DIY Guide - Rebuilding Your Porsche 914's Rear Brake Calipers

Rebuilding Your Porsche 914 Rear Brake Caliper with Integrated Handbrake 

Your Porsche 914’s rear brake calipers, unique with their integrated handbrake mechanism, are critical components that deserve more than a quick coat of spray paint to hide the rust behind your shiny wheels. These calipers, built by ATE, are designed to stop your lightweight classic when you’re navigating a world of SUVs and pickups. Neglecting them is not an option, they need proper care to deliver decades more of reliable service. This guide, tailored specifically to the 914 rear caliper, will walk you through the rebuild process with a focus on doing it right.

Why Rebuild Your 914 Rear Caliper?

The 914 rear caliper is a unique beast, featuring an integrated handbrake mechanism that adds a layer of complexity to the rebuild process. Unlike front calipers or later Porsche models, these calipers are some of the first to use a mechanical lever system for the parking brake (now almost all vehicles use a rear integrated handbrake), which requires extra attention during disassembly and reassembly. Over time, corrosion, seized pistons, and worn seals can compromise performance, especially if the car has been sitting for years. A proper rebuild, with zinc plating and factory-spec seals, ensures your calipers will last another 40-50 years. This isn’t about cutting corners with cheap seal kits or skipping steps—it’s about treating these critical components with the respect they deserve. 

If you’re a DIY enthusiast, this guide is for you. We’ll cover the tools, techniques, and pitfalls to avoid, including why you should never hone the bore, how to handle those precious Ribe fasteners, and why zinc plating is non-negotiable. Let’s get started.

Tools and Supplies You’ll Need

Before you touch a nut, gather the right tools and parts. The 914 rear caliper uses specific fasteners and components, and having the correct tools on hand will save you headaches. Here’s what you’ll need, with some specialty items you can order from places like Amazon and right here at PMB Performance:

  • Ribe R5 Bit (for M7 fasteners): The early 914 rear caliper (1970-1972) uses Ribe M7 fasteners, which are not interchangeable with Torx bits. These 5-point star bits are critical for safely removing and installing the caliper bolts. A Ribe bit set costs about $35 on Amazon. Treat these fasteners like gold—they’re NLA (no longer available) and stripping one means hunting for a core caliper to scavenge replacements. 

  • ATE or FTE Factory Seal Kit: Don’t skimp here. Cheap aftermarket seal kits disintegrate quickly because they do not use enough antiozonants in the rubber. Get the proper kit, including bore seals, dust boots, and handbrake mechanism seals. These kits can be found at the link at the bottom of this page, or on our website. 

  • Yellow Zinc Plating Service: You can find a local metal finisher who specializes in yellow zinc plating (not cadmium). This sacrificial coating is what ATE used to protect the caliper body and fasteners from corrosion. Avoid platers with high minimum batch charges—call around or use our expert, on-site zinc plating service. Use the discount code NEWSLETTER and get your plating for 20% off. https://pmbperformance.com/products/pmb-caliper-zinc-plating-service?_pos=1&_sid=54d7ffd27&_ss=r 

  • Black Zinc or Black Oxide for Fasteners: The caliper bolts should be plated in black zinc or treated with black oxide and oiled for longevity. Your player of choice should be able to help you here.  

  • Handbrake Components: Inspect the handbrake lever, return spring, and adjusting screw. Replacements are available from us, but originals can often be cleaned and reused. 

Common Tools Required:

  • Air compressor and air wrench 

  • 6-sided socket set (7mm deep well for bleeders, 11mm deep well for M7 nuts and inner adjusters) 

  • 3/8” ratchet with 3” extension 

  • Torque wrench 

  • 1/2” breaker bar 

  • Needle nose pliers 

  • Dental pick set 

  • MAPP torch 

  • Punch set 

  • Bench vise 

  • Vise-Grips 

  • C-clamps (at least two) 

  • Vibratory polisher or 0000 steel wool 

  • Brake cleaner 

  • Assembly Lube or Permatex Ceramic Lubricant 

  • High-temp paint (gray, for piston tops)

Step 1: Assess the Caliper Condition

Before removing the calipers, determine their condition. Has your 914 been sitting for years, or is it a daily driver? If it’s been dormant, the pistons are likely seized, and the handbrake mechanism may be rusted or stuck. If it’s a driver with regular fluid changes, the pistons might move freely. Either way, let’s start by jacking up the car, removing the rear wheels, and inspecting the calipers.

