Mazda 6 Forums banner

21 - 37 of 37 Posts

·
Registered
Joined
·
2,883 Posts
I'll see if I can tape it tonite and show you.

Jason
[/b]
No need. Mazda's published ratios are very likely wrong. I recall there was a last minute ratio change for US market ... not sure.

We can back check the ratios by just checking speed at rpm, say speeds at 4k rpm in 1-3, 3k in 4 and 5, and 2k in 6th. Assuming stock 18" tires.
 

·
Registered
Joined
·
2,652 Posts
No need. Mazda's published ratios are very likely wrong. I recall there was a last minute ratio change for US market ... not sure.

We can back check the ratios by just checking speed at rpm, say speeds at 4k rpm in 1-3, 3k in 4 and 5, and 2k in 6th. Assuming stock 18" tires.
[/b]
yeah, there was a last minute ratio change to the 6th gear and final drive. they wanted to make it so u wouldnt have to downshift to pass on the highway so they sacrificed mileage.
 

·
Registered
Joined
·
1,477 Posts
yeah, there was a last minute ratio change to the 6th gear and final drive. they wanted to make it so u wouldnt have to downshift to pass on the highway so they sacrificed mileage.
[/b]
Car and Driver mentioned the delay in releasing the Speed6 in North America was due to Mazda reworking the gear ratios to give the engine more usable low-end torque to suit American tastes. C&D didn't state if it was in all 6 gears or just 6th. However, I would assume that such a long delay and adding more usable torque would mean they tinkered with all the gear ratios.

To me it seems like 1st and 2nd gears are the weakest in this car. It's not very quick off the line unless you hold the clutch in and rev the rpms up to about 4K. Then drop the clutch as fluid as possible and hang on for your life because the car feels like it was launched from a canon.

But low RPM launches from a stop, even with the accelerator FLOORED, will produce flat acceleration until after, of course, 2500 RPM, but by the time you really feel the boost, it's time to shift.

Sigma, did you figure out the best launch RPM from a dead stop in 1st? I know it has to be around 4,000 RPM, but I don't think the clutch likes it.
 

·
Registered
Joined
·
676 Posts
That can't be right. 1st and 2nd cant be so close. It would mean you can either go up to 47mph in 1st gear and 73mph in second or 39mph in first and 47mph in second. :sarc:
[/b]
If i recall correctly some review (possibly C&D) said they had to shift to 3rd to get to 60, thus lowering the 0-60 time for the added shift. So 2nd doesnt go to 60
 

·
Registered
Joined
·
2,883 Posts
Well I already calculated the speed in each gears a few months back and everything was in-line with the gear ratio published by Mazda.
[/b]
http://forum.mazda6club.com/index.php?showtopic=49145&st=0

But you measure to verify calculated results. If you drop to 3800 on a 6k 1-2 shift, then the published data is right. Might be easier to shift at 3k and look for 1900 rpm.
 

·
Registered
Joined
·
998 Posts
Since the speedo is in 10mph increments, give or take a few mph.

At 4k rpm

1st: 22mph
2nd:37mph
3rd:50mph
4th:66mph

Im sure if it wasnt rush hour I could have set the cruise and determined a more precise mph.

Since Im too lazy, what do those compute to?
Jason
 

·
Registered
Joined
·
2,883 Posts
At 4k rpm

1st: 22mph
2nd:37mph
3rd:50mph
4th:66mph

------------

so by ratios, 6k in 1st is 33mph, which is 3570 rpm in 2nd.

added book numbers for 4k rpm:

1st: 22mph (21.1)
2nd:37mph (33.5)
3rd: 50mph (48.9)
4th: 66mph (64.0)

During hard acc'n, tach may not drop to true rpm in 1-2 shift. Mazda's published ratios gaining credibility ...
 

·
Registered
Joined
·
5,217 Posts
Discussion Starter #30
Car and Driver mentioned the delay in releasing the Speed6 in North America was due to Mazda reworking the gear ratios to give the engine more usable low-end torque to suit American tastes. C&D didn't state if it was in all 6 gears or just 6th. However, I would assume that such a long delay and adding more usable torque would mean they tinkered with all the gear ratios.[/b]
It was only the final that was changed. It was changed from the 3.350 that was for American mileage-oriented tastest to the 3.941 that was in the Euro/JDM versions of the MS6 from the start. This change was done after the head of MNAO tested both and said that the 3.941 gears were worth a 2mpg hit in mileage.
 

·
Registered
Joined
·
272 Posts
Anyone who wants to calculate, you can test this in excel:
tire width 215
tire ratio 45
diameter 18
wheel diameter 650.7 (width * ratio/100 )*2 + diam*25.4
circum (mm) 2044.23434 ( diam * pi )
circum (km) 0.002044234
tire rev / km 489.2 (1/circ km)

1st gear
Ratio 3.538
Final 3.941
Gear Ratio 13.943 (ratio * final)
Tire rev/km 489
rev / km 6821 (gear ratio * rev/km)
RPM 4000
Km / min 0.586 (rpm/rpk)
KPH 35.2 (kpm * 60)
MPH 21.86 (kpm / 1.609334)
RPM next gear falls 2530 (kpm * nextgear rpk)

Looks like the stated gear ratios are correct based on KevinK2's info.
 

·
Registered
Joined
·
320 Posts
Anyone who wants to calculate, you can test this in excel:
tire width 215
tire ratio 45
diameter 18
wheel diameter 650.7 (width * ratio/100 )*2 + diam*25.4
circum (mm) 2044.23434 ( diam * pi )
circum (km) 0.002044234
tire rev / km 489.2 (1/circ km)

1st gear
Ratio 3.538
Final 3.941
Gear Ratio 13.943 (ratio * final)
Tire rev/km 489
rev / km 6821 (gear ratio * rev/km)
RPM 4000
Km / min 0.586 (rpm/rpk)
KPH 35.2 (kpm * 60)
MPH 21.86 (kpm / 1.609334)
RPM next gear falls 2530 (kpm * nextgear rpk)

Looks like the stated gear ratios are correct based on KevinK2's info.
[/b]
Tire's rolling diameter is 635mm according to Bridgestone if I remember correctly.
 

·
Registered
Joined
·
2,883 Posts
It was only the final that was changed. It was changed from the 3.350 that was for American mileage-oriented tastest to the 3.941 that was in the Euro/JDM versions of the MS6 from the start. This change was done after the head of MNAO tested both and said that the 3.941 gears were worth a 2mpg hit in mileage.
[/b]
mazda lists same gearing for us, canada, and australia. that includes 3.941 final drive for 1-4, and 3.35 for 5 and 6. Uk seems to have much different, and taller gearing, with different FD ratios.
 

·
Registered
Joined
·
2,652 Posts
so i tried something today during acceleration. i completely skipped 2nd and went from 1st to 3rd. went to about 5500 in first and then dropped into 3rd and the rpm was around 2750, which is still in boost. i dont know if skipping a shift will help any in the traps, but it may be worth a shot to skip one shift. considering u hit 99 in 4th gear, thats only 2 shifts to get there.
 

·
Registered
Joined
·
5,217 Posts
Discussion Starter #37
No way that'd help. You're accelerating less than half as fast in 3rd as you are in 2nd. You'd save yourself a shift that takes less than a second but it would cost you several seconds in added acceleration time. It would take you twice as long to get from 25 to 50 in 3rd as it does in 2nd.
 
21 - 37 of 37 Posts
Top