Longbeach4x4

I bought a 1991 f150 xlt lariat that already had a lot done, Dana 44 up front, quad shock system (not sure if factory or aftermarket I know that came stock on some broncos) diff Locker on the 8.8 in the back, 4 inch suspension lift in front 3.5 in back, warn front bumper and ix9000 winch. Its 351w 5.8 V8 efi 4x4 e4od (last month got a remanufactured preformamce e4od from xtreme preformamce I blew mine but it was beat to hell when I got it) and 33x12.5x15 k02


the tag on my rear diff cover says 3.08 but I'm running 33s is there anyway to tell if when the previous owner regeared when adding the locker? I woulda..might as well you're already in there? Wondering if there's any way to tell how it's geared 3.08 (doubt it but who knows) 3.55? 4.10? 4.56??


Also might explain why speedo off? I know I have the yellow drive and driven gears in the tail shaft of the bw1356 (xtreme performance also sells a gear driven bw1356 that I'll be getting when I get my core for the blown e4od) but I figure no point to start changing those until I know for sure how the rear end it geared?

tried to do the math

(#drive gear teeth) x (axle ratio) x (revolutions per mile) / 1000

but without knowing for sure what the axle ratio is in kinda in a pickle

BLDTruth

Well the easy way to tell your gear ratio would be to see how many turns of your driveshaft it takes to get one revolution of the wheel - you would have to jack up the rear and index the driveshaft and the wheel for reference. The other would be to pull the cover on the rear diff and count the amount of teeth on the ring and divide by the number of teeth on the pinion.

Since it is a new to you truck, I would make sure the front and rear gears are the same before throwing it in 4x4.

Longbeach4x4

Sweet I hit a rock and put a mast dent in the stock 8.8 cover and curled up the bottom so now it drips I ordered one from ruff stuff should be here tomorrow sense I gotta take off the diff cover anyways count the teeth it is lol also I know it's not Ls so I know I don't need the additive but I have some synthetic 75w-140 that I got from my pops, he's been a mechanic sense before I was born he says it should be good but he also tried to tell me to put 0w-20 in my 91 f150 so I'm 50/50 on advice from him I know it calls for 80w-90 but the back of the synthetic MOC 75w-140 says it's a auricle replacement for 80w-90 and some others rather take a trip to auto zone and my some than put something sub par on my rear end and hurt something

ALTAJAVA

The rotate the tire and count driveshaft rotations is the easiest way, it is exceedingly difficult to count pinion teach with the carrier in the axle

Chris_1

iTrader: (1)

One revolution of both rear wheels. If only one wheel turns you have to do two revolutions.