Restoring a set of Turbo Calipers
 

I was given a set to restore a few months ago but they were in such bad shape, we ended up Cerakoting them vs restoring to original anodized condition. Those turned out beautifully but when I received another inquiry on restoring a set, I was eager to see how they would turn out.

Calipers as received. Notice how the piston housings are darker than the bridges. Turns out they are different aluminum alloys so they anodize differently and take up color differently. Did a fair amount of testing with various processes to even out the color but they will never match 100%. My anodizer does a lot of military work and we ended up using some special chemistry for a certain black helicopter. I, and more importantly the customer, are happy with the results.

http://forums.pelicanparts.com/uploa...1548288757.jpg


http://forums.pelicanparts.com/uploa...1548288757.jpg


http://forums.pelicanparts.com/uploa...1548288757.jpg


http://forums.pelicanparts.com/uploa...1548288757.jpg


http://forums.pelicanparts.com/uploa...1548288757.jpg



After disassembling, the seals and scraper rings had to be removed before stripping the old anodizing off. Seals pull out easily. Factory technique for removing the rings is to dent them with a small chisel or punch. I made one and it worked ok. Better process was to grab the lip of the ring with a small pair of wire cutters and twist. Doing that a few times shrinks the ring and they pop right out.

http://forums.pelicanparts.com/uploa...1548289123.jpg


http://forums.pelicanparts.com/uploa...1548289123.jpg



Caliper pieces stripped of anodizing. As with window frames you want to be as gentle as possible with the stripping solution as it will start to attack the bare aluminum while other areas still have anodizing. Better to chemically strip as best as possible with minimum attack and then physically remove any remaining anodizing. The goal for these was when the piston bores were clean, they came out of the stripper.

http://forums.pelicanparts.com/uploa...1548289322.jpg


http://forums.pelicanparts.com/uploa...1548289322.jpg


http://forums.pelicanparts.com/uploa...1548289322.jpg

Remaining anodizing was removed in the media cabinet and then the whole top side of each piston housing was evened out. From there they went into the tumbler for a while to create a good clean surface for anodizing.

http://forums.pelicanparts.com/uploa...1548289673.jpg


http://forums.pelicanparts.com/uploa...1548289673.jpg


http://forums.pelicanparts.com/uploa...1548289673.jpg



Even though there is practically no chance any media could be left in the passages after being tumbled, I spent a good 10 minutes on each caliper making sure they were perfectly clean.

First use Cerakote hanging wire and then with welding wire and then water pressure and a final check with light in both light and dark room settings. There is a greater chance of debris being in the calipers passageways when they were made than now.

http://forums.pelicanparts.com/uploa...1548289911.jpg


http://forums.pelicanparts.com/uploa...1548289911.jpg


http://forums.pelicanparts.com/uploa...1548289911.jpg


http://forums.pelicanparts.com/uploa...1548289911.jpg

I thought I had taken pics right after anodizing but apparently not. Next step is to remove the anodizing over the PORSCHE lettering. These are sand cast and machined so even though this was done at the factory when first made, this proved more challenging than I anticipated.

Tools used. The pneumatic pen spins at 56,000 RPM. An amazing little tool.

http://forums.pelicanparts.com/uploa...1548290276.jpg


Taped up and started filing away. Very uneven surface on this particular half.

http://forums.pelicanparts.com/uploa...1548290276.jpg


After a little work and then cleaned up with the wire brush on the pen.

http://forums.pelicanparts.com/uploa...1548290276.jpg


http://forums.pelicanparts.com/uploa...1548290276.jpg


Finally time to get the seals and scraper rings in. Tumbled/polished the pistons and then lubricated the seals with Sil-Glyde, worked perfectly, I used a bearing press disc with some duct tape to press them in place. The pistons are stepped to reduce contact with the pads which reduces temperature transfer from the pads to the fluid. Front calipers, the step is on the lower side, rear calipers the step is on the top side.

http://forums.pelicanparts.com/uploa...1548290276.jpg


http://forums.pelicanparts.com/uploa...1548290276.jpg


http://forums.pelicanparts.com/uploa...1548290276.jpg


http://forums.pelicanparts.com/uploa...1548290276.jpg



All done.

http://forums.pelicanparts.com/uploa...1548290276.jpg


http://forums.pelicanparts.com/uploa...1548290276.jpg

All hardware was stripped of plating, tumbled and then replated in yellow zinc. Got the pistons in and the pad plates with retaining springs. Sil-Glyde worked nicely on getting the springs in. New screws for the plates.

http://forums.pelicanparts.com/uploa...1548291087.jpg


http://forums.pelicanparts.com/uploa...1548291087.jpg


http://forums.pelicanparts.com/uploa...1548291087.jpg


http://forums.pelicanparts.com/uploa...1548291216.jpg


http://forums.pelicanparts.com/uploa...1548291087.jpg


http://forums.pelicanparts.com/uploa...1548291216.jpg



Hardware ready to go. The brass banjo fittings polished up nicely.

http://forums.pelicanparts.com/uploa...1548291216.jpg


http://forums.pelicanparts.com/uploa...1548291216.jpg


http://forums.pelicanparts.com/uploa...1548291216.jpg

Thats some PMB level of detail right there.

