Axle gearing for the trail

[NCFJ]

Axle Gearing for the trail

I have a 82 FJ60, stock running gear, desmog, troholl carb, Heavy OME lift,KM2 33s, working on bumpers and sliders.

I am setting up to do the axles at some point in the next few months, translates to when I have the cash to do it all at once. This will be primarily a trail rig. It will be trailered. We’ll drive it around town here at home and when on the road wheeling but no real highway time.

I am running 33s thinking max at 35s. I want to gear it pretty low. I am thinking minimum 4.88 gears . I would really prefer not to put a crawl box in this rig if I don’t have to. So the lower I can get the axles the closer to not having to buy a crawl box I am.

Anyone doing similar?

 

[slacker24-7]

I know ya have a pretty good plan, but my experience with trailered trail rigs is that you will soon out grow that plan, 35's probably wont keep ya happy long and neither will just 4.88's alone , you may be more disiplined than me, but i would need (want) a deeper crawl ratio than ya can get with diff gears alone, I have built alot of rigs and turned around and had to change out what i had done when i found it wouldnt do what i wanted it to, but luckily had pretty good luck selling parts.. the more ya wheel it the more ya will push the envelope , then ya have longs to buy $$ if the front is gonna live with a locker, etc...etc...etc..
of course they all cost $$ but there are alot of gearing options out there crawl boxes, tranny swaps etc.. i dont know that iwould go any deeper than 4.88's with the cruiser diffs...ya might take a look at where ya want it to be in 5 years then build towards that.

 

[GeologistFelix]

On 33" tires and 4.88 gears, you'll be running around 3000 rpms at 60mph. From what I understand, the 2F doesn't really like that, but if you aren't going to be on the highway for more than like fifteen minutes at a time, that would probably be ok. Even more so if you're willing to do 55 on the highway; that works out to around 2750 rpms.

4.56 gears would get you more like 2800 rpms.

Another thing to consider is the H41 transmission, which should just bolt in, and runs a whole lot cheaper than an H55. It has around a 4.9:1 first gear, and somewhat wider gear spacings than your stock H42.

H42 + 4.88 gears = 39.5:1 crawl ratio, 3000 rpms

H41 + 4.56 gears = 51:1 crawl ratio, 2800 rpms

H41 + 4.88 gears = 54.5:1 crawl ratio

The H41 goes for around $800 if you get it from SOR used; I'm sure they can be found for cheaper elsewhere though.

 

[NCFJ]

Good advice, thank you.

I should mention that this rig will be joined by a truggy that is under construction. I do plan on building out the axles and steering, perhaps even link the suspension one day. But 35s are about it. The truggy will be the hard core rig and the 60 will see lighter duty and something to head into town with when out wheeling. Trailering works for us, takes away the worry of making it home when you are out on the trail.

 

[NCFJ]

On 33" tires and 4.88 gears, you'll be running around 3000 rpms at 60mph. From what I understand, the 2F doesn't really like that, but if you aren't going to be on the highway for more than like fifteen minutes at a time, that would probably be ok. Even more so if you're willing to do 55 on the highway; that works out to around 2750 rpms.

4.56 gears would get you more like 2800 rpms.

Another thing to consider is the H41 transmission, which should just bolt in, and runs a whole lot cheaper than an H55. It has around a 4.9:1 first gear, and somewhat wider gear spacings than your stock H42.

H42 + 4.88 gears = 39.5:1 crawl ratio, 3000 rpms

H41 + 4.56 gears = 51:1 crawl ratio, 2800 rpms

H41 + 4.88 gears = 54.5:1 crawl ratio

The H41 goes for around $800 if you get it from SOR used; I'm sure they can be found for cheaper elsewhere though.

Thank you for the information. I like the deeper ratio of the H41. I plan to replace clutch next winter just because, may be the perfect time to swap out the trans.

Around here the fastest it will go, doing the speed limit is 50 MPH. Same applies in the local towns where we go to wheel. This is the rig my wife and her girlfriends can jump in and go to town if they want but can still hold it's own on class 3 & 4 trails. So the H41 with 4.88 gears looks pretty good.

 

[Kynot62]

If this thing ever hits the highway you might think about taller gears or an H55. I am running 33 KM2's with 4.88's behind an H55 and a 3B and while off road it's just about perfect on the road (even your occasional use) leaves a whole lot to be desired.

Lots of options all of them have their good and bad points, none of them are cheap unfortunately....

Must be a heck of a trailer that you can bring two rigs to wheel.. But why wouldn't someone just drive the tow rig if a run to town is needed?

Tony

 

[NCFJ]

It is also a business thing. I run a small fab shop, so having a couple different rigs with us when we go wheeling is the plan. Our rigs are also part of the business. The other idea is also to have something for my wife to drive on the trail that is user friendly. She is wanting an 80 bad for herself, but for now the 60 will have to do.

