Easy AP Racing Pad Change Question

[Drifty//]

How much should the pad retaining bolts in the front calipers be torqued?

The pads came pre-installed in the calipers, and I'm not seeing this listed anywhere in the installation instructions.

I was hoping to swap in my new track pads, tonight. But I guess I should wait to find out how to do it correctly.

[Ti-Jean]

I was in the same situation a while back and had to look it up. If I remember correctly it is 17ft/lb. I don't bother checking torque anymore and simply tighten until I feel resistance. 17 ft/lb is not much.

[Drifty//]

Thanks!! (and a double-thanks for the prompt reply!) Where did you find that information, originally?

I found that the bolts were loose enough that I could further tighten them by hand, before I tried removing them.

BTW, I only did one of the fronts, so far, but the sleeves that house the retaining bolts were really wedged in place. I had to pry them out and then use a rubber mallet to get them back into position. Positioning them to line up with the holes was really a pain! I had to use a flashlight to figure out which direction to push it in, then use a small screw driver (inserted through the hole) to guide the sleeve in that direction while hitting with the mallet. I don't believe they're supposed to be so tight.

[JAJ]

Originally Posted by Drifty//

How much should the pad retaining bolts in the front calipers be torqued?

The pads came pre-installed in the calipers, and I'm not seeing this listed anywhere in the installation instructions.

I was hoping to swap in my new track pads, tonight. But I guess I should wait to find out how to do it correctly.

From the AP Racing caliper drawing, the correct torque for the pad retaining bolts is 9.7 ft-lb, and the bleeder screws are spec'd at 12.5 ft-lb.

http://www.apracing.com/Drawings/cp5555_1cd.pdf

[Drifty//]

Originally Posted by JAJ

From the AP Racing caliper drawing, the correct torque for the pad retaining bolts is 9.7 ft-lb, and the bleeder screws are spec'd at 12.5 ft-lb.

http://www.apracing.com/Drawings/cp5555_1cd.pdf

Thanks! It seems rather incongruous that they're torqued so lightly, when the sleeves are jammed in there so hard.

BTW, your posts about this kit really helped me with my purchasing and installation decisions. So far, I'm very pleased with the street performance of the kit. I'm excited to see what they can do on the track!

[Drifty//]

So, I finished the last corner, not long ago. I can think of better ways to spend a Saturday night, but this is when I had time. If I'd have waited until the day of the event, I'd have certainly missed track time and would've had to borrow a couple tools. Either way, the next pad change will go much faster - there's a definite learning curve.

This is not quite the easy pad change I'd hoped for. Those sleeves are awful! They should fit better and there should be some kind of notch to help you position them properly. The friction pins in the rear calipers aren't as bad, but suffer from similar positioning problems.

I did find that it's easier to seat the friction pins with a pair of pliers than a hammer. Although hammer and punch are still the best way to unseat them.

[JAJ]

I'd forgotten about the sleeves. On mine they just popped out when the bolt was out of the way.

Take a file and just file the ends of the sleeves until they slip in and out without any drama. The purpose of the sleeve is to reinforce the top of the caliper and keep it from flexing inward under heavy braking. They don't have to be tight, just present. Stoptech achieves the same function with a cast bridge piece, AP does it with a couple of sleeves and Brembo monoblocks have a cast-in bridge, while Brembo's racing calipers have a pair of spring clips and no reinforcing at all.

The other tool that's really handy for changing pads is the Girodisk spreader. Yes, they're expensive, but there's just nothing like it for getting pads out quickly and easily.

[Drifty//]

Originally Posted by JAJ

I'd forgotten about the sleeves. On mine they just popped out when the bolt was out of the way.

One of the 4 came out fairly easily. The other 3 required serious prying (I used the pad backing plates & rotors to pry against). It really makes me wonder about their manufacturing tolerances, and whether the sleeves are really too long or whether the caliper halves are actually too close together.

Originally Posted by JAJ

Take a file and just file the ends of the sleeves until they slip in and out without any drama.

That was my plan.

Originally Posted by JAJ

The purpose of the sleeve is to reinforce the top of the caliper and keep it from flexing inward under heavy braking.

I wondered about this, and was planning to remove only enough material to get them in & out more easily. I was still planning on having them fit snugly.

Originally Posted by JAJ

The other tool that's really handy for changing pads is the Girodisk spreader. Yes, they're expensive, but there's just nothing like it for getting pads out quickly and easily.

