3.69 to 3.54 diff - PeachParts Mercedes-Benz Forum

pj67coll · #1 02-24-2019, 03:12 PM

Any likely hood of a noticeable difference in performance it I swapped out my 3.69 diff for a 3.54 one on my 81 240D? I'm thinking a marginal drop in revs at speed but would the performance hit be significant from a standstill?

- Peter.

bigpanda16 · #2 02-24-2019, 03:21 PM

Fairly negligible difference for the amount of effort. I did the 3.54 to 3.07 swap and the acceleration isn't terrible (obviously isn't what it was) but highway cruising is nice and more subdued at 75mph

Diseasel300 · #3 02-24-2019, 04:05 PM

My SDL had a 2.88 and the new SD has a 2.82. Not quite the same difference, but it's still not even noticeable. You'd notice the drop to a 3.07, I doubt you'd notice much of anything with 3.69 to 3.54. Basically a 4% reduction in RPM. At 4000 RPM, that's somewhere around 160 RPM.

pj67coll · #4 02-24-2019, 04:08 PM

Quote:

Originally Posted by Diseasel300

My SDL had a 2.88 and the new SD has a 2.82. Not quite the same difference, but it's still not even noticeable. You'd notice the drop to a 3.07, I doubt you'd notice much of anything with 3.69 to 3.54. Basically a 4% reduction in RPM. At 4000 RPM, that's somewhere around 160 RPM.

I'm less concerned about the performance. More abou trying to fix the issue with the rear end banging away like a slow firing machine gun. If I swap a different diff into it I need to be able to still keep up with traffic. Almost all my driving is town driving so I care less about highway performance than I do about being able to "almost" keep up with traffic, and not get rear ended when pulling away from a light.

- Peter.

t walgamuth · #5 02-24-2019, 04:24 PM

It should be very livable unless you live in San Fransisco.

Diseasel300 · #6 02-24-2019, 06:16 PM

If it's just swapping out a ruined rear end, go for it. I doubt you'll notice much if any difference since the ratio difference isn't very significant.

bigpanda16 · #7 02-24-2019, 08:00 PM

From the sounds of it, you may want to have a spare cv axle on hand when you do the swap. You won't loose any noticeable drivability with that numerical gear swap, but you'd be moving in the right direction.

pj67coll · #8 02-25-2019, 08:03 AM

Quote:

Originally Posted by bigpanda16

From the sounds of it, you may want to have a spare cv axle on hand when you do the swap. You won't loose any noticeable drivability with that numerical gear swap, but you'd be moving in the right direction.

I might try a new axle first. Problem is it could be one of three issues. Wheel hub. Axle or Diff. Really can't identify which so it's a process of elimination at this point.

- Peter.