New Bronco

[jwbronco]

I'm buying a bronco which will need to be rebuilt. My goal is to run 37" tires but I'm curious is it really worth it to upgrade the 44 and 9" or would I just be better off doing a 60hp up front and 14 bolt/sterling in the rear and just be done with it? I'd just like to know the breaking limit of the 44 up front because obviously you can take the 9 a long ways.

 

[DirtDonk]

What gearing are you planning to run with the 37's, do you think you'll ever go bigger, and how do you drive it?

Paul

 

[jwbronco]

I'm thinking that 4.88 or 5.13 but leaning towards 5.13. I was going to do a ZF5 but now after doing research I think I'm going to go with a 4R70W with a few upgrades. I'm also thinking that I might just get a 3spd Stak for transfercase and not deal with rebuilding the stock T shift. I already have a engine that I built for my 94 Lightning that I'll rebuild and it was putting out ~380hp and ~450trq and that should get it moving pretty good.

I always want to make sure that I have room to grow but I honestly don't see myself going much bigger then 37's

 

[Apogee]

Just my $.02, but I'd run RCV axles up front, 31-spline alloys in the rear (or 35's if you feel so inclined) with a nodular center section and you should be good to go. A lot of people I'm sure will say that the 1-tons are the way to go, but if you're trying to keep your weight down, you can make the D44 and 9" take a lot of abuse if built right. That's how I'm building mine at the moment...not to say 1-tons might not be in my future, just not right now. I'd like to keep my rig as light as possible so long as it still holds up with what I do with it.

If you see 40" or larger tires and rocks in your future, go D60 now and save yourself some cash. I see you're in Florida...so where do you wheel? If it's mud only, that takes a lot of stress off the drivetrain as compared to rocks.

 

[jwbronco]

I'm in the military and I'm trying to get stationed in Colorado. I'm not a big mud guy, I like technical trails. I sure wish Tellico was still open, I was up there in 2003.

 

[DirtDonk]

I don't like the 5.13 in a 44 and that size tire. The pinion is getting small enough even at the 4.88 level. That's one of the main issues that pushes people to the larger differentials anyway. Along with smaller axle shafts, the pinion gears just keep getting smaller and smaller until.... PING!!!
Not a good sound to hear on the trail.

Never happened to me, but have seen and heard of it plenty.

Paul

 

[TN1776]

I have 37" tires on my Bronco - two seasons of rock crawling and no problems yet. I have a 9" axle in the rear with 31 spline chromoly shafts. Up front I have a Dana 44 with chromoly shafts and CTM u-joints. I've got 4.11 gears front and rear, an NP435 and stock T-shift D20. My final crawl ratio is just under 70:1, and having just completed the Rubicon trail, its plenty slow. The only times I found myself wanting lower gears was in a few very steep, technical downhill descents. Uphill, crawling through rock gardens, traversing the slabs, etc.. no problem. I do run a very heavy flywheel behind my (carb'd) 351w. The engine will lug way down, even as low as 250rpms and just keep going.

I am sure if I was hard on the throttle and got into lots of situations where I'm subjecting the drivetrain to shock loading (hopping, etc), I might have problems... but for my driving style, I have not had any issues where the drivetrain didn't hold up.

Maybe its the low end torque my engine produces, but on-road driveability is no problem with 4.11 gears. My Bronco actually gets up and moves pretty well from a dead stop, even with the 37s. I wouldn't actually want lower axle gears - I can cruise all day long at 65mph spinning 2500 RPMs. If/when I go with lower gears, they will be in the transfer case.

 

[Broncobowsher]

Lots of power from a built 351, lots of gear including a Stak, starting with tall tires and that generally leads to even taller tires later, nothing invested into the D44 already (if you even have one?), techinical trails...

Just start with the D60.

You are questioning if you can build the 44 to be strong enough. You probably could, but you will always be questioning if you did. You know you can build the 60 strong enough. The question is do you do a 5-lug conversion to the front or do 8-lug conversion for the rear?

 

[jwbronco]

Well I would just use a 8 lug setup if I did a 60. I haven't spent a penny in the stock axles and I just wanted to hear that it really would be a waste to spend money on them. I just need to figure out the right width now. I've been thinking that 63-65" wms-wms would be a nice width and be big enough to grow into. I always like to have more back spacing to eliminate some of the scrub from big tires with little back spacing. I've been thinking that a 14 bolt or dana 70 would be the best rear axle.

 

[mavereq]

i think that most one tons are 67" but i'm not positive on that.

and i'm too lazy to look it up.