Thanks, I assume you mean this?

http://www.girodisc.com/Caliper-pist...er_p_5970.html

I actually got along just fine with one like this:

http://pkvista.com/TraqJunk/images/PadSpreader.jpg
http://pkvista.com/TraqJunk/PadSpreader_pix.html

I didn't order from them - I found that page by searching google images for one that looks like mine. To use it, I just pulled out the pads about 1/4th of the way and then used it at 2 or 3 points right next to the rotor. I think I saw a link to one like it on some other forum, and then I just searched ebay until I found one of this design. Perhaps mine is a cheap copy, but I hadn't seen this page when I bought it and it works well enough.

I'll bet the Girodisc spreader is safer for the piston & a bit faster, but I probably won't bother.

[Drifty//]

I had another question I was going to post in a new thread, but I guess it fits fine right here.

So, before pulling the trigger, I read the whole E92 M3 AP Racing BBK Review (long) thread, among others. Basically, you can learn a lot by just reading all of AP Racing - Chris_B's posts (best manufacturer rep I've ever seen on a forum - so sad he's no longer with them). I (and probably many others) would not have bought this kit without having read posts like the ones he made.

Anyway, one thing that caught my attention is how he recommended against using the anti-rattle clips:

NOTE: For both front and rear, I recommend NOT running the anti-rattle clip at the track. If they get hot enough for a sustained period of time, they will start to temper back and lose their effectiveness on the street.

http://www.m3post.com/forums/showpos...&postcount=306

So, do you track with the clips in? I assume he's talking about the bits of sheet metal held in by the sleeves & pins. Maybe it's just the pads I'm using, but it seems like they'd move around a lot, without those clips.

[Drifty//]

BTW, so glad to see you're still on here, JAJ. I assume you've posted a comparison between your M3 and the GT500? Do send a link, if you have. I hope you enjoy it!

[Ti-Jean]

Originally Posted by JAJ

From the AP Racing caliper drawing, the correct torque for the pad retaining bolts is 9.7 ft-lb, and the bleeder screws are spec'd at 12.5 ft-lb.

http://www.apracing.com/Drawings/cp5555_1cd.pdf

Sorry about giving the wrong torque spec initially, I was going by memory and 9.7ft/lb is the correct one. I got it from the same drawing posted. I used a torque wrench the first time and realized how ridiculous it is for this application and always did it manually afterward.

Originally Posted by JAJ

I'd forgotten about the sleeves. On mine they just popped out when the bolt was out of the way.

Take a file and just file the ends of the sleeves until they slip in and out without any drama. The purpose of the sleeve is to reinforce the top of the caliper and keep it from flexing inward under heavy braking. They don't have to be tight, just present.

I did similar but was a bit lazy so simply scrubbed the ends on the concrete for the first few times and they are fitting perfectly now.

Originally Posted by Drifty//

This is not quite the easy pad change I'd hoped for. Those sleeves are awful!

You'll see... after a few times you'll be expert and will get it done in no time. I can get all 4 corners in ~30min and <1hr including all the tool prep and clean up afterwards. I'm not that fast at it, just amateur.

As a side note, I'm running the anti-rattle clips on track and didn't notice any issues so far. I'm afraid I'll loose the clips if I don't install them when putting my race pads on The one thing I would suggest is to take off the bleeder valves plastic covers (don't know the name for it) for track duty. I can't tell you how many I lost at the track

[JAJ]

I haven't posted a comparison between the M3 and the GT500. There really isn't a way to compare them - they're both awesome!

Chris B was a great resource - I agree he was a big loss to the community when he moved on.

I always ran my anti-rattle clips, but then I never cooked my brakes either, so it wasn't a problem. If you run them till they glow, you might kill the springs, otherwise don't sweat it.

By the way, prying against the AP Racing strap-drive rotors is a bad idea. If you bend a strap it will cause balance issues. That's actually the reason I bought the Girodisk product. Later on, I discovered that Girodisk is about an hour and a half from where I live and I drive by them every time I go to the track. They're a great bunch of guys and they make great products.

[Drifty//]

Thanks for the info!

Originally Posted by Ti-Jean

I did similar but was a bit lazy so simply scrubbed the ends on the concrete for the first few times and they are fitting perfectly now.

I already got a file to shorten the sleeves, but I still think there should be notches in the caliper body to help you position them. Not a big deal, but it would have been a nice touch.

