For thoses of you that upgraded to 4:10's in you manuals. How much of a gain was there? I don't care about gas milage because it is a weekend dry day care only. Any regrets? Has anyone track tested your 4:10's to see what gains you got?

 

Once you install the 4.10s you'll wonder why they didn't come out the factory with them.

 

I had reservations before I did 4.10's, but now I'd never go back to pig gears. It's a night/day difference.

 

I do miss how long my 3rd gear was before, but it pulls so much harder now it's well worth it. I was waiting until I got my rims for my drag radials before hitting the track. Still waiting.

If you have any kind of vibrations at 75 or faster after getting the gears, try turning the rear of the driveshaft 180 degrees before doing anything else. Mine felt funny at 75-80 when cruising in 5th gear so I turned the driveshaft and it smoothed right out. it could also have been they tightened the driveshaft bolts too tight. 5 of them were really hard to turn and 1 was very easy. I guess they didn't read their ford service manual that says tighten in a star pattern to 41 ft lbs.

 

Good reminder on the star pattern torque sequence. My stock D/S and pinion flange had yellow marks on them both to indicate proper indexing.

 

don't know about 4.10s Ask me about 4.30s


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Wow, ittakes a brave man to run scremin motive 4.30s. Maybe I'd do it if I only do city and strip driving. But hey with 4.10s and the stock 17"tire height the effective final ratio is 4.34 or close to that.

 

Tim My 18s are about 1 inch shorter than my stock 17s

 

I didn't bust out the ratio calculator but I'm guessing for you around 4.56 maybe a little more. Yeow!!

 

does it do a lot worse on gas? how many miles per gallon worse?