brake caliper rebuild coming up - am I missing anything?

[Otter74]

I had to have an emergency rebuild of my LF caliper done in the spring, so that one is good now. But I might as well do the RF as well to eliminate any chance of it freezing in the future, and it's time for a fluid change, too.

I've got a seal kit ("rebuild kit") from our host, the ATE parts. I am aware that some piston boot seals can be quite hard to get on, depending on who makes it (I don't know whether the ATE seal is harder or easier.) I've got a grease gun to use to push the piston out (I don't have air, and a grease gun seems safer anyway) and the usual home shop tools and supplies to remove the caliper, clean it, sand the bore, etc. I may order new soft lines just because they're cheap (mine are from the early 2000s so not that old.) I know removing the pads is easy with a special tool, but that it's not necessary. I need a small punch to remove the pins that hold the pads in - better make sure I have one.

Am I missing anything? I'd rather not find halfway through the job that I'm missing something and have to finish the job the following weekend.

[Trackrash]

Were the pistons replaced in your other caliper when it was "rebuilt"?

IMO there is a good chance that there could be corrosion on the pistons. Not worth re-using pistons unless they are in pristine condition.

[Otter74]

No, the piston was reused. I had the LF caliper seize while I was driving through Nashville on my way from Chicago to Atlanta - Wickie Lawrie there rebuilt it for me more or less on the spot, and I needed to get on my way as soon as possible. That one has been fine since. The piston looked quite good (my memory was dim, but I did watch him do the work, as there was nothing else to do other than hang out with him and Clark Crawford). On that basis, if nothing else, I'd feel *relatively* good about the other one.

[uwanna]

No problems with the ATE dust seals on an '80SC front caliper, it just uses a circular spring to secure the dust seal.
The one with the dust seal mounting problems is the rear caliper from the '84 and up Carrera.

[OffCamber00]

Do you have the right grease for the pistons and seals? Might want to get an extra rebuild kit - the seals are a PITA to put on and if you haven't done it before, there is a risk of tearing it. if you don't have them, get yourself a set of flare wrenches for the caliper bleeder valves.

i'm not familiar w/ the grease gun method of popping the pistons, how does that work? does it fill your caliper up w/ grease? that doesn't sound....ideal.

[Trackrash]

I recently rebuilt my front S calipers. I believe they use the same seals as the newer calipers. They were a pain to install. Save your old dust seals to use to push the new ones in. I used a wood clamp to apply the pressure.

[kevingross]

Hi Otter, I think you're headed in the right direction. My thoughts:

- You can typically get the piston out while it's still on the car just pressing the brake pedal. With the pads removed, a few gentle presses on the brake pedal gets the job done. Maybe a little messy, but easier than fussing with a grease gun.

- I'd replace all the hardware while you're in there. So the bleeder valve, pad retention pins / clips, bolts. Yes, replace the soft line. Inspect the hard lines carefully, and if they have any significant corrosion, think about chucking them too.

- Use a little anti-seize on the bleeder valve threads, the soft line fitting to the caliper, and any other fittings you open. And the caliper bolts unless you prefer blue thread locker.

- If there is corrosion on the surface across which the piston seal travels, replace that surface be it the piston or caliper body.

- You can get a specific lube for assembly, a lot of rebuild kits will include a small packet. Or Porsche will sell you a 20 gm tube as p/n 000.043.305.11. Most people use a little brake fluid to lubricate, though, and that works fine.

- In addition to the tools you mention, I'd certainly use a torque wrench on the caliper bolts.

- Rather than sanding the piston and bore, I would use a milder method such as a brake hone, crocus cloth, or "scotch-brite" type scrubbing pad. You don't want the grit from sanding, and you want to be very careful about removing material.

Good luck with the project!

[franklinstower]

I would get the half seals too - PMB Performance has them... they also have a great tutorial on rebuilding calipers on their website. I find splitting the calipers makes it way easier to rebuild. You might as well have them re-zinked while they are apart unless that has been done to them before.

[fizeus]

When I rebuilt mine I used ATE Rebuild kit ... go with that and you will have no problems !!

Just in case you have M calipers... you also should buy a set of caliper internal gaskets (PET ID 901 351 928 10) and a M8 RIBE bit to open the calipers.

If you haven't replaced pistons and yours seems pitted probably now it's the right time to replace them (they are not cheap ... but we are talking about brakes!!!)

Also check your brake soft lines ...


This probably can help you or anyway guide you in the rebuilding process:

PMB - Caliper How To

[gtc]

Front seals and dust boots aren't so bad... it's the dust boots on the rear 3.2 calipers that are a real pain in the backside to install.

[Otter74]

Originally Posted by OffCamber00

Do you have the right grease for the pistons and seals? Might want to get an extra rebuild kit - the seals are a PITA to put on and if you haven't done it before, there is a risk of tearing it. if you don't have them, get yourself a set of flare wrenches for the caliper bleeder valves.

i'm not familiar w/ the grease gun method of popping the pistons, how does that work? does it fill your caliper up w/ grease? that doesn't sound....ideal.

I don't know, but probably. I've got some Syl-Glide and two kits' worth of whatever comes with that. Already have flare wrenches and a two or three torque wrenches.

Re: the grease gun, you screw the fitting on your gun into where the brake line would go - the threading is the same - and push the piston out with the grease. Obviously there's some cleanup afterwards. I read that here somewhere, and the guy who did my other one confirmed it does the job.

Originally Posted by kevingross

Hi Otter, I think you're headed in the right direction. My thoughts:

- You can typically get the piston out while it's still on the car just pressing the brake pedal. With the pads removed, a few gentle presses on the brake pedal gets the job done. Maybe a little messy, but easier than fussing with a grease gun.

