mclarenross Posted March 24, 2016 Share Posted March 24, 2016 I know that some say that you should aim for the same size disc on the front and rear, but my question is if I have 356mm on the rears, do I "need" to have 356 or bigger on the front? I'm looking at some high quality 330mm on the front and just want to make sure I'm not doing something that is unsafe... I would appeciate if the advice/ comments are from someone that understands brakes and what is safe/unsafe, will they lock up, will it become twitchy etc thanks Quote Link to comment Share on other sites More sharing options...
JackyBoi Posted March 24, 2016 Share Posted March 24, 2016 Considering the stock uprated brakes have 323mm front and 324mm rear (I think) you'll be fine Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted March 24, 2016 Share Posted March 24, 2016 Why are the sizes being changed? I assume it's because different calipers are being used? Quote Link to comment Share on other sites More sharing options...
MattP Posted March 24, 2016 Share Posted March 24, 2016 Considering the stock uprated brakes have 323mm front and 324mm rear (I think) you'll be fine The brake surface of the fronts is significantly larger than the rears even though the disc size is larger on the rear remember the rear discs have to enclose the handbrake mech and shoes. You can get away with UK fronts and J-Spec rears but as far as mixing and matching goes once you uprate a set of rears you to the size your talking about you would need to correct the bias to stop the rears locking up first (instability) Equally so uprateing to let's say brembos up front and Uk rears May not cause instability but may cause underbraking of the rear end which will actually translate to an increased stopping distance over say a full UK set up. Basically don't mismatch non oem callipers and if you do fit aftermarket make sure they are methodically matched for best performance. Everybody knows somebody with a large set of fronts and stock rears I'm not suggesting it doesn't work merely it may not be as effective as well sorted matched stock units. Big brakes are pretty though. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted March 24, 2016 Share Posted March 24, 2016 Everybody knows somebody with a large set of fronts and stock rears I'm not suggesting it doesn't work merely it may not be as effective as well sorted matched stock units. . Agreed, but one known exception is Brembo F50 calipers with 355mm discs on the front with stock UK rears. I've run that setup, and Bignum runs it now, and it's definitely superior to UK'S in all respects (other than cost, which is why I stuck with UK's this time) Quote Link to comment Share on other sites More sharing options...
MattP Posted March 24, 2016 Share Posted March 24, 2016 Agreed, but one known exception is Brembo F50 calipers with 355mm discs on the front with stock UK rears. I've run that setup, and Bignum runs it now, and it's definitely superior to UK'S in all respects (other than cost, which is why I stuck with UK's this time) I was going to mention F50s as I looked at them and loads of people run them up front with UK rears. I just didn't bother as Ross only has large rears by the sound of it. What brakes do you currently have exactly Ross and what are you looking at? Quote Link to comment Share on other sites More sharing options...
Nic Posted March 24, 2016 Share Posted March 24, 2016 Worth a read http://www.mkivsupra.net/vbb/showthread.php?324151-UK-brake-LS430-upgrade&p=4048430&viewfull=1#post4048430 Quote Link to comment Share on other sites More sharing options...
mclarenross Posted March 24, 2016 Author Share Posted March 24, 2016 Thanks guys, yeah good and interesting read. I've bought some. K sport 356 rears and looking at Alcon 330s up front, so it is a combination. But both reputable brands...? Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted March 24, 2016 Share Posted March 24, 2016 You need to do some proper calculations I'm afraid, you could be making your car unstable under braking depending how it effects the front / rear brake bias. DanDan did an excellent thread on the subject a few years ago. Quote Link to comment Share on other sites More sharing options...
Nic Posted March 24, 2016 Share Posted March 24, 2016 Might be worth talking to Dan, see here http://www.mkivsupra.net/vbb/showthread.php?225007-Big-Brake-Kits-Real-Numbers Quote Link to comment Share on other sites More sharing options...
mclarenross Posted March 24, 2016 Author Share Posted March 24, 2016 Thanks guys, great info there, looks like I'll need to sack off the alcons and find some k sport fronts. Thanks! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 26, 2016 Share Posted March 26, 2016 You need to consider many things. Total caliper piston area front and rear, disc diameter, but more importantly effective pad area and effective pad area OD and ID front and rear. Pad compound front and rear. Master cylinder bore size, servo effort. It's complex, maths will get you a long way to a workable package, but even so sometimes you screw up and end up with too much braking effort on one end or the other. You really must aim for a goodly amount more front effort or the set up will be dangerously bad. You are far better following trid and tested combinations or just buying a kit. If you don't have machining facilities for brackets and bells definitely buy a proper kit! Quote Link to comment Share on other sites More sharing options...
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