'Better' gearing for 2004-2006 STi

I am sure I am not the only one who thinks that the gearing on the 04-06 STi is too short. This became more prominent after I upgraded my turbo. First and second gear are pretty much worthless. Has anyone given much thought to improving the gearing? Couple options come to my mind:

• Upgrade to 07 STi transmission
  • Some of the gears are longer, but are they long enough?
• Raise the redline
  • Not really changing the gear ratio but you will make the gears more usable. For example, raising the redline to 8K RPM would raise the top end speed of 4th gear from about 100mph to about 115mph
  • Likely to step out of the powerband unless you have a BIG turbo
• Change final drive ratio
  • Will this affect the speedometer/odometer?

The last option is the most interesting to me. Anyone gone through a detailed parts/cost analysis on any of these?

 

Milo I feel your pain..... with my 275-40-17 v710s on stock rims I can only reach about 59 mph in second gear which hurts on most nationals style autox course. I'd love to do something about it but all those options will put the car in a highly prepped class. Next year I'm going to run a 245-45-17 to try and get a little more gearing.... that's all I could think of

 

Nope somethings you can backdate.... I know a final drive isn't allowed in Street Prepared so that must throw you in prepared.... a class commonly known for people saw-zawing their cars....

Edit: milo the final drive on our silver crx is awesome........

 

Wouldn't 275-40-17 and 245-45-17 give you very similar outer radius?

 

The 245-45-17 is a RE01.... the 275 is a v710.... pretty similar but I'll take what I can get . There is talk on SCCAforums about whether the 07 will be a better STU car due to it's taller second gear. I would think that final drive would be the most effective and painless way to get better gearing. I don't know how price would be for one. We paid $1000 for a final drive for the crx; the guy we bought it from paid $1750 orginally. Just think that's what it cost for a 20 year old honda

 

You can fit taller tires on to effectively lengthen the gear ratios. Final drive swapping gets to be expensive on these cars since you'll need 3 new diffs (front, rear, and center). Higher redline works well if you've got the turbo, cams, and heads to support it.

My speedo is well within stock specs even with a 4.44 final drive (much shorter than a normal 5spd). This is the other reason that I went with a JDM motor and its higher redline because the gears felt too short even at moderate power levels for a 6500rpm shift point. Add 2K revs and each gear becomes a lot longer, I calculated the difference for my transmission in my journal. In the tranny section of nasioc there is a gear ratio calculator spreadsheet that you can play around with to see how the gearing changes or tire changes will affect your rpms/gear.

 

Building your heads might actually cost less than a new final drive or gears.

 

I would rather have a 245/35-17, and then have a more usable 3rd gear.

 

To change the rev limit to anything meaningful you also need to do something about the crank.

 

There are people who run 8500rpms on stock crank.

 

http://www.iwsti.com/forums/showthread.php?t=84855&highlight=8500

 

That thread is not very convincing.

 

You dont need any new diffs when changing final drive.

Tallest final drive is 3.90 front and 3.545 rear. Milo already has the 3.545 rear. Meredith has 3.90 front and rear. In 06 and 07 the center has a reduction of 1.1:1. All you'd need to do is change the transfer gears to the 04~05 and then a 2.90 final would be 'ok'.

Otherwise, PPG is your ONLY option. 1st gear to 90mph FTW.

Or, start in 3rd gear.

 

that thread makes me laugh pretty hard.

 

http://forums.nasioc.com/forums/showthread.php?t=690248&highlight=8500

This is the more reliable thread I refer to. Other one was just quicker since I was surfing IWSTI

 

most of those people are running 7500 rpms which is only 300 more than stock. That would add a little top speed to each gear.

Of the 4 people on the first page going 7900+ one had bearing failure and another had to modify his oiling system to avoid starvation.

Going from 7500 to 8500 rpms is a huge jump. If things aren't balanced things can go bad quickly. A flywheel off by 1 ounce can be out of balance by as much as 200lbs once the rpms get to 8500.

 

Still makes me laugh.

 

Makes me wonder what those V-tech guys are doing with stock honda engines that go to 9300 daily.

 

Oh i thought stock redline was 6k lol

 

Naah that's just us and our lowly RS's

 

What is the cost involved?

 

I'm interested since I will be swapping to a 6 speed in the future.

 

Rear ring and pinion swap is around $600 plus parts.

Changing the stepper gears in the trans with the trans in the car is about $800 plus parts.

Stepper gears OUT of car is going to be $600 (like if we are doing front R&P already)

Front ring and pinion is going to be $1200. The pinion shaft is in the gearset, so the gearset needs to come out of the trans as well.

For the front R&P, the trans needs to come out and go back in, so add $600 for that labor.

I do not know the price of ring and pinions.

However, I'd recommend custom PPG gears instead of replacing the Rings and Pinions/stepper gears.

 

Dang all that adds up close to PPG gears doesn't it?

 

I'd guess so. I wonder what the benefits of PPG gears in a 6spd would be compared to PPG gears in a 5spd. Especially if you could pick your own gear ratios.

 

Yes.

 

The 6MT is absolutely unbreakable already, so adding PPG's would only serve to make it better.