I think I've answered brake upgrade questions 40 times this week, so I'm going to try to put everything into one article for future reference. This is written for model years 88 through 91.
First, safety. The brakes on your car are the only thing standing between you and disaster when you need to stop while driving. If you are uncomfortable or incapable of working on your car's brakes, please have a qualified professional perform the work.
With that out of the way, let's get started. If you're reading this you're probably interested in getting more out of your brakes. The way I see it, there are three components of the brake system that are more important than the others; these are the brake fluid, the brake pads, and your tires. These should be replaced/upgraded before you do anything else. Yes, tires are part of your brake system, remember that brakes can only stop your wheels, tires stop the car. So if you're riding around on some skinny all-season economy tires that you bought from Pep Boys when they were on clearance, you should correct that flaw before spending hundreds on a brake upgrade.
The second item I mentioned is the pads. In every instance I will recommend Hawk HPS brake pads, for a street car or occasional autocross use anyway. If you are using cheap brake pads, you'll have to understand that they are engineered for long life, low dust, and low noise. This means that the co-efficient of friction is neglected. You can't have a high-friction brake pad that produces no dust or noise and lasts forever, but Hawk HPS pads strike a great balance, IMO. I will leave other pad suggestions to comments below, and you can decide for yourself.
The third vital component is the brake fluid. Honda recommends replacing the brake fluid every 24 months or 30,000 miles with DOT 3 or DOT 4 fluid. If you don't know when your brake fluid was last replaced, get to it! My recommendation is a good DOT 4 brake fluid, though DOT 3 will work and you probably won't need more than that anyway. The brake system is not designed for DOT 5 fluid, don't use it! Brake fluid is not a fill-and-forget kind of deal, the system doesn't work very well when there is air in the lines. It needs to be bled so that all the air (and all the nasty old fluid) can be evacuated. Regularly bleeding the brake fluid at Honda's intervals is critical, because brake fluid absorbs water. This water will make its way to the lowest points of the lines (at the calipers!) and when the brakes heat up it boils, introducing vapor and reducing the effectiveness of the whole system. For help bleeding your brakes, check out this link. If your brake system is completely dry, you'll need approximately one liter (or quart) of brake fluid to fill and bleed the whole system. If you're just replacing the old brake fluid with new, you'll only need a half-liter (or pint).
And now, a comment on rotors. For a street car or autocross car, you'll likely never need rotors that are slotted and/or drilled. They won't help you stop any faster. Save some money and buy plain or "blank" rotors, unless you're specifically interested in the aesthetic appeal.
If you're confident that your brake system is performing as best as it can and you still want more, well, that's where it gets fun.
Rear Disc Conversion:
The first thing people usually ask about is a rear disc conversion, since only a minority of members have a 90 or 91 CRX Si with factory rear discs. Let it be known that the rear brakes do only a small portion of the work to stop your CRX, so it's not the first thing you should do when you want to stop better. Rear discs do look sweeter behind your wheels than rusty drums, and they're easier to work on, so those are your excuses for wanting to convert. For more details on how it's done and what you'll need, see the Rear Disc Conversion article. I would like to point out that if you have a CRX HF with stock HF front brakes, don't even think about rear discs before you've upgraded your fronts. You can still have awesome brakes without rear discs, so don't feel that you're required to do this either.
Upgrading Rear Drums:
If you don't want to spend the time and money converting to rear discs, or if you're just trying to save as much weight as possible, there are a couple options for improving the effectiveness of your rear drums. The first obvious choice is to use a more aggressive set of brake shoes. I don't have specific experience with them, but Porterfield is probably your best option for performance shoes. The other thing you can do is swap the stock iron drums out for the aluminum drums found on an 84-87 CRX HF. Good luck with your search. The aluminum drums are easily spotted because they're finned, as seen here.
