Broken differential C63S
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C 63 S
Broken differential C63S
Hi guys, I have a 2018 C63S PFL with 120,000 km. It has an electronic differential, and for some time now there's been a strange noise coming from the rear, like a "boo" sound and a rhythmic knocking sound. It gets louder with increasing speed. The car has always been serviced at the official dealership, and they changed the differential oil during the last service. I took it to an AMG specialist, and according to him, the problem is with the differential. The estimate is around €7,000. He says it's better to replace it with an original part and doesn't recommend repairing it. However, I've gotten a quote for repair, and the price is significantly different, less than €2,000. My question is whether a repaired differential is as safe as a new one. The price difference is substantial, but I don't want to compromise on safety. Do you know of any cases of repaired differentials? Apparently the parts won't be original, since Mercedes doesn't sell them, but they would be from the same manufacturers that make it, according to the mechanic.
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2019 C63CS
If it's a shop that has experience rebuilding these, then I don't see why not, but it's not an easy job due to the very tight internal tolerances. It has to be done right. Others have also replaced the electronic diff with a mechanical LSD and coded out the electronic diff. Those are all options. Not really much of a safety concern. Depending on how you are driving, you may not even take advantage of the locking part of the differential. If the locking part fails, it's just an open differential.
Having said that, replacing it with an original part is not a bad recommendation. AMG has revised the differential. The latest version that's in the 2019+ C63S FL can be installed in the PFL. It has revised friction material and other improvements. Compared to the original one that was in the PFL, it no longer even needs the fluid flush after the first 3000 km. It doesn't have to be a brand new differential, either. There are used ones that came of crashed cars, so you have several options ranging from replacing it with a brand new one, replacing it with a used one, replacing it with a mechanical LSD, or rebuilding it by a competent drivetrain specialist.
Having said that, replacing it with an original part is not a bad recommendation. AMG has revised the differential. The latest version that's in the 2019+ C63S FL can be installed in the PFL. It has revised friction material and other improvements. Compared to the original one that was in the PFL, it no longer even needs the fluid flush after the first 3000 km. It doesn't have to be a brand new differential, either. There are used ones that came of crashed cars, so you have several options ranging from replacing it with a brand new one, replacing it with a used one, replacing it with a mechanical LSD, or rebuilding it by a competent drivetrain specialist.
Last edited by superswiss; Jun 1, 2026 at 02:32 PM.
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From: Keep it simple - keep it OEM
AMG C63s Coupe
My question is whether a repaired differential is as safe as a new one. The price difference is substantial, but I don't want to compromise on safety. Do you know of any cases of repaired differentials? Apparently the parts won't be original, since Mercedes doesn't sell them, but they would be from the same manufacturers that make it, according to the mechanic.
To much talking to much.
Let show you the parts.
In the moment you dont know what is exacly damaged ! But you have price for repair ???
Good Luck
Last edited by C63s_Jack; Jun 1, 2026 at 04:06 PM.
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C 63 S
If it's a shop that has experience rebuilding these, then I don't see why not, but it's not an easy job due to the very tight internal tolerances. It has to be done right. Others have also replaced the electronic diff with a mechanical LSD and coded out the electronic diff. Those are all options. Not really much of a safety concern. Depending on how you are driving, you may not even take advantage of the locking part of the differential. If the locking part fails, it's just an open differential.
Having said that, replacing it with an original part is not a bad recommendation. AMG has revised the differential. The latest version that's in the 2019+ C63S FL can be installed in the PFL. It has revised friction material and other improvements. Compared to the original one that was in the PFL, it no longer even needs the fluid flush after the first 3000 km. It doesn't have to be a brand new differential, either. There are used ones that came of crashed cars, so you have several options ranging from replacing it with a brand new one, replacing it with a used one, replacing it with a mechanical LSD, or rebuilding it by a competent drivetrain specialist.
Having said that, replacing it with an original part is not a bad recommendation. AMG has revised the differential. The latest version that's in the 2019+ C63S FL can be installed in the PFL. It has revised friction material and other improvements. Compared to the original one that was in the PFL, it no longer even needs the fluid flush after the first 3000 km. It doesn't have to be a brand new differential, either. There are used ones that came of crashed cars, so you have several options ranging from replacing it with a brand new one, replacing it with a used one, replacing it with a mechanical LSD, or rebuilding it by a competent drivetrain specialist.
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C 63 S
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⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Yes, I have a repair estimate of around €2000 without them having to open it up. It wouldn't be with Mercedes parts, but with parts from "top-tier" manufacturers. I'm even thinking of asking them to show me how badly the differential is broken. I don't mind having the car out of commission longer; I'm going to the dark side this week. A Tesla is coming my way, yes, a Tesla…
Mechanically the main things that (can) go wrong are splines and gears which twist and begin to groan after you bump power up and hard launch over and over.
What mods have you done/power output? I'm curious what brand/sourced "parts" they'll be using if not oem or donor differential is used?
Last edited by Jimmy_c63s; Yesterday at 12:02 AM. Reason: Spelling
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From: Keep it simple - keep it OEM
AMG C63s Coupe
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C 63 S
My car is stock; the only thing I've added is the ASR exhaust valve actuator. I use it as my daily driver; in fact, I think I damaged the differential on one of my long trips with a heavy load. I drive it fairly normally, considering what kind of car it is, I don't think I'm pushing it too hard, but I do if I accelerate hard.
I'm not sure how to inspect the differential. The mechanic reinstalled it; should I ask him to take it apart again? The problem is, I can't really tell just by looking at it whether it's repairable or not.
I'm not sure how to inspect the differential. The mechanic reinstalled it; should I ask him to take it apart again? The problem is, I can't really tell just by looking at it whether it's repairable or not.
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From: Australia
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
My car is stock; the only thing I've added is the ASR exhaust valve actuator. I use it as my daily driver; in fact, I think I damaged the differential on one of my long trips with a heavy load. I drive it fairly normally, considering what kind of car it is, I don't think I'm pushing it too hard, but I do if I accelerate hard.
I'm not sure how to inspect the differential. The mechanic reinstalled it; should I ask him to take it apart again? The problem is, I can't really tell just by looking at it whether it's repairable or not.
I'm not sure how to inspect the differential. The mechanic reinstalled it; should I ask him to take it apart again? The problem is, I can't really tell just by looking at it whether it's repairable or not.
First thing that's done is diff fluid inspection by getting the rear diff oil drained and checking the magnetic drain plug plus the oil itself for significant glitter, metal particles or chunks. If there's a decent amount of debris that’s pretty strong confirmation of internal wear.
Next to be 100% sure the “boo” sound actually coming from the diff (and not wheel bearings or something else) use chassis ears or a mechanic’s stethoscope on the diff housing, pinion seal area, axle tubes and wheel bearings during a road test or on a lift.
Here’s what they look like
Ask the shop for any photos or notes from when they had the diff out and whether they can properly open it and document the internals (gears, bearings, etc.) before finalising the quote.
Also, ask if they scanned it with Xentry/Star (or equivalent) and saw any diff lock codes. Do this and you can confirm it's the diff without jumping straight into a big job.
Last edited by Jimmy_c63s; Yesterday at 05:56 AM. Reason: Added info
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⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
