Write up - NA to Turbo rear brake conversion
Posted: Thu Mar 24, 2005 1:14 am
A little background -
I have a 1993 FWD NA Sedan Legacy with currently 210k miles on it. The engine has had work done on the crankshaft and pulley. When I did that work I ended up pulling the AC system, condensor, compressor, all of it but a few hard lines attached to my firewall. This noticably shifted my weight distribution. I also have been running standard turbo rims with 205/60/15 tires. These tires are great but in the rain, and without having AWD and missing the weight of the AC in the front, it has a tendency to hyrdoplane somewhat easily and braking in the rain was significantly less than dry. I have been running some lifetime warrenty pads on the front and stock on the back. Having the opportunity to pick up some used rear turbo brake set for a great price, I jumped on them. The rotors are Bradi turbo rotors that have been both slotted and cyrotreated and less than 20k mi. on them. The calipers are stock turbo calipers with Mintex 1115 pads on them. I should also mention that I do a fair bit of driving up in the mountains and don't want/can't go to a 16" rim. This limits me some in my brake options as the WRX stuff is not an option.
Tools and Materials -
14 mm socket
12 mm socket
3/8" ratchet or similar
8x1.25mm x 20mm (2) bolts with corresponding socket, these you will only need if your old rotors are stuck on
New rotors, calipers, and pads
Anti-squeal grease
C-clamp, you'll need this if you have to push the new piston back into the caliper to clear the pads and rotor
12 mm open end wrench
Brake fluid
Torque wrench, yeah I don't have one myself but I should
Procedure -
First thing that needs done is the rear wheels removed and the rear end set on jackstands. Chock the front wheels good and take sure the parking brake is disengaged. Next remove the lock pin from the caliper and rotate the piston assembly up and out of the way. You might want to put a wire tire on it or have a friend hold it out of the way, just don't let it swing down on your arm. Now remove the 14mm bolt from the back of the wheel assembly that holds the bottom of the caliper. It is the only bolt in that area, can't miss it. Now swing the piston back down and remove the top 14mm caliper to wheel assembly bolt. Take off the whole caliper and you can set it on one of the suspension rods if you're careful not to knock it off or twist the hose badly. You are now ready to remove the caliper.
Removing the caliper should just be a matter of grabbing it and sliding it right off. If your rotor is like mine it's stuck on with a fair bit of force. Make sure your parking brake is disengaged and that you can freely rotate the rotor. From here you have a couple of options. If you don't care about the rotor just whack on it with a hammer in an even star patter until it comes off. I however recommend using the 8x1.25mm bolts and threading them into the two holes located around the center of the hub and 180 degrees apart, see Figure 1. Thread the bolts in slowly and at the same time and the rotor will pop itself right off into your hands. I recommend this over the hammer in the first place as it's just as quick and easy and saves putting unnecessary stress on any other components. Now go grab your new rotor and calipers.
Putting the new rotor on is as easy as sliding it on over the lug bolts. Check your parking brake pads before doing so just to make sure they look fine. They will be dusty but should have decent pad left on them. Now go ahead an put the pads and shims in the brakets and use a C-clamp to push the new pistons into the caliper if need be. Now using the two 14 mm bolts you kept, bolt the new caliper back onto the wheel assembly. Torque these bolts down to 25-33 ft-lbs. Before swinging the piston down over the pads, apply your anti-squeal stuff to the back of the pads where it contacts the piston and caliper, you put a tad on the shims too right? Note that some feel the shims are more harm than good. This may be true, however, if your pad doesn't sit real snug put the shims in. Swing the piston down into place and put the lock pin back in. Make sure the lock pins have a little grease on them before putting them back in. Torque these down to 144-204 in-lbs (note in-lb, not ft-lb). Now that your new caliper is mounted and ready, disconnect the brake line from the old caliper by losening the bolt. You don't have to completely remove this bolt but it does need to be full unthreaded from the old caliper. Now put this back on your new caliper and torque down to 132-180 ft-lbs. Make sure it's seated properly first though, you don't want to bugger the seal up.
