Just a reference question: My 325iS hits 3000rpm at ~71mph (I'm guessing the speedo is pretty close). This seems like a really fast engine speed for a fairly low road speed. What kind of speeds do you guys get? I checked my tranny and diff, the tranny is marked Getrag 260 and the diff is marked S 3.73 so they appear to be stock. However the car was originally an auto, and I was under the impression that 325iS AT's came with 4.10 gears. But the tag definitely says 3.73. I suppose there is a chance the tag was changed and not the diff for some dumb reason, but I doubt it.
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That sounds about right. I am trying to remember what my 325is is at about 70 but I haven't driven it on the freeway in months.. I will this sat tho.. :D:: PNW Crew ::
'87 325 4dr, '74 2002 -
Differential 3.73
Aspect Ratio
Width Diameter
Enter tire size: 215 40 17
Ratio 3.71 3.83 2.20 1.40 1.00 0.81
RPM 1st 2nd 3rd 4th 5th
750 4 4 6 10 14 18
1000 5 5 9 14 19 23
1250 6 6 11 17 24 29
1500 8 7 13 20 28 35
1750 9 9 15 24 33 41
2000 10 10 17 27 38 47
2250 11 11 19 30 43 53
2500 13 12 22 34 47 58
2750 14 14 24 37 52 64
3000 15 15 26 41 57 70
3250 17 16 28 44 62 76
3500 18 17 30 47 66 82
3750 19 19 32 51 71 88
4000 20 20 34 54 76 94
4250 22 21 37 58 81 99
4500 23 22 39 61 85 105
4750 24 24 41 64 90 111
5000 26 25 43 68 95 117
5250 27 26 45 71 99 123
5500 28 27 47 74 104 129
5750 29 28 50 78 109 135
6000 31 30 52 81 114 140
6250 32 31 54 85 118 146
6500 33 32 56 88 123 152
6750 34 33 58 91 128 158
7000 36 35 60 95 133 164Comment
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weird that you guys got 3.73 diffs.
my 87 325i with auto and 3.64 (used in both manual and auto cars here) runs 2600 at 70. i'm tempted to get a 3.91 for itComment
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huh, I guess it's pretty normal then. If i get around to my stroker this summer I will def. change to a higher geared rear end, seeing as how I tend to be on the freeway alot.Comment
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