Quote:
Originally Posted by L_Azevedo
Can someone help me with this essay ? I want to know if this differential has any problems related to wearing or some flaw in the design of the gears.
|
The only diff that has a somewhat weak spot is the e46 m3/z4m diff (but that's not an open diff, it's an LSD with a speeddependant oilpump/piston action)
That diff can develop an input shaft seal oil leak.
The s54 engine is a high revving engine, and the rear diff on the e46/z4m has a high final drive ratio, so the input shaft of that diff makes more revolutions per driven kilometer, thus it wears faster, mainly resulting in worn input shaft oil seals.
Further more there are 3 types/sizes of diff's fitted in the e46 chassis:
210 diff (only fitted to M3)
188 diff
168 diff
The numbers indicate the size of the crownwheel. The smaller engined cars got the 168 diff, the heavier engined cars got the 188 diff.
Except for the 210diff, the diffs also come in different ratio's
This is a (not complete) list:
http://www.bokchoys.com/differential/GearRatios.htm
You can see in the ETK which type of car got which diff, for examply by looking at what gasket/rear cover is listed:
318i got a 168 diff:
http://bmwfans.info/parts-catalog/E4...ve_gasket_set/
320i with m52 engine also got a 168 diff:
http://bmwfans.info/parts-catalog/E4...ve_gasket_set/
320d got a 188 diff:
http://bmwfans.info/parts-catalog/E4...ve_gasket_set/
The letter K after the 188/168 designation means 'Kurz" (german for "short"), probably a housing/fitting designation.
The 168/188k diffs out of the e46 differ from the earlier style bmw diffs, in that shimming the outputbearings of the diff (and the diff itself) is done by large circlips:
Here you can see 2 with their thickness laseretched in them:
For most of the adjustment on the 188k/168k diffs, you can look them up in the section for e36 cars; back in those days BMW fully supported diff rebuilds&parts. And as virtually all gears etc are the same for that car, you can use those specs.
For instance, backlash for a 188k diff is 0,06mm - 0,14mm
In the e36 section of TIS are also specs for preloading the bearings (mainly input shaft bearings), and some interesting pictures of what specialty tool to use for measuring that. A very sensitive torque wrench (click style) won't work as you have to measure drag forces.
This is an online version of TIS (technical information system); If you want to know how BMW's work (technically); learn how to use it.