No, nothing is cheap for sure. Between the 60 and the truggy I am looking at around $6K in axle upgrades. Fortunately I'll be building my own bumpers sliders cage and armor so there is only the steel to factor in there. The truggy will sit untouched until the 60 is trail worthy. We'll probably run it unlocked a time or two until I have the cash to do both axles. That's the thing with axles, unless you enjoy taking them apart and putting them back together, doing everything at once cuts down on the overall labor.

 

[kling-on]

I DD my 60 with 456's and 33 it's was ok on the street and great on the trail... Till I found out about a doubler So if your keeping 33 I'd go with 456, 35's 4.88 if it's a trail only I guess 33's and 488 will make you lift it faster

 

[GeologistFelix]

If you're only ever doing 50-55ish at most, 4.88 and 33s will be fine, I think. 50mph puts you at about 2450 rpms, which is kinda high for that low speed, but it's not going to hurt the 2F in the least. Just your mpgs, but I get the sense they're not a concern for this build.

 

[NocalFJ60]

This might help:

https://forum.ih8mud.com/60-series-wagons/240513-gear-calculator-microsoft-excel-download.html

 

[slacker24-7]

Thank you for the information. I like the deeper ratio of the H41. I plan to replace clutch next winter just because, may be the perfect time to swap out the trans.

Around here the fastest it will go, doing the speed limit is 50 MPH. Same applies in the local towns where we go to wheel. This is the rig my wife and her girlfriends can jump in and go to town if they want but can still hold it's own on class 3 & 4 trails. So the H41 with 4.88 gears looks pretty good.

i ran that combo in a 40 on 36's for several years it worked pretty nice.. you having a truggy will really cut down on ya wanting to build the 60 bigger.. kinda my thinkin as well (see sig)

 

[NCFJ]

Yes, I looked at your sig, you are on the same program. A HUGE pllus is that my wife likes the 60 a lot. I have had here driving it twice here on the property and nothing but big smiles. She told me today that she'll drive the 60 on the trail, not worried about hurting it. She told me that when we take the truggy out she will follow in the 60 with tools and trail spares to keep the weight off the truggy. I think I have created a monster.

You hit the nail on the head with not wanting to build the 60 bigger. We are looking for a good clean reliable rig that will always be there when we need it. It will also be one of the "rescue" rigs for our little trail group. More gear and capable of winching from front or rear. I am happy it is running reliable now. I can move my concern on to the rest of the drive train and getting some bumpers on it.

 

[Kynot62]

You will find it's not very practical to put 35's on a spring under 60. 33's are about max with the OME's. And don't think you can't wheel a wagon on 33's. We took two of them to Rubicon last August. Odd thing was I didn't put a scratch on my skidplate but I can't say the same for my sliders.

A little more winching with 33's but that's what I have the winch for...

Added benefit to keeping the wagon spring under is there is less temptation to go bigger

Tony

 

[Cruiserdrew]

Forget differential gearing to get you what you want. You won't be low enough. Gear to match tire size. That's it. 33s would call for 4.11 gearing. You want to run 35s-37s go to 4.88. For your described uses, I would build it to run 35s.

Best bang for the buck would be an SM465 mated to your split case. That adapter is available. To mate the 465 to your motor-all you need is a 3 speed bellhousing, a Chevy clutch disc and a few parts.

The SM465 gives you a very low first gear, a markedly improved crawl ratio, are cheap, and available everywhere. I was given one and bought another for $100-that gives you an idea of cost for one of the best offroad transmissions ever made. The adapter will cost more than the tranny.

In the future if you really like wheeling the truck, the addition of some of those 4:1 split case gears from Georg and AA and you are in super crawl territory without breaking the bank.

I might have different advice if you didn't plan to trailer it, but the SM465 is a beast of a transmission with a 6.5:1 low gear (factory is 3.5:1). It's a little clunky on the street, but so what. I have driven an SM420 (the older clunkier brother of the 465) for 10 years and it's solid. You do have to get used to the unsyncronized first gear, but that takes about 5 minutes, and you're set.

H41 is also a solid choice, but the first is not as low (4.9:1), and its significantly more $$. Still, it's a good choice.

Don't forget it is also possible to use your existing transmission and a 203 doubler. They are cheap and available. The adapter is expensive but not bad in the scheme of things.

If you have a bunch of money to sink into it, you would love a Toybox, but that's a lot more coin and mods.

No way I'd put an H55 in a trail rig. It's a great tranny, but it isn't needed.


edit: Last bit of advice---skip all of this, and get your wife an 80. Trust me on this.

 

[Kurtis]

Kling-on. What rpms do you turn at 80mph with your 5.3 4l60e and 4:56 gears?
I'm debating hard on just swapping in 4:11 diffs or going up to 4:56. I'm running the 4l60e as well. The auto 35s and 3.73s does fine on any of the off roading I do, I just want it to be in a little friendlier rpm range towing 5-6k. I don't rock crawl much, I mainly like having a vehicle that can get my other toys out if I blow up a bike or roast a trans in my rail.