Does the M3 manual have the same diff ratio problem as E60 M5 manual

werdn · 11-06-2020, 11:14 AM

I am in the market again for my second e9x m3, but this time I am considering a manual. When doing research, I came upon this question.

In the e60 m5, the manual option was not developed specifically for the m5. The m5 is supposed to have a SMG. Therefore, it seems like when paired with a manual, the car drives slightly differently than the SMG ones (i think the way power comes on or something). And to remedy this issue, I believe you have to change the ratios in the diff.

I was wondering if it was the same thing on the M3 of this generation, or if this isn't a thing for manual M3's.

Thanks in advance.

pbonsalb · 11-06-2020, 11:18 AM

For the E60 M5, SMG is the same trans as the manual, with the same gear ratios, but actuated automatically. It makes sense the diff is the same ratio. The E9x M3 7 speed DCT and 6 speed manual are different transmissions with different gear ratios that use different ratio differentials as a result.

kyrix1st · 11-06-2020, 11:20 AM

You should post this on technical section.

I believe E60 6MT uses same configuration as E92 M3 6MT, likely with 3.86 final ratio that some people upgrade to 4.10 for motorsport applications.

werdn · 11-06-2020, 11:50 AM

Quote:

Originally Posted by pbonsalb

For the E60 M5, SMG is the same trans as the manual, with the same gear ratios, but actuated automatically. It makes sense the diff is the same ratio. The E9x M3 7 speed DCT and 6 speed manual are different transmissions with different gear ratios that use different ratio differentials as a result.

Wait if the SMG and manual are the same transmission, how does the SMG have an extra gear? From what ive read the manual was taken from a 540i or a e39 m5

Richbot · 11-06-2020, 12:03 PM

Parts fiche for E60M and E90M has the exact same trans. GS653BZ. So far as I know, all GS653BZ's had the same gear ratios.

E9xM has a 3.85:1 rearend for the manual, 3:15 for auto.

I'm pretty sure E60M got a 3.62 diff regardless of transmission; there's no mention of an alternate ratio in the parts docs. It has nothign to do with the engine or power delivery directly, but the S85 is peaky as hell and it's just taller 1st-5th gear spacing compared to SMG, the S85's peaky nature matches better with a short gear stack, and then SMG has a nice tall cruise gear in 7th. E60M's tall rear tire (27" tall 285/35-19 vs a 26.3" tall rear tire on E9xM) and taller diff ratio than E90M (3.62 vs. 3.85) it tops out close to 75mph in 2nd, like a manual 911 or Cayman GT4 (E9xM is about 68-69mph regardless of transmission). This means you can't have fun banging gears before you're breaking the law, but otherwise, not a big deal.

SMG ratios, from BMW M Registry: 3.99 (1), 2.65 (2), 1.81 (3), 1.39 (4), 1.16 (5), 1.00 (6), 0.83 (7). The final drive ratio is 3.62:1.
GS653BZ ratios: 4.055 2.396 1.582 1.192 1.000 0.872 3.677(reverse)

Also pretty easily curable with a shorter wheel/tire package, like a 295/30-18 rear.

amrazM · 11-06-2020, 12:57 PM

Quote:

Originally Posted by pbonsalb

For the E60 M5, SMG is the same trans as the manual, with the same gear ratios, but actuated automatically. It makes sense the diff is the same ratio. The E9x M3 7 speed DCT and 6 speed manual are different transmissions with different gear ratios that use different ratio differentials as a result.

smg has 7 forward gears manual only has 6, im not sure if or where youve seen a 7 speed manual bmw m5.

tdott · 11-06-2020, 01:05 PM

The manual will always drive different in both cars. It's not like an e46 m3 where all the ratios are the same, and SMG is bolted-on. The only difference there is how the gears are changed.

A DCT vs Manual, is fundamentally very different 1 clutch vs two. And it has different gear ratios and a different final drive, then the DCT/SMG III has a 7th gear.

If anything, a DCT would feel more different than a manual compared to a SMG vs Manual because it's a single clutch vs dual clutch architecture.
Which transmission is better suited to the S65 is subjective so opinions will change, but the mechanical differences will not.

