How to rebuild brake calipers

[stuntman]

I did this little writeup for MotoIQ.com when I had to rebuild my front calipers in my M3. Rebuilding most 1-2 piston sliding calipers will be almost identical, regardless of make. My LF rotor was sticking causing the wheel to vibrate and shake violently after driving the car around town for a while. The harder I used the brakes (even only once) the worse the caliper would stick. Then the longer I drove, the worse the vibrations and shaking would get. If I stopped for a while and allow the brakes to cool off, the vibration went away. Occasionally while driving, the vibrations would randomly stop. Probably due to the vibrations knocking the piston back a little. Either way, this is another example of what I found to be somewhat common on high-mileage cars.

I ended up having to replace the LF caliper due to the dust boot coming up and corroding the inner bore of the piston. If you do a lot of regular maintenance on your car yourself, rebuilding a caliper really isn't too bad.

Check it out:

http://www.motoiq.com/magazine_arti...cleid/1685/how-to-rebuild-brake-calipers.aspx


Step-by-step how to:

-Replace your brake pads
-Replace your rotors *with 2-pc Performance Friction "Direct Drive" rotors
-Rebuild your caliper



Billy

 

[ChopsJazz]

Great write up Billy. I've done my front and rear calipers twice and have rebuilt Doug's calipers for him as well. Mine have about 70K miles on them since I rebuilt them last and I'm about ready to do them again.

 

[stuntman]

Great write up Billy. I've done my front and rear calipers twice and have rebuilt Doug's calipers for him as well. Mine have about 70K miles on them since I rebuilt them last and I'm about ready to do them again.

Thank you. Any additional NSX-specific comments you would like to add? Did you also use compressed air?

 

[nsxtasy]

I've had it done twice on my NSX fronts and once on my rears.

I don't know whether or not it's SOP but they replaced the pistons as part of the procedure.

 

[swerve2007]

Thank you. Any additional NSX-specific comments you would like to add? Did you also use compressed air?

compressed air is indeed the easiest way to deal with the boots. once you figure out how it works it is such a breeze compared with any other method.

 

[ChopsJazz]

No, didn't use compressed air to remove the pistons, but if I'd had a compressor it would have made the job a bit easier.

As to NSX specifics: I it a PITA to get the boots on the pistons during reassembly. It's nice if you can get a pair of 6 year-old hands (like Hugabuga's) to help with this part of the work. And the rear caliper is removed by screwing it in and out. I have the rear caliper piston tool if anyone needs it.

 

[pgilliam1]

Since there are knowledgeable posters here, let me ask you this:

My car has 118K miles and is a 1991. I was going to try and rebuild my calipers because the brakes didn't feel up to track standards (they faded terribly - my 1994 BMW had better brakes). I extended the caliper pistons out as far as I could without going beyond the seals and they looked like new (no pits, rust, nothing). The seals are also good (no leaks, tears, nothing). I'm now using ATE blue fluid with Hawk HP+ pads with new rotors and the braking is not great but better. Do I need to rebuild the calipers and would I see an increase in their performance?
Thanks and Happy Motoring!

 

[docjohn]

Since there are knowledgeable posters here, let me ask you this:

My car has 118K miles and is a 1991. I was going to try and rebuild my calipers because the brakes didn't feel up to track standards (they faded terribly - my 1994 BMW had better brakes). I extended the caliper pistons out as far as I could without going beyond the seals and they looked like new (no pits, rust, nothing). The seals are also good (no leaks, tears, nothing). I'm now using ATE blue fluid with Hawk HP+ pads with new rotors and the braking is not great but better. Do I need to rebuild the calipers and would I see an increase in their performance?
Thanks and Happy Motoring!

What pads?

 

[pgilliam1]

What pads?

Pads are Hawk HP+. I'm braking later and harder, which I think helped my fading more than anything else. But that's not my concern. I'm looking for improvement, and if rebuilding calipers would help, then rebuild I will. My pad wear is even side to side, so the calipers seem to be doing equal duty.

 

[docjohn]

I'm asking because fade in and of itself is more a function of poor heat management/poor bedding/glazing/boiling fluid than it is caliper derangement.

 

[BATMANs]

I'm asking because fade in and of itself is more a function of poor heat management/poor bedding/glazing/boiling fluid than it is caliper derangement.

pad material too.

 

[pgilliam1]

I'm asking because fade in and of itself is more a function of poor heat management/poor bedding/glazing/boiling fluid than it is caliper derangement.

Agreed. But does rebuilding the calipers (at this age and mileage), if there doesn't appear to be a problem, help in their performance? Do they lose function if resonably maintained over time and use? I'm not one that wants to spend time and money if the results don't warrant it. To me, the brakes are the weakest part of the NSX and the system that most needs improvement for high performance performance. Again, the only question I have is: Does rebuilding the calipers help in their performance?
Happy Motoring!

 

[ChopsJazz]

IMO, rebuilding the calipers will not add performance, unless you were experiencing a binding piston or torn boots or seals. I currently have a sticky caliper and I know that the heat that I was generating on the track is deteriorating the boots, hence my desire to rebuild them soon.

 

[nsxtasy]

My car has 118K miles and is a 1991. I was going to try and rebuild my calipers because the brakes didn't feel up to track standards (they faded terribly - my 1994 BMW had better brakes). I extended the caliper pistons out as far as I could without going beyond the seals and they looked like new (no pits, rust, nothing). The seals are also good (no leaks, tears, nothing). I'm now using ATE blue fluid with Hawk HP+ pads with new rotors and the braking is not great but better. Do I need to rebuild the calipers and would I see an increase in their performance?

No. The purpose of rebuilding the calipers is if there is a problem - specifically, if the boots are torn or "crispy" or melted, or if something is sticking.

Fading is another issue entirely. A properly operating NSX brake system has better brakes than a 1994 BMW, so something is obviously wrong. Here are the most common reasons for fading. Ond is using crappy brake pads (worse than stock; you can buy generic brand pads at the auto parts store, for example), which just aren't up to the demands of track use. Another is "green pad syndrome"; the first few track sessions with even very good brake pads, the pads will "outgas" and fade big-time. After those first few track sessions, the fade should go away and the brake pads should no longer fade for the rest of their lifetime. This can be avoided by bedding the pads (a proper bedding procedure gets them hot enough to outgas) before using them on the track. Another cause is using old brake fluid, whose boiling point has dropped, rather than high-performance fluid that has been changed within the previous six months. One other cause is using the brakes too much; it's a common mistake by beginners at the track to use too much brakes, by using them over too long a distance (rather than by braking hard over a short distance) and by slowing the car down too much, i.e. going through the corner slower than the car AND the driver are capable of.

does rebuilding the calipers (at this age and mileage), if there doesn't appear to be a problem, help in their performance? Do they lose function if resonably maintained over time and use?

No and no.

 

[pgilliam1]

No and no.

That's what I hoped someone would say :smile:. I agree with everything you said, except that I still think my BMW had better brakes .
Thanks and Happy Motoring!

 

[pgilliam1]

IMO, rebuilding the calipers will not add performance, unless you were experiencing a binding piston or torn boots or seals. I currently have a sticky caliper and I know that the heat that I was generating on the track is deteriorating the boots, hence my desire to rebuild them soon.

When I was checking my calipers for signs of wear, all I found was that my top pins were worn and that allowed the caliper to twist slightly. With the caliper removed from the mount, try and move the pins in all directions. I found my top pins had much more slack than the bottom pins. I replaced the worn pins and regreased them all. Better, but still not great - IMHO.
Happy Motoring!