Re-gearing

Okay here is one I have noticed alot of people talking about regearing their rigs. I have not done mine but not sure if it has been done. But I doubt it. My bronco is strictly for wheeling, however I have to do a fair amount of driving to get to where I off road. Reading one of the other threads either Bill or JSM84 suggested 4.56 gears. Would this be practical for a 40 mile drive to the mountains? I dont mind going slower than the rest of traffic, it gives people a chance to check my ride out but it seems I could use the extra punch off road with the new gears and I am looking into getting a set of 35's or maybe 37's for my ride, which means I am begging the wife with not much luck.

Okay I was reading on the net and am now more confused. What is the stock gearing for the rear diff? Is it just the ring and pinion I would be replacing? Do I need to swap out the front gears at the same time? Is randy's ring and pinion and good place to shop? And is it the higher the gear ratio the lower speed but higher torque or is the the lower ratio?

I would agree 456 with 33s would be a bit heavy but if you are thinking of bigger then I would go that route. I have concidered 456 for my 32s and I do not plan an getting any bigger but here in CO I spend most of my time trying to go slower on the trail so 456 would help alot. I also have a 5 speed so with the overdrive gearing it would only ***** me a little on the road, would make the mountain passes much nicer though.

yes 456 would be slower more power than 410. On the highway your rpm would be much higher.

Stock should be 355. Not sure on yours but on some the carrier needs to be changed to get to 456.

Yes both front and back HAVE to be done at the same time.

BTW 35 or 37 would require 4-6" of lift.

i did a monster fender trim and have plenty of clearance for the meat and with out jacking my center of gravity up too much. Thanks for the advice on the gears, but I hope I get lots of it since I value all of the guys' opinions so highly. I am basically looking for more off the line performance when I am off road I dont go fast but could use the help in torque.

If you're not sure about gears it's kind of simple but hard at the same time. If you have 3.55 gears for every 3.55 times your driveshaft turns your axles will turn once. Also a little thing people suggest around these parts are if you're going over 35" tires to upgrade your axles as well. Mainly the front TTB since it's not fond of bigger tires. There are however, people running some pretty big tires on theme with super low gears that don't seem to have much of a problem. Also, if it's maily off roading I would get lockers front and rear too. Hope this helps.

So its not just slapping in the new ring and pinion there is more to it. Which lockers are better the mechanical ones or like air lockers? So I am looking at new gears front and back possibly lockers front and back and maybe new axles front and back. Well they might just put it out of range for me for a while now we are talking a grand or so. And that is buying the cheaper gear. I was hoping for something a little cheaper. Any other suggestions would be nice.

noahsdad86 said:

Okay here is one I have noticed alot of people talking about regearing their rigs. I have not done mine but not sure if it has been done. But I doubt it. My bronco is strictly for wheeling, however I have to do a fair amount of driving to get to where I off road. Reading one of the other threads either Bill or JSM84 suggested 4.56 gears. Would this be practical for a 40 mile drive to the mountains? I dont mind going slower than the rest of traffic, it gives people a chance to check my ride out but it seems I could use the extra punch off road with the new gears and I am looking into getting a set of 35's or maybe 37's for my ride, which means I am begging the wife with not much luck.

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Ok, here's your basic rule of thumb. For 33's you can usually leave it stock but you'll notice some bog & lugging when you drive but not a whole lot. 4.10/4.11's are usually the best choice for 33's. You'll want 4.56's for anything in the 35"-37" range and when you're running 38's-40's then 4.88's start looking good and anything 44" and larger is gonna need 5.13's.

Now of course these are just ballpark numbers especially around the 37/38" range your driving style can have a lot to do with just how happy you are with the chosen gearset. Having said that, changing gears is an economically painfull upgrade so make sure you go with something that you'll like because most guys don't want to do it a second time just to finetune their choice by one notch either way.

It's not so much about being a little slower than the guy next to you at the lights, the whole idea is to get the truck back into it's powerband. When you run larger tires you really ***** up your final drive ratio. By changing the gears you restore balance to the universe and not only are you back where you're supposed to be as far as the powerband goes but you'll also get back a good chunk of the milage that you lost, so for a 40mi trip you'll appreciate having the right gears with gas being $3+ a gallon.

As far as the lockers go. The air lockers are big $$$ and if you have it to spend they're great, no doubt about that. Mechanical lockers are sturdy but in such a short wheelbase vehicle as the Bronco you'll find that they don't like to unlock very often and you're always dragging one of your rear tires thru every turn you make & this not only wears on them pretty badly but it sets up a really wierd wear pattern. I was rotating mine every month (and that was using the spare for a 5-tire rotation) and STILL burning up a set of 38's every 18 months. That gets expensive fast. Personally I prefer the mechanical limited slips. Dyneer (the Detroit Locker guys) makes a really slick one that uses helical gears instead of the usual clutch pack deal. I hate clutch L/S diffs they wera out every few years and you have to keep adding friction modifier to the pumpkin. The gear driven diffs are dead-nuts reliable and really hard to break (I've never broken one and it hasn't been for lack of trying)

For budgeting purposes you can generally figure on $1200-$1500 for each axle to change the differential & gears.

