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Discussion Starter #1
I got the chance to drive the 6-speed day before yesterday and the car does not feel nearly as fast in 1st and 2nd gear as the SMG. I was looking at the gear ratios and noticed something interesting. The 6-speed car is really geared different than the SMG.

This is why the 6-speed car is not as fast, regardless of the difference in the number of gears.

6-speed final ratio for 1st gear = 11.8958 : 1
SMG final ratio for 1st gear = 14.4438 : 1

6-speed final ratio for 1st gear = 7.032 : 1
SMG final ratio for 1st gear = 9.593 : 1

What this tells me is that the 6-speed really needs to 3.91 diff! With the 3.91 diff the ratio for 1st gear is a littler higher than the SMG and 2nd gears are effectively the same between the SMG and 6-speed.

Regardless, the 6-speed was very nice to drive.
 

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I got the chance to drive the 6-speed day before yesterday and the car does not feel nearly as fast in 1st and 2nd gear as the SMG. I was looking at the gear ratios and noticed something interesting. The 6-speed car is really geared different than the SMG.

This is why the 6-speed car is not as fast, regardless of the difference in the number of gears.

6-speed final ratio for 1st gear = 11.8958 : 1
SMG final ratio for 1st gear = 14.4438 : 1

6-speed final ratio for 1st gear = 7.032 : 1
SMG final ratio for 1st gear = 9.593 : 1

What this tells me is that the 6-speed really needs to 3.91 diff! With the 3.91 diff the ratio for 1st gear is a littler higher than the SMG and 2nd gears are effectively the same between the SMG and 6-speed.

Regardless, the 6-speed was very nice to drive.
I've owned both and nonanalytically the 6 speed feels slower. IMHO:cool2:
 

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In other threads discussing the gear ratios both SMG and 6 speed had the same final drive ratio, not the huge difference cited above (3.62 vs 2.93). The reference does look like the format BMW has in the brochures, but I can't find 6 speed ratios in the "07 manual (they must be there!!!), so where did this info come from? Yes, the first and second trans. gear ratios are lower in the SMG, and on up, with top being about the same.

I don't think it is correct (the 2.93 #). If it is, then cruise at 60mph for 6 speed is under 2000 rpm? Anyone???
 

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Gear Ratios

E60 M5 6MT

1st: 4.06
2nd: 2.40
3rd: 1.58
4th: 1.19
5th: 1.00
6th: 0.87
Final: 3.62

E60 M5 7SMG

1st: 3.99
2nd: 2.65
3rd: 1.81
4th: 1.39
5th: 1.16
6th: 1.00
7th: 0.83
Final: 3.62
 

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Discussion Starter #5
In other threads discussing the gear ratios both SMG and 6 speed had the same final drive ratio, not the huge difference cited above (3.62 vs 2.93). The reference does look like the format BMW has in the brochures, but I can't find 6 speed ratios in the "07 manual (they must be there!!!), so where did this info come from? Yes, the first and second trans. gear ratios are lower in the SMG, and on up, with top being about the same.

I don't think it is correct (the 2.93 #). If it is, then cruise at 60mph for 6 speed is under 2000 rpm? Anyone???
I pulled that information off of the BMW website.
 

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Discussion Starter #6
E60 M5 6MT

1st: 4.06
2nd: 2.40
3rd: 1.58
4th: 1.19
5th: 1.00
6th: 0.87
Final: 3.62

E60 M5 7SMG

1st: 3.99
2nd: 2.65
3rd: 1.81
4th: 1.39
5th: 1.16
6th: 1.00
7th: 0.83
Final: 3.62
Are you sure? The BMW website and the M5 brochure that I have both show that the rear end of the 6-speed as 2.93?
 

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Sorry, something here does not add up. Yes, the BMW site shows the 2.93 ratio for the 6 speed rear end ratio. And C&D shows something like 24.6 (hard to read the small print) mph per 1000 rpm in 6th and 3.6 for axle ratio.

Doing the driveline math, if the ratio were in fact 2.93, then the rolling diameter of the drive wheel/tire would be around 21 inches. That is clearly wrong. If the axle ratio is actually the 3.62, then we get a drive wheel/tire diameter of about 26 inches, which is way way way closer to what I hope comes on mine!!! (15 DTG).
 

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Barry, yes, essentially correct. But there is a small difference even in "common" gears like first and top, but nothing like enough to barely notice let alone any personality change. Interesting that even with one less ratio they actually go to a slightly shorter first gear and slightly taller top.

By historical standards these are both "close ratio" boxes, as any 6 or 7 speed unit would have to be. The old Corvette close ratio (as advertised in 1965 for example) was a 4 speed, but first was very tall, almost 1/2 of top. I think it would reach 60 depending on choice or rear axle ratio (several available) in first gear.

