After swapping over the m113k from a donor 2005 S55amg, I looked around for what else I could swap over and figured the calipers would be the prime target.
Here is my write up for anyone looking to upgrade from a single piston front, single piston rear NA crossfire to 8 piston front/4 piston rear. I tried to find details but only found that people have 'done it' but now how.
I only did this because my calipers were 'free'

Things you'll need:
Calipers
Brake pads
2x BREMBO 09.B747.51 360mm ( Brembo 09.9547.33 360mm DO NOT WORK. the caliper inner brake pad rod will contact the center hub of the rotor) - used 2013 CLS550 as reference
2x Brembo 09.9257.41 330 mm - used 2007 slk 55 amg w/ performance package
You can use brembo parts site and search for those if you need cross reference.

9/16 Reamer - to enlarge the front caliper mounting holes. This took most of the time. Just go slow and make sure you're going straight.
4x m10x1.5 30mm long flange bolts for the rear - maker sure they are at least 10.9 grade bolts
4x m14x1.5 40mm long hex or flange bolts for the front - make sure they are at least 10.9 grade
6x M14 flat 2.5mm washers (I used stainless steel A4). 1 will fit between the caliper and the spindle and 2 on the outside so the front caliper centers


You'll need to cut the dust shield in the front and the rear so the calipers fit. Even had to bend some parts of the dust shield back so they dont contact the rotor.
Rear rotors alignment bolt will match up, but the front rotor you will have to secure it other ways. I just used a nut on a stock lug bolt to hold the rotor in place.
you can use the stock crossfire brake pad sensor

STRONG SUGGESTION:
-deep clean what you can on the calipers while they are out. There is a video out there showing you what you can use (i used water, soap, and iron remover wheel cleaner)
-try and rebuild the calipers if they have never been rebuilt. I've had several pistons with ripped dust shields. I've never rebuilt calipers before but it was fairly easy. Just look around how its done.
-replace the brake lines. Stock 2005 S55amg fit just make sure they are facing the correct way (front should point slightly up when mounted and rears should point down to create a U shape instead of and S shape if they face upwards)
-When you bleed the system, do a full system flush to put in DOT4


So i have these on, but I'm trying to figure how how what kind of rims can go on. Stock ones obviously would never fit and I would rather not use any spacers.
If anyone have comments suggestions before I figure out my rim situation, let me know. I'll most likely not take it out of the garage until spring time anyway.



rear caliper/rotor comparison

front caliper comparison

front rotor comparison top

rear caliper/rotor mounted

stock rear rotor/caliper

rear caliper brake line ( wrong way. I had to swap them so it points down instead of up)

Front rotor/caliper mounted

view of the mounting bolts

front caliper brake pad sensor

 

Wheels? With rotors that big you shouldn't need any wheels! 😁😁

 

Excellent write up! Those actually appear to be the 6 piston calipers, of which many variations exist. The 8-pot versions use multiple pads, and are often not as high performing as the 6 piston versions.

I also have an M113K swap car, and have been working on the brakes. I just went to the SLK/CLK55 4-pot rears, but had not quite worked out the right combination of parts up front. Currently I have C43 AMG 345mm front brakes. I have a pair of 2013 CLS63 6-pot front calipers that I plan to use for the next upgrade. The rotors seem to be the real trick. I have CLS rotors (one piece), W211 Brembos, and R171 SLK55 Brembo hats. The CLS and E class rotors have too much offset, and will make the rotor hit the spindle. My plan is the move the SLK55 hats to the E class rotor discs. This should give me the thicker 36mm rotors on the correct SLK platform offset. This is a bit theoretical, as I haven't found the time lately to try. If you could shed more any more light on your setup, if would be appreciated.


Adding on. I did go with a closed 10mm hub centric spacer up front for the C43 brakes. Preliminary mock ups on the car with the CLS63 caliper just bolted in place (temporarily for fitment) showed clearance on the stock 18" wheel.

