Gear question, don't worry, it's a NEW ONE.

Skidzz · Nov 27, 2006

When I had my car at MD, they told me that my gear was WAY too tall to be the 3.27's that the car is supposed to have. They told me that I probably had 2.73's or maybe 3.08's and that they must have made a mistake when the car was assembled. At 70 mph in 5th gear, I run at about 2000 rpms. I know there are some gear calculators online, but I don't have the links. The reason I want to know is because I'll be buying my 4.10's soon and I'm guessing I will need to know what gears I had before so I'll know how much to recal. the speedometer by.

BurningRubber · Nov 27, 2006

Sounds like 3.27's, I have 3.27's and I tach around the same.

Heres a calculator to make sure.

http://www.tchracing.com/tech/gearc...m&givenval=70&givenvaltype=MPH&selectedgear=5

Skidzz · Nov 27, 2006

BurningRubber said:
Sounds like 3.27's, I have 3.27's and I tach around the same.

Heres a calculator to make sure.

http://www.tchracing.com/tech/gearc...m&givenval=70&givenvaltype=MPH&selectedgear=5

Wow, I think you're right then. Looks like I do have 3.27's, just like I should. Damn it, that's the last straw. I am going to MPH next time.

superstang01 · Nov 27, 2006

BurningRubber said:
Sounds like 3.27's, I have 3.27's and I tach around the same.

Heres a calculator to make sure.

http://www.tchracing.com/tech/gearc...m&givenval=70&givenvaltype=MPH&selectedgear=5

i have 3.27 and i run around 2100rpms in 5th

steveb24 · Nov 28, 2006

when i had 3.27's in 5th i was tachin around 1800 at 70. if not lower.

HoustonGT · Nov 28, 2006

steveb24 said:
when i had 3.27's in 5th i was tachin around 1800 at 70. if not lower.

ummm, were you running weird sized tires or something? I was right at 2000rpms at 70mph in 5th gear, which the calculator also verifies

COramprat · Nov 28, 2006

Check the door panel for the sticker. You wouldn't have 3.08's unless you were an auto. But I wouldn't go as far and say there wasn't a mistake. Factory could have had a mis-batch and loaded them in your car when you were supposed to have 3.27's.

Kurgan · Nov 28, 2006

(with a T-45)
2.73:1 @ 70 mph = 1675.9 rpm
3.08:1 @ 70 mph = 1890.7 rpm
3.27:1 @ 70 mph = 2007.3 rpm
3.55:1 @ 70 mph = 2179.2 rpm
3.73:1 @ 70 mph = 2289.7 rpm
3.90:1 @ 70 mph = 2394.1 rpm
4.10:1 @ 70 mph = 2516.8 rpm

I wrote that calculator. It will never be dead on to the exact RPM since tire diameters can vary between brands and depending on how worn the tread is, and because a lot of the gear ratios in transmissions and rear ends is kind of a rounded off value.. but it should be very damn close -- easily within 100 RPM.

I've actually used this calculator to re-program my SCT chip to get my speedo correct for my gear-driven TKO and I got the speedo tuned dead-on with the 1st try using my calculator.

EDIT: Added 3.55-4.10

Black'02 · Nov 28, 2006

COramprat said:
Check the door panel for the sticker. You wouldn't have 3.08's unless you were an auto. But I wouldn't go as far and say there wasn't a mistake. Factory could have had a mis-batch and loaded them in your car when you were supposed to have 3.27's.

Most likely if they put in the wrong gears his spedo would be calibrated to the gearing he was supposed to have making it pretty obvious, i would think.

The shop you took the car to may not have been familiar with the gearing in the transmission. The rear gear isnt the only part that determines the rpm at a given speed.

Black'02 · Nov 28, 2006

HoustonGT said:
ummm, were you running weird sized tires or something? I was right at 2000rpms at 70mph in 5th gear, which the calculator also verifies

His car is an '02 which has the 3650, and 5th gear is a lower ratio then the t-45.

Kurgan · Nov 28, 2006

Black'02 said:
His car is an '02 which has the 3650, and 5th gear is a lower ratio then the t-45.

Which the calculator linked to above also verifies, as there is an option to select TR-3650. And it says 3.27:1 @ 70 mph = 1857.5 rpm.

HoustonGT · Nov 28, 2006

Kurgan said:
Which the calculator linked to above also verifies, as there is an option to select TR-3650. And it says 3.27:1 @ 70 mph = 1857.5 rpm.

Ahh, gotcha. Makes a bit more sense now. Maybe thats why some of you guys on here (01+) get better gas mileage than me and a few of the other people.

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