- I'd replace all the hardware while you're in there. So the bleeder valve, pad retention pins / clips, bolts. Yes, replace the soft line. Inspect the hard lines carefully, and if they have any significant corrosion, think about chucking them too.

- Use a little anti-seize on the bleeder valve threads, the soft line fitting to the caliper, and any other fittings you open. And the caliper bolts unless you prefer blue thread locker.

- If there is corrosion on the surface across which the piston seal travels, replace that surface be it the piston or caliper body.

- You can get a specific lube for assembly, a lot of rebuild kits will include a small packet. Or Porsche will sell you a 20 gm tube as p/n 000.043.305.11. Most people use a little brake fluid to lubricate, though, and that works fine.

- In addition to the tools you mention, I'd certainly use a torque wrench on the caliper bolts.

- Rather than sanding the piston and bore, I would use a milder method such as a brake hone, crocus cloth, or "scotch-brite" type scrubbing pad. You don't want the grit from sanding, and you want to be very careful about removing material.

Good luck with the project!

Kevin, thanks for those suggestions - I think I'll try popping the cylinder out when the caliper is still on the car. There's gonna be a mess either way I do it. I do have suitable torque wrenches and anti-seize.

Originally Posted by franklinstower

I would get the half seals too - PMB Performance has them... they also have a great tutorial on rebuilding calipers on their website. I find splitting the calipers makes it way easier to rebuild. You might as well have them re-zinked while they are apart unless that has been done to them before.

Do I really need to split the caliper? If nothing else the first one wasn't split and it didn't seem necessary. Even if I did I wouldn't get it re-coated 'cause then it wouldn't match the other side and I'd be compelled to do that one, too. Plus I can't see them and they get covered with dust anyway, so I don't really care. I'll check the video, thanks.

[scary driving]

One of the kits our host sells has the ring to hold the dust boot, and another has the retainer type (I can't remember which is which). The retainer type is a PITA. While you're splitting the calipers, make sure to push the pistons out with compressed air first. Polish them and don't forget to place the half moon in the correct position. It's really not a hard job. You can do it in an afternoon if there are no surprises.

[OffCamber00]

you should not have to split them. I went thru *many rebuilds on my Carrera calipers and never split them.

[gtc]

+1
No reason to split the calipers unless you are replating them. And in that case, i would just send them to PMB.
(Been there done that)

[30westrob]

If you want a long lasting repair on cast iron calipers you should split the halves and have them yellow zinc plated. The original plateing on the caliper bores has been compermised by the corosion. Cleaning the bores without replating will leave a fertile area for corosion to resume, in a resonable time. Rob

[DanielDudley]

Originally Posted by 30westrob

If you want a long lasting repair on cast iron calipers you should split the halves and have them yellow zinc plated. The original plateing on the caliper bores has been compermised by the corosion. Cleaning the bores without replating will leave a fertile area for corosion to resume, in a resonable time. Rob

Assembly with brake grease really holds corrosion at bay. I typically just lube the piston seal and the outer portion of the bore, plus a light coat on the piston. Most will end up in and around the outside bore and on the exposed part of the piston.

Not much moisture makes it past that.

I have seen guys smear a really light coat on the dust seal as well, to keep it from deteriorating. The old FIATs had aluminum calipers that were prone to corrosion and seizing. This assembly process stopped that. We would even grease new units in this way before installation.

[Otter74]

Re: brake grease are we talking about Syl-Glide or similar (my preferred for things like caliper slide pins on cars with floating calipers), or whatever is labeled "brake grease" at my FLAPS or...? I've got all sorts of greases but I don't really recall what without going out to look, but I'm not going to put moly wheel bearing grease or assembly lube or something like that in there.

[kevingross]

Otter, yes, a light smear of grease recommended for floating caliper slides / pins.

[Otter74]

I realized that I hate rebuilding brake calipers, so I spent the extra money and ordered a shiny pair of PMB rebuilts along with new soft lines. It occurred to me at the time that I should get new hard lines at each front wheel because I'm taking them off anyway and they're like $5 each, but I didn't because there's nothing wrong with the ones on the car.

Then I start on the left front wheel and, despite care, PB Blaster and correctly-sized flare nut wrenches, I round off the nut on the fitting at the strut (it had already been slightly buggered when it was removed in April when that caliper was rebuilt.) Now I pay the price for not ordering all the cheap just-in-case- stuff the first time and get to wait until the weekend to finish the job!

Now that it's rounded and I have to replace the line anyway, is there anything better than just gorilla-ing that nut loose with small Vise Grips or something?

I could just leave the lines alone (I have no specific reason to replace them - the soft lines are only about 15 years old) and only replace the calipers and finish the job this afternoon, but I'd rather do it right by doing everything, and I'll have to deal with it eventually.

[fizeus]

Originally Posted by Otter74

I have no specific reason to replace them - the soft lines are only about 15 years old

You can't be serious ...

If you are serious ... you should just think what can happen to your car (and probably to drivers and passengers) if your 15$ soft line, maybe one day, start feeling tired and just break near a stop or in the traffic.

Otter ... you are spending money buying rebuilt calipers from a reputable shop, don't risk your car, your life, and other's people life for an old stupid soft line... just replace it !!

if the nut is gone, just alternate PB Blaster and heat and patience... and with one or two visegrips you will be able to remove it.
I had to go around this process 4 or 5 times....

If you really can't do this job by yourself, just pay someone can do this for you, like you are doing with calipers.
Also keep in mind that soft lines can corrode from the internal part so some rubber can go into the caliper and hog passages and piston making your calipers requiring a new rebuilding process in a few hears ...

here my 2 cents