Oh yeah, depending on what gears you choose you may *have* to swap axles if it's a gearset you really want to run. Both the ring & pinion grow in size as you move up the ladder and you hit a point where the gears just won't fit into the carrier. A 9" usually tops out at 4.56's and even then you usually have to do some grinding to make them fit. I've had to clearance a couple 9's for 4.11's (usually those fit ok but some 3-members are a bit tighter than others, don't ask me why)

Well now that was a response. Thanks for the info I have been online all morning looking at parts and if it was just the gears I can get sets for about 500 bucks for front and back. If I do lockers I would probably spool the front diff for $$$ reasons and get a nice detroit for the rear. But it looks like this might wait a while I had no idea it was such a huge project. Couple more questions though, an 85 bronco has which rear end 8.8 or 9 and how many splines are the axles? And the front is a dana 44 right. Are either one running in reverse? These are all question brought up by looking up parts.

The front is reverse rotation, I hope I got that right if not I am sure to be slapped by someone here. The rear in a 85 could go either way. If you look at it from the back of the truck and see a cover with bolts around the edge it is 8.8 if you do not it is 9" Hope this helps, I have gone through this recantly want to do gears and an ARB in back but that is more than I can afford, but I also do not want to only do part of the job because the labor is the worst part and I would feel real stupid doing it twice.

Oh yea I am pretty sure they are 31 spline axles.

One route you can go if you have a decent salvage yard is the front and rear out of an older F-250 or 350 with the gas engines in them. I believe they run 4.10's stock and if you get one out of a 350 you may end up with a full floating rear axle. the f-250 would have the d44 TTB set up but with different gears. You can find out what gears a truck is running just by checking the stick on the door jamb. I know I can get any rear axle from a truck that's single wheeled for around $180 and that's taking the driveshaft off and unbolting it from the leafs so that'll include the drums, iner axleshafts, gears and carrier. Another thing if you can get your hands on a full floating rear end you'll have **** breaking it with any tire size. Full floating rear ends take the weight of the vehicle off of the axle shafts and puts it on the axle housing instead. You can identify a full floater by the axle ends, you'll be able to pull out the axleshaft without taking off the tires. They're generally 8-10 lug too. Also, on the door jamb you can tell if they're limited slip or open as well. I can't remember how but you can. Maybe someone here can tell you more about that. But if you're wanting to run big meats that may be the way to go for now. If you can weld you can get a leaf sprun strait axle for your truck too and that's not to hard to do from what I'm told. Hope this helps a bit!

OKay bidi, now explain to me the difference between my axle and a floating one? I am not following on the setup. I am going to the junk yard today after some other parts maybe i will peak around for some of the trucks you mentioned. How hard is it to just pop the cover and pull the ring and pinion. Too much work for a junk yard or is it pretty easy,

On the "average" 1/2 ton axle the weight of the vehicle actually sits directly on the axle itself therefor putting stress on the axleshaft. It's right at the end of the axle on the bearing. A full floating axle the axle itself has no weight of the vehicle on it. The axle tube holds the weight instead.

"A semi-floating axle is very common on the rear of most 4x4s. It consists of an axleshaft on each side that is splined on the inner end where it mates to the differential and has a wheel ****** where the wheel studs mount at the other end. This assembly typically mates to the end of the axlehousing using some type of ****** arrangement. The axleshaft also rides on a large roller or ball bearing out at the end of the axlehousing.

The axleshaft in a semi-floating assembly serves two purposes. First, it attaches to the wheel and is used to support the weight of the vehicle and its cargo. Second, the axleshaft must transmit the rotational torque from the differential out to the wheel.

A full-floating axle can be found on the rear of some 4x4s, but it is generally reserved for vehicles that are designed for severe duty, or are intended to carry heavy loads. This type of axle uses an axleshaft on each side that is simply splined at both ends or splined on the inner end and has a drive ****** on the outer end. The shaft mates to the differential in the same way as a semi-floater. However, the outer end of the shaft differs. Here, the splined end of the shaft slides into a locking hub or an internal splined steel drive plate that bolts to a hub cap, similar to what is found on a front axle. In some cases, the drive ****** may be part of the shaft itself. In either case, the axleshaft is allowed to float in the system.

