Considering going to 3.727 gear/pinion in 6MT

[serialk11r]

Originally Posted by JC

That's assuming you drive all highway and doesn't include installation......
If you all you want is a quieter car take off the sound tube and add some sound insulation. It will save you $500+ and actually make your car noticeably quieter.

Several people have said this, but remember there are a few different variables here. One of which is the cost, I imagine it's possible to find diffs for less than 500 from crashed donor cars. Another is the amount you're changing the ratio, changing the ratio more doesn't cost more money, but it yields more fuel economy returns.

Say some company made some custom gearsets to replace the stock 6th gear, with a 0.62ish ratio for ~20% less revs. At lower highway speeds you would see almost 10% more fuel economy rather than ~5%. For some people the AT FRS/BRZ gearing is enough to pay off the 1000 dollar cost difference in just a few years of highway commuting. Of course, since there are no lower OEM 6th gears that we know of, this will end up being a more expensive mod than say, putting a 0.730 gear on a Celica C56 transmission.

[FT_Monk]

OP, You can install taller tires. It is cheaper, quickly reversible and no thing can go wrong like removing trans to replace gear.

[serialk11r]

Originally Posted by FT_Monk

OP, You can install taller tires. It is cheaper, quickly reversible and no thing can go wrong like removing trans to replace gear.

To get 10% greater rolling diameter you'd be raising the car 1.2 inches or so...

[FT_Monk]

^^^ Only .6 inch taller measured from the center of the wheel. You can also lower the car to compensate for the taller tire. Even with the cost of lowering car, it is still much less risky and less costly then remove and replace trans gears.

[serialk11r]

Originally Posted by FT_Monk

^^^ Only .6 inch taller measured from the center of the wheel. You can also lower the car to compensate for the taller tire. Even with the cost of lowering car, it is still much less risky and less costly then remove and replace trans gears.

No, the tire diameter is about 24" so you'd be raising it 1.2". To drop the car 1.2" properly is going to cost some money.

[FT_Monk]

Originally Posted by serialk11r

No, the tire diameter is about 24" so you'd be raising it 1.2". To drop the car 1.2" properly is going to cost some money.

Actually you are right! Your math is spot on and replacing transmission gear and diff is more effective and cheaper.
Good luck.

[Laurie]

I'm struggling to find info on what the stock ratio is on the Automatic Transmission Toyota 86? There's quite a few times I'd like the power to kick the tail out and in 1st gear I'm on the limiter, 2nd gear I'm too low down. Also 5th and 6th are definitely low RPM cruising gears... I'd happily go numerically higher on the final ratio to get better acceleration and better torque...

[Swift]

Great thread and love how manufacturers use 10yr old parts, makes our jobs easier. Glad to know the different R/P sets available!

[Racecomp Engineering]

Bringin this one back...........

I want a different final drive for better acceleration while being NA.

Cusco 4.55 gets installed in the morning. Will report back on how it feels.

Current top speed if you had a lot of power is 168mph. New top speed with 4.55 ratio is 147mph at 7400 RPM. Around my home track ,Summit Point...this ratio will for sure drop lap times.

One thing is for CERTAIN........the final drive in the box is for sure a TOYOYA MOTOR COMPANY part.

Full review shortly.

Myles

[Captain Insano]

Yes please report back ASAP!

[wparsons]

Originally Posted by serialk11r

No, the tire diameter is about 24" so you'd be raising it 1.2". To drop the car 1.2" properly is going to cost some money.

You're only raising the car by the difference in radius, not diameter. Unless the new tire is 2.4" taller, you're not raising the car by 1.2"

The car is supported by the hub of the wheel, not sitting on top of the tire.

You will decrease gap to the fender by 0.6" as well though, so even though the car is higher from the ground the gap is smaller and it'll look lower. With that a 0.6" drop will get the car back to the original ride height, but you will have reduced fender gap by 1.2".

[mike2100]

Originally Posted by Racecomp Engineering

haha exciting!

[ShoNUFF]

Not sure everyone realizes that OP is trying to nueter the performance to increase MPG?

No disrespect to OP but I'm just..



On a sports car forum? REALLY?

I guess it's the 21st century.. might as well go green?

[FreshFRS]

Originally Posted by ShoNUFF

Not sure everyone realizes that OP is trying to nueter the performance to increase MPG?

No disrespect to OP but I'm just..



On a sports car forum? REALLY?

I guess it's the 21st century.. might as well go green?

If i end up going with a PD supercharger this might be a viable option as performance would not be affected. plus 0-60 would be had in second about 6800 vs limiter 2nd/really early 3rd stock and would allow the supercharger to work more. but as an N/A car i would not do it.