Successful Brake Booster Fitment! [960]

[petershen1984]

Today I replaced my brake booster on the '92 960. Appearantly it was damaged by long term usage of a steering wheel lock (by the previous owners) that also "lifts" the brake pedal, pulling on the brake booster itself. The booster still responds to vacuum input and works properly, but there is some length of travel before the brakes are felt. I've panic-stopped a few times, but the braking force didn't feel as though I slammed on the brakes.

When the old booster was removed, one could actually push down on the actuator and feel the gap (although it won't go down further for lack of vacuum). This corresponds to the feel when applying the brakes when the engine is not running, but only then I couldn't know any better.

My replacement booster came from a donor 740 vehicle, in spite of the differing dimentions. My mechanic and I speculated whether it will fit, noting that the later 960s and 940s use the same booster.

The 740 (940, '95 960, S90) booster has a shorter diameter and is wider (sitting on the floor), and the original booster from 1991~94 are of wider diameter and less thickness.

Removal of the booster (by my new mechanics) involved working under the driver's kick panel. To give as much clearance as possible, the throttle pedal and cable was removed. (I had some fun playing with the "throttle cable lever" on my hands and vocalizing engine noises.... they jokingly said, "Having fun?")

The master cylinder, to which the booster is mounted, is unscrewed and simply swivels out of position (literally) with the brake lines still attached. The booster job is done without disturbing the state of the brake fluid.

The new booster was literally a drop-in replacement, and once the booster was mounted to the pedal and chassis, the master cylinder simply fastened onto the booster in the new mounting position.

In troubleshooting this issue (the pedal feel), I've bled brake fluid, replaced rotors and pads, all to little avail. At last, the firm pedal feel is restored with a new donor booster. At a bargain price, it has some swooshing noise, which I can live with, but the pedal feel is definitely what it's supposed to be on a luxury Volvo with ABS.