Porsche brembo caliper brake swap for 473$

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Dustert73

Stripping bolts since ‘10
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I want to kick this off by saying this thread is for entertainment purposes only. What you use this information for is completely your responsibility. I take no responsibility for your actions.

With that out of the way. This is how I swapped 4 piston Porsche brembo calipers onto my 1973 Plymouth duster for 473 dollars (including tax and shipping). It should go without saying that I deal shopped, and used all available discounts at my disposal to get that price. I don’t have sponsors, and aside from my speed perk rewards at advance auto, I don't have any special accounts at the other parts stores.

Most importantly these brakes will fit a 15 inch wheel. I have them under my factory steel wheels currently.

I’m going to separate the posts to keep the pictures organized. If you have any questions or see anything in the thread that I should change to make it easier to understand please feel free to share.

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These are the front calipers from a 1997-2008 Porsche Boxster *base model* utilizing 36/40mm piston bores. Not to be confused with S model calipers, they are different. Casting numbers needed are 986.351.421 and 986.351.422.

I purchased my 986.351.422 caliper from a junkyard online named Brickyard Imported Car for 90$. Then my 986.351.421 caliper from eBay for 99.98$.

Rotors are the beloved late 70’s Chrysler 11.75 units. Which I picked up on amazon for 123.54$. (Powerstop rotors P/N AR8309XPR)

If you look on www.car-part.com you can see junkyard inventories across the states. I searched for a 1999 Porsche Boxster. When I bought my caliper from imported car I called them and they shipped it to me without batting an eye.

Before stripping all the grime and paint off, I tasked myself with removing the pistons and related seals. Which if you’ve never messed with 4 piston brembos before, this step is kind of a pain. I had to use c clamps, a scrap wood block, and compressed air to walk each piston out evenly. Because if you try to hit the fluid passage with only compressed air, one or maybe even two of the pistons will pop out. Leaving you with reinstalling the separated pistons in order to remove the other remaining suspects.

After the pistons and seals were removed. I stripped the calipers of their paint and road grime. One of my calipers required the cast in Porsche script to be removed. Which some 120 grit sandpaper handily accomplished.

After a thorough cleaning with IPA, the calipers were sprayed with VHT engine primer and ford semi gloss black. The calipers in my last pic are Jeep calipers I’m currently in the process of swapping onto the rear.

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Ever price a new Porsche rotor.....WTH? $$$
Some sort of super hard nano-coating that's on them now.
 
Next is the arduous task of fabricating the mounting brackets. The material in question being 3/8 thick angle iron I had access too already.

I started this process by locating the caliper properly on the rotor. Using the correct size feeler gauges taped to the pad pins inside the caliper; this is how I centered the caliper to the rotor. Then I used shims I had previously purchased (toilet shims lol) to properly locate the caliper-to outer diameter of the rotor clearance. All while giving consideration to the pad contact area on the rotor.

Once the caliper was correctly located I used my transfer punch set to find and mark all the mounting holes that needed to be made.

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Nice job?

What size diameter are the rotors?
 
I want to kick this off by saying this thread is for entertainment purposes only. What you use this information for is completely your responsibility. I take no responsibility for your actions.

With that out of the way. This is how I swapped 4 piston Porsche brembo calipers onto my 1973 Plymouth duster for 473 dollars including tax and shipping. It should go without saying that I deal shopped, and used all available discounts at my disposal to get that price. I don’t have sponsors, and aside from my speed perk rewards at advance auto, I don't have any special accounts at the other parts stores.

I’m going to separate the posts to keep the pictures organized. If you have any questions or see anything in the thread that I should change to make it easier to understand please feel free to share.

View attachment 1715572673

The piston size in those calipers might be a little on the small size so keep an eye on your proportioning. I used Big Reds from a 911 Turbo when I did my Porsche swap.
DSC_1148 (Large).JPG
 
Next is the arduous task of fabricating the mounting brackets. The material in question being 3/8 thick angle iron I had on hand already.