Beautiful work. I have a 930 and the front brakes have been dragging so I replaced the seals and scraper rings. The pistons and bores were clean so didn't do any work on them.

Question for you: the pistons are very tight in the bores although I've run them through the bores w/o seals and scraper rings and all pistons moved freely. After replacement, they are still dragging. The rotors are somewhat worn on especially on the outside. Is it possible that with new pads and worn rotors that the pistons are getting cocked in the bores and dragging?

Pretty cool Shaun! That cerakote is spot on.

Spectacular. It’s art. Major caliper envy.

I don't think so. First I would check to make sure your steps are oriented correctly. If they are then I would next check to make sure the rotors are in spec. If they are, I think it might be prudent to disassemble the entire caliper and check the passageways to ensure they are clear.

Thanks! These are anodized using a special military chemistry. The set I did in Cerakote a few months are here. These the customer finished building.

http://forums.pelicanparts.com/uploa...1548297092.jpg


http://forums.pelicanparts.com/uploa...1548297092.jpg


http://forums.pelicanparts.com/uploa...1548297092.jpg


http://forums.pelicanparts.com/uploa...1548297092.jpg


http://forums.pelicanparts.com/uploa...1548297092.jpg


http://forums.pelicanparts.com/uploa...1548297092.jpg

Thanks for the response. I did blow out the passageways with electrical cleaner which leaves no residue as well as high pressure air. When installing the pistons, they had to be exactly straight otherwise would hang up going into the bore after sliding through the scraper rings. I don't think the calipers were overheated as I've never abused the brakes.

The steps are on the bottom side like you mentioned.

Amazing work, my ocd is satisfied.

That’s some fantastic work right there! As soon as I get back to the states I’ll be getting these rebuilt and back on the car. Shaun does fantastic work and the costumer will be very happy with the product. He takes some serious pride in his work and goes above and beyond to ensure it is done right.


Sent from my iPhone using Tapatalk

Not only is Shaun's work exceptional but his customer service matches his work.

Very nice work, indeed.I wish I had a set that I could send you.
Considering these are sand castings, the anodizing turned out exceptionally well and appears to hide the surface irregularities superbly. Type II or hardcoat? Hard to tell from the photos.

damn you shaun! anther temptation.

Built them up this morning. A few quick pics before getting these packed up and shipped out.

http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg


http://forums.pelicanparts.com/uploa...1548346801.jpg

Fantastic work by Shaun once again! Both sets of calipers look fantabulous!!!!

Do the pistons typically need much tumbling or polishing? Their anodized surface is usually very resistant to attack, as long as nobody has mangled them like this

http://forums.pelicanparts.com/uploa...1528716323.JPG

The rule of thumb for the piston steps is they are oriented to be perpendicular to the rotor. If you were to draw an arrow in the direction of forward travel around the rotor, the arrow should hit the step perpendicular. On the Ate calipers it's 20° that gets the piston in the right position

http://forums.pelicanparts.com/uploa...1528739873.jpg

However, on the 930 calipers the steps can be aligned parallel with the edge of the pad box. Just make sure you point the steps to face the direction of travel. That means on the front calipers the steps point up (calipers are mounted in front of the axle) and the rear caliper has the steps facing down because 930s have the calipers mounted behind the axle.


The purpose of the step is to reduce tapered pad wear. Apparently the step allows pad outgassing without the pad coming off the face of the rotor. Without the step the pad tilts away from the rotor face and you get tapered pad wear. It's not insignificant pad wear either. It's actually very substantial if the brakes are used hard like on the track. Later calipers on other cars like the 944 Turbo, 928 S4, 944S2, 964, etc. that have calipers with different sized pistons accomplish the same thing without the need for stepped pistons. The differing piston diameters take the place of the stepped pistons.

Keep up the great work Shaun. Very impressive level of detail and beautiful results.

Seriously excellent work!! They are beautiful. Trying to locate a passenger side big fin caliper for my ride so I can do this project. These pics are pure car porn! :cool:

Thank you James! Email me or give me a call when you get back, I can give you some tips on building them. Stay safe!

Mike, these were done with a proprietary military chemistry used on a certain black helicopter.

