Brake rebuild questions

[Wavey]

I'm rebuilding the brakes on my Carrera over the winter, in preparation for some track days next year. No upgrades other than Super Blue, just rebuilding the calipers, and replacing the rotors, master cylinder, hoses and Metal Master pads. The car is mainly street-driven, with very occasional track use.

There are some things I'm wondering about:

1. Any reason not to blow out the metal brake lines with brake cleaner and compressed air while everything's apart? Just to get everything clean.

2. Any reason to leave the backing plates on? I'm thinking about just removing them while it's easy to do. Seems like they'd run cooler, but might be more succeptable to water. I'll be installing the Ruf bumpers later and will probably add ducts with appropriate backing plates then.

3. Any reason not to pitch the brake pad sensors?

Thanks!

[Superman]

1. No.

2. Probably not, though in rainy Seattle I've elected to leave them on. Many folks remove them for cooling purposes.

3. No. In fact, I might just use SC pads. They're the same except they lack the sensor cutout. You'd get slightly more surface area.

[Rot 911]

What Supe said.

[lally911]

1) Can't hurt to blow out the lines.
2) Replace with cooling kit (see below)
3) sensors not needed. If you are tracking the car you will be looking at your pads a lot anyway so will know when they are worn. Clip the wires then wire them together to make the idiot light go out on the dash.

While you have the brakes apart put in a cooling kit. If you are just starting out on the track you may have a tendency to overcook the brakes for a while ( I know I did ). The best upgrade was the rotor cooling kit - think I got mine from OG Racing.

[Wavey]

Thanks guys! I figured it was all OK, but there's always the law of unintended consequences. I'd probably be smart to go ahead and do the ducted front backing plates now - I can add the bumper duct and hoses later.

[MotoSook]

Yeah..yeah..what Sup said

Dave, I'm getting the Ruf bumper too! The Carrera is going to be a clone of your car I hope to make it to Tweeks in the summer. Have fun with the brake job. I just rebuilt the front calipers on my Carrera last weekend. Get some 800 grit sand paper to clean the oxidation off the pistons and bores of the calipers. Go easy with the sand paperand don't use an axial motion.

[Early_S_Man]

Wavey,

As to question #1 ... 91% isopropyl alcohol or methanol would be an appropriate solvent to clean your hard brake lines with ... it will dissolve any remnants/clumps of old brake fluid/water/corrosion products left bhind when you drain the lines. I always use the following procedure when converting to DOT 5 silicone brake fluid, and have never had any problems with corrosion resulting from old brake fluid.

The procedure I use is to be sure the air supply has a moisture filter/separator on it:

1. Drain the lines first by blowing with low-pressure air [10 - 15 psi] ... until no more fluid drips out of line into large glass jar from clear vinyl tubing slipped over the double-flare nipple.

2. Feed alcohol through lines with large 50 cc syringe [available at agricultural feed/supply store] with clear vinyl hose attached. Feed enough alcohol to assure that clear, clean alcohol is running out the hard line. This can take a few minutes with the long line through the tunnel!

3. Blow out lines for at least five minutes with dry air at 50 - 60 psi. Repeat after 15 minute 'sitting' time.

[dfink]

Be very carefull not blow fluid onto the paint. Brake fluid has to be the best paint remover ever developed. Even a rag with some fluid on it from cleaning up can take paint off.

[Wavey]

Originally posted by Souk
Dave, I'm getting the Ruf bumper too! The Carrera is going to be a clone of your car I hope to make it to Tweeks in the summer. Have fun with the brake job. I just rebuilt the front calipers on my Carrera last weekend. Get some 800 grit sand paper to clean the oxidation off the pistons and bores of the calipers. Go easy with the sand paper and don't use an axial motion.

Hey Souk - I was just thinking about you over the weekend! I was having a perfectly-poured pint of Guinness Stout and I remembered that you promised me one about a year ago. So, you're saying my car's a fat pig too? Let me know when you're coming down to Brad's, if I'm in town maybe we can hook up.

Thanks for the tips, guys. I'll be doing this over the winter while things are slow in the shop. I've got a feeling I'll be tearing into the suspension too, as long as the car is up on jacks - you know - "while I'm in there". Already got some Bilsteins. I smell PolyBronze....

[MotoSook]

I'll be having a Guinness for you over the weekend Dave. I haven't decided if I'm driving down to get the part yet, but getting together sounds like a good deal. I have a few question I'll e-mail you with privately.

[CRH911S]

To get to the backing plate don't you have remove a spacer or sleeve or something? I didn't remove the backing plates because I thought the cooling slots were sufficient and it looks like this part would need to be pressed on and off when needed.
Not trying to steal this post. Thought this might add to the discussion.

[MotoSook]

No, but you'll have to remove the rotors forst.

[Wavey]

Now that I think of it, while the rotors are off it probably wouldn't hard to leave the backing plates in place, cut holes and fabricate ducts. Plus save about $150 for ducted plates.

[Superman]

Unless you are prepared to cut the backing plates off, you would need to remove the hub. Removing the hub destroys the rear wheel bearing.

Frankly, I'm not sure it's fruitful to remove the backing plate. First, rear brakes do almost nothing. Second, 911 brakes are overdesigned. Third, Carrera rotors and calipers are probably your best and cheapest bet if you did have brake fade issues caused by heat. But I'd be a little surprized if you had rear brake heat issues in the first place.

[MotoSook]

Super is right. I still have the rear plates on my '76-3.0, and I never got any fading in it on the track (but the car is lightened. The brakes on it are the SC brakes..

The Fat Bastard Carrera though, needs help. The plates are still on all corners. I went through the pads a lot faster in it than I do in the '76 (but the Fat Bastard is 2600lbs w/o me in it). I could feel a little fading as the pads wore and heating increased (not specifically related to the thinning pads), or it could be I don't like the vacuum assist. The front's could benefit from removing the plates and cooling, but the rears..not that much.

[Wavey]

Right, I'm just thinking of cooling on the front brakes.