I do think the pad change on these is better than removing the caliper, especially since I don't have to worry about having a place to rest it on (my toolbox got really dirty that way) and possibly rupturing the brake line, if it falls. I'm comparing them to the Alcon monoblock calipers I had on my last car. Not bad, but I thought it would be a good idea to get a kit where pad changes were as easy as possible. These are a definite step up, but perhaps not quite the sub-5 minute per corner operation I'd hoped for.

Ideally, I'd like to be able to arrive at the track 30 min before the first session and have my pads and wheels swapped w/o losing driving time, as I don't always get the pads swapped the night before. It's a bit optimistic, I know. I'm not a morning person and I like to get in a much sleep before a track day as possible.

Originally Posted by Ti-Jean

The one thing I would suggest is to take off the bleeder valves plastic covers (don't know the name for it) for track duty. I can't tell you how many I lost at the track

Do you lose the bleeder valve covers while driving on the track, or you mean while servicing your brakes? Do you put them back on for the street?

[Drifty//]

Originally Posted by JAJ

By the way, prying against the AP Racing strap-drive rotors is a bad idea. If you bend a strap it will cause balance issues.

Sure, but I meant applying radial pressure (i.e. pressing against the outer edge, toward the wheel hub). I don't see how straps can be bent in that way, and the kind of force we're talking about is nothing compared to the torque applied by the brake pads.

I did read that you shouldn't use caliper spreaders against the face of the rotor - that I understand and have not done. I used my caliper spreader between the pad faces, only.

[Ti-Jean]

Originally Posted by Drifty//

Do you lose the bleeder valve covers while driving on the track, or you mean while servicing your brakes? Do you put them back on for the street?

I mean that I lose then on track. I don't know why and how... all I know is that I'll go out will all 8 (2 per corners: inside and outside) but return with 1 or 2 missing.

[dogbone]

I have the AP kit on my car. I've done a zillion pad changes at this point. I've even replaced the front rotor rings myself. (What fun!)

First, I have to say, the AP kit is one of my favorite mods on the car. They are simply awesome on the track, and I've done over 30 track days with them----super hot 110 Degree days, cold days, hilly tracks, flat tracks, hi speed tracks, tight turn tracks. No matter what you throw at these brakes, they don't care and just keep working great. Nothing phases them. However, pad choice and brake fluid (get SRF) has a lot to do with it. What track pads did you go with?

Also, if you have questions about the kit, Jim Hodgman at Stillen (the AP distributor) is a great resource. Really friendly guy, and willing to help. He took over Chris' job. I've met him several times, and he's knowledgable and friendly.

I also invested in a GiroDisc piston spreader. I was changing from track pads to street pads and vice versa so often, I was tired of pushing pistons with my fingers. Actually, I had a weird experience......the long side of the GiroDisc was slightly too wide for the front AP caliper.......And the narrow side wasn't really spanning all three pistons the way I would have liked, so I ended up having to grind the long side down......phew.....let me tell ya, that's some seriously hard metal. Doing it without a piston spreader is doable and generally fine, but the piston spreader sure is convenient, albeit ridiculously expensive.

Anyway, even without the piston spreader, the time it takes me to do each corner, including jacking up the car, removing the front wheel, pulling the street pads, installing track pads, re-installing the wheel, lowering it and tightening the wheels bolts is down to 5 minutes on each front wheel. The rears take a few minutes longer because those silly push pins are a pain in the ass.......For the life of me, I cannot figure out why they didn't just put the same kind of screws that are in the fronts, on the rear calipers........having to hammer those silly pins from the back side of the calipers is just a stupid design......ah well, the kit is amazing. I guess they can have a little funk in the design..... Anyway, just keep doing the changes and you'll get it down to 30 minutes.

A few other notes about the AP kit:

-It is commonly said that the front rotors are 36mm new and finished at 34mm. That is actually incorrect. I have carefully gone over this topic with Stillen. A brand new rotor is actually 35.56mm thick, not 36mm. And it does have 2mm of wear range. That means it's used when it gets to 33.56mm. One might say, it's only 0.44 mm, who cares? Well when you only have a 2mm wear range, 0.44 mm is 22% of your rotor life. Let's say a front rotor's life is---I'm approximating here----around 35 track days. 20% of that would be 7 track days. These are $900 rotors. You want them to last as long as possible. (When I brought this topic up with Stillen, they ended up asking AP what the heck was going on, because even Stillen said they were 36mm. AP responded back, "Hey, we're in England! We don't do metric!!" haha It turns out 35.56mm is exactly 1.4 inches.)

