Winter project - SC brakes - a few questions

[tirwin]

I seemed to have survived another turkey, mac'n'cheese, pecan pie & football-induced coma. Hope you all had a glorious Thanksgiving.

I've been reading up on the 16 squintillion brake threads but I have a few lingering questions. Just organizing my thoughts while I have a little down time.

1) Is there any reason to believe that the future availability of replacement parts is an issue for the A- & M- calipers used on the SC?

New A- & M-calipers are NLA, correct? Wide A & M used on the later Carreras are still available though.

PMB Performance can restore these calipers (note: they call their process a restoration, not just a rebuild) but this comment on the PMB website made me wonder.

Referring to the A-caliper: "These are tricky to restore because of the smaller Ribe (reebie) R6 head on a large M9 fastener. Ruined fasteners are what we hear most... sorry, those are NLA."

But they also state that the A-caliper is one of the most common calipers on the planet, so I'm confused by these statements. If it's one of the most common, why are components NLA?

1a) If I do need to rebuild my calipers, a complete restoration by PMB seems pretty cost effective when I look at the cost of a rebuild kit plus my time. And restoring the calipers seems a whole lot less expensive than any of the Carrera/Boxster/996 upgrade options.

2) I see a lot of recommendations to improve heat dissipation for better performance and lifespan, but I don't see many threads discussing brake cooling options for the SC.

Pelican sells a cooling kit: 1983 Porsche 911 SC Coupe - Brake Performance Upgrades - Page 1

Part #: PEL-PBSCBPAZK

There is a note that says it may interfere with factory sway bars. Anyone have any specifics? Any feedback?

And there is also a Rothsport air deflector plate that prevents air from escaping through the hubs when used in connection with a cooling kit.

Part #: PEL-RS-185

Are there other options/ideas for improved cooling out there?

3) If rotors/pads need replacing, I will likely go with Zimmerman standard rotors (not drilled or slotted) and Porterfield R4-S pads. I've been running these on the car and I'm pretty happy with them so I see no reason to change. It looks like the same part number for front and rear. Can anyone confirm?

Pelican only shows a part number for the front but Porterfield website says it's the same front and rear. Just want to make sure I order the right P/N for the rear.

4) I did some hard driving in the North GA mountains and the brakes don't feel the same afterwards. Don't know if I boiled the brake fluid -- it was pretty fresh. Maybe there is still some air in the lines. I need to replace the old rubber brake lines anyway so I'll just go ahead and use braided stainless steel lines and bleed and flush again. Planning on using ATE Super Gold DOT4 brake fluid unless anyone has a different opinion.

Thanks in advance.

[RichardNew]

If you're concerned about brake heat the first thing you need to do is measure it.

You probably aren't running that hot. I've never see high temps on street car. On a track car you can go over 1100-degrees at the rotor. Even that isn't a problem if you have the correct pads.



Once you determine the temperature you can make an informed decision.

"The original brake pads that came with your production car operated best in the 100° to 650° range. Race pads operate best in the 600° to 1500° range. Race pads are just getting effective at roughly the same point where the OEM pads are becoming useless."

Here's the complete article.

Richard Newton

[Joe Bob]

Those bolts are an easy replacement. Drill out the holes and use a larger bore fastener. Easy unless you are a concour weenie and need it OE. They also can be, for now, sourced from junk calipers. There was a recent thread on it.

Further, there are more than a few aftermarket calipers you can use....

[HaroldMHedge]

993 air deflector plates provide another option for cooling.

More brake cooling. . . 993 air deflectors option?

[tirwin]

Originally Posted by RichardNew

If you're concerned about brake heat the first thing you need to do is measure it.

You probably aren't running that hot. I've never see high temps on street car. On a track car you can go over 1100-degrees at the rotor. Even that isn't a problem if you have the correct pads.

Thanks, Richard.

I was under the impression that cooling was good for two reasons: 1) it improves lifespan of wear components and 2) it is cheaper than bigger rotors. The thinking being that people go to bigger rotors for better heat dissipation whereas adding cooling might be a cheaper solution. Still your point about matching pads to temp/use is well taken.

Coming down the mountain roads it is possible that I am on the brakes much more than usual. How much is hard to say. But the problem is there isn't usually a good place to pull over to check the brake temps. Under normal driving circumstances I would guess that temps are rarely a problem. Never had an issue before and it could be something else besides cooling -- like the old brake lines that I know I need to replace.

I like the idea of the paint. I have a hand-held pyrometer but it's an inexpensive one.

[tirwin]

Originally Posted by Joe Bob

Those bolts are an easy replacement. Drill out the holes and use a larger bore fastener. Easy unless you are a concour weenie and need it OE. They also can be, for now, sourced from junk calipers. There was a recent thread on it.