Front Brake Upgrade Options:
Most of the front brake upgrades involve swapping the knuckles. If you have an HF, you can get a simple but effective upgrade by switching to CRX Si front knuckles and brakes. Note: HF axles are smaller, and will not work with Si or Dx hubs. You'll need to swap the axles when you swap knuckles on an HF (CRX Si axles work fine).
If you already have the 9.5" vented front brakes of a Dx or Si, the next step up is 10.3" front brakes from a 90-91 Civic Ex or 90-93 Integra. Finding the Ex parts is difficult these days, but usually there's a 2nd gen Integra in every salvage yard. Again you'll be swapping the whole knuckles with brakes attached, and Dx or Si axles will fit. You will need at least 14" wheels to clear 10.3" front brakes, you can't be sleeper and install them under 13" steelies.
Whenever buying used knuckles, I recommend replacing all of the wear items. This includes the rotors, the pads, the calipers, the wheel bearings and the lower ball joints. Ultimately, this maintenance will be at your discretion.
If you're looking for yet larger brakes, there are several aftermarket or custom options for 11" or even bigger front rotors. Fastbrakes.com is a good place to start, but details here can be left to a future "Brakes 102" article. Even drag cars or all-out track cars won't need brakes this big, so you're doing it for show.
Brake Lines:
Stock rubber brake lines are mushy and probably deteriorating by now. If you're removing even one end of one brake line, it's good enough reason in my opinion to swap them all out for some shiny braided stainless steel brake lines. If you have rear discs, order a brake line kit for a 91 CRX Si. If you have rear drums, order a set for a CRX with rear drums. Using 10.3" Integra/Ex front brakes doesn't change what lines you should buy. Goodridge, Earl's, or Neuspeed (if you like yellow) are all good choices for lines.
Proportioning Valve:
This is a commonly overlooked but very important part of your brake system. Whenever you are converting to rear discs or upgrading your front brakes, you need to swap the appropriate proportioning valve to maintain proper brake balance. These are the common valves, applications, and the cars they're found on:
1725 valve (88-91 CRX with rear drums)
2040 valve (90-91 CRX Si) - used with 9.5" front brakes matched with rear discs.
4040 valve (90-93 Integra) - used with 10.3" front brakes matched with rear discs.
3540 valve (90-91 Civic Ex and some 88-91 Preludes) - used with 10.3" front brakes matched with rear drums.
Proportioning valves can be identified by the number stamped on them. Here's a pic of a 4040 valve for example. They're located in the engine bay on the passenger side shock tower, with two hard brake lines going in and four coming out; pretty easy to spot. Whenever you are working with the nuts on the hard brake lines, use a 10mm flare nut wrench to avoid stripping them. This also applies to the lines attached to the master cylinder.
Master Cylinder/Booster:
Swapping the master cylinder out for a larger one will reduce the brake pedal travel required to apply the brakes. It will also equally increase the pedal force required to stop. The end result is a brake pedal that feels more solid. These are the sizes and the cars they're found on:
13/16" - 88-91 CRX with rear drums
7/8" - 90-91 CRX Si (rear discs)
15/16" - 90-91 Civic Ex, 91 Prelude Si, or 90+ Integra (non-ABS)
1" - 94+ Integra with ABS
The Civic or CRX master cylinders can be swapped onto your stock brake booster with no problems. The Integra master cylinders require that you also swap the matching Integra brake booster. The Prelude Si MC requires a slight bend to one of the hard lines, but will work with your stock booster. From what I've been told, you can attach the hard lines to the Prelude MC and then bolt the MC to the booster, and the required bend will take care of itself. The master cylinder is an independent upgrade, it is not required by any other brake system modification, however I recommend using at least the size that Honda used for whatever car you're taking the brakes from. That means use a 7/8" MC or larger when you have 9.5" front brakes and rear discs, and use at least a 15/16" when you have 10.3" front brakes and rear discs.
I don't see the need to necessarily upgrade the brake booster by itself. They are simple devices that very rarely fail, and removing/installing them is more trouble than it's worth.