-Cracking - when you track, these rotors will start to show surface cracking. This is normal. Cracking is fine as long as it does not appear at the edge of the rotor. As long as the edge of the rotor is crack-free, the rotors are fine to use. I had a TON of cracking on my front rotors. I kept sending pictures to Stillen, and they kept saying that as long as the width of the rotor was in spec, I could keep running the rotors. Ultimately, the width of the rotors got below spec before any cracking was an issue.

-There are rubber dust boots around the rear pistons. I've found that several have cracked. Stillen can sell you more dust boots. The dust boots themselves are not hard to replace, but accessing them is impossible while the caliper is attached. I had to remove the two main screws and pull the caliper. Once you do that, then replacing the dust boots is pretty simple. You need to use Red Loctite on those main screws that hold the caliper to the bracket and torque to 50 ft lbs.

-I track with the rattle clips. Never had a problem.

-I don't EVER use that pin with the spring on the fronts that hold the pads off the rotors. Ugh---those things are a nightmare---springs shooting everywhere. Forget them......

Have fun!

[Drifty//]

Wow, that's a really informative post. Thanks!!

Originally Posted by dogbone

However, pad choice and brake fluid (get SRF) has a lot to do with it. What track pads did you go with?

I'm using AP's PRF 660 fluid and Carbotech XP 12 (ceramic) pads. I've used Carbotech on my previous track car and had good experiences with both their street and track pads. We'll see how they handle the M3, but at least these are bigger calipers & rotors than I was using before. Also a more aggressive pad compound, good to 2000 degrees.

Originally Posted by dogbone

the piston spreader sure is convenient

Did you see the spreader I linked above? It's not as nice as the Girodisc, but probably doesn't take a whole lot longer.

Originally Posted by dogbone

For the life of me, I cannot figure out why they didn't just put the same kind of screws that are in the fronts, on the rear calipers........having to hammer those silly pins from the back side of the calipers is just a stupid design

I found that the right kind of pliers makes them easy to get back in. I put one jaw on the backing plate of my pad and the other on the head of the pin. It's a little awkward and slightly prone to slipping off, since you're squeezing at an angle and not exactly along the shaft of the pin, but it's probably a lot easier than a hammer and safer for your caliper.

I think they're called tounge-and-groove pliers. They look like these:

http://en.wikipedia.org/wiki/Tongue-and-groove_pliers

Originally Posted by dogbone

-I don't EVER use that pin with the spring on the fronts that hold the pads off the rotors. Ugh---those things are a nightmare---springs shooting everywhere. Forget them......

Huh? Not sure what you're talking about. Is this a part of the caliper, or some aftermarket accessory?

[dogbone]

Originally Posted by Drifty//

Wow, that's a really informative post. Thanks!!

Sure! hehe I've had a nice journey with these brakes. It's fun to vibe with others that have them. They're not as popular as some of the other brands, and that's just fine with me.

Originally Posted by Drifty//

I'm using AP's PRF 660 fluid and Carbotech XP 12 (ceramic) pads. I've used Carbotech on my previous track car and had good experiences with both their street and track pads. We'll see how they handle the M3, but at least these are bigger calipers & rotors than I was using before. Also a more aggressive pad compound, good to 2000 degrees.

I've been known to get preachy about brake fluid, but I'll do my best to keep it to a minimum here. Ti-Jean, who has already posted in this thread is using the AP brake fluid with his AP kit. His take on it is that he does overcome the fluid and that he can feel it in the brake pedal, but that it recovers pretty quickly. Castrol SRF just simply does not change in feel EVER. It's always the same----hot tracks, cold tracks, fast tracks, slow tracks......Let me give you an example. I had my first trip to Laguna Seca at the end of June. It was hottttttt----way hotter than usual. All the locals were complaining. The track surface temp was around 140 degrees by 10AM. After a few sessions, I remember coming off the track thinking, "gee this track is pretty easy on brakes." And mind you, I have Hankook TD in 295 square, so I have a lot of tire surface and grip to work with when braking---plenty to torture a brake setup at the very least. Well, as the weekend wore on, I heard many people (with nice car setups) talking after they came back to the paddocks that their brakes were just simply being overworked and giving them trouble. I drove two full days there plus an extra session on a third day, and I never once had any brake issues. No pedal changes, no pad fade, no anything. And that's how every track session goes with the AP kit. So, my humble opinion is don't mess around. Get SRF, and be happy!

