My m62 swapped e30 is running a 5 speed box from a 530i. The current differential is a s2.93 and I'm still pulling 3800 rpms and 80mph. I feel this is a bit high for prolonged periods of time. I guess I will have to opt for a 6 speed transmission in the future to bring down the rpms. Anyone else running high rpms at highway speeds?
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Have you counted turns on that diff? 3800 @ 80, even with a 1:1 5th doesn't line up.2006 GMC Sierra 2500HD 4WD LBZ/Allison
2002 BMW M3 Alpinweiß/Black
1999 323i GTS2 Alpinweiß
1995 M3 Dakargelb/Black - S50B32/S6S420G/3.91
1990 325is Brilliantrot/Tan
1989 M3 Alpinweiß/Black
Hers: 1996 Porsche 911 Turbo Black/Black
Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd
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Yeah, that's not correct. Your speedo is wrong, your tach is wrong, or you do not have a 2.93. What are you using for tach calibration?
With a 2.93 and ZF320, 80mph is 2700 rpm's in 5th.
A 4.10 diff would have you at about 82mph at 3800 RPM's.
Also, to the other posters point, the Getrag 420g and ZF320 have the exact same gearing for the first 5 gears, the 420g just has an additional .82:1 overdrive gear.Last edited by JGood; 03-28-2017, 04:10 AM.
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Solved!
Originally posted by nrubenstein View PostHave you counted turns on that diff? 3800 @ 80, even with a 1:1 5th doesn't line up.
Originally posted by JGood View PostYeah, that's not correct. Your speedo is wrong, your tach is wrong, or you do not have a 2.93. What are you using for tach calibration?
Originally posted by delamaize View PostI agree with Jgood, something is off....
So thank you Jgood(again) and everyone else that answered. I feel like an idiot but sometimes you need a second opinion. Rpms are much lower now. Thinking I should be around 3k at 80mph. Now I glad I didn't sell my S3.25 diff so I can install it.
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