Quote:
Originally Posted by diamondnik  The website I used coincides with realoem information, for example e34 525i uses a 25.4 MC up to 9/91, then it switches to 25.4/20.66.
So after crunching some numbers it seems that when I installed the 25.4/20.64 MC with otherwise stock brakes (54/34) brake bias shifted considerably - in a bad way. With same amount of force, compared to standard 23.81 the new MC caused decreased line pressure in front and considerably increased pressure in the back.
The brakes I plan on using now (57 in front with 325 disc, and 38 in back with 272 disc) will offer almost same as stock brake bias if used with 23.81 or 25.4 master cylinders, but when used with stepped 25.4/20.64 brake bias changes; theoretically the change would increase rear line pressure but I'm not sure that is happening because rears never lock up right now. For those rears to get more line pressure the MC piston would also have to move farther but if the pedal doesn't move more, rear pistons aren't getting more pressure. What I mean is, the large bore responsible for line pressure creates stiff feeling and modulation is affected it. |
I am a bit confused.....
The master cylinder for our ti's (318ti/323ti) is said to be 23.81mm. The same master cylinder is used by several other BMW's as well. On my master cylinder it can be read the numbers 23/20 (see the circle in the picture below). I suspected that this meant a diameter of 23.81mm front and 20.64mm for the rear although this is not read by the datasheets.
I had an old master cylinder in my garage and decided, in the name of research, to dismantle it and do some measurements.
As can be seen from the picture, the results of the measurements for the front are 23.8mm (i.e. 23.81mm) and the rear is 20.6 (i.e. 20.64mm) and the master cylinder for our ti's are definitively stepped. Is there a possibility that the standard rear diameter used for the BMW master cylinders is 20.64mm if not otherwise noted?