Q. How do I upgrade the brakes on my 968.
A. DISCS for use with Big Red or Big Black type
calipers (all 322mmx32mm)
965 (911-964 3.6 Turbo)
1-piece disc, cross drilled, 45mm top hat
965-351-045-00
965-351-046-00
928 GTS
1-piece disc, NON cross drilled, 45mm top hat
928-351-045-01
928-351-046-01
993 Twin Turbo
2-piece disc, cross drilled, 40mm top hat (separate disc and mounting
‘hat’)
993-351-045-10
993-351-046-10
discs are seldom used, 993RS cheaper
993RS
1 piece disc, cross drilled, 40mm top hat
993-351-045-00
993-351-046-00
DISCS for use with M030 (928 S4) calipers (all 304mm x 32mm)
968 M030
1-piece disc, cross drilled, 45mm top hat
965-351-041-01
965-351-042-01
928 S4
1-piece disc, NON cross drilled, 45mm top hat
928-351-045-01
928-351-046-01
Discs with a ‘top-hat’ (offset) dimension of 45mm will have
an outer disc pad face in the same position as standard – the larger
discs are thicker (32mm vs 28mm) therefore the inner pad face of the
discs are 4mm further in (into the car). This will close the gap between
the disc face and the track rod end – it has been suggested that
heat build up from the disc can be a problem, but I have never heard
of any actual experience of this.
Discs with a ‘top-hat’ dimension of 40mm will have an outer disc pad face 5mm further out than standard (also pushing the caliper further out by 5mm and closer to the spokes of your wheels). The inner pad face of the discs will be –1mm further out from standard (further out of the car) and hence remains virtually the same distance from your track rod end.
NOTE: the M030 spindle/hub assembly locates the disc approximately 3mm further out to compensate for the additional thickness of the discs from standard.
CALIPERS
Big Reds (993 Twin Turbo calipers)
993-351-425-10
993-351-426-10
36mm/44mm piston sizes
Leading, radial mounting, bleeder screws & cross-over tubes require
swapping over for trailing mounting. Pad retention springs will be upside-down.
Red in colour.
Big Blacks (928GTS calipers)
928-351-423-03
928-351-424-03
36mm/44mm piston sizes
Trailing, radial mounting, bleeder screws & cross-over tubes in
correct position. Pad retention springs in correct orientation. Black
in colour.
M030 calipers (928 S4 calipers) (also used on 944
S2 M030, 944 Turbo S)
928-351-421-03
928-351-422-03
36mm/44mm piston sizes
Trailing, radial mounting, bleeder screws & cross-over tubes in
correct position. Pad retention springs in correct orientation. Black
in colour. Note: depending what year car these are from, the piston
seal/dust seal design can differ. The older design is less robust/efficient.
The later design is the same as that used on the Big Reds/Big Blacks.
For these you can either use the standard 968 M030 dross drilled discs
or the 928 S4 NON cross drilled discs. Both are the same size and offset.
CALIPER ADAPTORS
Adaptors will be required to fit any of the M030, Big Reds or Big Blacks
to a standard 968 spindle. Adaptors are usually universal – in
that if you rotate them they will allow fitment of any offset disc noted
above with appropriate caliper. The caliper mounting hole in the adaptor
is usually offset by 5mm from one edge of the adaptor compared to the
other to make up the difference in disc ‘top-hat’ offset.
Note: some adpators are actually dimensionally ‘off’ – that is, they offset the caliper incorrectly so that the disc does not sit centrally in the gap of the caliper where the disc sits (maybe by 1 or 2mm). Also they may not sit the caliper – and hence pad – correctly on the disc pad face (distance from the edge of the disc to the centre of the disc). My adpators were as this and required some machining and shims! (shims are ok - since the rear calipers mount using shims as standard to centralise them on the discs)
For cars with M030 - why on earth you would want to change your calipers to Big Red / Big Black’s I don’t know – but if you do, adaptors are NOT required, but you would be limited to the 45mm offset 322mm discs.
For my upgrade I used Big Reds with 993RS discs (about the cheapest holy discs + 1-piece), also preferred the offset pushing the caliper further out. IMHO, bought as new, Big Reds + discs are only required if the cost outweighs the cost of buying used S4 caliper + a refurb + new S4 discs. Big Reds give TOO MUCH braking power, and I have not come across any tyres (standard 17” wheels) that do not lose traction when braking hard. This is why I now have 18” wheels with 235 road legal ‘slicks’.