Further, there are more than a few aftermarket calipers you can use....

Good! Didn't realize it was that easy.

[Luccia at Pelican Parts]

The Porterfield PMB-AP45R4-S pads in the catalog are listed for the fronts only, not rears:

1983 Porsche 911 SC Coupe - Brake Performance Upgrades - Page 2

According to the Porterfield website the AP45 part number (pelican # PMB-AP45R4-S) works for Front for PORSCHE: 78-89 911 and lists nothing for rear application. The part number AP31 on Porterfield (pelican # PMB-AP31R4-S HERE) lists for REARS FOR PORSCHE: 78-89 911. Hope this information helps.

What brake fluid do you run? I'd highly recommend trying out the Ate Typ200 fluid (706232-GOLD HERE). I run this fluid on the street and track and have never boiled it. It's cheap and works as anticipated. That fluid with SS lines will do wonders.

Let me know if you have any questions.

[tirwin]

Originally Posted by HaroldMHedge

993 air deflector plates provide another option for cooling.

More brake cooling. . . 993 air deflectors option?

Excellent! I've never seen this option before.

[tirwin]

Originally Posted by Luccia at Pelican Parts

The Porterfield PMB-AP45R4-S pads in the catalog are listed for the fronts only, not rears:

1983 Porsche 911 SC Coupe - Brake Performance Upgrades - Page 2

According to the Porterfield website the AP45 part number (pelican # PMB-AP45R4-S) works for Front for PORSCHE: 78-89 911 and lists nothing for rear application. The part number AP31 on Porterfield (pelican # PMB-AP31R4-S HERE) lists for REARS FOR PORSCHE: 78-89 911. Hope this information helps.

What brake fluid do you run? I'd highly recommend trying out the Ate Typ200 fluid (706232-GOLD HERE). I run this fluid on the street and track and have never boiled it. It's cheap and works as anticipated. That fluid with SS lines will do wonders.

Let me know if you have any questions.

Thanks for clarifying the part numbers on the Porterfields.

I have 1L of that brake fluid I previously bought.

[betterair]

I ran 6 3day de on the porter fields and sebro slotted rotors this summer ,they still hv life left in them (1/3 left),So I am a fan of these pads on the SC . No fade at big or smaller tracks .Also used 2.5 in ducts in this equasion to the rotor /no backing plates, just fresh air.

[Walt Fricke]

Perhaps one reason the Ribe bolts are NLA is that there is no reason to remove them. The normal home "rebuild" for these calipers involves replacing the square cut seal, cleaning up the pistons, blowing any gunk, and putting it back together. And finally wrestling the new dust boots back on. Anything beyond that is basically cosmetic.

You can purchase the brake block off pieces, but it is so easy to use tin snips, a hole punch made for leather, and some thin aluminum to make your own. It is just an annulus with five holes for the rotor fastener heads to stick through (you don't sandwich this piece. Drill five 1/8" holes in the rotor and pop rivet the aluminum piece in place. You can remove it when it becomes rotor replacement time by drilling the rivets, and reuse the plate you made.

And of course remove the backing plates. But if this is a street driven car only, you really don't need to duct any air to the brakes - just don't brake so much, and use a lower gear coming down curvy hills to keep the speed down.

[tirwin]

Originally Posted by betterair

I ran 6 3day de on the porter fields and sebro slotted rotors this summer ,they still hv life left in them (1/3 left),So I am a fan of these pads on the SC . No fade at big or smaller tracks .Also used 2.5 in ducts in this equasion to the rotor /no backing plates, just fresh air.

Great feedback. Appreciate it!

If I may ask, what type of ducts did you use? Any pics of your setup?

[tirwin]

Originally Posted by Walt Fricke

Perhaps one reason the Ribe bolts are NLA is that there is no reason to remove them. The normal home "rebuild" for these calipers involves replacing the square cut seal, cleaning up the pistons, blowing any gunk, and putting it back together. And finally wrestling the new dust boots back on. Anything beyond that is basically cosmetic.

You can purchase the brake block off pieces, but it is so easy to use tin snips, a hole punch made for leather, and some thin aluminum to make your own. It is just an annulus with five holes for the rotor fastener heads to stick through (you don't sandwich this piece. Drill five 1/8" holes in the rotor and pop rivet the aluminum piece in place. You can remove it when it becomes rotor replacement time by drilling the rivets, and reuse the plate you made.

And of course remove the backing plates. But if this is a street driven car only, you really don't need to duct any air to the brakes - just don't brake so much, and use a lower gear coming down curvy hills to keep the speed down.

Good info, Walt. Thanks!