The very foundation of Tru6 is surface prep. Honestly, that is 90% of what I do and specialize in. In this case, these were both mechanically and chemically polished to create the best possible surface for anodizing. The combination of the anodizing and prep, these are nicer than factory new.

http://forums.pelicanparts.com/uploa...1548362735.jpg

Thank you Kevin!

Those are ugly, ouch, I've never seen anything like that. I like to polish things so I do any chance I can. These pistons were all in good shape but I feel like they get "freshened" being in the tumbler (no abrasive media) for a bit.

Great info on the piston steps, thanks.

On orientation, I went by the original pieces, this link Tech Article: 930 Brakes and the manual. Reading the tech article, it says the step is to reduce heat transfer from the pad to the piston. Must be fun to be an engineer and think of things like that, and what you say, when desiging something.

Proper restore. Great photo's.

This is some more very impressive work by Tru6. We don’t do much micro-restoration like this, but I can’t wait to see what my little Dino mirrors look like when Shaun is done having them plated! The calipers are amazing. - Matt

fantastic work...

shaun whats the going rate to restore 930 calipers? i have a couple of set that may need to be redone

mucho want!!!:eek::eek:

Thank you!

$900 per pair. More than PMB but I think worth the extra $101.

Absolutely spectacular work Shaun.....thank you for putting a price out there.

This will be number 1 on my wish list for a Santa Stocking Stuffer this year......nice to have a target.

Approx turn around time?

Scott

Thanks Scott! Figure 2-3 week turnaround time. That can easily go to 4 but a good estimate.

Shaun, were did you buy your banjos?
Thanks
Bill K

Hey Bill, those came with the calipers. I tumbled them and then polished them.

That's what I what I was afraid of.
Both my sets (on two cars) came without.
You should see how the resulting brake lines (home-made) look.

Bill K

Geronimo, do you mean THIS 32C? I do not recall getting a member #.
sadly I sold it last year, hated to but needed funds for my 930 project.

http://forums.pelicanparts.com/uploa...1548790962.jpg

I had to get new banjos / hollow bolts as the set I obtained only had ONE. and it turns out those crossover tube are NLA, so will have to make some. got the banjos but got the wrong hollow bolts, waiting on the correct ones.

http://forums.pelicanparts.com/uploa...1548792624.JPG

To reinforce the near-originality that you're getting with a restoration like Shaun's, here's a picture of a new 930 Brembo caliper. They don't make them the same as they used to. New ones come with white zinc fasteners and the anodizing is a shade of purple, not true black.

http://forums.pelicanparts.com/uploa...1548792851.jpg

Bill K,

If you're making your own brake lines regularly, the hot setup i've found is to use the very nice cunifer tubing and a quality flaring tool. Belmetric has quality cohline tube nuts and the cunifer tubing. The cunifer is SO nice because its corrosion resistant and so agreeable to bending.

I have the Eastwood turret style tool (unfortunately just one more example of someone copying and Chinese-ing the original brilliant tool, which I believe was made by Sykes Pickavant) and it makes excellent flares every time. The only issue i've found, and it's a minor one, is the resulting opening in the end of the line is too small. So I open up the hole with a small file after flaring (and clear out the debris with brake parts cleaner) to make it the same size as the tubing ID prior to flaring it.

Here's a basic line I made to fit the 930 caliper to my strut. Looks just like the original you can buy from Porsche. However I also recognize that new OEM Porsche brake lines like these are very affordable. A new line like the one I made myself is currently like $13.

http://forums.pelicanparts.com/uploa...1548793194.jpg


But I also made some very long lines on my '86 Carrera in the front that would have been very expensive to buy. These were the lines that come from the tee near the steering rack and connect with the soft lines at the struts. Anyhow, I feel like the quality flaring tool pays for itself very quickly. Other split bar flaring tools are junk and are to be avoided. They are very inconsistent at making uniform flares and are basically dangerous in my mind when it comes to something important like brakes.

thanks for the quick reply..

nice work on the lines Kevin. There is a good reason to make your own over buying new. New have an extremely durable green coating on them. Fine for most cars but not for anything that will be shown or someone wants "off the assembly line" originality. I've stripped and replated a lot of these lines...have stripped and plate a lot of brand new Porsche parts for customers since the plating is either the wrong color or is just plain ugly. Fan straps are hideous from Porsche. Same with spring plate covers, etc.


http://forums.pelicanparts.com/uploa...1548857092.jpg

Those are so much more beautiful than slathering red or yellow paint on them.

put new seals in mine, the inside ones.
had problems getting the pistons back in.
contacted brembo about it. they sent me a part number for soaking the seals.

did you actually pout grease on the pistons/seals

Sil-Glyde

So nice!
I feel bad for having shaved off some fins on my rear calipers....