I have a 1998 Nascar edition. They are 3.73 from the factory on the Nascar. I will be changing the gears. Planning on 4.10 unless someone tells me I can go higher without any problems or other major modifications.

Help?

 

Go with whatever you'd like. But if you have a chip, you need to get it re programmed to compensate for the new gear. You could easily over rev. and of course your spedo would be off. If you don't have a chip, I'm not sure how you would compensate for it........

 

You can go as high as you want to. Just don't plan of getting on the interstate. In my truck with 4.10. At 75 mph the engine would run at 27-2800 rpm. But I know a guy who has 5.xx in his f-150. He just keeps it in town or on short trips to the track.

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'96 F-150 302
Hedman Hedders, Catco Cat., Gibson Super Truck, K&N F.I.P.K.

 

I have just installed 4.56 gears in my 97 f150 and turn 2850 rpm @ 80mph I have 265 70 17's and the only jproblem that I'm having now is getting my speedo re-calibrated. Ford said they can do nothing for me, the speedo shop said I'm off 30% and I have a 19 tooth gear in there now and can only go to a 21 tooth, each tooth is 5% so I can only change 10% what good is that? I have a superchip so I called them and they also can't do anything for me...........THIS SUCKS!!

The only other lead I have is Abbott they have an Electronic Ratio Adapter (ERA), and hopefully this will work for my truck.

www.abbott-tach.com

Oh yea I almost forgot, It will over rev if you have a superchip, they are re-calibrating mine at this time.

 

how about 1700 rpm at 70mph. i need regearing but thats a whole other subject. i heard each tooth was 5 mph not 5 %. so if your off by 30% at 50 mph that would be 15mph. 2 teeth would get you close. only off by 5 mph. i know its a % ratio and the faster you go the more its off but it might be close.