We have a 94 E420 and would like to get a little better off the line performance out of it. We have just bought a set of 16 x 7.5 wheels and now we are looking into shorter gears. The car we have does NOT have ASR just ABS so what I need to know is what differentials will fit and what models have which gears ? I have a good relationship with my local wrecker and can get a differential that they have on hand for about $150 but currently they only have a few 124s ( 260E,300E (88), 300TE (91), and a few others that I did not dig into). I also understand that the V8 cars and the twin cam coupes have a larger style housing on their differentials.
Would a differential from a car with ASR also work ? would a differential from a 129 be exactly what I am looking for ? Do any of the cars besides the 500E have a LSD ?

Thanks for any help you can provide

Barry Wolff

Barry,
Been there...looked into that. (with my ex 400E) If your car does not have ASR then you have to use a diff from a car that also does not have ASR. You can try a diff from a M103 300E. The 3.07 ratio will be very short and really give you ooomph off the line. Top speed will be much less than stock, limited to redline in top gear. The 300E's used that ratio but also reved to 6500rpm +, the 4.2 V8 only wants to rev to 6000rpm. Fuel mileage and cruising rpm's will be a bit busy. You will also run into a problem with speedo calibration. Switching to the 2.65 from the DOHC 6-cyl W124's should also work. It will give you more punch than the 2.24 but still let you have easier cruising rpm's. The 500E's all had ASR plus the tires fitted were a taller rolling radius so it will not practically retrofit. (Plus I doubt you'd find a used 500E diff) I believe the euro-spec 400E's/E420's had a 2.65 ratio.

It depends on your driving style. If you dont' have to do much high speed highway cruising but want maximum in-town power, go with the 3.07. That ratio will make you very quick and but also be a bit more of a headache. The 2.65 from an E320 should go in with much less work. (speedo config should be much simpler) The 300E had the 3.07 from 87-92, the 93 300E and 94-later E320's had the 2.65. Just be sure to find one from a car that does not have ASR.

You may want to talk with Benmac in Tech Help on speedo/odo calibration and conversion. Please let us know how it goes. Oh, BTW if you can't find the diff your looking for you can fill out a PartsShop parts inquiry and we will check to see what used ratios we have available for your application. If you need anything else or DIY help that is what we are here for.

Hope this helps...Lee

92' Fire Breathing 500E

SInce the external housing has different external dimensions than other W124 chassis the swaps from those sources won't work, ex for 500E. Will look at euro fische for possible swap.

Hmmm...glad Benzmac and I didn't try and go through with the swap on the 400E. (foot in mouth)

Lee

MB DOC told me that in the Euro parts he found a match. It is from a Euro 5 speed 129 body SL. He will be more specific.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Does this mean that the 129 diff does not fit on the on 124 ? I was reading in my owners manual and it listed the 124 coupe as a large diff. Does the 124 use a 124 only diff ?


Barry Wolff

Some of the 124 cars with M104 engines use a simular rear axle as the 400E, but the gear ratio is 2.65/1. On the 300SL upto 1994 the rear end case is the same part #, on the stick shift cars the ratio was 3.46/1. The factory part # is 129-350-03-14. The stub axles from the 400E rear may have to be swapped. The car would be a LION on 0-60!
Gas mileage would suffer & engine would pull a lot more revs!