  • For a Sitting Car: Leave the caliper attached to the brake system. If they have thick or good pads in there, remove them to allow some piston movement. Place an old brake pad backing plate or, our favorite, pieces of one of those larger paint sticks in the bore to prevent the piston from popping out completely. Have a friend press the brake pedal to use hydraulic pressure to free the pistons. Listen for cracking sounds as the pistons start to move. If they’re frozen solid, you may need bench-top methods (see below). 

  • For a Driver: Press the brake pedal a few times to ensure the pistons move freely, then remove the caliper from the car.

Step 2: Disassemble the Caliper 

With the caliper on the bench, start by removing the accessories:

1. Pads, Pins, and Springs: Use needle nose pliers to remove the pin clips, leveraging against the caliper body. Drive out the pins with a punch, keeping a finger on the spring to prevent it from flying off. Remove the pads and set aside the pins and springs for plating or replacement. We now make all of the factory style pad hardware kits and highly recommend them due to the rust and heat cycling of the older springs and pins: https://pmbperformance.com/collections/pmb-brake-pad-hardware-kits

2. Bleeder Valves: The 914 rear caliper uses M7x1 bleeders. Use a deep well 7mm socket to remove them. Be careful, some of the “deep well” sockets out there don’t fully engage. If that’s your case use small Vise-Grips with a firm grip and lots of heat from your MAPP torch to break them free, then finish with an open-end 7mm wrench.

3. Piston Dust Boots: Use a dental pick to remove the wire clip around the dust boot, then remove and discard the old boot.

4. Split the Caliper Halves: Early 914 rear caliper uses four M7 Ribe fasteners. Clean rust or paint from the Ribe heads with a dental pick. Fully seat a Ribe R5 bit with a light hammer tap for maximum grip. Use a 11mm deep socket and small (18”) breaker bar to loosen the nuts in a burst motion. If they resist, apply penetrating oil, heat with a MAPP torch, and tap the fastener end lightly. Be patient—stripping these NLA fasteners is a costly mistake. Heating the nut to a cherry red glow will literally save you time and money. These calipers are NLA and “expensive”.

5. Piston Removal:

  • Free-Moving Pistons: If you haven’t figured it out by now, these calipers are unique.  The old C-clamp and compressed air trick doesn’t work with these pistons. This is why we were able to split the calipers prior to getting the pistons out. If you’ve determined that your pistons are freely moving, you simply use a 4mm hex and crank them out! Easy right? There are a few tips; Tip 1:  On the outboard (we call it the nose section) piston you can remove the small c-clip on the outer adjuster, then remove the thin M8 (13mm) hex. Now you can use a 4mm socket bit and an extension and literally tap your piston out. This often saves that very delicate 4mm hex. Be very careful to make sure you keep that adjuster intact. Tip 2: For the back ½ piston it’s important to understand the relationship with the adjusters. It starts with the pistons. Both internal adjuster mechanisms are “right-hand thread”. This means pistons are interchangeable. There is a small gear (or there should be one) in your inner adjuster cavity underneath the factory 4mm drain plug.  This gear is required to turn the internal adjuster. Why? Because that handbrake shaft is in the way. Understanding this, you now know why the gear turns the adjuster in the opposite direction. Moving on; you’ll need to get at that gear and most often, the access cover can be fused in place. We recommend heat and a cold chisel at the 8:00 position on the cap. Tap the cap until it spins and only then use the 4mm hex to finish removing it. Once you gain access to the gear the handbrake arm can help with leverage on the piston. You can tap the arm back lightly with a hammer being extremely careful not to break off the stop pin.  This will move the piston out in 1/8” increments. Use the gear to bring the arm back into position and do it again. Tap, tap, tap and repeat. 

  • Stuck Pistons: If your calipers are frozen up solid there’s a few things you can do. First, we recommend soaking each caliper ½ in a penetrant. Most FLAPS sell a gallon of carburetor cleaner.  Let them sit in that can overnight (at least). Then you’re going to need to try tips 1 & 2 from the above paragraph. If it’s still stuck, apply heat with a MAPP torch to expand the caliper body or use a large C-clamp to push the piston inward slightly to break the bond. Let “patience” be your virtue. They will usually start to move once the piston bond has been broken in the bore. 

6. Adjuster Mechanisms:

Outer Adjuster: Now that the pistons are out, we’ll need to get the adjuster screws/mechanisms out.  For the outer adjuster, if you followed the tip in the piston removal section, you’re already done.  If not, use a small screwdriver and a pick to carefully remove the small c-clip on the shaft (above the thin 13mm nut).  Tighten the nut with a handheld 13mm socket (not too tight) enough to get it away from the clip. Be careful to make certain that clip doesn’t fly across the room.  Next, remove the 13mm nut and push the adjuster through the caliper ½. You may need to push the adjuster to the caliper casting and then screw it back into place. Push again and screw back into place until the piston pops out.

