Steven6282

There are lots of threads on how to do brake swaps and stuff but I can't seem to find anything on how to choose which brake upgrades are right for me.

My car, an 86 z28, standard stock discs in the front, drums in the rear right now.

I enjoy autocrossing my car and brakes are fairly important for this. Right now I've just been getting off the gas and braking a little earlier to compensate for the poor brakes on my car, but I could really make up some time if I could stay on the gas longer and brake harder.

So what should I look at for brake upgrades to make the most improvements. Will converting to discs on the rear be a huge improvement in situations like this, or do I simply need better front brakes for a more noticeable improvement first? What makes a brake system better? Is it the size of the disc, the size of the pad, or the caliper itself?

Any suggestions on which brake systems I should go with? I want to maintain the ability to use my 16" Iroc Rims, and it would be nice if I can use my 15" z28 rims as well as I was planning to put slicks on them next year for auto crossing.

I found this conversion kit for the rear on ebay, how good of a system is it?
http://www.ebay.com/itm/390373277373...84.m1423.l2649

Thanks for any suggestions / information!

highgear

Going with a rotor that has some sort of venting will help. The heat and gases that build between the pad and rotor will cause what's called "brake fade". That's a situation where it takes more pedal effort to provide the desired brake force. Also the larger your pad area the better the braking ability. Going with a larger caliper (multi piston) you get a larger contact area and even pressure. Pad material is just as important. Ceramic is a good upgrade over organic, and something like the ferro carbon from Hawks Performance would be ultimate.

For racing at all you definetly want to ditch the drum rears. Just as a stock rotor retains more heat than a vented, drums retain the most. During frequent hard braking the temp can get unbelieveably hot. At that point the brakes aren't going to be working much and all the heat is radiating into your hubs and axles etc.

I don't know how fast you go, or how fast you want to stop, but I'd say discs on the back, vented rotors up front, and ceramic pads at the very least. If your serious about racing, than your going to want bigger rotors and calipers as well. I'm sure you'd have to increase the wheel diameter at that point.

Steven6282

It's nothing to bad. Depends on the course, but not usually anywhere near as bad as PDX runs. The fastest course I've been on I hit 86 mph and had to loose most of that speed in about 60 or 80 feet. My brakes currently were barely able to do it. That was an unusual course though, that was set up on a road course. Normally speeds don't get over 50 mph but the braking points are very common to need to go from 50 to 15 or 20 for a sharp u turn or something like that. Most of the time I can simply let off the gas a 1/2 second early and the transmission + weight of the car slows me down enough that I don't have to use the brakes as much. But over the course of an entire course if I could stay on the gas and brake harder later then I could easily make up a 1/2 a second to a second, which is a pretty large amount for autocross.

My car is more of a fun car though and I want it to look a certain way, which includes the reconditioned 86 iroc wheels that I have. So I don't think I'll ever be serious enough in this car to need brakes that would require changing out the wheel. Maybe in another car down the road if I ever get sponsors to help pay for stuff I might.

highgear

Hawks third gen list a rear disc conversion kit for 375... They have some other parts you might want to check out. With that kind of braking I'd buy some ceramic pads for the front. They should be reasonable, last set I bought was about $50. I wouldn't be in a rush but the next step I'd look for some conversion parts. Maybe watch the classifieds.

Maybe consider weight loss? I don't know a ton about suspension work but I know that can play a big roll too. Maybe tighten up the body roll so you can take a corner at 17mph instead of 15? Just throwin some ideas, anyways. Be safe and have fun with it.

Steven6282

Ah yeah forgot to mention I already have ceramics on the front.

That hawks conversion kit is 525 if you add a parking brake (yeah I park on hills sometimes I want a parking brake), and cross drilled / slotted. I don't know if I need cross drilled / slotted, but I've read that it's better for hard braking and doesn't have any ill effects for normal breaking so may as well go ahead and get that too. I'm pretty sure the hawks conversion kit is the exact same kit as the one I linked on ebay. I mean they even use the same picture for it.. hehe.

I've also already done a ton of suspension work to the car. There is very little body roll now (koni yellows, eibach pro kit springs, all bushings replaced, ball end LCAs and LCA relocation brackets, new front and rear sway bars, completely rebuilt the front end steering components). Really the only things I have left to do to my car is swap in my T56, rebuild my rear end with a posi unit (another thing that should help me a lot in autocross), and brake upgrades. Everything else beyond that are things that I want to do but aren't really necessary because they are just cosmetic, like a ZL1 hood and a reproduction dash, etc.