Now go and do the same thing on the other side.
Once you have both sides ready, you need to bleed the air of them. You will need a friend to help you with this. Remove the rubber cover on top of bleed valve and loosen the valve a 1/4 turn. Now have your friend step on the brake and hold it down while you tighten the valve back. Just repeat this, making sure your resevoir stays full, until all the air is out of the system. Once both sides are bled, put your wheels on and put her back down on the ground.
** All torque specifications have come from my Haynes manual
Pictures -
** Average picture size is around 130kb
Old rotors and calipers
New rotors
New calipers
Installed, wheel off
Installed, left
Installed, right
Retaining my sleeper status
No bling bling here
Conclusions -
Holy smokes, what a difference. The car is more balanced and exhibits little nose dive now under hard braking. Some might consider it more than a little but it is significantly better than before and I still have stock struts and suspension. My stopping power in the rain has been dramaticaly increased and the whole right side locks up about at the same time and with relative ease. On dry I have a stopping distance of 120ft. Yes this is accurate within 5 foot and is scewed toward the high side. My right rear wheel is the first to lock now I think, I haven't visually confirmed this but through multiple tests it sounds and feels as this is the case. Some people put a portioning valve from a BF into their BC but I have no intentions of doing so. I think this would be excessive and actually slightly hindering driving on the gravel and dirt. On the gravel it stops quicker than before but the most noticable difference is that my entry speeds have increased slightly due to less weight shift when I tap the brake to throw the weight forward and the back end out. With the car staying much more level during braking, the slide is much more level and initiates smoother. Having the wagon (BF) prop valve would definately be excessive. It will take me some time to get used to the increased pedal response and the braking bias. I have also taken the car through several consequecutive turns requiring heavy braking and couldn't feel any fade in the braking. All in all I am extremely happy with this upgrade and feel as though my brakes are now more than sufficient and I have retained my sleeper look and I can keep my 15's. I may experiment with different pads down the road to try and get the fronts to lock before the back but as it is now I feel it is close enough that I will leave it alone.
I have a 1993 FWD NA Sedan Legacy with currently 210k miles on it. The engine has had work done on the crankshaft and pulley. When I did that work I ended up pulling the AC system, condensor, compressor, all of it but a few hard lines attached to my firewall. This noticably shifted my weight distribution. I also have been running standard turbo rims with 205/60/15 tires. These tires are great but in the rain, and without having AWD and missing the weight of the AC in the front, it has a tendency to hyrdoplane somewhat easily and braking in the rain was significantly less than dry. I have been running some lifetime warrenty pads on the front and stock on the back. Having the opportunity to pick up some used rear turbo brake set for a great price, I jumped on them. The rotors are Bradi turbo rotors that have been both slotted and cyrotreated and less than 20k mi. on them. The calipers are stock turbo calipers with Mintex 1115 pads on them. I should also mention that I do a fair bit of driving up in the mountains and don't want/can't go to a 16" rim. This limits me some in my brake options as the WRX stuff is not an option.
Tools and Materials -
14 mm socket
12 mm socket
3/8" ratchet or similar
8x1.25mm x 20mm (2) bolts with corresponding socket, these you will only need if your old rotors are stuck on
New rotors, calipers, and pads
Anti-squeal grease
C-clamp, you'll need this if you have to push the new piston back into the caliper to clear the pads and rotor
12 mm open end wrench
Brake fluid
Torque wrench, yeah I don't have one myself but I should
Procedure -
First thing that needs done is the rear wheels removed and the rear end set on jackstands. Chock the front wheels good and take sure the parking brake is disengaged. Next remove the lock pin from the caliper and rotate the piston assembly up and out of the way. You might want to put a wire tire on it or have a friend hold it out of the way, just don't let it swing down on your arm. Now remove the 14mm bolt from the back of the wheel assembly that holds the bottom of the caliper. It is the only bolt in that area, can't miss it. Now swing the piston back down and remove the top 14mm caliper to wheel assembly bolt. Take off the whole caliper and you can set it on one of the suspension rods if you're careful not to knock it off or twist the hose badly. You are now ready to remove the caliper.
