Can i swap differential from 94 E320 Wagon to 90 300E? Anyone knows this car? - PeachParts Mercedes-Benz Forum

diesel_fan · #1 05-18-2010, 11:29 AM

Hello, everyone!

Recently purchased 1990 300E that was custom lowered by PO. Car is super good cosmetical condition with just over 100K on the engine. Engine and tranny runs strong, but i there is a little noise from the rear end (especially when i am accelerating) and small vibration between 60-70mph from the drive shaft. I have not had a chance to check my flex disks yet, but i am trying to be prepared for diff swap. I have a chance to get rear differential and speedo from 94 e320 Wagon with 100K on it.
So my question is as it says in the title: Can i swap differential from 94 E320 Wan to 90 300E? I believe gears ratio is different, so what changes in performance i will face?
I will also post a picture of this car - so, if anyone knows more about history of this car, please, let me know. PO was not very cooperative.... But price was very tempting, so i can't pass on it. Ran auto check - all good and clear. This car spend most of it life in Nevada, but now in TX.

Thanks in advance!

lkchris · #2 05-18-2010, 12:02 PM

It's a lower ratio, so top speed will be reduced and highway rpms and fuel use will increase.

diesel_fan · #3 05-18-2010, 12:13 PM

Quote:

Originally Posted by lkchris

It's a lower ratio, so top speed will be reduced and highway rpms and fuel use will increase.

Thank you! I guess i need to look for something else. How about diff from 87-91 300E? Or from 92 400E?
Or, i put it that way, which diff is best to use in 300E w/out increasing fuel consumption and RPM's?

Thanks again!

babymog · #4 05-18-2010, 12:42 PM

The '94 sedans are 2.65:1, a lower ratio than your car, would improve fuel economy and reduce highway RPM. I believe that the wagon is the same.

The only downside would be a little slower launch.

diesel_fan · #5 05-18-2010, 01:08 PM

Quote:

Originally Posted by babymog

The '94 sedans are 2.65:1, a lower ratio than your car, would improve fuel economy and reduce highway RPM. I believe that the wagon is the same.

The only downside would be a little slower launch.

Thank you, Jeff!

So lower ratio will reduce RPM's and higher will increase? That exactly opposite from what LKCHRIS mention from previous post....
Also, do you guys know if its direct bolt in swap?
I believe i saw somewhere on this forum or another Mercedes forum spreadsheet or PDF file with all model and diff listing ratios... Have to digg for it...

Thanks again, Jeff!

junqueyardjim · #6 05-18-2010, 01:40 PM

A 3 to 1 ratio is faster then a 4 to 1 ratio. In any rear axle or differential numerical set up, the "1" refers to the axle making one revolution. The other number like 2.88 or "3.0" or 3.07 or 4.88 or 7,20 and more on cars and big numbers on big old gasoline powered trucks refer to the number of times the drive shaft rotates, (or engine crank rotates) if the vehicle is in direct drive.

diesel_fan · #7 05-18-2010, 03:19 PM

I think i found that spreadsheet/pdf with w123 and w124 differential info...

ke6dcj · #8 05-19-2010, 08:53 AM

All W124's in the USA with the DOHC M104 engine use the 2.65 diff, which I believe is MY 1993-1995.

Find one with an instrument cluster and the driveshaft, to swap and you'll be set.

So if you have access to a 1994 W124 wagon's diff, driveshaft, and speedo, you're set.

The 400E's use I think a 2.24 diff, but it is 4-bolt configuration, with different splines, and a different cover.

:-) neil

diesel_fan · #9 05-19-2010, 10:04 AM

Thank you!
So i need to swap driveshaft as well? On 95 wagon half of the driveshaft as removed by someone..

I think in 94 sedan driveshaft is in the trunk. Do i need to balance driveshaft, if its been removed and no markings on it?

Thanks in advance!

Quote:

Originally Posted by ke6dcj

All W124's in the USA with the DOHC M104 engine use the 2.65 diff, which I believe is MY 1993-1995.

Find one with an instrument cluster and the driveshaft, to swap and you'll be set.

So if you have access to a 1994 W124 wagon's diff, driveshaft, and speedo, you're set.

The 400E's use I think a 2.24 diff, but it is 4-bolt configuration, with different splines, and a different cover.

:-) neil

lkchris · #10 05-19-2010, 11:39 AM

Quote:

Originally Posted by babymog

The '94 sedans are 2.65:1, a lower ratio than your car, would improve fuel economy and reduce highway RPM. I believe that the wagon is the same.

The only downside would be a little slower launch.

"Lower" and "higher" refer to the road speed at a given engine rpm. That is standard industry terminology.

Therefore, for example, a 4.11 is "lower" than a 3.83.

babymog · #11 05-19-2010, 12:30 PM

Quote:

Originally Posted by lkchris

"Lower" and "higher" refer to the road speed at a given engine rpm. That is standard industry terminology.

Therefore, for example, a 4.11 is "lower" than a 3.83.

I agree, provided one doesn't say "lower ratio" in which case it refers to lower numbers. "so top speed will be reduced and highway rpms and fuel use will increase" would indicate a slower rear screw which the '94 doesn't have. (ref: post #2)

2wheelsoff · #12 05-19-2010, 01:45 PM

Quote:

Originally Posted by diesel_fan

Thank you!
So i need to swap driveshaft as well? On 95 wagon half of the driveshaft as removed by someone..

I think in 94 sedan driveshaft is in the trunk. Do i need to balance driveshaft, if its been removed and no markings on it?

Thanks in advance!

on BMW e30's the driveshafts are marked on each half with a white dot. I am guessing there should be some type of marking. In BMW's the myth is you needed to balance the driveshaft complete (both halves together). In our several mix and matches, there was no vibration coming from the drive shaft as long as the makings were lined up. Each half was balanced on its own. Not sure this is the same for Mercs, but the driveshaft design is very similar.