Bigger brakes

[MikkiJayne]

oh gotcha I read that wrong!

A hydraulic handbrake is not allowed for road use here. We have to have something mechanical.

Aren't the 17z discs smaller than the stock FL S8 fronts though? 330mm I think, compared to the S8's 345mm. People seem to use a 345mm Mercedes ML disc with the 18z too so also no bigger.

I have attempted to figure out fitting an 18z caliper to a 365mm RS4 front disc, but could see no way for it to work as the mounting lugs for the caliper and upright both occupy the same place, so I'm keen to see what you come up with. It would be much easier with radial mount calipers. That said, it might be possible with the ML disc. Just no upgrade in size, although the Porsche monoblock calipers appear superior to the S8 Brembos in pretty much every way.

It springs to mind actually that I don't think I've tried the 18z caliper with a stock S8 disc. Hmm...

[Audifan]

It's ok, no worries.

Bummer to hear. The other option is try and custom fit these for mechanical setup.

Yes they list the 17z calipers to use 330mm discs and 18z calipers to use 345mm discs but I'm sure you can use larger discs for either calipers. After some searching this guy is using 350 mm discs with 17z calipers

I did some more searching and found that the C5 RS6 and B7 RS4 use 8-piston calipers and 365mm discs. So I guess the other option is to try and fit 8-piston calipers for the front and use 365mm discs. Will these fit with 18" wheels?

[MikkiJayne]

I've done B7 RS4 brakes on a D2. Thats easy as they are radial mount calipers the same as the D2 Brembos so the adapter is a 10mm thick flat plate with 4 holes in it. I would expect they fit in some 18s as thats what the B7 had stock, although the RS6 had 19s.

The 18z will fit over a 365mm disc no problem - it just needs a litle grinding at the outer edges. But, the mounting lugs then occupy the same place in space as the lugs on the upright so you can't even put the caliper on the disc, let alone contrive an adapter. I'll get a pic tomorrow - its a vexing problem since those calipers are cheap and easily available.

[Stromaluski]

I would think it would be easier to simply swap to D2 A8 spindles and then use D3 brakes? D3 A8 have 360mm rotors. D3 S8 are 385mm rotors.

[Audifan]

Originally Posted by Stromaluski

I would think it would be easier to simply swap to D2 A8 spindles and then use D3 brakes? D3 A8 have 360mm rotors. D3 S8 are 385mm rotors.

Yeah but how is 2-piston (which are on the same side) calipers better then 4, 6 or 8 piston calipers!?!

[Stromaluski]

Originally Posted by Audifan

Yeah but how is 2-piston (which are on the same side) calipers better then 4, 6 or 8 piston calipers!?!

Depends on how you qualify one setup as being better than another.

[MikkiJayne]

Well, the 2 piston D3 calipers

• Work properly
• Are simple to service
• Don't seize up if the day has a Y in it
• Don't squeak
• Fit on larger discs than stock
• Are reliable
• Work properly (I know I already mentioned this, but I though it was important enough to mention again)

I am pretty sure the FL S8 Brembos were a fashion item rather than a technical solution, since W12 had larger brakes with sensible 2-piston sliding calipers. The RS 8-pots aren't much better in terms of maintenance, although they are very effective. I do like the Porsche 6-pots from an engineering standpoint, but I haven't ever driven with them.

The downside of the D3 385mm setup is the sheer weight of the discs - 18Kg (40lbs) each Thats just stupid and not good for handling so I plan to fit the 360s as they are a reasonable compromise in terms of braking performance v weight v cost. Alas they won't work with the very lightweight RS6 365mm discs, but you can't have everything.

If only the Porsche 6-pots could be made to work with the RS6 discs that would be a perfect solution. I keep holding out for a set of Q7 4m Akebonos, but they rarely come up in pairs, and never when I have any money.

[Audifan]

Originally Posted by Stromaluski

Depends on how you qualify one setup as being better than another.

I'm no expert with brakes but my guess is that having pistons on both sides of a caliper have better clamping force then having pistons on the same side.

[Audifan]

Originally Posted by MikkiJayne

I've done B7 RS4 brakes on a D2. Thats easy as they are radial mount calipers the same as the D2 Brembos so the adapter is a 10mm thick flat plate with 4 holes in it. I would expect they fit in some 18s as thats what the B7 had stock, although the RS6 had 19s.

The 18z will fit over a 365mm disc no problem - it just needs a litle grinding at the outer edges. But, the mounting lugs then occupy the same place in space as the lugs on the upright so you can't even put the caliper on the disc, let alone contrive an adapter. I'll get a pic tomorrow - its a vexing problem since those calipers are cheap and easily available.

Yes please post some pictures. It sounds like I might go this route