ive been planning a ring and pinion swap on my truck for the past few months. its a 97 old body f350. got a dana 60 up front and a sterling 10.25 out back. im running 38's on it now, but i plan on going to 44's EVENTUALLY. its got the stock 4.10's in it right now, and the thing is a dog. once you get it off the line, it rols pretty well, but accelerating from a stop and trying to downshift an auto tranny to pass or something is a pain in the ***. at first i was thinking about going up to a 5.13 ratio. ive been told that they will be a good match for the 38's. ive been thinking alot more about it lately and im thinking that maybe i should jsut save myself the trouble, and go right to the 5.38's in preparation for the 44's.

my motor is a basically stock 351w. i mean i have an intake and a dual exhaust, but nothing extremely serious. im thinking that the 5.38's will give me a big advantage in torque where my motor lacks. sometimes i have trouble spinning the tires in the mud, and i feel like im having to attack obstacles with alot more speed than id like. i got no crawl. i also drive it on the street alot and i find myself often on highways doing like 70. my rpms stay around 1200 in 4th gear and get up to like high 2's when i grab 3rd to accelerate. the engine does fine at higher rpms, but i dont want to scream the hell out of it and damage it if i get a taller gear.

sorry for the long post, but i want opinions on wether or not i should match 38" tires with 5.38 gears. are the gears gonna be too tall and make me scream my engine alot on highway? i know ill eventually get to 44" tires, but its maybe a year down the road. should i get the 5.38's now, or jsut 5.13's? help me out, cause im kinda confused. thanks alot

 

Tough decision, but if you know you are going to run a 44 inch tire, I would not hesitate to install the 5.38's. The litttle engine will really appreciate it, and this gear is not so low, that you can't run them with the 38's. Matter of fact you and the 351 might like the ratio so much that when you do go to the 44's you might be a little disappointed by the lack of acceleration, But I believe that the 5.13 is just not enough for a 44 inch tire and the 351, and the 5.38 will be better in the long run.

 

How does 4lo do off road? It should be able to pull the tires and make up for the
axle gearing!! I would wait until you got the 44 for the gear change unless you like
high rpm clatter, Something fun to mess with gear calc. http://members.optusnet.com.au/~zerosin/gearcalc.html

 

I'm running 4.88s with 44s and a 400/4speed. I don't know what rpm I'm running on the highway but it pulls along ok at 70mph. It spins all 4 pretty good in the mud in 4lo, basically revving as high as you would want. Wheelspeed is important too in the mud to clear your tires so you have to be careful not to gear too low.