I started this process by locating the caliper properly on the rotor. Using the correct size feeler gauges taped to the pad pins inside the caliper. This is how I centered the caliper to the rotor. Then I used shims I had previously purchased (toilet shims lol) to properly locate the caliper-to outer diameter of the rotor clearance. All while giving consideration to the pad contact area on the rotor.

Once the caliper was correctly located I used my transfer punch set to find and mark all the mounting holes that needed to be made.

View attachment 1715572654

View attachment 1715572663
Don't use angle iron for the bracket, have a local machine shop build the brackets from some 6061-T6 bar stock. Should be a simple bracket to machine. The Porsche hardware will be metric.
viper_c.jpg
 
I ask for you guys to be patient please. It’s going to take a little while for me to process and upload my saved info.
 
Once all the mounting hole locations were found, I moved on to drilling the bracket. Spindle side of the adapter called for 1/2 inch holes, while the caliper side of the bracket needed 31/64 holes.

After that step was accomplished, I cut down the bracket and contoured the edges to fit between the lower ball joint and upper spindle mount.

Then came the process of mirroring the adaptor I just made for the left side of the vehicle. Which was simple enough with the use of c clamps, a sharpie, and my transfer punches.

I am by no means a mechanical engineer (which I’m sure you guys can tell by my drawing). I measured to the best of my ability. These measurements would at least get me into the ballpark next time I wanted to do this swap. I did have to minutely round file the mounting holes, and flat file some of the brake pad pins in the caliper to get everything to fit properly. I’d also cut over the total length and width measurements next time too. To give enough material to remove and sand to the final shape.

After mirroring the adapter, I sprayed them with the leftover high temp VHT engine enamel paint I had used on the calipers.

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After the brackets were fabricated, I moved on to rebuilding the calipers. I was able to find a kit on eBay that had all the seals needed for both calipers including two new bleeder screws for 30.64$ (Centric P/N 143.37013). Once I was finished installing those, I could finally move onto the extremely important step of applying the brembo decals to the calipers. Which I purchased from amazon for 4.57$.

When that project changing step was completed I was finally able to mount the calipers with a set of power stop pads I purchased off amazon for 44.30$ (P/N Z23-737 and mounting bolts bought from my local rural king for 19.43$ (12mm by 80mm socket head cap screw part # 87443 with related 12mm hardware)

After mounting the caliper, I could tackle the brake hoses. Which are the rear brake hoses from a 2004 Chevrolet Silverado 3500 8.1 (Dorman P/N H620042) that were purchased off amazon for 31.80.

Banjo bolts, new dust caps, and two cans of brake clean were sourced from advance auto for 27.70$ (Dorman banjo bolt 14100 x2, Dorman hub dust cap 13996 x2). I had to remove (from memory) around four threads off the banjo bolt in order for it not to bottom out in the caliper, and bend both hoses accordingly to make them fit.

I also had to file off the factory locating tang on the hose where it meets the factory A body brake hardline. So it would fit in the factory A body brake hose frame bracket.

* WARNING This is the part of the swap that’s not for the faint of heart* I had to sand down one of the rotor hats due to a high spot in the metal left from the manufacturing process that was making contact with the pad. The other rotor fit wonderfully. Also I needed to sand the brake pads themselves due to the friction material being only marginally too thick to correctly install.

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Now, after much reading, the final step in my swap. I did not count this in the total for the swap because it is unnecessary. There are many cheaper ways to secure hardware. But I think this is extremely cool.

I purchased a safety wire drilling fixture off www.aircraftspruce.com to drill all the mounting hardware for safety wire, and boy, was it a large undertaking. I probably went through 20+ 1/16 drill bits. Turns out the cheap Milwaukee black oxide drill bits worked the best.