The first Porsche Turbo (1976?) was a 4 speed because with the massive amount of torque (in those days) the five speed, already a Porsche standard for many years, was deemed unnecessary.
 

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Discussion Starter #12
Barry, yes, essentially correct. But there is a small difference even in "common" gears like first and top, but nothing like enough to barely notice let alone any personality change. Interesting that even with one less ratio they actually go to a slightly shorter first gear and slightly taller top.

By historical standards these are both "close ratio" boxes, as any 6 or 7 speed unit would have to be. The old Corvette close ratio (as advertised in 1965 for example) was a 4 speed, but first was very tall, almost 1/2 of top. I think it would reach 60 depending on choice or rear axle ratio (several available) in first gear.

The first Porsche Turbo (1976?) was a 4 speed because with the massive amount of torque (in those days) the five speed, already a Porsche standard for many years, was deemed unnecessary.
The 5-speed wasn't deemed unnecessary on the 930, it was not up to the task of the new turboed engines torque. Later versions of the 930 came with a 5 speed tranny, I believe in 1985 or 1986.
 

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Discussion Starter #13
Sorry, something here does not add up. Yes, the BMW site shows the 2.93 ratio for the 6 speed rear end ratio. And C&D shows something like 24.6 (hard to read the small print) mph per 1000 rpm in 6th and 3.6 for axle ratio.

Doing the driveline math, if the ratio were in fact 2.93, then the rolling diameter of the drive wheel/tire would be around 21 inches. That is clearly wrong. If the axle ratio is actually the 3.62, then we get a drive wheel/tire diameter of about 26 inches, which is way way way closer to what I hope comes on mine!!! (15 DTG).
Agreed, but two things come to mind:

1. Why rely on what C&D publishes? C&D does not verify speed in gear at 1,000 rpms. They simply do the math. I have seen mistakes on other cars I have owned in the car mags when it comes to drive ratios. Not to mention stupid errors like tire sizes (all they need to do is look at the tire).

2. Why would C&D determine the final drive ratio as something different than what BMW publishes in their brochures and on their websites? Typcially the car mags get their information from the manufactures' published documents. But then again, C&D might have determine something wrong with the numbers that they ended up with and modified the final drive ratio? I find it really hard to believe that BMW would make such an flagrant error in their documents.

I wish I would have determine in 5th gear what the specific speed was at 3,000rpms while driving the 6-speed. That would tell the story.

Could someone with a 6-speed tell us how fast the car is going in 5th gear at 3,000rpms?
 

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Discussion Starter #14 (Edited)
By the way, at the end of the day this is why I'm going back to SMG. (Also I'm not as fast as I used to be.)
That is funny, I feel the same way, not nearly as fast as I used to be.

I am getting ready to get rid of my Silverstone and replace it with an Interlagos Blue and was thinking of getting the 6-speed. I have 21,000 miles on my car and not a single SMG problem, but was thinking of a change in configuration. But after driving the 6-speed, which was very nice, I have decided to get the new car with an SMG.
 

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The 5-speed wasn't deemed unnecessary on the 930, it was not up to the task of the new turboed engines torque. Later versions of the 930 came with a 5 speed tranny, I believe in 1985 or 1986.

1989 was the first 5 speed 930 and +1 on your explanation.
 

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No, not 5th. Someone go 60 in top (6th) and report approx. rpm at that speed. if 2400 - 2500 range then axle is probably near 3.62. If 2000 or below, then the 2.93 # would be more correct. That tall gearing with the anemic torque at 2000 would result in not very responsive performance without downshifting a couple or three cogs.
 

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Just playing with the numbers suggests that with a 2.93 rear axle the speed at redline in 2nd gear would be 89 mph!

I am just believing the C&D info for now as it makes way more sense. That is, a typo at the BMW site is more likely than them ever putting a 2.93 into a car with an engine having the torque/rpm characterisitcs of the V10.
 

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Discussion Starter #18
No, not 5th. Someone go 60 in top (6th) and report approx. rpm at that speed. if 2400 - 2500 range then axle is probably near 3.62. If 2000 or below, then the 2.93 # would be more correct. That tall gearing with the anemic torque at 2000 would result in not very responsive performance without downshifting a couple or three cogs.
The reason I mentioned using 5th is that 5th gear is 1 : 1 to the rear end, which makes the math a littler easier.
 

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No, not 5th. Someone go 60 in top (6th) and report approx. rpm at that speed. if 2400 - 2500 range then axle is probably near 3.62. If 2000 or below, then the 2.93 # would be more correct. That tall gearing with the anemic torque at 2000 would result in not very responsive performance without downshifting a couple or three cogs.
Speed, Gear, RPM

60, 5th, 2,650
60, 6th, 2,300

Almost got killed doing this........:cool2:
 
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