i bought my 4.10 gears at a ford expo last summer. i brought it to a shop to have them put in my car, and i was expecting a crazy change. it felt different, but not as much as i thought. On the highway at 70mph im at 2400 rpm with 4.10's with overdrive on(its an auto) before i cruised at 2000 rpm at 70mph. i guy i know said that there is no way that there are 4.10's in there. Who else has an auto w/ 4.10's, if you do what rpms are you at going 70? I cant really open up the diff. and count the teeth to check, so this is next best.
AODE Rpm's with 4.10's
- Thread starter davins130
- Start date
With stock 17" tires, 245/45-17, it would be at 2504 rpm at 70mph.
With soemthing like 255/45-17, it would be at 2470 rpm at 70mph.
There's also the matter of how your speedometer is recalibrated for the gears. With a different speedo gear, it will be off by a little. However, with a correctly calibrated Speedcal, which is what I use, it will be as accurate as it can possibly get.
With soemthing like 255/45-17, it would be at 2470 rpm at 70mph.
There's also the matter of how your speedometer is recalibrated for the gears. With a different speedo gear, it will be off by a little. However, with a correctly calibrated Speedcal, which is what I use, it will be as accurate as it can possibly get.
Your previous gears of 3:27, 2000 rpm, at 70 mph puts you with stock 245/45 x 17" tires. Using that, you aren't going 70 mph, but only 66.75 mph. 3:90 gears would give you 2400 rpm at 70 mph, or more likely is that you didn't install a speed calibrator and your speedometer is off. At 70 mph you should be turning 2516 rpm with 4:10's. FYI, a speed calibrator is the only way to fully correct this for an auto trans. Switching to the 21 tooth gear will make it closer, but it will still be off by 2-3 mph.
95Vert
New Member
It's still going to be off with the speedo gear, right around 3-5 mph(I think). Just turn the wheels once, and see how many times the d/s turns (make sure to mark both). This way you'll see what gears you installed, a little over 4 d/s turns means you have 4.10s, and so on. BTW, how's the launch??
95Vert
New Member
willys1
Active Member
Its more then 3-5. Its 1mph off for every 10mph your going.If you going 20,,your really doing 22. If your doing 60,,your really doing 66!! At 2500rpm's,,Im doing 72mph.Sorry,its the other way around.If your doing 22,your really doing 20.,,And if your doing 66,your really doing 60 ,ect,,,,,,They dont make a gear for 410's.The biggest you can get is a 23 toothed speedo gear,and thats for 373's.At least thats how AOD's are!!davins130 said:
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