JeepCoMJ

So along with my other extreme list of mods to the truck, I just bought a xj 44 rear with 4.88's, welded, disc conversion, and matching 4.88 gears for the front with setup/install kit. this is all new with zero miles

anyways,

The truck is an 87 swb with dana 44 rear and 4.10 gears, and 33" tires...but they're bald and need replacing by spring. I'm running 6.5" of lift on shortarms, and am not into trimming excessively. power is no problem...It's mid-HO conversion with a punched 4.0 with borla, 62mm TB, 2k intake, etc.

what size tires do I need in order to run decent RPM at 65 mph? I don't mind if it's 2700 or 2800 rpm, but as it is with 33's and 4.88's I think I'd be somewhere around 4000...and that's no good. the truck won't be driven on the interstate regularly, but if I don't have a tow rig/trailer, I still need to get the 4 hours to McCaslin, Rib Lake, or Attica.
similarly, what size tires do you think I can fit in there? I'm thinking I should longarm it and lift it another couple of inches... as I say, I don't want to trim up the body...at least not the bed. front fenders I could care less about. the inner fenders will be trimmed for clearance too.

also, I'm keeping the dana 30 front, unless I can sell the gears and get a waggy 44 front or something along those lines, shorten it, and regear it. does anyone have full info on what needs to be done regarding shortening the axle? I don't need specs or anything on mounting it...that's easy. but, turning and shortening then getting the right shafts made, and if the hubs can be altered to be a 5 on 4.5 bolt pattern.

Thanks,

Pat

COSXJFAN

I have 4.88s and run 33" tires and at 65 I'm at about 2600 RPMs. I have an AW-4 auto tranny. HTH!!

JeepCoMJ

huh. that seems to be the consensus. I also have an aw4.

maybe I don't mind this upgrade at all I'm basing my highway experiences on a truck with 21 year old engine that sat for 10 years...it's tired as hell, so it took more to get it up to RPM's.

what kind of gas mileage do you get?

COSXJFAN

On the hwy I get anywhere from 12 to 16 mpg, depending on the conditions. I live at 6,000' elevation, and my trails are from there to 12,000', so I don't get as good as someone at a lower elevation would. I love the power in 4-low, it is worth the higher revs to me. HTH!!

JeepCoMJ

hopefully I'm not gonna get that bad of gas mileage...

your local mileage is higher, yes?

I'm also at a lower altitude so that should help, and I have a high altitude CPS that I will be installing to adjust timing.

SeriousOffroad

Here's the links I used when I built my axle.
http://www.trailhed.com/d44.html
http://77cj.littlekeylime.com/Dana44_2.htm

Knowing the caster angle on a stock Dana30 is important too. You'll need to set your narrowed axle's pinion at the correct angle and still maintain the proper caster otherwise your steering won't return to center.
Prefered is 7.0 Deg
Range is 5.25 to 8.5 Deg
Max left/right difference is 1.25 Deg.


Best Gear Ratio Calculator Ever!!
http://www.grimmjeeper.com/gears.html

JeepCoMJ

thanks for the calculator...I figured out what I needed to know.

upping to 34" tires and adding 1" front lift and swapping to 4wd rear springs maybe with 1" shackle