If the import calipers run a 15/16" master I dont see why AP racing calipers would be any different.

Quote: Originally Posted by LAZYASS Mate that isn't true it is only the VT brake upgrades that have problems because the caliper pistons are so big at 42mm ea the master cyl doesn't cope with the fluid fill and you get a lower pedal. If a decent upgrade is done like the Group A or many others you don't need to do the booster or sometimes not even the master cylinder its just everyone puts VT brakes on there car because they are affordable and then they find they need a bigger master or booster mod and ends up costing alot more in the end.. I think that answers your question about why late model commodores have larger master cyls and boosters

So for a pair of calipers with 4x 32mm pistons and VLT rear calipers what is the optimum master cylinder size? Is there an equation for this?

guys im saying to get 100% out of your brakes now the peddle being squishy would effect how well you can brake if you cant controll how well you are applying the presher compared to the new cars casue of a master or bososter well you not getting 100% of your brakes like i stated 100% out of your brakes now if BMW AMG & Racecars and alot of other performance cars use bigger masters and boosters it's for more of a reason than just comfort.

i dont think a vn booster and master would give you the 100% out of your brakes in a big brake upgrade, ie ap racing AMG BMW racecars

Quote: Originally Posted by redVLTjet i dont think a vn booster and master would give you the 100% out of your brakes in a big brake upgrade, ie ap racing AMG BMW racecars Why? AP Racing's two largest master cylinders are 15/16" and 1". I dont see why using a stock item of the exact same size would cause major difficulties.

ok ill get a price check on there masters and boosters from AP then ill ask how come the so much when my one on a std vn is better and will cost 1/100 time's cheaper then there's ill see what there explanation is there would have to be unless holden really has the leading edge in masters and boosters all the way back in the days of the vl's and vn's

PHS u obviously love ap racing.... personally, i think they are a bunch of wankers... u probably jsut dont get it... they wanna sell you "larger master cylinder and brake booster" FOR PROFIT! they will tell you any bull**** to make you buy it and make more money... ive been in a VS clubby 300+ rwkw with standard brakes, (vlt) and they woudnt stop it, after it got a larger power increase 330+ and VT twin pistons, (no change from the 15/16 master and stock booster) MUCH BETTER performance

PBR makes all of holdens and HSV's and Ford products.. FPV uses PBR and brambos... They still used a 15/16th master when they went to 2 pot in VT... You can go on and on about brakes etc which is better etc but it all comes down too.. How much are you willing to spend on your brakes... Alot of people forget if you upgrade your HP you also have to upgrade your brakes to stop the damm thing... I find the VT brake upgrade to be pretty good... If you want something better well yeah get something like AP etc...

i dont give a rats ass about AP Raceing but they do make good brakes ok when i get my 20,000 doller brake upgrade ill just go to the wreckers and get a vn booster and master im sure she'll do the job fine well at least thats settled VN & VLT MASTERS AND BOOSTERS ARE GOOD FOR GETTING 100% PERFORMANCE OUT OF ANY BIG BRAKE PACKAGE you's win DONT CHANGE MASTERS OR BOOSTERS if you have one from a VN or VLT to any other there's no diff

If the master and booster out of a VT etc didnt help please tell me why cebco brakes offers a whole brake package? includes master booster front rears... At the end of the day if my car was a track car i would be using porsche...

Quote: Originally Posted by PHS ok ill get a price check on there masters and boosters from AP then ill ask how come the so much when my one on a std vn is better and will cost 1/100 time's cheaper then there's ill see what there explanation is there would have to be unless holden really has the leading edge in masters and boosters all the way back in the days of the vl's and vn's No one actually said the VN item was better, simply that they are the same specifications and do the same job as the AP Racing product.

i do beleve the vt-vy calapers fit in 15in rims, the gtr clapers are bigger and need at least 16ich rims if you are goin for 2nd hand vt calapers than get them mechaned for ballance. also break fluid helps and a good set of pads, the metal kings are too hard for street use m my opinion, and over the std pads i would go std. i changed break fluid to dot 4 with new std disks and std pads (holden) and my stoping was at least 50% better than before

