Retrofiting S63 S65 CL63 calipers
Member
Joined: Jul 2025
Posts: 123
Likes: 22
W221.156 S350
Quick update, I've come across this https://mbworld.org/forums/s-class-w...00-brakes.html which would be a decent upgrade from the basic brakes on the S350.
I reached out to Steve from MBenzNL and confirmed the following parts (which I also double checked with the local dealer). Will be having those hopefully sometime by late Spring.
A221 421 18 12 Front rotor (x2)
A003 420 93 83 Front caliper
A003 420 94 83 Front caliper
A005 420 66 20 Front brake pads
A221 420 05 48 64 Front brake hose (x2)
A171 540 06 17 Front wear sensor
A230 423 08 12 Rear rotor (x2)
A004 420 37 83 Rear caliper
A004 420 38 83 Rear caliper
A005 420 67 20 Rear brake pads
A221 420 02 48 64 x2 Rear brake hose
A211 540 17 17 Rear wear sensor
I reached out to Steve from MBenzNL and confirmed the following parts (which I also double checked with the local dealer). Will be having those hopefully sometime by late Spring.
A221 421 18 12 Front rotor (x2)
A003 420 93 83 Front caliper
A003 420 94 83 Front caliper
A005 420 66 20 Front brake pads
A221 420 05 48 64 Front brake hose (x2)
A171 540 06 17 Front wear sensor
A230 423 08 12 Rear rotor (x2)
A004 420 37 83 Rear caliper
A004 420 38 83 Rear caliper
A005 420 67 20 Rear brake pads
A221 420 02 48 64 x2 Rear brake hose
A211 540 17 17 Rear wear sensor
Super Member
Joined: Oct 2023
Posts: 568
Likes: 197
W221 S500
Quick update, I've come across this https://mbworld.org/forums/s-class-w...00-brakes.html which would be a decent upgrade from the basic brakes on the S350.
I reached out to Steve from MBenzNL and confirmed the following parts (which I also double checked with the local dealer). Will be having those hopefully sometime by late Spring.
A221 421 18 12 Front rotor (x2)
A003 420 93 83 Front caliper
A003 420 94 83 Front caliper
A005 420 66 20 Front brake pads
A221 420 05 48 64 Front brake hose (x2)
A171 540 06 17 Front wear sensor
A230 423 08 12 Rear rotor (x2)
A004 420 37 83 Rear caliper
A004 420 38 83 Rear caliper
A005 420 67 20 Rear brake pads
A221 420 02 48 64 x2 Rear brake hose
A211 540 17 17 Rear wear sensor
I reached out to Steve from MBenzNL and confirmed the following parts (which I also double checked with the local dealer). Will be having those hopefully sometime by late Spring.
A221 421 18 12 Front rotor (x2)
A003 420 93 83 Front caliper
A003 420 94 83 Front caliper
A005 420 66 20 Front brake pads
A221 420 05 48 64 Front brake hose (x2)
A171 540 06 17 Front wear sensor
A230 423 08 12 Rear rotor (x2)
A004 420 37 83 Rear caliper
A004 420 38 83 Rear caliper
A005 420 67 20 Rear brake pads
A221 420 02 48 64 x2 Rear brake hose
A211 540 17 17 Rear wear sensor
360mm front discs, larger caliper and pad. Rears are probably similar across the range.
P/NS:
A221 421 16 12/07 Front Disc x2
A220 421 01 71 Disc retaining screw x2
A003 420 53 83 Caliper Kit
A003 420 54 83 Caliper Kit
A221 420 05 48 Hose X2
A000 428 06 73 Hose Retaining Spring
A000 420 92 04 Front Pads
Super Member
Joined: Oct 2023
Posts: 568
Likes: 197
W221 S500
A cautionary note, and something no one on this thread has mentioned:
You may also need to adjust the pedal push rod throw and possibly the master cylinder. From experience, fitting '04 Monaro VXR brakes to an Opel Omega noticeably altered the pedal feel. Fortunately that had enough adjustment on the pedal rod to reduce the slack down to about a mm of pedal travel.
