Quote:
Originally Posted by swogee
I have been keeping my eye out for a suitable differential at the PNP. It seems that the correct ratio final drive of 2.65 was specific to diesels only. Final drives with the correct ratio of 2.65 were used 6 years including 1987 300DT/TDT, 1990-1993 300D 2.5T, and the 1995 E300D.
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That is basically correct - with the exception of the 1995 E300 which has a 2.87 gear ratio.
However, the 90-95 cars have smaller flex discs and input flanges, so you'd need to swap the input flange. This is somewhat of a gamble as you must be careful to get the nut tight enough to preload the bearing, but not so tight that it overloads the internal crush sleeve. The factory procedure specifies a rotational torque meter which basically nobody has and costs a fortune. Most mechanics mark the position of the nut and put it back in the same spot when replacing the pinion seal; this is rudimentary but apparently works ok - but I'd measure the different flanges carefully to make sure the nut
should be in the same place if swapping. A list of the various US-spec diffs are on my website in
this PDF file. Another option might be to swap the rear driveshaft half from the donor car. Ideally you'd get a good one from a 1987 300D/TD though, as this is the only bolt-in solution.
Quote:
Originally Posted by swogee
GSXR, you mentioned a LSD core. Did you fit the LSD core into the final drives of your 300DT? Where did you find the LSD cores?
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My first LSD build was for my 1987 300D. I converted an ASD diff. The cores are difficult to find, and you have to be REALLY careful to make sure that it's really an ASD diff when buying from a distance, possibly sight unseen. You need either a photo of the diff, or the VIN of the donor car to verify if it's correct.
Quote:
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Originally Posted by babymog
LSD cores come from ASD cars.
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That is correct. And ASD was a relatively rare option. And if you buy a used one, it will need a clutch pack refresh ($$$). While I highly recommend this upgrade (especially if you notice the lack of traction from the stock peg-leg diff on wet or dirty pavement, like I did) it's NOT cheap. Expect $1k minimum, and more like $1500+. You can buy the LSD brand new from MB for about $1200, which will have new clutches, then install that into your donor diff... with new seals etc it will be $1400-$1500 plus the cost of the donor diff. The part number varies with gear ratio, see page 4 in the above PDF. Although MSRP is $1640, you can get it from parts dot com for ~$1127 plus shipping (choose "Freight-Quote" at checkout to avoid the flat 15% S&H fee).
Quote:
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Originally Posted by babymog
The '94/'95 E320 also had a 2.65:1, plenty of those out there. Might be a different flange on the pinion, Dave will know.
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Yes, most of the late M104-powered W124's have 2.65 ratios, as seen in my PDF file. However these are larger 210mm diffs. It should be possible to swap that in but it won't be easy, once again the input flange is different, and when it's all done it just adds extra weight for the stock engine to turn (but it is a nice upgrade if you're building a SuperTurbo). If you use one of these it has to be from an ABS car, not ASR, as the ASR cars do not have the provision for the pinion speed sensor required on the '87 300D.
There are a couple 1987 300D diffs available from a salvage yard in SoCal for ~$250,
M&M Imports. There's one in San Jose (
American Imports, an oxymoron, no?) but no price listed. Another is in
Santa Clara. Might be worth a couple phone calls...