I'm going to replace the brake lines and flush/bleed as a first step. The 993/964 air deflectors seems like they are easy and cheap enough.

[Charles Freeborn]

1.) No. Those calipers are on literally hundreds of thousands of cars of numerous marques
2.) You can do this, but they will hang down below your lower control arms and risk being torn off during normal street driving. http://www.***************/brake-cooling-kit-replacement-hose-for-911-porsche-1969-1989.html Stock brakes should be fine until you get to either very heavy braking on the street (bad boy!) or track use.
3.) Good choices. You can even switch out the front pads to OEM style (Textar or similar) for winter use when you're not likely to get the R4-S's up to temp. Switching out front pads takes literally minutes.
4.) If the feel returned to normal after cooling off you were experiencing normal fade brought on by heat. If the spongy - ness remains, you may have boiled the fluid, glazed the pads or rotors. Step up to dot 4. Other possibilities will be addressed when you do the re-fresh.

Switching out soft lines is always good practice. Depending on use, a 5 year duty cycle is not out of order. Racers do them every season, or sometimes more often.

[tirwin]

Thanks, Charles.

I'm probably going to rebuild the calipers. I was looking through old records and I have no indication of it being done by a PO so it's time. I have not had as much time to work on the car as in the past because of work travel. I know I could do the rebuild but I may go the PMB route if I can just have stuff show up ready to be installed and I can spend an afternoon knocking it all out at once.

[RichardNew]

Tirwin

You can use an infrared scan gun to quickly check rotor temps. As I said the Pagid folks like to use a pyrometer. If you already have one just use that. The trick is to do it quickly as brake rotors cool very quickly.

Be careful of asymmetrical cooling.

"Another type of cooling problem is an imbalance between the inner and outer faces on the rotor. Andreas Boehm of Pagid feels too many people have a brake duct that only directs air to the inboard side. You really want to “force cooling air into the eye of the rotor and out through the vanes. If the rotor temperatures are asymmetrical the brake paint will display this by being different on the inboard side of the disc from the outboard side of the disc.”

Once you measure the rotor temps you'll realize that you really don't need to spend money on cooling.

I might also flush the entire system with denatured alcohol before I take everything apart. Then when I add the new fluid there is no residue left in the lines.

Richard Newton

[uwanna]

Originally Posted by tirwin

Thanks, Charles.

I'm probably going to rebuild the calipers. I was looking through old records and I have no indication of it being done by a PO so it's time. I have not had as much time to work on the car as in the past because of work travel. I know I could do the rebuild but I may go the PMB route if I can just have stuff show up ready to be installed and I can spend an afternoon knocking it all out at once.

Tim,
Just an idea, since you're replacing the rotors with new, how about you buy the bigger Carrera rotors (20mm vs 24mm) and use Carrera calipers. A much more robust brake system for not much more cost. For a start, I have a set of Carrera front calipers that only have 20K miles on them (with a boxed rebuild kit) that I'll give you and then you'll just need to source a rear Carrera caliper set which you could find on the forum. They all use the same pads. The bigger rotors are what you need for less fade due to better thermal dissipation.
Grant

[tirwin]

Grant, that's too good of an offer to pass up! Let's do it!

[Jim Smolka]

PP has a great tech article on a cooling kit for 911 brakes

http://www.pelicanparts.com/techarticles/mult_brake_cooling/mult_brake_cooling.htm

Also, 2nd the idea of Carrera brakes for an SC.

And while you are in there... Recommend replacing the front bearings. A really great project. When the hub is off the strut, recommend cleaning and media blasting the hub. Looks great when finished. Leave the old races in place until you are done cleaning the hub. Used rags stuffed into the hub to keep the media out. A bearing race kit is a great tool to have when replacing the bearing races. Of course, get a good set of bearings (e.g., Timken, etc.) is needed too. Pelican sells a really cool bearing grease packing tool. The Mobile One red synthetic bearing grease is good stuff.

Just my $0.015 worth

[Walt Fricke]

The problem with the under the suspension scoops shown in the referenced article is that they are pretty vulnerable. Dip a wheel off the track where there is a lip, and you might tear one right off. The same kind of thing can happen in street driving also - and they aren't needed there anyway.

The solution seems to be an air scoop of the sort Porsche has taken to using on later cars. Maybe a 993 RS or Cup part to start with? You fashion a bracket for the A arm, and this is attached to it and sticks up, not down. It directs the air which reaches it up and into the center of the rotor. Combined with a block off piece, it gives great cooling. Guys racing with stock SC brakes often use these. To be sure they have brake duct openings in the front spoiler/valance, which sends more air into this area for these to deflect. Not sure how well they work if you have the standard front spoiler.