Rear diff ratio question - E350 W212

Merkz

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I have a droning noise coming form my rear diff which I am told is a bearing issue on my 2010 E350 CGI Blue Efficiency W212 7sp auto estate. My local Mercedes Benz independent specialist tells me the best solution is to get a used rear diff as fixing the existing one or getting a new one would be relatively very expensive. They tell me that a diff from any W212 E350 will do, but I am finding that there are two different ratios available, these being 2.24 and 2.47. Does anyone have any idea which is the correct ratio for my model? Thanks in advance for any input.
 
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Merkz

Merkz

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Managed to get onto the MB Teilekatalog and found that my model - 212.257 is seemingly a 1:2.82 ratio it turns out. This is the same as the 212.059 and 212.259 and some non-212 models. The diff part no. is specified as A2043500214, and cover part no. is A2043510408 (see pic). However, the part no. on my diff cover is A2093510705. So this is getting confusing. Can anyone can shed any light on this?
 

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Wighty

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I have a droning noise coming form my rear diff which I am told is a bearing issue on my 2010 E350 CGI Blue Efficiency W212 7sp auto estate. My local Mercedes Benz independent specialist tells me the best solution is to get a used rear diff as fixing the existing one or getting a new one would be relatively very expensive. They tell me that a diff from any W212 E350 will do, but I am finding that there are two different ratios available, these being 2.24 and 2.47. Does anyone have any idea which is the correct ratio for my model? Thanks in advance for any input.
What does the Indy say about the ratios ? Would it matter ?
 

Uncle Benz

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The crownwheel and pinion are the only parts that vary according to ratio. You must use the same ratio as you have already or the car will be in limp mode all the time. Why don’t you just get your original diff rebuilt with new bearings? Simple job for a specialist. Steve at Autoeurope Engineering in Charlwood does them for me.
 

EmilysDad

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The crownwheel and pinion are the only parts that vary according to ratio. You must use the same ratio as you have already or the car will be in limp mode all the time. Why don’t you just get your original diff rebuilt with new bearings? Simple job for a specialist. Steve at Autoeurope Engineering in Charlwood does them for me.
Why would the car be in limp? A different diff ratio would just give different engine revs for a given speed.
 

Uncle Benz

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Why would the car be in limp? A different diff ratio would just give different engine revs for a given speed.
Engine, transmission and ABS ecu’s are in constant communication. The wheel speeds won’t match what the transmission is expecting to see. Seen it before.
 
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Merkz

Merkz

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The crownwheel and pinion are the only parts that vary according to ratio. You must use the same ratio as you have already or the car will be in limp mode all the time. Why don’t you just get your original diff rebuilt with new bearings? Simple job for a specialist. Steve at Autoeurope Engineering in Charlwood does them for me.
Thanks for this suggestion. I will look into it :)
 
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Merkz

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Re the using a different ratio, as a few have mentioned here, I understand there can be complications with communicating with the auto gearbox. I did read somewhere that might be possible to work around it with remapping, but you also change the performance & fuel efficiency which I don't really want to do.

Thanks for all the input, it's much appreciated!
 

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