently, the likelihood of stress fractures is much lower with grooves compared to drilled, although still greater than standard discs of course.

Cheers n

Si

Aah, at last, someone who agrees with me point for point on disc technologies!

[dan_b]

There's an RS2 on pistonheads at the moment that claims, "The car also benefits from having the bigger 993 turbo brake upgrade with bigger calipers and drilled discs front and rear."

Is this really necessary?
Won't it just mean bigger bills when pads or discs need replaced?

Thanks,
JohnB

There are those brake-fetishists who would argue that you can never have big enough discs and calipers, and on the whole they're right, although there are always other factors to consider, like disc mass, disc diameter, disc thickness, brake pad material, numbers of pistons in the caplipers, type of brake fluid, and how wide (and sticky) your tyres are.

I've never heard any S2/RS2 owner say that they were perfectly happy with stock brakes though, and of course Audi did offer a factory upgrade on the standard RS2 (304mm)...