Re: E28 Brake Bomb Fixed

[Nathan J Nagel <gearhead+@xxxxxxxxxxxxxx>]

Excerpts from internet.bmw: 26-Aug-98 E28 Brake Bomb Fixed by Charles
Yia-Chun Lee@eul 
>  
> I wanted to thank all those who helped with tips on replacing the Brake
> Bombe on my 535i.  I completed the job in a few hours and the brakes feel
> great in a panic stop.  I was wondering if someone can explain how this
> bomb works and why it goes out.  Thanks again.
> Charles Lee
> cyclee@domain.elided
> 85 535i 180k
> BMW CCA# 148454

The power brakes on the 535i work off of hydraulic pressure generated by
the power steering pump, not engine vacuum as in most other cars.  The
"bomb" is a hydraulic accumulator, that is, it stores the hydraulic
pressure so that if you jam on the brakes suddenly (requiring more
pressure and volume than the pump is able to provide) you will still
have full power to your brakes.  If you've ever lived in a house with a
well that has a water tank with internal diaphragm, this works on
exactly the same principle (on a smaller scale).  Not sure why they
fail, but I've heard that replacing the filter in the bottom of the
power steering fluid reservior can keep your new "bomb" from meeting an
early death.

good luck,

nate 

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