Failure to do these could significantly reduce the effective pedal travel meaning that if you need to stand on the brakes you won't be getting full braking force. More importantly Brake Assist may not work properly.
Yes your new brakes will look all fancy, but they may actually perform significantly worse than the standard ones.
The physics is pretty straightforward:
Increasing the piston area means the master cylinder needs to move more fluid over the same distance.
For example:
If you double the piston size at the caliper, the master needs to push twice as much fluid.
If your upgrade increases the caliper piston area by 20% you'll only achieve 75% from the pedal. At best, you will end up with a dead spot on the first quarter of pedal travel. Worst case your brakes won't be effective in an emergency.
Consider the implications of stopping after the accident rather than having no accident.
I would strongly suggest that you identify the Master Cylinder currently fitted to your car and compare the part number to the S65. Use a dealer for this (BenzNL would tick that box) rather than relying on internet EPCs/eBay sellers. If the numbers are different, then you need to change the master cylinder.
You may also need to adjust the pedal push rod throw and possibly the master cylinder. From experience, fitting '04 Monaro VXR brakes to an Opel Omega noticeably altered the pedal feel. Fortunately that had enough adjustment on the pedal rod to reduce the slack down to about a mm of pedal travel.
Failure to do these could significantly reduce the effective pedal travel meaning that if you need to stand on the brakes you won't be getting full braking force. More importantly Brake Assist may not work properly.
Yes your new brakes will look all fancy, but they may actually perform significantly worse than the standard ones.
The physics is pretty straightforward:
Increasing the piston area means the master cylinder needs to move more fluid over the same distance.
For example:
If you double the piston size at the caliper, the master needs to push twice as much fluid.
If your upgrade increases the caliper piston area by 20% you'll only achieve 75% from the pedal. At best, you will end up with a dead spot on the first quarter of pedal travel. Worst case your brakes won't be effective in an emergency.
Consider the implications of stopping after the accident rather than having no accident.
I would strongly suggest that you identify the Master Cylinder currently fitted to your car and compare the part number to the S65. Use a dealer for this (BenzNL would tick that box) rather than relying on internet EPCs/eBay sellers. If the numbers are different, then you need to change the master cylinder.
Member
Joined: Jul 2025
Posts: 123
Likes: 22
W221.156 S350
This is very important information. Thank you for the heads up.
The upgraded brakes come from the S600 armoured B7. Using a vin from that, it looks like the brake master cylinder and the vacuum booster are both different from the ones installed on the S350.
The upgraded brakes come from the S600 armoured B7. Using a vin from that, it looks like the brake master cylinder and the vacuum booster are both different from the ones installed on the S350.
A cautionary note, and something no one on this thread has mentioned:
You may also need to adjust the pedal push rod throw and possibly the master cylinder. From experience, fitting '04 Monaro VXR brakes to an Opel Omega noticeably altered the pedal feel. Fortunately that had enough adjustment on the pedal rod to reduce the slack down to about a mm of pedal travel.
Failure to do these could significantly reduce the effective pedal travel meaning that if you need to stand on the brakes you won't be getting full braking force. More importantly Brake Assist may not work properly.
Yes your new brakes will look all fancy, but they may actually perform significantly worse than the standard ones.
The physics is pretty straightforward:
Increasing the piston area means the master cylinder needs to move more fluid over the same distance.
For example:
If you double the piston size at the caliper, the master needs to push twice as much fluid.
If your upgrade increases the caliper piston area by 20% you'll only achieve 75% from the pedal. At best, you will end up with a dead spot on the first quarter of pedal travel. Worst case your brakes won't be effective in an emergency.
Consider the implications of stopping after the accident rather than having no accident.
I would strongly suggest that you identify the Master Cylinder currently fitted to your car and compare the part number to the S65. Use a dealer for this (BenzNL would tick that box) rather than relying on internet EPCs/eBay sellers. If the numbers are different, then you need to change the master cylinder.
You may also need to adjust the pedal push rod throw and possibly the master cylinder. From experience, fitting '04 Monaro VXR brakes to an Opel Omega noticeably altered the pedal feel. Fortunately that had enough adjustment on the pedal rod to reduce the slack down to about a mm of pedal travel.