Inner Adjuster: With the piston out the inner adjuster is next. At the base of the inner adjuster, you will find a c-clip that is holding the hat and spring that are keeping the inner adjuster in place.  You’ll need to remove that c-clip while, taking precautions to ensure it doesn’t fly across the room.  I like to do this with a thumb over the top of the adjuster screw.  Use a pick to pull the clip toward the adjuster and out of the clip journal.  If you have a mid-1975 and later rear caliper this will be extremely difficult.  The clip was changed in these years not to include the smaller c-clip removal holes. We recommend a 90-degree pick and a very small screwdriver. Use the pick the lift the small, angled edge on the end of the clip while sliding the small screwdriver in behind the clip. Once you get behind that edge of the clip, do your best to keep the screwdriver there and pull at the clip until it comes out. This will take immense patience.  Do not worry about damaging the clip, we have new ones available. Once these clips have been removed, the hat, the spring and the adjuster should slide out. Remove the seals on the adjuster shafts and clean the shafts with brake cleaner for reassembly.

7. Handbrake Mechanism: The 914 rear caliper has a handbrake lever, return spring, and spring seat. While the handbrake shaft seal is critical to prevent dust and dirt from getting in the shaft bore, it does not create a seal. First let’s remove the spring and seat. There is yet another clip holding the washer that caps off the assembly. Remove that clip and washer. Next, take a very small Vise-Grip and pull the spring up and off the seat. The seat should then spin off. You may need to tap a very small screwdriver under the seat to convince it to move. They can become corroded in place. Next, let’s remove the lever by extracting the Welsh plug. This can be accomplished but cutting a groove in the top of the plug (don’t go too deep and damage the adjuster inside) large enough to pry it up with a flat blade screwdriver or, drilling a hole in the end and using a small sheet metal screw to pop it up with. Then, remove the inner c-clip and carefully pull the shaft out the opposite direction with a twist and pull motion. Inspect the return spring and spring seat for wear. Clean reusable components with brake cleaner and set aside.

8. Bore Seals: Now that the adjusters are out of the way, it’s much easier to remove the bore seals. Remove the seals with a 90-degree dental pick and discard them. Clean all fluid passages and bores with brake cleaner and compressed air.

Step 3: Prep for Plating

Send the caliper body, fasteners and pins, to a *qualified plater for yellow zinc for the caliper body, black zinc or black oxide for the fasteners and clear zinc for the handbrake arm and washer. We’ve sung the virtues regarding the importance of zinc plating to replicate ATE’s original corrosion protection. A good plater will media blast the caliper body to remove rust, ensuring a clean surface for plating. Insist on plating the bores as well. They were designed to be plated. Unplated bores will rust quickly in the presence of hygroscopic brake fluid. If your plater can’t do black zinc, black oxide with oil is an acceptable substitute for fasteners.

*I mention “Qualified Plater” above because we have seen quite a few caliper bodies “ruined” by platers that leave them in the acid too long damaging the very sensitive M10x1 fluid inlet and M7x1 bleeder threads. If you have ANY doubts, please send the calipers to us for plating.  We do it every day, all day long.

Step 4: Restore the Pistons

While the caliper parts are at the plater, clean up the pistons. Most pistons can be reused unless they are heavily rusted.

  • Cleaning: Use a vibratory polisher with small ceramic media and mild solvent for 30 minutes for a factory-like finish. Alternatively, use a tumble polisher for an hour or 0000 steel wool for the sides and a wire brush for the tops. Avoid sandpaper to prevent out-of-round issues. 

  • Handbrake Components: The piston interfaces with the handbrake mechanism via your adjusters (screws). Clean these with brake cleaner and compressed air. 

  • Painting: Tape off the piston sides with 3M blue tape and spray the tops with high-temp gray paint (muffler or BBQ paint) to match the factory finish.

Step 5: Reassemble the Caliper

With your freshly plated parts and polished pistons, it’s time to rebuild:

1. Install Bore Seals: Use your fingers to walk the new ATE bore seals into place in the caliper bores. Ensure they’re fully seated.

2. Reassemble Handbrake Mechanism: Install the handbrake arm shaft. Use the new shaft seal from the kit. Install the c-clip and put a dollop of assembly lube on the end prior to installing the welch plug. Installing the welch plug can be accomplished at home using a socket and a bench vise to press the plug flat compressing it into the journal. Check the handbrake arm making sure it moves freely before installing the adjuster.