Removing the caliper should just be a matter of grabbing it and sliding it right off. If your rotor is like mine it's stuck on with a fair bit of force. Make sure your parking brake is disengaged and that you can freely rotate the rotor. From here you have a couple of options. If you don't care about the rotor just whack on it with a hammer in an even star patter until it comes off. I however recommend using the 8x1.25mm bolts and threading them into the two holes located around the center of the hub and 180 degrees apart, see Figure 1. Thread the bolts in slowly and at the same time and the rotor will pop itself right off into your hands. I recommend this over the hammer in the first place as it's just as quick and easy and saves putting unnecessary stress on any other components. Now go grab your new rotor and calipers.
Putting the new rotor on is as easy as sliding it on over the lug bolts. Check your parking brake pads before doing so just to make sure they look fine. They will be dusty but should have decent pad left on them. Now go ahead an put the pads and shims in the brakets and use a C-clamp to push the new pistons into the caliper if need be. Now using the two 14 mm bolts you kept, bolt the new caliper back onto the wheel assembly. Torque these bolts down to 25-33 ft-lbs. Before swinging the piston down over the pads, apply your anti-squeal stuff to the back of the pads where it contacts the piston and caliper, you put a tad on the shims too right? Note that some feel the shims are more harm than good. This may be true, however, if your pad doesn't sit real snug put the shims in. Swing the piston down into place and put the lock pin back in. Make sure the lock pins have a little grease on them before putting them back in. Torque these down to 144-204 in-lbs (note in-lb, not ft-lb). Now that your new caliper is mounted and ready, disconnect the brake line from the old caliper by losening the bolt. You don't have to completely remove this bolt but it does need to be full unthreaded from the old caliper. Now put this back on your new caliper and torque down to 132-180 ft-lbs. Make sure it's seated properly first though, you don't want to bugger the seal up.
Now go and do the same thing on the other side.
Once you have both sides ready, you need to bleed the air of them. You will need a friend to help you with this. Remove the rubber cover on top of bleed valve and loosen the valve a 1/4 turn. Now have your friend step on the brake and hold it down while you tighten the valve back. Just repeat this, making sure your resevoir stays full, until all the air is out of the system. Once both sides are bled, put your wheels on and put her back down on the ground.
** All torque specifications have come from my Haynes manual
Pictures -
** Average picture size is around 130kb
Old rotors and calipers
New rotors
New calipers
Installed, wheel off
Installed, left
Installed, right
Retaining my sleeper status
No bling bling here
Conclusions -
Holy smokes, what a difference. The car is more balanced and exhibits little nose dive now under hard braking. Some might consider it more than a little but it is significantly better than before and I still have stock struts and suspension. My stopping power in the rain has been dramaticaly increased and the whole right side locks up about at the same time and with relative ease. On dry I have a stopping distance of 120ft. Yes this is accurate within 5 foot and is scewed toward the high side. My right rear wheel is the first to lock now I think, I haven't visually confirmed this but through multiple tests it sounds and feels as this is the case. Some people put a portioning valve from a BF into their BC but I have no intentions of doing so. I think this would be excessive and actually slightly hindering driving on the gravel and dirt. On the gravel it stops quicker than before but the most noticable difference is that my entry speeds have increased slightly due to less weight shift when I tap the brake to throw the weight forward and the back end out. With the car staying much more level during braking, the slide is much more level and initiates smoother. Having the wagon (BF) prop valve would definately be excessive. It will take me some time to get used to the increased pedal response and the braking bias. I have also taken the car through several consequecutive turns requiring heavy braking and couldn't feel any fade in the braking. All in all I am extremely happy with this upgrade and feel as though my brakes are now more than sufficient and I have retained my sleeper look and I can keep my 15's. I may experiment with different pads down the road to try and get the fronts to lock before the back but as it is now I feel it is close enough that I will leave it alone.