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Discussion Starter · #1 ·
Hey guys,

I was feeling nerdy today. So, I did some calculations and created some graphs to compare the stock Mazda 3 5-speed manual transmission versus the Mazdaspeed3 6-speed transmission when used in a regular Mazda 3. The data might be useful for those interested in swapping the MS3 transmission to their Mazda3's.

Variables:
- Overall tire diameter based on stock 2004-2009 Mazda 3 17" wheel/tire package (205/50/17)
- 5-speed transmission ratios taken from 2006 Mazda 3 specifications
- 6-speed transmission ratios taken from 2007 Mazdaspeed3 specifications
- Final drive ratio for 6-speed gears 1 through 4 (3.941:1) used for gears 1 through 6, with the equivalent ratios for gears 5 and 6 calculated (Remember, gears 5 and 6 have a final drive of 3.350:1)
- Maximum engine speed of 6800 RPM

Now for the resultant data (pretty self explanatory):








My conclusion: This upgrade is worth every penny and all the headaches!

As always, thoughts and comments are welcome.
 

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I guess I should read a little better next time. I noticed it on the first post after you replied.

Did you use the circumference of the tire or did you use the rev/mile rating for the stock RSA's?

It looks like a good upgrade for track days and autocrossing. But I am not sure what class that would put you in for autocrossing.

Big difference in rev drop between 1st and 2nd gear.
 

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Discussion Starter · #5 ·
You read it correctly the first time. I just edited the main post a few min ago hehe.

The tire circumference is based on the tire size, not the RSA's specifically.

Yeah, the kicker for me is the 1-2nd shift. It keeps the RPM's up. The 1st to 2nd gear in the stock 5 speed in the Mazda 3 annoys me every time I have to make that shift. Also, gear for gear, the MS3 unit is much closer. As you said, big advantage for track days, and probably autocross too.
 

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It depends on what year Mz3 you have.

04-05 hubs are different so the axle splines won't match. So you need to buy no hubs.
You have to replace shifter linkage, including shifter and base,both axles,joint(jack) axle,driver's side motor mount,and lower transmission mount,new clutch,and fly wheel. You might have to replace the shifter cable braket that attaches the shifter cables to transmission. (not 100% sure on that one)
I am not 100% positive the conectors are plug and play for the back up lights and the neutral switch. The master cyclinders are the same though.

If you don't have a lot of performance mods I don't know if the extra weight of a six speed would be worth it.
 

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Discussion Starter · #9 ·
LOL

Are you asking me to calculate and plot the 2010 models too? Anyhow, thanks for the ratio table. I'll be sure to add this data to the analysis when I get home tonight!
 

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Discussion Starter · #10 ·
p.s. do we know what the weight difference is between the two boxes? Just because it is a 6 spd, does not necessarily mean it's heaver than the 5 spd. Many variables here... I think Aisin manufactures the 6spd from the MS3? I'll see if I can get a weight comparo.

As for performance, I think it will be great for an N/A vehicle, especially on a road course.
 

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I am not sure about the weight difference. It could be marginal.
I believe your right on the Aisin manufacturing the 6sp. Funny thing is on the Tripoint car it was a second faster around the track then the Ms3 and I thought I remember them saying it had to do with less shifting with the 5spd. I wonder if the mz3 can take full advantage of the 6spd on the track since the computer limits are top speed to 115 mph?

Ha ha if you want too. I was just posting that to give people an idea on what changed.

How did you calculate rpm drop?
 

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Discussion Starter · #12 ·
Yeah, I could see how certain gearing could be better for different tracks. However, all of the tracks in my area would definitely suit the 6spd ratios. Anyhow, it's still pretty interesting stuff. Was the Tripoint car turbo'd?

Haha, I was just joking. Yeah, i'll definitely calculate the 2010 ratios as well (based on the 2004-2009 Mazda 3 tire sizing). It's pretty easy since I have the template setup. Who knows... These gear boxes might be able to be retrofitted to our generation Mazda3's? It could be an option somewhere down the road, for sure.

As for the calculation of RPM drop, it is basically looking at the road speed at the RPM of the previous gear, then calculating what the RPM would be for the gear in question.
 

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I do prefer the normal 3's 5 speed because I have to shift less. The car has enough torque that it's always at a good enough spot without needing shorter gearing to downshift more frequently and keep the revs up to stay in the powerband like with the 6 speed. In autocross, you get an extra 10mph or so in 2nd without needing to waste time shifting to 3rd, which can be super helpful on really fast courses. On the track at Mazfest this year (Cal Speedway) I was able to top out at around 115mph in 4th on the main straight without needing to shift to 5th, which was nice, and only had to downshift one gear where the speeds were downshifting two on some corners.
 
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