I'm using the M/s from my donor cavalier (SRI 16V K reg) and it's an ATE type with 2 outlets. One is M10 (nearest the pedal) and one is M12 (nearest the front of the car). I took it off of the original car and all that were in the holes were pies/nuts(no valves). The original car had ABS and I don't know which port is for the front and which is for the rear (maybe it does'nt matter).
Can anyone confirm or tell me which is which???

I isnt M12 i believe, i think it is not mectric.

Is it ali, just over 4" long with mounting holes offset?

I think it is a front/rear split for abs cylinders.

I`ll check my haynes manual

Darren

BTW most cylinders have the same bore, so pressure it almost equal.

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Is it ali, just over 4" long with mounting holes offset?

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I isnt M12 i believe, i think it is not mectric.

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Hi, sorry if that sounded pedantic, just saying to prevent buying wrong item.

Ok ate cylinder, believe closest to the pedal is front, furthest is for back.
Looking at the manual i believe it has a smaller bore for the rear which should produce less pressure. Can`t be 100% due to manual not saying but i was going to use a carlton which had a similar ate cylinder.

Is there numbers on the cylinder, if so where are they, as the bore size on disimilar bores are cast on the outside.




Darren

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Hi, sorry if that sounded pedantic, just saying to prevent buying wrong item.

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Hi i`ll say the bore is 22mm for both.
You might like a carlton 2l cylinder, may fit servo (if you are using one). It has a 22 / 19mm split so less pressure is given to the rear. remember it is pi*r^2 so the line pressure at the rear is a reasonable amount less. I was going to use this cylinder until i went for vectra abs, which uses diagonal split so needed equal bores.

Just had a thought, it was my local factors that said it was imperial, they might have been wrong.

Darren

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You might like a carlton 2l cylinder

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On every vehicle that I have worked with a front-rear split the front section supplies the front brakes.

turbodisplay, smaller bore will give more pressure, not less, don't confuse everybody!!!

A smaller bore will give less line pressure, less area, as this is a dual circuit master cylinder.

It is stroke not force that comes into play:

Check wickapedia:
http://en.wikipedia.org/wiki/Hydraulic_brake

pedal > 22mm piston > 19mm piston

area of 22 piston = 380

area of 19 piston = 283

force of 1 at pedal end,

force in 22 chamber = 380

force in 19 chamber = 380 * 283/ 380 = 283

force ratio 380/ 283 = 1.3
Darren

[Edited on 17/4/07 by turbodisplay]

from your wikipedia link:

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A larger diameter master cylinder delivers more hydraulic fluid to the slave cylinders, yet requires more brake pedal force and less brake pedal stroke to achieve a given deceleration. A smaller diameter master cylinder has the opposite effect

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Yes, but remember you are not acting on the 19mm directly.
The 19mm is a slave pistion.
the less area of the 19mm piston will result in less force exerted when compared to the 22mm pistion.

If the pistons are parrallel as in a ballance bar then yes, smaller bore more pressure.

Been thinking over this one and have come to the conclusion that both cylinders will produce the same pressure, not more or less (I WAS WRONG) well half wrong .

I still think it is for the rear (the 19mm) as it will displace less fluid. I think it is to reduce total pedal movement.

Darren

Well after some investigation i'd say the following.
1 the front chamber seems to have a greater flow
2 the front chamber seems to apply pressure very slightly before the rear chamber.

Me being stupid here:

Is that front being closest to the pedal, or front of the car?

Darren