Quote: Originally Posted by VL_RB25DE i do beleve the vt-vy calapers fit in 15in rims, the gtr clapers are bigger and need at least 16ich rims if you are goin for 2nd hand vt calapers than get them mechaned for ballance. also break fluid helps and a good set of pads, the metal kings are too hard for street use m my opinion, and over the std pads i would go std. i changed break fluid to dot 4 with new std disks and std pads (holden) and my stoping was at least 50% better than before www.dictionary.com (http://www.dictionary.com)

I have the VT conversion in my VL. I have standard pads in it, and the braking was alot better than the standard VLT brakes. But I was not happy with them at a recent track day. I have also decided to use better fluid and replace the front pads with EBC Red stuff, and the rears with Green stuff.

Quote: Originally Posted by PHS I could put a AP Racing 4piston caliper with 330mm rotors on a VN for instance and it will stop great and have good pedal feel and you won't need to put a bigger booster on it dude thats very far fetched if you think you can put these brake on a std vn and get 100% of what there capible of out of them thats just a joke im sure if you talk to AP Racing the'll tell that the recomended master and booster is bigger than a STD VN and why are the newer commo's masters biggger ? clearly cause they work better hey i dont even care im putting vt 298 twin pistons cal's on my vlt soon and i wont upsize master or booster but i bet if i did get a master and booster out of a vt with these brakes it would be better My suggestion is cut down on the AGRO tablets, everone has an opinion and yours to a point is validated and just on that maybe i want to save the day sometimes .The newer commodore master cylinders are bigger with a stepped bore because of the size of the fluid displacement needed for the brake system eg; ABS unit, twin piston calipers and the rear as well you will also find i reckon the pedal ratio is different to .What you have to remember is with some of your comments ,that, ok, it will sometimes benefit with a larger master and booster but as i have said many times before the larger the bore size the better the pedal feel but you have to use twice as much force to get the same amount of pressure out of it.Going from a 3/4 bore master to 1" bore 75% more force is needed on the pushrod so you have to be built like a brick sh@#$&^%$ you won't get it but a modified booster may help if you get more pressure out of it.Also the pedal ratio on cars (leverage) is different on some models so this will make a difference as well.We have done many brake kits with 4/6 piston calipers on road cars and race cars and what we get out of the brakes is more than sufficent for the car.Race cars and some road cars use Wilwood and AP master cylinders and other brands as usually single masters and are used for twin master cylinder/pedal box set ups with a balance bar and and adjustable bias as well as a certain pedal ratio to obtain maximum braking but this involves bigger dollars than some are prepared to spend or can afford . PS Did you talk to AP Racing and what did they say????????????? Some original photos have not been recovered yet.

Quote: Originally Posted by VLHERO www.dictionary.com (http://www.dictionary.com) thank you smart ass

I think lazyass hit the nail on the head with that explanation. So basically, a smaller master cylinder will give you a higher clamping pressure at the wheels than a larger one, the trade off being a greater pedal travel required. So if you do a brake upgrade you should be able to get away with leaving the master cylinder standard. The booster size doesn't have to be changed but with turbo cars, and cars with more extreme cam profiles, which will have less engine vacuum, it may become necessary to put a bigger booster on to hold a bit more vacuum.

Quote: guys im saying to get 100% out of your brakes now the peddle being squishy would effect how well you can brake if you cant controll how well you are applying the presher compared to the new cars casue of a master or bososter well you not getting 100% of your brakes like i stated 100% out of your brakes now if BMW AMG & Racecars and alot of other performance cars use bigger masters and boosters it's for more of a reason than just comfort. What size master cylinder do BMW AMG etc use? BTW race cars don't run boosters at all. All performance brakes are going to need a recommended master cylinder bore size and i think you'll find a holden 1" is adequate, the Front+Rear proportioning has been designed to suit the weight distribution of your car so it would be the best option!!

umm if race cars dont run brake boosters how the hell does it get vac then?? The booster is what gives you vac for the brakes to work... without that the brakes will not work... and all you will be getting is the sound of air being pushed... So in other words they do hand brakies every single corner at the same time as they downshift gears and use there knees to turn the steering wheel to which ever side they are turning...