No rear brakes - std setup?

[hennabm]

A mate of mine with his 89 325i auto is telling me he has no retardation on the rear brakes at all.

The car is standard with ABS. The light is behaving. The pedal feels normal and no work has been done on the car for over a year.

It pulls up straight when driven so the fault is across both rear wheels.

Has anyone come across a simialr problem?

[flybynite]

Not had that before but could be a few things. Does the ABS work on the front? Has he tried a stop on gravel?

My thinking is it could be the ABS unit as they do get gummed up, master cylinder or something in the pipe between the ABS unit and the rear T-piece that splits to the rear wheels. That can get a bit crusty too.

By the way, how is the henna chromie? Mine is still needing a bit of fettling bit I'm holding yours up as the standard I need to get it to

[hennabm]

Thanks mate.

I was thinking the same about the abs unit. I just wondered if anyone had had the same.

The old 323 is still with me and doesn’t change.
It gets out a little each year.

[hennabm]

A bit more on the car today.

The ABS clicked and jittered every time the key was activated, so as an initial investigation we cracked off pipes along the line. First off was the abs unit to the rear pressure regulator on the nsf of the chassis. Fluid coming out there under pressure.
Then to top side and underside of said regulator and fluid coming from both sides.
Then on to the T piece above the rear subframe. First the feed in pipe and yes we had fluid.
Then to each outlet and again fluid.

Then we went to the flexis from body to trailing arm. Cracked the joint on each one in turn; pressured the system and - no fluid. This was on the trailing arm side as it was the easier to access.

Seems like both flexis are blocked. This to me seems undos unlikely but it is the only point where fluid does not escape from a cracked joint when under pressure.

I will change all 6 flexis (F&R) and see how we go.

I’m now waiting for the parts from BMW. I’m pleased the bill isn’t mine!

[fixedwheelnut]

A bit more on the car today.

The ABS clicked and jittered every time the key was activated, so as an initial investigation we cracked off pipes along the line. First off was the abs unit to the rear pressure regulator on the nsf of the chassis. Fluid coming out there under pressure.
Then to top side and underside of said regulator and fluid coming from both sides.
Then on to the T piece above the rear subframe. First the feed in pipe and yes we had fluid.
Then to each outlet and again fluid.

Then we went to the flexis from body to trailing arm. Cracked the joint on each one in turn; pressured the system and - no fluid. This was on the trailing arm side as it was the easier to access.

Seems like both flexis are blocked. This to me seems undos unlikely but it is the only point where fluid does not escape from a cracked joint when under pressure.

I will change all 6 flexis (F&R) and see how we go.

I’m now waiting for the parts from BMW. I’m pleased the bill isn’t mine!

More common than you think, normally causes brakes binding before total failure, as the pressure can force through the restriction but the natural return of the caliper seal cannot. at least it is a relatively cheap fix.