Failure to do these could significantly reduce the effective pedal travel meaning that if you need to stand on the brakes you won't be getting full braking force. More importantly Brake Assist may not work properly.
Yes your new brakes will look all fancy, but they may actually perform significantly worse than the standard ones.
The physics is pretty straightforward:
Increasing the piston area means the master cylinder needs to move more fluid over the same distance.
For example:
If you double the piston size at the caliper, the master needs to push twice as much fluid.
If your upgrade increases the caliper piston area by 20% you'll only achieve 75% from the pedal. At best, you will end up with a dead spot on the first quarter of pedal travel. Worst case your brakes won't be effective in an emergency.
Consider the implications of stopping after the accident rather than having no accident.
I would strongly suggest that you identify the Master Cylinder currently fitted to your car and compare the part number to the S65. Use a dealer for this (BenzNL would tick that box) rather than relying on internet EPCs/eBay sellers. If the numbers are different, then you need to change the master cylinder.
Super Member
Joined: Oct 2023
Posts: 568
Likes: 197
W221 S500
I don't know if the 350/v6 rears are vented, but the standard Euro S500 brakes are.
This would give you:
360mm fronts with 4 pot Brembos calipers.
320mm vented rears.
A decent upgrade which would fit 18" wheels.😉
Parts for the fronts, as listed above, is approximately £1,250. Just replaced mine with new MB parts.
Rears is probably £1,000 for discs, calipers pads and hoses.
That might sound like a lot, but a disc and pad change all round is £650 with new fittings (included in the caliper price) and the front calipers are £420 each without any AMG tax😉
This would give you:
360mm fronts with 4 pot Brembos calipers.
320mm vented rears.
A decent upgrade which would fit 18" wheels.😉
Parts for the fronts, as listed above, is approximately £1,250. Just replaced mine with new MB parts.
Rears is probably £1,000 for discs, calipers pads and hoses.
That might sound like a lot, but a disc and pad change all round is £650 with new fittings (included in the caliper price) and the front calipers are £420 each without any AMG tax😉
Last edited by AL5461; Feb 26, 2026 at 03:36 AM.
Member
Joined: Jul 2025
Posts: 123
Likes: 22
W221.156 S350
MB cutting corners where it can, mine are solid rears,
so are the S500 sold here afaik.
so are the S500 sold here afaik.
I don't know if the 350/v6 rears are vented, but the standard Euro S500 brakes are.
This would give you:
360mm fronts with 4 pot Brembos calipers.
320mm vented rears.
A decent upgrade which would fit 18" wheels.😉
Parts for the fronts, as listed above, is approximately £1,250. Just replaced mine with new MB parts.
Rears is probably £1,000 for discs, calipers pads and hoses.
That might sound like a lot, but a disc and pad change all round is £650 with new fittings (included in the caliper price) and the front calipers are £420 each without any AMG tax😉
This would give you:
360mm fronts with 4 pot Brembos calipers.
320mm vented rears.
A decent upgrade which would fit 18" wheels.😉
Parts for the fronts, as listed above, is approximately £1,250. Just replaced mine with new MB parts.
Rears is probably £1,000 for discs, calipers pads and hoses.
That might sound like a lot, but a disc and pad change all round is £650 with new fittings (included in the caliper price) and the front calipers are £420 each without any AMG tax😉
Super Member
Joined: Oct 2023
Posts: 568
Likes: 197
W221 S500
Rear Calipers:
L: A2214230381
R: A2214230481
Caliper bracket, x2:
A2214230294
Caliper sliders:
Sleeve set, x2: A0004200076
Pins, x4: A0004210818
Rear pads:
A0044204420 or A0004230230
Rear pad retaining Spring, x2:
A0004218591 or A0014212291
Rear discs, x2:
A2214230412
Rear hoses, x2. Should be the same as your existing:
A2214200248
Parking brake kit:
A2214200520
That should be the rear shopping list😉
The calipers and brackets are different to accommodate the larger diameter and thicker discs.
With the upgrade to the front brakes the extra at the rear will still be balanced 👍Just double check the master cylinder is still compatible 😉
Last edited by AL5461; Feb 26, 2026 at 08:08 AM.
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