Also notice that I went to longer wheel studs and nuts up front. This was a great upgrade, in of itself. It did correct the thread engagement from the spacer, plus these are actually stronger than the factory lug bolts.

 

Also, the Goodridge stainless steel lines for a Crossfire or R170 (available from @NeedsWings ) work on all of these various calipers, and will fit the Crossfire properly. The SS lines are a nice upgrade on any of these cars.

 

What I did to pick out the rotors is look at the stock rotors on bremboparts site. They have very detailed diagram of all the measurements so then I tried to get the same hat as stock crossfire but instead of 300, I needed 360mm.
I tried to get clever and fit slk 55 amg p030 360mm front rotors (Brembo 09.9547.33) but with 8 piston caliper, the inner pegs of the caliper contact the hat.

front rotors from slk 55 p030 did not work


these are 8 piston front calipers and 4 piston rear calipers. Take a look at image labeled "front rotor comparison top" and you can see all 4 pistons on one side.
6 piston caliper is easier to mount since I hear the bolts are same M12 instead of m14 for the 8 piston version, but I dont have any experience with 6 piston calipers to be sure.

One thing I read somewhere is if you dont use all the calipers from the same system then your brakes might not distribute the braking as designed and create a larger bias than originally designed. I'm no expert to know the actual effects, but maybe something to think about.

I read up spacers can create extra load on the bearings especially with a swapped engine/calipers/rotors extra weight. I might end up with spacers but would be my last choice. Was looking at larger 19/20 inch rims from another AMG model but hard to say if those would clear

 

It's possible that a larger diameter wheel will help, but it is not a clearance problem there that is the problem, so much as the backspacing. That is why I needed the spacers for the C43 4 piston calipers. I think that 6mm would be enough, but the standard hub centric spacer is 10mm. This one: is specific for the MB hub and cap. It does fit tightly in the wheel, and usually stays in the wheel when I remove it. I have considered having the spacers turned on a lathe, to make them thinner, but have left it for now, waiting on the CLS brakes. The extended length studs are stronger material than the OE lug bolts, and take up the difference in length for the spacer. I have had no issues in over a year's worth of driving in almost all conditions. I have checked the front wheel bearings multiple times. They haven't needed to be re-greased, or tightened.

 

Thanks for the spacers info. I've been trying to find some reputable ones to consider so I'll use these if I go the spacers route. I'll still have to measure out and validate the caliper wont rub the inner rim and 10mm is enough

 

I’ve always wanted a 19’ and 20’ replica SRT6 or SE wheel setup. Alas no one has made replica wheels that I know of for any XF at all. Surprised no one has ever made them. I know the XF wasn’t a “massive” hit but I’ve seen cars with shorter lifespans and smaller prod #’s have replica wheels made for them. The XF Concept cars 19’ fronts and 21’ rear would probably be the perfect setup.

 

I have Stoptech 355mm rotors and ST-40 calipers. (4 piston) I went with custom wheels. The stock wheels require spacers to clear the front calipers .... or I could have ground on the calipers to gain the clearance needed to run without spacers. I imagine the 8 piston calipers need custom wheels or 19" MB wheels. I believe my front Forgestars are ET32.

Les

 

Just a quick final update. aftermarket 18 inch rims I had laying around were not enough to clear the caliper and 10mm spacer was not enough for stock NA rims (the spokes contacted the caliper)

BUT combination of 10mm spacer and the aftermarket rims just cleared it. Had to buy 39mm shank wheel bolts to accommodate the spacer but that's specific to this rim.

Maybe 15mm spacer and stock NA rims would work but I wont go that route.
Also, one thing I missed is that these rotors are designed to work with M14 bolts but crossfire wheels/hubs use M12 bolt. There's a slight gap around the rotor hole and lug bolt so I'll try to fill the gap with an M12 time-sert. I dont think they make 360mm rotor with M12 bolts.

Just like any car work, do things at your own risk.

 

Thank you for posting back in here with the update!