Identifying 911 front brakes and strut assemblies:Front Struts:
Boge strut housings were standard equipment, and are the most common found on the 911. They are black (sometimes gray) in color, and used a standard hydraulic shock insert. The advantage of a Boge strut is that you can replace the shock insert with either Boge, Koni, Bilstein, KYB, or your favorite brand shock insert.
Koni strut housings were optional equipment on 911s through 77, and are identified by their red/orange color. Most Koni shock inserts were originally hydraulic, capable of being adjusted firmer or softer by removing the shock and manually adjusting the setting. Newer Koni replacement inserts are gas shocks with adjustment made by turning a knob at the top of the shock (taking only a few seconds to change the firmness).
Koni struts can only use a Koni shock insert.
Bilstein strut assemblies were optional equipment on the 911, and standard equipment on the 911 Turbo. They are identified by their green (sometimes yellow) color. Bilstein struts can only use Bilstein shock inserts.
Front Brakes:
M calipers. Stock, steel calipers for 911’s through 75. Caliper mounting bolt spacing on strut is about 3 inches. Figure 1 and Figure 2 show 'M' calipers installed on a car.
S calipers. Aluminum, larger calipers used on 911S and ‘S’ option cars through 77. Mounting bolt spacing on strut is about 3.5 inches. Cannot be put on ‘M’ caliper front end. Can be used on A caliper front end.
A calipers. Stock, steel calipers used on 75-83 911. Mounting bolt spacing on strut is about 3.5 inches (same as ‘S’ caliper). Carrera calipers were used on 911’s from 84-89, and accomodate a brake pad wear sensor. Figure 3, Figure 4, and Figure 5 show 'A' calipers from a 911SC front suspension.
All 911s through 89 used the same size front torsion bar (19mm). Note: The 914 torsion bar and the 911 torsion bars are not interchangeable, as the number of splines on the bar are different.
911 Rear Shocks and brakes:
Can usually be identified by color, although the brand is usually stamped on the lower section of the shock.
Black or gray: Boge
Green or yellow: Bilstein
Red/orange: Koni
White: KYB
Rear calipers were the same for 911’s from 69-83 (‘M’ type)
Rear calipers on 911’s 84-89 were Carrera type
