Brake Calipers - Modified Piston and Dust Seals

89porsche05

Subject: Brake Calipers with Improved

Piston Seals

Model Group

944 Turbo
4
944 S2, 928 S4

Part Identifier Number

4739/41 8907







ATTENTION: This bulletin replaces Technical Bulletin Group 4, Number 8907, dated June 2, 1989.

The front and rear brake calipers of the 944 S2, 944 Turbo, and 928 S4 for Model 89 received modifications in the area of the pistons and dust seals (now similar to the two piston calipers). Refer to the chart below for identification.

Replacement and repair procedures are different for each type of caliper and are detailed on the following pages.



Repair Instructions

Caliper Replacement

New type calipers can be fitted to earlier cars. After stocks of early version calipers are used up, only the new type calipers (with dust caps and modified pistons) will be available. New version calipers (with dust caps) cannot be paired with early version calipers (with scraper rings). Measure the brake piston diameters to be certain the correct calipers are installed during repairs. Failure to install brake calipers with the correct piston sizes side to side will cause uneven braking. Use the following chart to determine piston diameter applications.
Caliper Repairs

Repair sets for early version and new type calipers are available. New type pistons and dust caps cannot be installed on early version calipers. When rebuilding brake calipers, use only sliding lubricant P/N 000 043 117 00 on the pistons and sealing rings during assembly. Refer to Technical Bulletin Group 4, Number 8901, dated April 2l, 1989 for further information.



Brake Caliper and Repair Set Applications

944 Series
* After stocks are used up, calipers with 36 mm/38 mm piston diameter will no longer be available. When repairing, use calipers with 36 mm/40 mm piston diameter and install in pairs.

** When used up, brake calipers with scraper ring will no longer be available. When repairing, use
calipers with dust caps and install only in pairs.

*** In production, brake calipers with dust caps were installed on the rear axle from VIN: 95 KN 150216.
Visual inspection of front calipers is necessary for caliper type identification.

**** Front and rear calipers require visual inspection to determine caliper type identification.



Brake Caliper and Repair Set Applications

928 Series
* When used up, brake calipers with piston diameter 36/42 mm will no longer be available. When repairing, use calipers with piston diameter 36/44 mm and install in pairs.

** In production, brake calipers with dust caps were installed on front and rear axle from
VIN: 92 KS 860282.

*** When used up, will no longer be available. When repairing, use brake calipers with dust caps and
install only in pairs.