I am in the process of completing a BMW E30 325i racecar, based on a shell from a 1990 316i non-ABS model. The car will remain non-ABS, so I have purchased a new ATE brake master cylinder BMW part number 34311154405, which is deemed correct for a non-ABS system. This master cylinder has 3 ports, 2 ports at the far end(furthest from the firewall) and the single port closer to the servo. The 2 ports facing horizontally have a smaller holes for fluid to pass through. The single port at the end facing downwards has a larger hole for fluid to pass through. I have assumed that the 2 ports at the end, next to each other, could not be for the front brakes since one has a larger hole for the fluid. This would mean that the circuit comprises split front brakes and a single line for the rears.
Can anyone confirm that this is correct?
Also, that means this MC a single diameter bore. Correct?
Brake master cylinder question
Moderator: martauto
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Brianmoooore
- E30 Zone Team Member
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- Joined: Mon Jan 10, 2005 11:00 pm
Brake circuit split on an E30 is simple front/rear, with a pressure limiter in the rear line (close to the M/C) to help prevent rear lock up.
The two ports adjacent to each other are one each for each front brake. The only difference with an ABS master cylinder is that one of the two ports is undrilled and unmachined, with a single line going to the ABS pump for the front brakes, and a line for each front brake coming from the ABS pump.
Standard cylinder is stepped, 22.20mm and 17.46mm.
The two ports adjacent to each other are one each for each front brake. The only difference with an ABS master cylinder is that one of the two ports is undrilled and unmachined, with a single line going to the ABS pump for the front brakes, and a line for each front brake coming from the ABS pump.
Standard cylinder is stepped, 22.20mm and 17.46mm.
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DanThe
- E30 Zone Team Member
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- Location: Staffs
The front half of the cylinder is smaller than the rear so that the piston can be fitted, this means the rear brake circuit which moves less fluid and uses a smaller piston is always at the front
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richard33
- E30 Zone Newbie
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- Joined: Sat Jan 07, 2017 11:00 pm
Many thanks for the replies - however I am now more confused, as the two replies appear to contradict each other!
The photo shows the MC.
As I said in my original post, the 2 ports at the far end of the cylinder have different size fluid transfer holes - the horizontal one is about 2mm and the bottom one is about 4mm. Why would this be the case if they are both used to feed the front brakes?