I have a pair of those pliers. I'll give them a shot. Anything must be better than hammering that silly thing.....

Originally Posted by Drifty//

Huh? Not sure what you're talking about. Is this a part of the caliper, or some aftermarket accessory?

Some early users of the AP kit complained that street pads made a groaning sound at slow speeds on the street. AP looked into it and determined that the front pads were resonating against the rotors at these low speeds and making this unpleasant sound, so they came up with a metal pin and a spring that were meant to keep the pad from pressing against the rotor so hard, thus eliminating the groaning sound. You know how there's a hole in the center top of the front pad? The pin bridges across the top of the caliper and sits in these holes on each pad. And there's a spring that goes around this pin that pushes against each brake pad. Basically the pin's job is to keep the spring from flying off while it's pushing against the pads. Anyway, the whole thing is a pain in the ass because you have compress the spring while trying to get the pin in the holes and it pops out of your fingers and flies into your eyes-----OMG, what a pain. The pin and spring barely work at stopping the groaning sound, and I never use them. Anyway, I just mentioned it so that if you were struggling with putting them on and off, I was telling you to just forget them.

[JAJ]

Originally Posted by dogbone

...I had a weird experience......the long side of the GiroDisc was slightly too wide for the front AP caliper.......And the narrow side wasn't really spanning all three pistons the way I would have liked, so I ended up having to grind the long side down......phew.....let me tell ya, that's some seriously hard metal. Doing it without a piston spreader is doable and generally fine, but the piston spreader sure is convenient, albeit ridiculously expensive...

I just kept a set of worn-out pad backing plates on hand to drop into the caliper so I could push all the pistons in at once. Worked like a charm, no filing needed.

On the weekend I installed a set of Stoptech 355 mm brakes with 6 piston calipers on the GT500. Now I can use my 18" rims again. The Stoptech ST60 takes the same pads as the AP Racing CP5555, so I'll be burning up another set of pads to use as a backstop for the spreader.

[dogbone]

Originally Posted by JAJ

I just kept a set of worn-out pad backing plates on hand to drop into the caliper so I could push all the pistons in at once. Worked like a charm, no filing needed.

On the weekend I installed a set of Stoptech 355 mm brakes with 6 piston calipers on the GT500. Now I can use my 18" rims again. The Stoptech ST60 takes the same pads as the AP Racing CP5555, so I'll be burning up another set of pads to use as a backstop for the spreader.

Interesting. I didn't want to add more pieces to the puzzle, so spending 20 minutes grinding the tool down and then spraying some orange spray paint on it seemed simpler in the long run for me.

It doesn't need much grinding. But that metal is impressively hard, so it takes some work. I called GiroDisc to give them the feedback that it didn't fit the front calipers. They seemed unaware of it. It's just a bummer that you spend that much on a tool and it requires so much tweaking or workarounds. It is a nice tool though. I would recommend it to someone who is tired of pressing pistons with their hands.

[Drifty//]

Well, the sleeves didn't need much filing. After just a few passes, they now slide in/out pretty easily, but still have small enough tolerance that they could brace the caliper when it's under compression.

I got a small torque wrench, though it uses inch-pounds. So, I torque the pad retaining bolts to 116 inch-pounds.

The pliers are working very well for the friction pins. I did need to crimp down one of the friction sleeves that didn't seem to fit in the caliper.

I tried running without the front anti-rattle clips and it seemed to work okay. They sure do make a bit of noise, driving around at low speeds.

Even though the installer left the dust guards in place, I still used less than 1 mm of pad material per day, and the inside pads didn't show significantly more wear than the outside ones. And that's in spite of the fact that my instructor had me on the brakes earlier & longer than necessary. I'm glad I didn't pay extra for brake ducts!

The Carbotech XP12 pads are working very well, for me. They have enough torque to lock the wheels in a 90 MPH downhill braking zone, yet they're still easy to modulate and seem like they'll last a decent amount of time. Never a hint of fade from either the pads or fluid. Air temperature was about 90 degrees and the sun was out for pretty much the entier first day.

[Drifty//]

BTW, anyone can PM me if they want the set of pads that came with the kit. They've never been used on the car - I used Carbotech with this kit from day 1, since you don't want to switch between organic and ceramic pad compounds on the same rotors (or else you should at least scrub the old transfer layer off).