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Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 12:56 am
by drndrn
Hey fellas,

I've recently upgrading from the 2.5NA brakes to GT/3.0R brakes. I was told that I would need to replace my brake master cylinder too to get the most of this mod. Is this true? Or do all Lib's share the same master cylinder?

Any info would help.
Thanks

Darren.

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 4:25 pm
by senator
i think they a same BMC…I think, no point changing it unless your increasing the diameter of your rotors significantly.

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 4:37 pm
by drndrn
Well.. The standard NA brakes were 277mm (I think) and the current GT's are 316mm. So does that warrant a change?

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 5:01 pm
by smythie
It's not really rotor size that you would change your master cylinder for though is it?

I would have thought you might change master cylinder to match a possible change in effective piston areas (remembering a twin piston sliding caliper will have the same effective area as a 4 piston opposed that has similar sized pistons). And you'd only be doing that if you thought the increase in effective piston areas across the car was big enough that you would run out of piston travel in the master cylinder during normal operation.

I wouldn't be changing master cylinder unless I had radically changed the effective piston areas (different calipers)

Happy to be corrected though

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 5:18 pm
by senator
smythie wrote:It's not really rotor size that you would change your master cylinder for though is it?

I would have thought you might change master cylinder to match a possible change in effective piston areas (remembering a twin piston sliding caliper will have the same effective area as a 4 piston opposed that has similar sized pistons). And you'd only be doing that if you thought the increase in effective piston areas across the car was big enough that you would run out of piston travel in the master cylinder during normal operation.

I wouldn't be changing master cylinder unless I had radically changed the effective piston areas (different calipers)

Happy to be corrected though


+1,

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 5:51 pm
by Jimmy S
I wouldn't worry about it...

I am changing from the GT brakes to the STi Brembo's and leaving the master cylinder as is! I don't expect that there will be any issues, although I haven't got it back yet!

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 10:19 pm
by jdm rsk
i went from front 2 pot 275mm, rear 1 pot to front brembos 327mm and rear 2 pot and didnt change it....

Re: Brake Master Cylinder

PostPosted: Thu Jul 09, 2009 10:24 pm
by tangcla
Changing the master cylinder will affect the pedal feel, put the rotors/calipers on first and see how it feels. With more reservoir it will give... more? or less? sponginess.

Re: Brake Master Cylinder

PostPosted: Fri Jul 10, 2009 9:02 am
by Kevlar GT
Just go and buy a cusco top strut brace with brake booster and it will sort any spongy feel and stiffen the front end up some more. I have the Brembo's up front and said brace and it has not shown any poor feel.