Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
60 mph is 1900. 75 mph is 2600-2700. I have a 5.3 with a cam that likes 2000 + thou4.56 isn't too much for that small a tire? That's what size I'm running and I was looking at getting 4.11's soon.
So after awhile of driving my truck and noticing it doesn’t quite have the “oomph” off the line I was expecting (it’s a 355 with heads cam and intake) I did some investigating and found that have 3.08 rear gears, which I thought was very odd considering that the truck originally had a 4.3 in it and must have been apalling off the line. The truck still does just fine, I would just like some more punch. So I’m considering switching to 3.42’s to get a little more down low and still not be screaming on the highway at 60 miles an hour lol. I’m running 275/60r15 tires on a 10 bolt 8.5 inch rear end.
So with all that being said, here comes the tsunami of questions...
Has anyone done this or a similar swap? If so, what results did you see? Will I need to set pinion depth with the new gears or not? If I do need to set it I suppose getting the master bearing kit is the way to go? And finally, is it worth it to throw an LSD in while I’m in there? I’ve heard tru tracs are the way to go. What do y’all think?
Swapped out my 3.08s to 3.42s when I rebuilt the rear of my 90 c1500. 350, auto, 235 tires. Made it far more drivable, pulled a trailer better (5k lbsish), and keeps a happy rpms at 75 unloaded in od. Gears are the best mod for these trucks. No supplement for mechanical advantage. If you want a tire burner id go at least 3.73 with reasonably sized tires. But 3.42 is a good size for a wake up in a truck that needs to go freeway speeds and still do work.
Ya, 275 tires i don't think I'd go smaller than 3.73. Your mileage will more likely increase than decrease.This is my main focus really, living in San Antonio if I’m going anywhere it’s on the freeway. But it’s sounding like 3.73s will do just fine for that? I’m definetly not opposed to making a little smoke once in awhile (it oughta shut my Ford friends up pretty quick lol). I’m getting 12.5 mpg as it sits and would love if it stayed there and not get worse. But it’s a truck, and a fun truck at that. I always say “if I wanted fuel economy, I’d buy a corolla” so it’s not the end of the world if fuel economy suffers a little in the name of horsepower and fun.
Well shoot. It sounds like I’ll be getting 3.73s and a tru trac then! I can certainly tell the truck lugs a bit up hills in overdrive on the highway, and around the city in stop and go those gears will definetly help. And also the yippee-yahoo factor is a major consideration lol.