Mild Wheeler Rear Axle options

[RamJetFSJ]

Im building a mild wheeler, more of a expedition/camping rig, than a wheeler, but I want the rear to be pretty bullet proof, so I dont get stranded by it, or have wheel part ways with the rest of the rig cruising down the freeway.

What I have so far. Ram Jet 350 crate motor. 400 ft lbs of torque. Stock AMC 20 rear. 32" mud tires.

What I will have. 4.10 or 4.56 gears. Some sort of locker or helical limited slip. A lot of weight of camping gear, possibly a roof top tent. Probably some towing, but sub 3000 lb range.

So Im having a really hard time deciding which direction to go. Ive thought of everything from just upgrading the shafts in the 20, to cab & chassis 14 bolts. I want strength, but I dont want massive axles with no ground clearance. I have been toying with converting to wide track which would mean 35" tires, but more than likely, Ill stay narrow and have a max of 33" tires.

So my basic options:

AMC 20 with gears/LS/locker
AMC 20 with gears/locker/upgraded shafts
AMC 20 with same + Mitchell Differential full floater kit

Pros of these. Keep NT stance, no body work. Keep 6 lug. Cons. full floater is expensive! Might not be strong enough w/o full floater.

Dana 60. Out of what? Would have to be custom to keep NT width. WT width would be possible if using a J20 or similar. Should be strong enough. Cons, would require finding a WT front 44 8 lug. Would require making the Wag a WT (not easy w/ rear doors).

Cab & Chassis 14 bolt. About the same width as WT axles. Same Cons as above D60. Definitely strong enough. Loss of massive amounts of ground clearance + added weight.

Other options? Maybe getting luck and coming across a Ford 9" already built and the right width on Pirate4x4? Not sure what else to look for....

Now heres the real kicker. Id really like to keep the stock waggy coffin gas tank, so the rear end would need to clear that. I have a rear mounted gas tank going in, but I want to keep the option of a massive amount of fuel for longer trips. Anybody know if a J20 rear D60 will clear a coffin tank with only 4" of lift?

I need some insight from the pros on which direction I should go in...

[RamJetFSJ]

Parallel question, but has anyone see something similar to the TABOR Plate for AMC 20s?
http://www.betterscoutparts.com/Page_1.html

[Stuka]

The M23 could certainly be made strong enough to do what you want. I would suggest Chromo shafts, give it a basic truss (Keep tubes from spinning), and a selectable locker, or LSD. A auto locker plus lots of weight in back not only make daily driving a pain, but will kill shafts (they end up twisting the splines over time). You have to get in the habit of keeping the front tires straight when starting from a stop. Otherwise you have to slip that inner tire to start moving. I have had detroits in both of my FSJ's, so speaking from experience.

For other options, a C&C 14FF does have a narrower WMS, but the drums end up sticking way inboard. Disc brakes may work though. GM's had very narrow spring perches, narrower than a wagoneers as I recall. So clearance may still be an issue, just in a different manner. And once you trim the bottom lip off the diff (20 mins with a sawzall), you don't lose much clearance.

A J20 rear axle is wider than a WT D44, fender cutting and/or flares is a must.

Not sure you will find a 9" that is the right width. You may be able to find one that was setup for coils with a TJ, they are the same width as a NT waggy. But most things are narrower (CJ/YJ) or wider (Full size anything).

Since you have a 80+ most any centered axle *should* clear your tank. 70's rigs its another story. Although the deeper pinion of a 14 bolt may not clear without enough lift.

So... I guess it comes down to what you want to spend and what you want to spend it on.

[RamJetFSJ]

So... I guess it comes down to what you want to spend and what you want to spend it on.

Thanks Stuka. Yep, that right there is my problem. I don't want to do it twice, and don't really want to start another big project. I have a line on a AMC 20 w/ 4.10s and a Truetrac for $250. I would want to at-least do upgraded axles on it, so I may go that route now. Im just very cautious as I dont want to dump a bunch of money into a 20 just to dump it an go to something completely different...

[AwesomeJ10]

Im just very cautious as I dont want to dump a bunch of money into a 20 just to dump it an go to something completely different...

Well then I think the choice is obvious.

D60 or 14 bolt rear. D44 or D60 front.

Of course you will then need to go back to some stock spring with SOA and buy some 8 lug wheels/tires. Lot's of $$$

You can fab your own D44 FF like redone is currently working on too...


EDIT: the reason I always encourage people to go with FF is because our stock SF axle will leave you 100% stranded when they break. (sure, there are 'methods' to limping along real slow). If they break on the HWY (which they are known to do), it can be a disaster because the rear tire will go flying down the hwy and you will lose control. There is no disadvantage to going FF except the cost. If you are concerned about width, get some cheap H2 wheels that suck the tires inside.

