Quaife only fits up to the 3.06 gears. Then the carrier switches to a different offset for the ring gear to align with the pinion. Stupid Mercedes way of setting up differentials.

How are you going to handle the change in wheel speed signal ratio to the trans computer?

Diffs ( non brand specific ) with a wide range of ratios have always moved the ring gear mounting surface but not for every ratio like MB. An example of a USA unit would be 3.27 and smaller number is one carrier and 3.45 and larger another.

In order to accomplish this wide range, the ring gear must be thicker as the numbers get larger. This leads to more rotating mass / material used. MB kept the ring gear thickness the same across all ratios and just moved the flange. We also don't know if there was a thickness limitation in their gear cutting machines when this was instituted.

While this causes issues for the microscopic number of people that swap ratios, it works out better for the 99.99999% that drive the car and not change things.

I use tone wheels bolted to my axle flanges. Changing the number of teeth on the tone wheels fools the trans control module. Been working fine for about 6 months now.

And I guess Quaife doesn't make one for the 3.27. what about Wavetec.

As stated by others, it was the only choice. I built the diff from my 91 300CE and that car never felt over geared. To be honest though, that car had the best off idle torque of any 104.980 I've ever driven, and that's more than a few. Don't really know why, and never put much energy into finding out. The '90 CE has the '91's fuel distributor and EHA, its injectors, and its EZL, but the '90 still doesn't pull the same off idle, not even close. Long story short, in its current form its not a really fast car, so a bit of gearing change wont be a big deal. The '91 met its demise in a full throttle turn under adverse traction conditions when one wheel spun up and the other didn't have enough grip to keep from spinning out. If it had a limited slip diff, I doubt that would have happened.

A limited slip might have helped as long as both tires don't break traction, however, once traction is lost the tail will come around. RE the loss of traction limit with a LSD might have been higher and more severe due to the loss of lateral grip where an open diffs loss of traction is lower and more stable due to a loss of forward motion.

A limited slip tends to break traction of the inside wheel during a turn under power. ( Think a solid non diff axle / go kart ) This is usually OK unless the outside wheel has limited traction. I'm betting this is why MB decided to use ASR rather than a LSD. Going the ASR route also gives the possibility of ESP.

Will the change from 2.47 to 2.82 result in an even tone wheel tooth count change?

2.65 is the baseline with a 48 tooth wheel.

To use a 2.47 ratio multiply tooth count by 2.65/2.47 = 48*2.65/2.47 = 51.49 Round to 51.

To use a 2.82 ratio multiply tooth count by 2.65/2.82 = 48*2.65/2.82 = 45.11 Round to 45.

Didn't think this would work but it does. Still looking for any adverse issues at this time but none so far.

2.47 is about the worst case scenario. I could probably use a 51 or 52 tooth wheel. That is one of the reasons I elected to try it first.

In another thread I recall whipplem104 saying that the room for wheel speed error is very small, looks like there is some room.

I don't know what the threshold is but 1% appears to be acceptable, 7% is not acceptable.

% error threshold is somewhat vehicle speed dependent. At low speeds in low gear you can have more slip from driveline components and resolution. And your rpm differential is low. At high speeds you may find that error of a small percent is large enough to trip a fault. I do not think 1% will ever throw a fault. I do not know the exact number or actual fault threshold. But I would say probably up to 3% would work but maybe not sustained. 1-2% is pretty typical variance in meaurement though.

1% seems to work well for at least up to 100MPH at this point, with at least 10 min sustained speeds of 90MPH last weekend and has worked well since September.

I dug out my V8 rear diff cover and snapped a couple of comparison pics for those unfamiliar with the difference. The V8 part has a 129 part number. It also has cooling fins and vertical internal baffling in addition to mounting points spread several inches further apart compared to the 6cyl part.

After cleaning it up good I ran a bead of sealer and bolted it up. I also cleaned up the ABS sensor bracketry and bolted that to the housing. At this point it is finished. Still no Idea when I'll get it swapped in with a V8 rear subframe. Rear lower ball joints are also on the to do list so that is a whole bunch of labor added all up. Just in time to loose one of my weekend days to the farmers market my nursery sells at starting this weekend. Not enough hours in the day or days in the week.:rolleyes:

Just to round out the thread , please post the part numbers on the covers when you get a chance.