BlackenedBird

iTrader: (5)

Since you are running Autocross....The first thing I would do is look at the rules for the classes & decide what will work for the class you are in or if you want to go to a higher class & upgrade to that.

Instead of $375 for just brakes you could swap in an entire rear end to get your discs & , depending on what you have now, upgrade to better gears and/or a posi center section.

Then there is the matter of going to bigger wheels which opens the door for even bigger brake rotors.

Steven6282

I've been looking for a rear end with disc brakes for about 8 months now and have yet to find one that is cheap enough and close enough to get. I'm not paying 600 dollars for one then having to spend another 800 dollars rebuilding it. One of the things making it hard to find one is because I'm not putting a 4th gen rear under the car. It's to wide and I hate the way it looks when using stock third gen wheels making the tires poke out past the fenders.

Also the class is not an issue, I've already taken that into consideration. The cam in my motor that I put in before I decided to start autocrossing automatically puts me in SM. I've been running CP since I'm running street tire and CP has a slightly better pax modifier.

But it doesn't really matter to me if I stay in SM or move to CP. I'm not doing autocross right now to be extremely competitive. It's just fun to do and me and my friends have fun competing against each other. If I ever get serious in the sport and go pro, it will most likely be with sponsors and in a car that is much better suited to autocrossing, like a miata or something. Even if I spent 10k on my camaro prepping it for CP as much as possible, there are still other cars out there that will blister it, the camaro is just not all that great of an autocross car. It's to heavy, and not nimble enough. But I'm having fun with it, as I said it's my fun car!

Also as I said, I do not want to change my wheels. I'm very firm on that, I love the way my reconditioned 86 iroc wheels look and will not change them for any amount of extra braking power. I don't mind switching to another wheel while autocrossing, in fact I will be when I get slicks next year, but for driving on the street, my iroc wheels will be on it.

87350IROC

iTrader: (2)

Ok, a lot of funky info on this thread. First of all I agree with Blackened Bird that you should check the rules for your class. But it looks like you are ok with changing class, so not problem there.

Next, I would not worry about upgrading your rear brakes. The front brakes do that majority of the stopping and I would start there first. The front brakes on these cars are awful.

So we are talking front brake kits that fit inside the OEM IROC wheels. Below is a table of common brake swaps I have put together. Out of the ones that fit your wheels, I would recommend the 13" Wilwood FSL kit. You are not going to fit a larger rotor inside those wheels. With that kit you can even do a ton of damage on a road course.

Now as far as rotors. Slots and holes do not prevent fade and do not cool the rotor. They are a carry over from the old days when they were required to vent gas from between the pad and rotor. The gas reduces the friction been the pad and rotor. Today's pads don't require venting. Today slots and holes provide a slightly better initial bite and look pretty, at the cost of pad life and a higher likelihood of cracking. Fade on the other hand is the reduction in braking force due to either the pad or fluid overheating.

Finally pad area has nothing to do with the performance of the braking system. Pad VOLUME on the other hand determines the pad life and the heat capacity of the pad.

Whatever you do, you will probably want to install an adjustable brake proportioning valve so you can optimize your overall front / rear braking potential.

The table below assumes all setups have the same pad compound, same hydraulic system, and same loses due to brakes lines, caliper flex, etc...

Right click - view image for larger

Homer23

I do some autocrossing and I say that you should ask other racers that have done brake upgrades some suggestions. I would also say that slicks should help out your braking a lot, not to mention making the car lighter.

Base91

iTrader: (1)

This tells me you haven't reached the limits of what the stock brakes will do. I'd also ditch the ceramic pads and use stock for auto-x. Ceramic may be good for a road course but likely won't get hot enough in auto-x. If you can lock your front wheels with the tires you have (and from what you've described you should) then you have enough brake power. Learn to get them up to the point of locking and stop slowing down early. As said above an adjustable proportioning valve would be a really good and cheap start to squeeze out as much as the drum have to give. You could also look at braided lines for better feel. Spend the money on the best tires you can get and if you find you can't lock them up get a brake upgrade then.

91phoenix

iTrader: (5)

I do not know much about autocross and its requirements for braking so this may not necessarily apply. You should be able to upgrade to the 1LE front brakes and PBR rear discs and still run 15" wheels. The 1LE fronts are not real cheap but may help. The 4th gen 93-97 rear discs can be adapted to work with your rear and are essentially the same as the factory PBR's from 89-92. This will work with most 15" wheels but not all. Some have needed a small spacer.