Comments or omissions appreciated.
First, safety. The brakes on your car are the only thing standing between you and disaster when you need to stop while driving. If you are uncomfortable or incapable of working on your car's brakes, please have a qualified professional perform the work.
With that out of the way, let's get started. If you're reading this you're probably interested in getting more out of your brakes. The way I see it, there are three components of the brake system that are more important than the others; these are the brake fluid, the brake pads, and your tires. These should be replaced/upgraded before you do anything else. Yes, tires are part of your brake system, remember that brakes can only stop your wheels, tires stop the car. So if you're riding around on some skinny all-season economy tires that you bought from Pep Boys when they were on clearance, you should correct that flaw before spending hundreds on a brake upgrade.
The second item I mentioned is the pads. In every instance I will recommend Hawk HPS brake pads, for a street car or occasional autocross use anyway. If you are using cheap brake pads, you'll have to understand that they are engineered for long life, low dust, and low noise. This means that the co-efficient of friction is neglected. You can't have a high-friction brake pad that produces no dust or noise and lasts forever, but Hawk HPS pads strike a great balance, IMO. I will leave other pad suggestions to comments below, and you can decide for yourself.
The third vital component is the brake fluid. Honda recommends replacing the brake fluid every 24 months or 30,000 miles with DOT 3 or DOT 4 fluid. If you don't know when your brake fluid was last replaced, get to it! My recommendation is a good DOT 4 brake fluid, though DOT 3 will work and you probably won't need more than that anyway. The brake system is not designed for DOT 5 fluid, don't use it! Brake fluid is not a fill-and-forget kind of deal, the system doesn't work very well when there is air in the lines. It needs to be bled so that all the air (and all the nasty old fluid) can be evacuated. Regularly bleeding the brake fluid at Honda's intervals is critical, because brake fluid absorbs water. This water will make its way to the lowest points of the lines (at the calipers!) and when the brakes heat up it boils, introducing vapor and reducing the effectiveness of the whole system. For help bleeding your brakes, check out this link. If your brake system is completely dry, you'll need approximately one liter (or quart) of brake fluid to fill and bleed the whole system. If you're just replacing the old brake fluid with new, you'll only need a half-liter (or pint).
And now, a comment on rotors. For a street car or autocross car, you'll likely never need rotors that are slotted and/or drilled. They won't help you stop any faster. Save some money and buy plain or "blank" rotors, unless you're specifically interested in the aesthetic appeal.
If you're confident that your brake system is performing as best as it can and you still want more, well, that's where it gets fun.
Rear Disc Conversion:
The first thing people usually ask about is a rear disc conversion, since only a minority of members have a 90 or 91 CRX Si with factory rear discs. Let it be known that the rear brakes do only a small portion of the work to stop your CRX, so it's not the first thing you should do when you want to stop better. Rear discs do look sweeter behind your wheels than rusty drums, and they're easier to work on, so those are your excuses for wanting to convert. For more details on how it's done and what you'll need, see the Rear Disc Conversion article. I would like to point out that if you have a CRX HF with stock HF front brakes, don't even think about rear discs before you've upgraded your fronts. You can still have awesome brakes without rear discs, so don't feel that you're required to do this either.
Upgrading Rear Drums:
If you don't want to spend the time and money converting to rear discs, or if you're just trying to save as much weight as possible, there are a couple options for improving the effectiveness of your rear drums. The first obvious choice is to use a more aggressive set of brake shoes. I don't have specific experience with them, but Porterfield is probably your best option for performance shoes. The other thing you can do is swap the stock iron drums out for the aluminum drums found on an 84-87 CRX HF. Good luck with your search. The aluminum drums are easily spotted because they're finned, as seen here.
Front Brake Upgrade Options:
Most of the front brake upgrades involve swapping the knuckles. If you have an HF, you can get a simple but effective upgrade by switching to CRX Si front knuckles and brakes. Note: HF axles are smaller, and will not work with Si or Dx hubs. You'll need to swap the axles when you swap knuckles on an HF (CRX Si axles work fine).