Quote:

Originally Posted by pbonsalb

For the E60 M5, SMG is the same trans as the manual, with the same gear ratios, but actuated automatically.

I think you are referring to the SMG II in the E46 M3.
E60 M5 has SMG III which has a 7th gear and is different than the manual box.

pbonsalb · 11-06-2020, 02:01 PM

Quote:

Originally Posted by werdn

Wait if the SMG and manual are the same transmission, how does the SMG have an extra gear? From what ive read the manual was taken from a 540i or a e39 m5

Sorry, my error. I was thinking E46M3 SMG.

11-06-2020, 11:14 AM	#1
werdn Lieutenant 656 Rep 472 Posts Drives: 997.1 GT3 Shark, ex E92 M3 ZCP Join Date: Sep 2017 Location: Palos Verdes Peninsula (Los Angeles) iTrader: (0)	Does the M3 manual have the same diff ratio problem as E60 M5 manual I am in the market again for my second e9x m3, but this time I am considering a manual. When doing research, I came upon this question. In the e60 m5, the manual option was not developed specifically for the m5. The m5 is supposed to have a SMG. Therefore, it seems like when paired with a manual, the car drives slightly differently than the SMG ones (i think the way power comes on or something). And to remedy this issue, I believe you have to change the ratios in the diff. I was wondering if it was the same thing on the M3 of this generation, or if this isn't a thing for manual M3's. Thanks in advance.
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11-06-2020, 11:18 AM	#2
pbonsalb Lieutenant General 5234 Rep 10,616 Posts Drives: 18 F90 M5, 99 E36 M3 Turbo Join Date: Feb 2011 Location: New England iTrader: (4)	For the E60 M5, SMG is the same trans as the manual, with the same gear ratios, but actuated automatically. It makes sense the diff is the same ratio. The E9x M3 7 speed DCT and 6 speed manual are different transmissions with different gear ratios that use different ratio differentials as a result.
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11-06-2020, 11:20 AM	#3
kyrix1st Colonel 2362 Rep 2,362 Posts Drives: G87 M2; E92M3 MT&DCT; M3 euro Join Date: Sep 2014 Location: nyc iTrader: (0) Garage List 2004 BMW Z4 [0.00]	You should post this on technical section. I believe E60 6MT uses same configuration as E92 M3 6MT, likely with 3.86 final ratio that some people upgrade to 4.10 for motorsport applications. __________________ Pass me if you can.
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11-06-2020, 12:03 PM	#5
Richbot Major General 2760 Rep 5,483 Posts Drives: Jerez Black E90 Join Date: Sep 2007 Location: STL iTrader: (5)	Parts fiche for E60M and E90M has the exact same trans. GS653BZ. So far as I know, all GS653BZ's had the same gear ratios. E9xM has a 3.85:1 rearend for the manual, 3:15 for auto. I'm pretty sure E60M got a 3.62 diff regardless of transmission; there's no mention of an alternate ratio in the parts docs. It has nothign to do with the engine or power delivery directly, but the S85 is peaky as hell and it's just taller 1st-5th gear spacing compared to SMG, the S85's peaky nature matches better with a short gear stack, and then SMG has a nice tall cruise gear in 7th. E60M's tall rear tire (27" tall 285/35-19 vs a 26.3" tall rear tire on E9xM) and taller diff ratio than E90M (3.62 vs. 3.85) it tops out close to 75mph in 2nd, like a manual 911 or Cayman GT4 (E9xM is about 68-69mph regardless of transmission). This means you can't have fun banging gears before you're breaking the law, but otherwise, not a big deal. SMG ratios, from BMW M Registry: 3.99 (1), 2.65 (2), 1.81 (3), 1.39 (4), 1.16 (5), 1.00 (6), 0.83 (7). The final drive ratio is 3.62:1. GS653BZ ratios: 4.055 2.396 1.582 1.192 1.000 0.872 3.677(reverse) Also pretty easily curable with a shorter wheel/tire package, like a 295/30-18 rear. __________________ Last edited by Richbot; 11-06-2020 at 12:23 PM..
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