For a full-floater system, the axleshaft only serves to transmit the rotational torque from the differential out to the wheel. It does not carry the weight of the vehicle like a semi-floater does. On a full floater, a spindle is attached to the outer end of the axlehousing. The hub's cap is attached to this spindle and rides on tapered roller bearings. It is this assembly that carries the vehicle weight. As such, a full-floating axle system is considerably stronger than an equivalently sized semi-floating system."

This is from http://www.off-roadweb.com/tech/0112or_sem...xles/index.html

If you need more information just copy and past the above URL in your URL bar. Pretty good information.

As for pulling the gearset out it's not to dificult, most axles have a "C" clip that hold them in so you have to pull off the cover and pull those out so you can pull out the axles. Then there are four bolts (two on either side) and it'll come out with a little spinning to get the gears off of the pinion gear. Now the pinion is a little different. You'll want to take the bolt off of it before doing anything else so you can use the tires to help hold it. This usually takes a helping hand or two since I believe the bolt is on somewhere around 200ftlbs or so i think. Also remember, in doing gears you have to go word for word in the instructions or your lovely new gears wont last for long. They're a bit difficult to do from my understanding since you have to have shims for the pinion and ring. Hope this helps and doesn't discurage you to doing it. Another thing to note is every axle has a different size gear that can be put in it like the biggest for an 8.8 is 4.88's I think and if you want to go lower you have to get a different axle to hold the larger ring gear and also so you don't end up with a super small pinion gear.

EDIT: If you do this at the Junkyard dont forget your 1/2" sockets and your breaker bar!

Simi Floating Axle ^



Full Floating Axle^

Maybe this will help so you can "visualize" them. If you see a full floater you can pull off the bolts to the end (not the lug nuts) and pull the axle out with the tire on and everything and the vehicle will stay there.

Thanks for the excellent information Bidi. This might be a project I save for later when I have more time, more help and more money. My father in law has been in a funk lately and has not been wanting to play 4x4s. He is depressed about his cherokee problems. I so greatly appreciate everyones help with this. Now I can say I learned something at work today.

noahsdad86 said:

Well now that was a response. Thanks for the info I have been online all morning looking at parts and if it was just the gears I can get sets for about 500 bucks for front and back. If I do lockers I would probably spool the front diff for $$$ reasons and get a nice detroit for the rear. But it looks like this might wait a while I had no idea it was such a huge project. Couple more questions though, an 85 bronco has which rear end 8.8 or 9 and how many splines are the axles? And the front is a dana 44 right. Are either one running in reverse? These are all question brought up by looking up parts.

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Like the man said, an 85' can have either. Take a look at it, if it's a one-piece axle with just a removable cover on the *back* of the axle it's an 8.8" if the bolts are on the front then you have the 9" where the entire carrier can be removed. Just a quick note here, if you *do* have a 9" you can save a few bux by picking up a spare chuck (center section) from a junkyard. Bring the carrier to whoever sets up your gears and have them install the gears & diff in the spare carrier & then bring it home and swap carriers in the driveway. You'll need a slide-hammer & a Saturday afternoon but it'll save you probably half of what the complete job would cost at a shop. But I believe it'll be an 8.8", I'm pretty sure 84' was the last year Ford put the 9" in Broncos and 96" was the last year it was in pickups but with assembly lines being what they are I'm quite sure there are more than a couple 85 Bronco's out there with the 9". If it's an early build-date they you might just have one or if you've got a 351 instead of the 302. They got real quirky about this stuff, trying to remember it all makes me want to reach for a beer.

Yup, you've got a Dana44IFS front end, and yes I believe it's a reverse rotation

Great responses guys!!! I'm going to pin this topics, since it's a common question asked. Remember that when you re-gear, it's a good idea to get a master install kit with new bearings & seals. And the split for needing a new carrier in the front axle is 3.92:1 & up. JSM84

Since this topic is now "pinned", I'll add this link to a really good gear ratio "calculator". The author has really done his homework on this one. The calculator allows you to experiment with different ratios and transfer/transmission combos. He has it set up with drop down menus that allow you to select practically any transfer case, transmission, and ring/pinion setup and then see what your engine RPMs will be at various road speeds. If your equipment is not listed, it also has the option to manualy enter values.

Grimm Jeeper Gear Ratio Calculator

Yeah, it's a jeep site. But they really did their homework made it usefull to anyone, not just jeepers.

One last thing i just remembered. As an alternative to regearing both of the axles you can now get a diffrently greared planetary gearset for most transmissions. This will allow you to change the final drive ratio *at the transmission* instead of regearing both axles. It's a bit more of a kick-in-the-pants when you change gears but hey, for the $2K you could save it's worth considering if you need to rebuild your tranny *anyways*

Just a thought.