I have driven my car with this setup for a couple weeks now. In all normal conditions for me. Daily driving, higher speeds on the highway, and hard braking sometimes. While it still needs to be tuned in better, it is way better than my last setup which was the standard 73+ single piston caliper and 10 inch rotor.

One thing I like about the swap is the WHOLE rotor face is being utilized by the brake pad during its sweep. My factory hardware did not do this.

I’ll be proofreading this in the days to come. So don’t be surprised if each post gets edited slightly. Thank you for reading through this thread!

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Parts list and total:

Powerstop rotors AR8309XPR (Amazon 123.54$)

Casting/PN 986.351.422 (BRICKYARD IMPORTED CAR 90$) and 986.351.421 (eBay 99.98$)

(X2) Dorman banjo bolt 14100, Dorman hub dust cap 13996 brake clean (13.85 advance auto)

Powerstop pads Z23-737 (Amazon 44.30) comes with new hardware

Dorman H620042 brake hoses
2004 Chevrolet Silverado 3500 8.1 (Amazon 31.80)

Centric 143.37013 seal kit (eBay 30.64) *found kit for both calipers*

Duplicolor engine enamel ford semi gloss black (advance auto 1.06)

Brembo decals (Amazon 4.57)

Hardware 12mm-80mm socket head cap screw part # 87443, nuts and washers (rural king 19.43)


= 473.02$
 
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Don't use angle iron for the bracket, have a local machine shop build the brackets from some 6061-T6 bar stock. Should be a simple bracket to machine. The Porsche hardware will be metric.
View attachment 1715572680

Man, that would be wonderful. But I feel like the cost of the material and machine work required would exceed the price of all the parts I have in this swap combined.

While for sure not the most ideal bracket. I’m confident in the strength of the material I used. I’ll be removing and inspecting it semi-regularly to see if there’s any stress cracks developing.
 
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Man, that would be wonderful. But I feel like the cost of the material and machine work required would exceed the price of all the parts I have in this swap combined.

While for sure not the most ideal bracket. I’m confident in the strength of the material I used. I’ll be removing and inspecting it semi-regularly to see if there’s any stress cracks developing.

Keep an eye on the edge that was the corner on the angle. Billet isn’t necessary, but the forming process of the angle does make that edge weaker. If I was going to fabricate those I would use two pieces flat steel and weld them together.

Something else to consider, you could run a fillet weld on the inside edge of that bracket. The fillet would add a nice radius for strength, and the heat might remove some stresses from the forming process.
 
Keep an eye on the edge that was the corner on the angle. Billet isn’t necessary, but the forming process of the angle does make that edge weaker. If I was going to fabricate those I would use two pieces flat steel and weld them together.

Something else to consider, you could run a fillet weld on the inside edge of that bracket. The fillet would add a nice radius for strength, and the heat might remove some stresses from the forming process.

Thanks for looking out and the ideas! In the upcoming months I’ll be keeping an inspection routine. I like the fillet weld idea! I unfortunately don’t have a welder though. If I did I would have added at least gussets for more peace of mind.

With saying that, I am still confident enough in the material as is to drive daily and ride with my loved ones in the car and feel safe. I’m also confident in my inspection ability, which should catch any possible stress fractures before it propagates enough to become a safety hazard. In the future I would like to add more strength to the bracket.
 
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Thanks for looking out and the ideas! In the upcoming months I’ll be keeping an inspection routine. I like the fillet weld idea! I unfortunately don’t have a welder though. If I did I would have added at least gussets for more peace of mind.

With saying that, I am still confident enough in the material as is to drive daily and ride with my loved ones in the car and feel safe. I’m also confident in my inspection ability, which should catch any possible stress fractures before it propagates enough to become a safety hazard. In the future I would like to add more strength to the bracket.
To inspect for cracks in the angle iron I would use a dye penetrant for the inspection or take them to a machine shop for magnetic particle inspection.
Nice work by the way.
 
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