3. Install adjuster mechanisms: Ensure the adjusting screw is clean and functional. Install a new 11x1 seal in the seal journal before moving forward. Next fill the cavity where the small push rod resides with assembly lube. Put the pushrod into the lube pocket and lubricate the seal lightly with assembly lube. Carefully twist the adjuster mechanism into the socket in the caliper so as not to tear the seal. Drop the spring over the adjuster, drop the hat over the spring and drop the clip over the hat.  Next, using a 12mm deep well socket and a large c-clamp, press that hat and spring mechanism down tight. It has to be far enough to get the c-clip into the clip journal.  Tip: Get the back of the clip in first and work your way out to the ends.  Go back and test the hand-brake arm for function.  It should still move freely and snap back into place under the spring pressure. The outer adjuster is much easier to install. Install the new (very small) seal onto the adjuster shaft by walking it down hoola-hoop style “over” the clip journal and into the proper seal journal. Put a light coating of assembly lube on the seal and twist the adjuster into the caliper body. Take great care to maintain the integrity of this small seal.  Install the thin 13mm (not too tight) but past the clip journal. Now install the small c-clip.

4. Install Pistons: With the adjusters back in place, it’s time to pull the pistons back in.

  • Apply a small amount of assembly lube to the bore. Install the dust seal around the piston top before inserting it (these lube packets come in PMB rebuild kits). 

  • Press the piston lightly into the bore so that it comes in contact with the adjuster in the piston. Spin the piston until it begins to seat on the adjuster. Apply even pressure with your thumb and using a 4mm hex on the end of the adjuster, screw the piston in. Once you feel the piston bottom out, reverse the direction until you feel it start to move back out again.  This is an important step of pre-loading your adjuster. 

  • Secure the dust boot with the wire clip.

5. Reassemble Caliper Halves: Build the calipers in a horizontal configuration so ½ seals do not get misplaced and pinched during assembly. Place the EPDM square cut o-ring seals in the grooves of the caliper’s nose section. For vented rotors (rare GT caliper only), add spacers and additional o-rings. Align the back half, insert the M7 fasteners, and finger-tighten the nuts (or fasteners on late model calipers). Adjust the halves to align as best as possible. Then with an 11mm socket on a 3” extension, tighten the fasteners as much as you can by hand.

6. Torque Fasteners: Once the calipers have been tightened sufficiently to hold the seals in place, we can now finish the torquing process.

Mount the caliper in a vise. Use the R5 Ribe bit (early calipers) to hold the fastener (do not turn it) and a 11mm socket with a torque wrench.

  • Using the wrench, torque M7 fasteners in this sequence (number left to right, 1-2-3-4): 

  • Torque One: 7 lb-ft, order 2-3-1-4. 

  • Torque Two: 17 lb-ft, order 2-3-1-4.

7. Install handbrake arm Spring: Install the spring seat on the handbrake arm. Next, using a very small set of Vise-Grips install the springs on the arms.  Place the spring tab on the outside against the pin on the caliper. Twist the spring until the inner tab aligns with the slot on the adjuster arm.  Use a medium flat blade screwdriver to seat the spring on the arm. Cap it off with the handbrake arm washer and small clip.

8. Install Bleeders and Accessories: Screw in the M7x1 bleeder valves with a 7mm socket. Reinstall the pads, pins, and springs, ensuring the handbrake lever moves freely and engages the piston.

Step 6: Final Checks and Installation

Double-check the handbrake operation. Ensure the lever engages and releases smoothly. Ensure the inner piston moves roughly 1/8”. Install the caliper on the car, reconnect the brake line, and bleed the system thoroughly. Change your brake fluid annually to prevent future corrosion.

Why Not to Cut Corners

Big-box rebuilders often skip zinc plating, use cheap seals, and install pistons incorrectly, leading to rust and failure within months. The 914 rear caliper’s handbrake mechanism adds complexity, and improper assembly can cause leaks or binding. By following this guide, using factory seals, proper plating, and correct techniques—you’ll restore your calipers to better-than-new condition, ready for decades of service.

Final Thoughts

Rebuilding your 914 rear caliper is a rewarding project that preserves the soul of your classic Porsche. With the right tools, a bit of patience, and a commitment to quality, you’ll have calipers that outperform those from budget rebuilders. Attention to detail (like proper plating and handbrake assembly details) makes all the difference. Now, go admire your work—and change that brake fluid every year!

If you find this process a little daunting, we’re always here for you. We’ve taken over lots of ½ finished DIY projects with no malice. We started this company in the garage so, we’re here for ya! 

 

Use code: NEWSLETTER for 20% off any caliper products on this page!