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Master Cylinder Sizes for dual setup
mikeb - 3/1/12 at 01:45 PM

I've got the OBP pedal box with twin master cylinders.
They send me two 0.7" cylinders.
I using standard sierra calipers on the front and drums on the rear.(may up grade after IVA to discs)

I've used search but can't find anything conclusive but one post saide .625 for the front and .7 for the rear. Is this the right choice to get the bias about right for fine tuning with bias bar?
Cheers

[Edited on 3/1/12 by mikeb]

macc man - 3/1/12 at 06:13 PM

Usually the rear cylinder is larger than the front to give more effort to the front brakes. You should have been sent two different sizes. Give them a call they will give good advice.

phil clegg - 6/1/12 at 10:24 PM

i fitted this system on my haynes,it came with different cylinders ,the brakes were still crap,i had to put different cylinders on than supplied to get good brakes,mine are rear disc,it took a few attempts ,i will check my cylinder sizes and utu if you want with finished spec,phil 07957617548

ChrisLeary - 6/1/12 at 11:00 PM

quote:
Originally posted by mikeb
I've got the OBP pedal box with twin master cylinders.
They send me two 0.7" cylinders.
I using standard sierra calipers on the front and drums on the rear.(may up grade after IVA to discs)

I've used search but can't find anything conclusive but one post saide .625 for the front and .7 for the rear. Is this the right choice to get the bias about right for fine tuning with bias bar?
Cheers

[Edited on 3/1/12 by mikeb]


I took delivery of my OBP pedal box a couple of weeks ago and had also been sent two 0.7 cylinders, I'd read on their site that the front cylinder should be a 0.625,i gave them a ring, and 2 days later I received the correct one.I'm looking forward to getting the system installed.

Regards, Chris

mazie - 7/1/12 at 11:06 AM

Im using a 0.625 front and 0.7 for the rear, not been tested yet though !

DRCorsa - 7/1/12 at 11:33 AM

This will strongly depend on your car's weight distribution.
In my setup (BEC) where the weight distribution is expected to be close to 50-50, after some calculations i found out i need 2x0.7" MCs.
If you are building a CEC, then 0.625 front, 0.7 rear will be more reasonable.

It will depend on the "ratio" between the font and rear caliper piston area too!

[Edited on 7/1/12 by DRCorsa]