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TWIN Rear Axle Differential Oil Change Procedure in WIS?
All,
New to MB and my 118 CLA 45 (longtime BMW owner/mechanic) and I have searched WIS but cannot find any procedure for draining and refilling the "TWIN Rear Axle Differential" on the 4MATIC+-equipped 118s & 177s. There is info throughout, including capacities: "Rear Axle Differential = 0.48L; Left Clutch = 0.37L; Right Clutch = 0.35L," oil specs: "Rear Axle Differential for gear set = MB235.63; Rear Axle Differential for coupling = MB235.64," and tightening torques: "left/right clutch oil drain screw = 22nm; left/right clutch oil level screw = 22nm; filling screw/drain screw to housing cover at front/side = 35nm," but no procedure whatsoever. I am always one to perform my own maintenance when possible to save a trip to the dealer, but I can't even determine if/when MB wants you to change the oil in these. I'm very aware that BMW considered many of their fluids to be "lifetime fills" - even though enthusiasts generally disagreed. Does MB consider certain fluids to be lifetime? I do know some AMG models have a very early and frequent diff oil change schedule and I'd be surprised if the TWIN in our 4MATIC+ system didn't require changing at some point. Would appreciate any info anyone has on this - thanks!
Update: As I have continued to search for information on our CLA 45's rear differential, I discovered the same torque vectoring rear axle is installed on both the 2022 Audi RS3 and 2022 VW Golf R. The unit appears to be manufactured by Magna Drivetrain and is similar in design to GKN’s new Twinster torque vectoring rear end. The Magna unit in our cars features three distinct “sections”: the center ring and pinion gear, left clutch pack, and right clutch pack. All three sections seem to have their own drain plugs and fill plugs and require two distinct oils meeting 235.63 (75W80) and 235.64 (74W70) spec. According to WIS, MB seems to want the rear fluids changed at 30K miles, while the service interval for the same unit in the VW is every 40K miles. I do have access to erWin (VW maintenance and data portal) and will attempt to look up the required fluids/periodicity/maintenance procedure and report back.
How do you know they are the same, and pardon my ignorance but what is WIS?
This does appear similar in operation (as noted in the photo) to the RDU I had in my Focus RS. FWIW I believe the change interval on that was 60K miles. I had my RS for 38K and never changed it. I did ~5 track events and would have fun drifting the car around empty parking lots in the winter. I probably won’t be doing either of those in my AMG.
Please continue to keep us posted. I too like doing my own maintenance. I have changed oil in all my vehicles and plan to do the same with this car. Especially with how much Mercedes charges, they basically gouge their customers. They wanted $1k for a few fluid changes and cabin filter change in my wife’s GLB 250. Probably 2 hours of labor and $150 worth of parts.
I guess I don’t know for sure the differentials are the same; however, I have read the press releases for all three cars and they, along with the pictures provided, indicate the rears are the same in all three. What may be different is the programming that controls the behavior of the electronically actuated clutch packs. It is reasonable to assume that different manufacturers could spec a different fluid for the same unit based on this – I will try to confirm this as well. What is really confusing me at the moment is MB’s 235.63 spec for the gear set portion of our rear differential which, when looked up on MB’s Operating Fluids website states, “No products available.”
Additionally, WIS = Mercedes Workshop Information System (also known as ASRA). This is MB’s software suite that explains maintenance procedures, provides technical specifications, etc. I believe this is being phased out in favor of Xentry so I have some learning to do.
Update: The Magna torque vectoring rear axle is covered in detail in VW’s erWin system. Below are some notes:
- VW calls for the fluid in the left and right clutch packs to be changed every 40,000 miles or 4 years
- “Depending on the driving style of the customer, oil depreciation in the torque splitter may occur earlier than expected”
- The left and right clutch pack’s oil condition can be checked electronically using diagnostic software and a readout is called for at each inspection
- After changing the fluid, the oil adaptation values must be reset using diagnostic software
- Oil level must be checked with oil between 68 and 104 degrees Fahrenheit and you can access the oil temperature via diagnostic software
- VW wants all drain and fill plugs replaced when removed (all six of them) and all torqued to 15 nm
- Otherwise, servicing is a straightforward affair involving draining, filling, checking, and resetting
Based on the diagrams in VW’s service literature, there are subtle differences in the case casting, mounting points, and right electronic actuator orientation (I assume these are different for packaging considerations) but the design and internals appear to be identical to the one installed in our cars. In terms of fluid specs and part numbers, I am still trying to confirm because VW lists their specs separately, but I believe them to be:
Still looking for a MB part number that corresponds to the 235.63 spec so if anyone has this, please post. Once I get my Xentry up and running and sort out the oil requirements, I plan to accomplish this service.
Well, good news and bad news: I got my Xentry up and running on a dedicated laptop but the version I have (2021) does not contain the document for the rear differential fluid change procedure for the C118 or W177 models. However, searching around on a UK A45 forum, I believe I have located the correct document number for the W177 (should be the same procedure for the CLA 45): AP35.00-P-3501F. Of course, a Google search for this yields no results. So, if anyone has a version of WIS at home and can search the document number, I'd be very interested in the results.
Update: The Magna torque vectoring rear axle is covered in detail in VW’s erWin system. Below are some notes:
- VW calls for the fluid in the left and right clutch packs to be changed every 40,000 miles or 4 years
- “Depending on the driving style of the customer, oil depreciation in the torque splitter may occur earlier than expected”
- The left and right clutch pack’s oil condition can be checked electronically using diagnostic software and a readout is called for at each inspection
- After changing the fluid, the oil adaptation values must be reset using diagnostic software
- Oil level must be checked with oil between 68 and 104 degrees Fahrenheit and you can access the oil temperature via diagnostic software
- VW wants all drain and fill plugs replaced when removed (all six of them) and all torqued to 15 nm
- Otherwise, servicing is a straightforward affair involving draining, filling, checking, and resetting
Based on the diagrams in VW’s service literature, there are subtle differences in the case casting, mounting points, and right electronic actuator orientation (I assume these are different for packaging considerations) but the design and internals appear to be identical to the one installed in our cars. In terms of fluid specs and part numbers, I am still trying to confirm because VW lists their specs separately, but I believe them to be:
Still looking for a MB part number that corresponds to the 235.63 spec so if anyone has this, please post. Once I get my Xentry up and running and sort out the oil requirements, I plan to accomplish this service.
I finally got my ISPPI (the new EPC) account ironed out and I'm able to login. I can confirm the following MB part numbers for the TWIN rear axle:
for hypoid chamber (235.63): A0009893608 (thanks MBDKPDN, you were 100% correct) for clutch packs (235.64): A000989440611 CDNW drain/fill plugs (they list 4 required but add two more if also replacing the hypoid chamber oil): A1779901100
02-21-2023, 07:14 PM
MB235.63 Part number A000989360811