[RamJetFSJ]

Totally agree the FF is very important. The biggest issue is this is not a full blown, full width 1 ton type of vehicle. I think the AMC 20 is strong enough for what Ill be doing, but I am very worried about the SF state of it. Believe me, if there was a proven FF conversion for this axle, Id do it in a minute. I have found one company that will do it, but Im not sure how proven the design is. Nice thing is, it will keep the stock width, keep the 6 bolt wheel, and make the upgrade pretty painless. Im really leaning this way, as I really dont think a huge rear axle is needed for this build.

http://mitchelldifferential.com/full-fl ... rsion-kit/

[Stuka]

Have you called warn to see if their CJ M20 hubs will work on an FSJ M23 housing? You would need different shafts due to width, but the hubs may work fine? Only thing is they would be 5x5.5, which you can convert your front D44 too.

[RamJetFSJ]

Have you called warn to see if their CJ M20 hubs will work on an FSJ M23 housing? You would need different shafts due to width, but the hubs may work fine? Only thing is they would be 5x5.5, which you can convert your front D44 too.

I believe Warn no longer makes that conversion.

[Stuka]

Have you called warn to see if their CJ M20 hubs will work on an FSJ M23 housing? You would need different shafts due to width, but the hubs may work fine? Only thing is they would be 5x5.5, which you can convert your front D44 too.

I believe Warn no longer makes that conversion.

yeah just checked, Warn discontinued all their FF kits.

[RamJetFSJ]

I had been looking for a used Warn kit, thats how I started searching for full floaters and came across the Mitchell Diff one.

[Stuka]

You could always get a 74-79 J20 D60, and have the long side shortened. Would make the rear dif centered(ish), and be the right width. Not sure on the cost of shortening these days.

[RamJetFSJ]

You could always get a 74-79 J20 D60, and have the long side shortened. Would make the rear dif centered(ish), and be the right width. Not sure on the cost of shortening these days.

Thats a viable option.

Back to the 20 (M23).. How much stronger are the 4130 axles. Could I be pretty safe with them and often bearing replacement/repacking?

Im pretty confident in the pumpkin and the rest of the housing (once the tubes are welded and its trussed), so I think that will be my best bet for now, I just have to decide if drop in upgrade axles will suffice, or if I should spend the money now on FF...

(Parallel question. Can the housing be welded/trussed with the gears/axles/dif assembled, or should it be bare?)

[shimniok]

Get a strong cover. That's the only thing I've broken on my rear axle running up to 8-rated trails, though with a less torquey 360 and auto trans. I dropped my AMC rear on a rock, bent in the diff cover like it was tin foil, leaked all over. I since got a used Crane diff cover. Shouldn't happen ever again. I had my tubes stitch welded to the center, otherwise all stock. You might be able to find thicker tubes.

[Stuka]

I think you will be ok with it. It's stronger than a GM 10 bolt, and they put those behind their current V8's.

I would sway away from an auto locker though. Stick with selectable or an LSD.

As long as you keep an eye on your bearings, I think you will be fine. Especially with your tire size.


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[The PIG Smith]

Heavy duty ford 8.8 housing, spool, 35 spline, BIG disc brakes and calipers, girdle, etc. It's got 4.10 gears right now but I'll be switching to 3.31 before it hits the road again.

Greg had a Ford 8.8 in his Wagoneer that he drag races.
I've seen this axle and it is tough as they come....it has to be the way Greg uses it.

He is now building a killer Cherokee that will sporting an engine that will produce four digit horsepower.
This wicked Cherokee now uses that Ford 8.8 axle.

My advice would be to seek out a Ford 8.8.
It would be MUCH easier to adapt to your FSJ, then cutting down some FF axle.
They are close to the same width as your Wagoneer M23 and have 6 on 5.5 bolt pattern.
Also, most of these 8.8 units come with rear disc brakes and it would not hard to find one with some sort LSD.
Can you say BONUS?

[Stuka]

8.8's don't have 6x5.5 stock, he has custom shafts to get the 6 lug. The 8.8 that is the right width is 5x4.5.


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[jaber]

So... I guess it comes down to what you want to spend and what you want to spend it on.

Thanks Stuka. Yep, that right there is my problem. I don't want to do it twice, and don't really want to start another big project. I have a line on a AMC 20 w/ 4.10s and a Truetrac for $250. I would want to at-least do upgraded axles on it, so I may go that route now. Im just very cautious as I dont want to dump a bunch of money into a 20 just to dump it an go to something completely different...

If it just the axles walking out of the housing you are worried about, doing a disc conversion is a simple way to keep them in the tubes.

[The PIG Smith]

8.8's don't have 6x5.5 stock, he has custom shafts to get the 6 lug. The 8.8 that is the right width is 5x4.5.

I think you are correct.
But even with custom Chrome Moly Axles that has the 6x5.5, factory rear disc brakes, possible LSD, my opinion this would be one tough axle.

[carnuck]

Check the full size vans for D60 rears.

[csuengr]

I have been using a GW rear D44 in my CJ for six years. 35" tires, ARB, and 4.10 gears, powered by a LT1, TF727 and NP231/D300. I have been rock crawling as well as easy trips and all day trips that covered 300 miles. Never had any issues. I still have the stock covers because I don't drive by braille.