SUPERDUTY CUMMINS NV4500 VERY LOW TOP SPEED
 

hey guys, i put a 93 12v in my 2003 f350 with an NV4500 trans and i have very short gears and at about 65mph its just over 2k rpm's. first gear is super short, kind of like a granny low. not sure what i have for gears thinking 4:10 but i really need to lower them to get better speed but still need to haul my 44' enclosed trailer. do you think putting taller gears in the axles will be enough or will i have to re gear my tranny too... thanks in advance!!

I would personally run 3:54's you will have top end back and still have the torque to move the trailer

Yeah, you have plenty of power potential in that motor to run higher gears. Being a 1st Gen motor it wont turn very high rpm. You can get a 3k governor spring kit which will allow you to turn more rpms. 2k at 65 isn't too bad. And I've never heard of anyone regearing the transmission, not sure if its possible. I'd just put 2" taller Tires on it, that'll drop your rpms.

Put 3.55s in, maybe also get a taller tire, call it a day.

Thanks guys ill put in 3.55's not too expensive!

I'm running 285 75 16 tires with 3 73 gears with a first gen 12V and 3200 rpm gov spring and a NV4500 tranny! The tires are about 33 inches tall and I can bounce right up there to 90 in a heart beat, but it does like to cruse along at 65 mph! If I had 3 54 gears then 70-75 would be more of its comfort zone! My Super Duty had a V10 by the way !
It sounds like your pump might be limiting your top speed or else you have a fuel problem! filter or fuel lines???

good luck anyway. :dang:

what the shop teacher said

It only counts if he was wearing his safety glasses.

Actually I am wearing my safety glasses