323mm under 16s

[Rusty]

The 314mm disc is front vented and the 323mm is rear vented. My thinking is that a rear vented disc is going to work better with brake cooling ducts for track use.

So... I tried this today but it's just not going to happen with the 996 425/6 calipers I have. Fitted a 10mm and then 15mm spacer to see if I could manage it but it rubbed the inner wheel... just. It was damned close though

I did have a look at the brembo catalogue and there is a 320mmx30mm disc by Mercedes but the offset is all wrong - the hat height is 20+mm over the A8 and so the lower BJ becomes an issue.

There is also a 321mm A6 disc that is identical to the 314mm disc, i.e. it's front vented, so this isn't ideal but it's an interesting option to add a little more meat to the brake sandwich and still allow for the OE ABY Avus 16s to be used for winter.

[robo]

The 314mm disc is front vented and the 323mm is rear vented. My thinking is that a rear vented disc is going to work better with brake cooling ducts for track use.

So... I tried this today but it's just not going to happen with the 996 425/6 calipers I have. Fitted a 10mm and then 15mm spacer to see if I could manage it but it rubbed the inner wheel... just. It was damned close though

I did have a look at the brembo catalogue and there is a 320mmx30mm disc by Mercedes but the offset is all wrong - the hat height is 20+mm over the A8 and so the lower BJ becomes an issue.

There is also a 321mm A6 disc that is identical to the 314mm disc, i.e. it's front vented, so this isn't ideal but it's an interesting option to add a little more meat to the brake sandwich and still allow for the OE ABY Avus 16s to be used for winter.

You could remove little bit of meat from your caliper.
I had to do this in order to fit 996 caliper on my UR with 15'' wheel.

[Rusty]

I've inadvertently done that already, after a caliper bolt fell out on the way home from Combe many years ago

I spaced the calipers around 4.5mm to test for the 323s but will try and space it around 3mm for the 321s, as they're a little under that and my current pads are bang in the centre of the friction face of the disc, so there's a little breathing room.

[shaun5]

Just use Mov-it disc's 323mm disc and 16" Avus wheel / no spacer

[Rusty]

Lots of wedge though?

[Rocco]

Just use Mov-it disc's 323mm disc and 16" Avus wheel / no spacer

movit calipers too?

[shaun5]

Lots of wedge though?

Yep it was back in 2000 but its saved me several times from crashing so worth the money

[shaun5]

movit calipers too?

Yep the complete set up bought back in 2000.

[Rocco]

Yep the complete set up bought back in 2000.

very nice then,lucky guy

[Rusty]

322x22 according to the website.

Interested by these 321s, might have to have a looksee.

[shaun5]

322x22 according to the website.

Interested by these 321s, might have to have a looksee.

Im sure mine are 323x32. not 100% sure tho. Pretty sure ive got an old set of disc's somewhere. About £400 a disc last ones i bought £1000 for disc and pad change

[Rusty]

Yeah, that's a bit on the steep side Bit different to £250 for grooved discs and DS2500 pads

[Rusty]

A6 321mmx30mm discs are looking like an interesting option for some added meat, or machining down some 323mm discs to 320mm to get the improved cooling. I need to test fit a wheel when I get time and see how much I can space the caliper out (not much). All are the same hat height and thickness:-

[UrS4boy]

A6 321mmx30mm discs are looking like an interesting option for some added meat, or machining down some 323mm discs to 320mm to get the improved cooling. I need to test fit a wheel when I get time and see how much I can space the caliper out (not much). All are the same hat height and thickness:-

Thanks for posting those up Andy. Just for the record, with the North American Girling G60 UrS4/S6 struts (different than the Euro/ROW UrS4/S6 struts), I am running 928 GTS Black calipers mounted to OE RS2 caliper brackets (mounted to the strut) with the 323 x 30 early S8/later D2 A8 rotors under the 16" five spoke Fuchs wheels. There were issues. Some people have gotten away without any spacer. I had to run a 5 mm H&R hubcentric spacer *AND* I had to get the wheels rebalanced because the weights hit the caliper. The resulting location of the weights is not optimal and there is some vibration at 130 kph and up. I don't think there is any such issues with the 6 spoke 16" Avus wheels on a C4 UrS.

[Rusty]

What part numbers are the 928 calipers? Are they the 2 piece 993 items? There was very little chance of fitting my current 996 calipers under the Avus with a 4.5mm spacing. With a 3mm spacing, it will be very tight but the chances of massive brake temperatures while running those wheels are low...