If you already have the 9.5" vented front brakes of a Dx or Si, the next step up is 10.3" front brakes from a 90-91 Civic Ex or 90-93 Integra. Finding the Ex parts is difficult these days, but usually there's a 2nd gen Integra in every salvage yard. Again you'll be swapping the whole knuckles with brakes attached, and Dx or Si axles will fit. You will need at least 14" wheels to clear 10.3" front brakes, you can't be sleeper and install them under 13" steelies.
Whenever buying used knuckles, I recommend replacing all of the wear items. This includes the rotors, the pads, the calipers, the wheel bearings and the lower ball joints. Ultimately, this maintenance will be at your discretion.
If you're looking for yet larger brakes, there are several aftermarket or custom options for 11" or even bigger front rotors. Fastbrakes.com is a good place to start, but details here can be left to a future "Brakes 102" article. Even drag cars or all-out track cars won't need brakes this big, so you're doing it for show.
Brake Lines:
Stock rubber brake lines are mushy and probably deteriorating by now. If you're removing even one end of one brake line, it's good enough reason in my opinion to swap them all out for some shiny braided stainless steel brake lines. If you have rear discs, order a brake line kit for a 91 CRX Si. If you have rear drums, order a set for a CRX with rear drums. Using 10.3" Integra/Ex front brakes doesn't change what lines you should buy. Goodridge, Earl's, or Neuspeed (if you like yellow) are all good choices for lines.
Proportioning Valve:
This is a commonly overlooked but very important part of your brake system. Whenever you are converting to rear discs or upgrading your front brakes, you need to swap the appropriate proportioning valve to maintain proper brake balance. These are the common valves, applications, and the cars they're found on:
1725 valve (88-91 CRX with rear drums)
2040 valve (90-91 CRX Si) - used with 9.5" front brakes matched with rear discs.
4040 valve (90-93 Integra) - used with 10.3" front brakes matched with rear discs.
3540 valve (90-91 Civic Ex and some 88-91 Preludes) - used with 10.3" front brakes matched with rear drums.
Proportioning valves can be identified by the number stamped on them. Here's a pic of a 4040 valve for example. They're located in the engine bay on the passenger side shock tower, with two hard brake lines going in and four coming out; pretty easy to spot. Whenever you are working with the nuts on the hard brake lines, use a 10mm flare nut wrench to avoid stripping them. This also applies to the lines attached to the master cylinder.
Master Cylinder/Booster:
Swapping the master cylinder out for a larger one will reduce the brake pedal travel required to apply the brakes. It will also equally increase the pedal force required to stop. The end result is a brake pedal that feels more solid. These are the sizes and the cars they're found on:
13/16" - 88-91 CRX with rear drums
7/8" - 90-91 CRX Si (rear discs)
15/16" - 90-91 Civic Ex, 91 Prelude Si, or 90+ Integra (non-ABS)
1" - 94+ Integra with ABS
The Civic or CRX master cylinders can be swapped onto your stock brake booster with no problems. The Integra master cylinders require that you also swap the matching Integra brake booster. The Prelude Si MC requires a slight bend to one of the hard lines, but will work with your stock booster. From what I've been told, you can attach the hard lines to the Prelude MC and then bolt the MC to the booster, and the required bend will take care of itself. The master cylinder is an independent upgrade, it is not required by any other brake system modification, however I recommend using at least the size that Honda used for whatever car you're taking the brakes from. That means use a 7/8" MC or larger when you have 9.5" front brakes and rear discs, and use at least a 15/16" when you have 10.3" front brakes and rear discs.
I don't see the need to necessarily upgrade the brake booster by itself. They are simple devices that very rarely fail, and removing/installing them is more trouble than it's worth.
Comments or omissions appreciated.
