polyfc

ok, here's the deal. First I got some four piston calipers from a friend of mine and they're kind of old. He said something about buying a rebuild kit, never heard of it though. But what would I need to do to put the four pistons on in place of the single that's on there. I know damn near nothing about brakes except for the basics. So any help is greatly appreciated

Joe

nonameo

to do the 4 piston conversion you will need 5 lug rotors as well. The rotors are a different diameter which makes them incompatible.

Crionics

Easiest thing to do would be to unbolt the whole hub assemblies since it's a direct bol-on from there. That means the three bolts three bolts that hold the carrier on in the rear and the knuckle up front.

Also, the lines hitting the caliper up front are different.

KNONFS

iTrader: (14)

You have a 91 GTU? I believe these already have 4 piston calipers. If not, besides the alipers, you need the "hard line". The hard line is a metal brake lines that goes from the caliper itself to the rubber brake line.

bingoboy

since you have an S5, the calipers are a direct swap/bolt on. you don't even need new rotors. the rebuild kit can be had from the likes of mazdatrix and will do the 2 calipers for ~$25 if i recall correctly. it's just a matter of getting the pistons out of them. compressed air works for that with something in the center like a block of wood so they don't go shooting all the way out. you will also need the hard line that was orignally connected to the 4 piston calipers.

totallimmortal

if you're car is four lug you should need the hubs and rotors, and I also reccoment the brake booster off a 5 lug car as it's larger. some people say some of these aren't needed but i know the bigger brake booster works better, and i know that the calipers don't bolt onto the four lug hubs, and i don't think that the caliper will fit under 14 inch wheels that came stock on my four lug

polyfc

My car is a five lug and I do have the hardlines. Not sure how good they are though. So since i have the 5 lug they should just bolt right up correct? Also how difficult is the whole caliper rebuilding and is it worth it as far as the quality? Thanks again for the help

polyfc

crionics, what do you mean by the lines hitting the caliper up front are different. There in a different place on the cars that come with the 4 piston as opposed to the ones that come with the 1?

bingoboy

ok buddy here you go. i have an 89 gtu, and i did this swap myself in a couple hours. i rebuilt the calipers first. at the same time i installed stainless steel brake lines (make sure you buy the ones for 4 piston calipers if you do this) and also bought hawk hps pads. the rotors you have are the same. i left my original rotors on since they looked to be in very good condition.

don't listen to what crionics is telling you as it does not apply to your S5 gtu. if you wanted to you could simply unbolt your single piston calipers and bolt on the 4 piston calipers with the 4 piston original brake lines and you'd be done.

as for rebuilding, i think it's worth it for the price (if you have the ability to do so). i actually pried the pistons out of the calipers (i guess this means they were actually in pretty good condition). be very careful that you do not score the side of the piston yourself. if you run into a scored or rusted piston (on the smooth outside it should be nice and shiney looking, nevermind the middle as its going to be filled with crap) you probably want to go hunting for another caliper to use. the rebuild consists of popping out the 4 pistons and replacing a rubber o-ring inside the caliper that goes around the piston. to remove pistons that are more stuck, people have used a piece of wood of some type to put between the caliper and then shot compressed air into the brake line spot to get the pistons most of the way out, and from there they can be pulled out with fingers.

KNONFS

iTrader: (14)

Exactly!

totallimmortal

so the s5 cars use the same hub for 4 and 5 lug? I know that the s4 uses smaller rotors and a differnent hub

theonlygreat

S5's do not have 4 lugs as an option.