Well I just bought a 79 Bronco and now I have to decide what to do with it. All the guys I know have at least 40s on their trucks so I probably should go that big to be able to hang with them in the mud. There is one guy running 44" boggers all the way around on a 78 half ton but he has the $$$$$ axles, u-joints, etc. How much lift would I need to run 40s with some fender trimming? How long will the stock half ton diffs last? Should I just swap in 1 ton diffs and save myself a lot of hassle and expense over the long run? Or should I stick with a smaller tire and plan on being pulled out a lot?

Either way I have to buy tires and rims and probably regear. I just don't want to pour money into 1/2 ton size tires, rims, gearing, etc. just to change it all to bigger stuff a year from now...

 

If you want 40s then your gonna want to replace with 1ton axle or youll regret it in the long run.

 

The 1/2 ton axles won't like those 40s.
I have 36.8" tires on my 79, and I take it farely easy.
I wanted 38.5x15 boggers, but knew the first time I got in a bind my axle shafts, u joints, and everything else would explode.

IF you can, look into 1 ton axles front and rear, but if that is out of the question, then get chromoly axle shafts for the front and OX or CTM u joints, and put a D60 in the rear.(I'm sure you could get a D60 at a junkyard for about $20-50).

Just a suggestion, 38.5x15-15 Boggers are GREAT in the mud, and fairly cheap, but if you want alittle taller, there are 39x13.50-15 Irocs for the same price, and they're pretty good in the mud too.

Of coarse the first upgrade with have to be axle strength, then gearing. No less than 4.88, and since this will be a off road rig(I'm assuming), then why not 5.13s.
If off road only, go with a spool, or welded diff in the rear, but if you have the money go with a detroit locker.
Up front, I'm going to suggest a Aussie locker, just b/c I really like mine.

From there, the engine will be next. The 351M or 400 can be built to have some decent power, but for how easy it is to put a 460 with more power, why not.

As far as lift goes, I have a 6" lift, and clear my 36.8" tires with plenty of room for flex. I could easily fit 39.5s, but without much room for flex, so with trimming, it'd be perfect.
edit:Computor was messing up, so ignor next post

 

The 1/2 ton axles won't like those 40s.
I have 36.8" tires on my 79, and I take it farely easy.
I wanted 38.5x15 boggers, but knew the first time I got in a bind my axle shafts, u joints, and everything else would explode.

IF you can, look into 1 ton axles front and rear, but if that is out of the question, then get chromoly axle shafts for the front and OX or CTM u joints, and put a D60 in the rear.(I'm sure you could get a rear D60 at a junkyard for about $20-50).

Of coarse the first upgrade with have to be axle strength, then gearing. No less than 4.88, and since this will be a off road rig(I'm assuming), then why not 5.13s.
If off road only, go with a spool, or welded diff in the rear, but if you have the money go with a detroit locker.
Up front, I'm going to suggest a Aussie locker, just b/c I really like mine.

Just a suggestion, 38.5x15-15 Boggers are GREAT in the mud, and fairly cheap, but if you want alittle taller, there are 39x13.50-15 Irocs for the same price, and they're pretty good in the mud too.

From there, the engine will be next. The 351M or 400 that came in it, has the potential for some real power, but for how easy it is to put in a 460, why not.

As far as lift goes, I have a 6" lift and my 36.8" tires have all the room in the world to flex, and I know I could fit 39.5s, but without much flex room. If you trimmed the fenders w/ a 6" lift, then you'd have plenty of room. Depending on how much you like your fenders, you could make enough room to run 49s.
There's a guy on here running 39.5s on stock F100, and another one with 6" lift, and 44s(KO76). They don't like fenders too much though. lol

 

I was able to fit 39.5 Swampers on my F-150 with 9" of lift. They never rubbed or anything, and I did some big jumps in that thing. All I ever had in that was the stock 1/2 ton running gear and stock drivetrain and I never broke anything. You just have to know how to drive it. What I'm saying is you can't do obviously dumb stuff like lock it into 4-lo cut the wheel all the way to the side and drop the clutch in first gear and expect your u-joints to like it. Use your head. You should have alot of fun in that truck.

 

I already have a 14 bolt rear I was thinking about using and I know where there is a D60 front for around $900 so maybe I should just stick with my original plan and swap them in right away. Then I'll only be buying wheels and tires once... With fender trimming I will need 6 inches of lift then? I want to keep the CG low if possible

 

You could clear 39.5s with 6"s of lift, and alittle finder trimming.
Or you could put a 4" lift, and cut till it stops rubbing.

The 14 bolt would work fine, and a D60 front would be great, and like you said, do it right the first time, and save your self the money and trouble from haveing to did it all over again.

 

The rear fenders are rusted right out and it will be purely for trails. I don't plan on keeping the body straight.

 

In that case, put a 4" lift at the most, and just cut the heck out of the fenders.

What tires do you think you'll be going with?

 

Well my nearest wheeling buddy is running 44" boggers with a very healthy 489 BBC. Most of the other guys are running 39.5 swampers or swampers on front/boggers on rear. There is a set of 39.5 TSLs that I could get pretty cheap but they're 15" rim size. I think if I want to play with these guys at all I'll have to go 39.5 at least

 

with these tires, what are you plannin on spinnin them with?

 

Just the 351 for now then a 460 later. Regear as soon as possible. I probably won't be driving it until next summer. Do stuff as the $$ allows

 

If you put those tires on without regearing, you will be sorely disappointed. I bet you'll be turning about 1000 rpms on the highway at 65 mph.

 

I will definitely regear if I do tires that big...but I don't think I should waste time regearing the stock diffs

 

that makes me so happy to hear someone else feel that way!

$900 is a decnt deal on the front 60 and since you have a 14 bolt already you have no excuse!

just slap those axles in, get the tires and wheels you wanna run and THEN figure out how you need to clear them. heck for all you know you may just need to hack the fenders some.

-cutts-