Master cylinder help! My 1996 Z3 just had its first brake job

Apr 27, 2022
Hey Gang - just bought a 96’ Z3. Vehicle history states the three owners before me have replaced exactly one set of pads (rears) over 26 years and 50,000 miles. Suffice it to say, a bit of brake work was needed. I need some advice about a Master Cylinder replacement….

It had squishy brakes during my first test drive - pedal decompressing further than normal, creeping while at a stop, reduced braking distance, signs I’ve associated with a failing master cylinder. I went ahead and changed the fluid (finally) using a pressure bleed - fluid was obviously very worn, to the point where I had to clear a bit of calculus at the nipple to get fluid flow. No improvement.

I am more confident it’s the master cylinder at this point. I’ve felt this before in other vehicles, and I’ve done this job on other vehicles with staggering improvement. My 2 questions to the forum is - This vehicle has an ABS system, but I’m not sure a modern reader is going to open the ABS valves for me - required after I introduce air at the master cylinder. How have you guys figured this out? Apart from bench bleeding the new Master cylinder, installing, and pressure bleeding while manipulating the ABS system, are there any other tips I’ll run into as a guy who has never done this in a Z3 before?

My mechanic skill comes from a lifetime of errors, a Haynes manual, and a bit of confidence with a wrench. The Z3 Haynes manual instructions for a master cylinder replacement states - “please don’t do this.” What’s the fun in that?:cool:


Zorg Guru (IV)
New Zealand Zeds
Dec 9, 2014
Timaru, New Zealand
Model of Z
3.0L, 2.8L, 2.0L Z3 Roadsters
Welcome to the forum.

The fun you'll have is finding a scanner to talk to he ABS unit. Your car has an OBD2 compliant DME but the rest of the cars modules are OBD1/ADS. So, you need scanner that can talk both OBD1/ADS and OBD2.

I purchased the Foxwell NT530 with BMW software as it OBD1/ADS and OBD2 capable. Have not yet tried to talk to a OBD1 ABS as yet.

There is also the NT680 family of all vehicles, all module scanners.

A bit more reading:
Apr 27, 2022
Thanks NZ00Z3 - there’s such a wealth of information on OBD1/ADS and OBD2/DME. Diagnostic wiring diagram confirms pin 20 of the OBD1 port commands the ABS module.

I’m going to try the INPA computer rig route and report back here. From what I have been reading - an INPA computer rig with a true com1 port grants the greatest level of data and control.

I didn’t realize my Z3 would take me back to school. I haven’t studied this hard for years.:oops: