Rear axle and 258 upgrades

beachbuggy · #1 (**permalink**) 02-19-2006, 10:58 AM

Hi y'all,

I'm new to this website and impressed with all of the knowledgeable Jeeper's here. I hope I can tap into some of this experience for upgrade suggestions on my Jeep. I have an '82 CJ-8 that I've had for a little over a year.

I'm about to undertake 2 main projects.

First, I'm going to pull the 258 this week for a rebuild. I want to get the most out of this engine that I can, without spending a ton of money.

Here's my plan:
- Keep the Weber 32/36 I have on it. I've already trashed the Carter BBD.
- port and polish the stock intake
- add an exhaust header and all new exhaust
- do the TDI or HEI ignition upgrade
- install a slightly more aggressive cam (?)
- oversize bore the cylinders (?)

I would like to hear your suggestions. It's warm weather daily driver that hits the beach and a few mud holes occasionally but doesn't see any hard 4x4'ing. No rocks to crawl here at the beach. (The jetty at the inlet is tempting though.)

The second thing is that the rear AMC 20 open face is whining pretty loud when running at speed on the highway and I can't take it anymore.

I want to upgrade to at least a limited slip rear end. And since I'm going to move up from 31" to 33" tires I would like to get away from 3.31 rear dif gears to something more in the 4.10 range.

I don't want to pay a shop $900 to rebuild it and from all of the reading I've done I don't think I've got the tools or ability to do it myself without screwing something up on the alignment.

So, what do you think is the best bet?

1. Upgrade the existing axle, and if so with what?
or
2. Find an axle out of a junk yard. If so, what's the best one to look for? An axle swap is definitely something I can do myself since I'm going to do a suspension lift about the same time anyway.

Thanks for any feedback,

Craig · #2 (**permalink**) 02-19-2006, 01:18 PM

Don't know about your year of jeep but a lot of the guys with YJ's ugrade their rear axle to an 8.8" out of a Ford Explorer. If you get 96 or newer (I think) it has disc brakes and an optional limited slip rearend. This axle is almost the same width as a YJ's....only 3/4" narrower. Also much stronger. As for any of your ugrades, I wouldn't put anything into it if you plan on driving it in salt water at the beach. The salt will just destroy everything you put into it.

nica89yj · #3 (**permalink**) 02-19-2006, 03:08 PM

Cant u put a protective coating of some type to protect the engine and drive train? If i were to keep my jeep at the beach i would find a way to protect it man. We kept my Quad at the beach and man the salt killed her.

yjdave · #4 (**permalink**) 02-19-2006, 09:29 PM

Sounds like you have a good plan..Keep the amc 20 and buy the one piece axle kit change your carrier and throw a lock-rite in. There isn't really another axle that will be close except maybe a scout II d44. The motor sound like you've got it figured right. Spend a little extra on the head and punch the block out 30-40.

beachbuggy · #5 (**permalink**) 02-21-2006, 07:58 AM

Rust is always a problem here, especially on older jeeps and trucks. I had all of the inside of the tub Rhino lined and I've put POR 15 on most of the underside. I always hose it off good after driving it on the beach. Hopefully I can stay ahead of the rust problems.

I have heard of Scout II d44 swap but had not heard of the Explorer axle swap. I'm guessing the spring perches would have to modified for a CJ.

Is Lock-rite a brand of locker? I haven't done enough homework on lockers yet.

Bounty__Hunter · #6 (**permalink**) 02-21-2006, 08:19 AM

The AMC20 has the weak 2-piece axleshaft design that often spins the splines at the hub, leaving you stranded. If your gears are okay (you mentioned gear whine or other noise) consider upgrading to 1piece shafts as well.

The Ford 8.8 from an Explorer would be a good swap as they come in 4.10 and with a limited slip diff in many applications. I would have the axleshafts and rotors redrilled to match your 5x5.5" lug pattern (the 8.8 is 5x4.5").

Consider a 4.0L HO head when you do the rebuild, you'll make a lot more power. Better head to sink money into as well.

Then there's the 4.6L stroker using a 4.0L block and 258 crank, but how wild do you wanna get?

beachbuggy · #7 (**permalink**) 02-21-2006, 10:20 AM

Is the 4.0L HO a direct bolt up or does it require modifications? I've seen references to people doing it but haven't seen where anybody has posted a "step by step" kind of thing where they tell how they did it and if there were any changes they had to make to make it work.

I'll search the junkyards for the 8.8" Ford. That should be pretty common rear end.

Thanks for all the good inputs.

yjdave · #8 (**permalink**) 02-21-2006, 07:38 PM

Double check the 8.8..I believe it is wider then your 20.

beachbuggy · #9 (**permalink**) 02-22-2006, 10:13 AM

I'll check the spring mounts and overall width. The less modifications the better. I'm hoping to find a rear end that will give the upgrades I need and not require too many modifications. If there's not a good swap option out there I'll just rebuild the AMC 20 instead.

Just trying to get out cheap and easy. As always.

currupt4130 · #10 (**permalink**) 02-22-2006, 11:27 AM

the cj axles were in the range from 50-56 inches wide i believe, depending on wether or not you have a narrow or wide track axle. the ford 8.8 is in the range of 59 inches wide (58.75). your rear axle is 55 inches wide according to some quick research. If you could find a dana 44 from a 86 cj7 you would be set, they are widetrack and were used in place of the amc 20. Like mentioned above you could use a scout rear axle, which is 58 inches wide. your front end is 55.8 inches wide so in order to run the scout rear axle and still maintain a balanced look and keep your steering in order, you would need to run 1.5" wheel spacers (scout axles are relatively abundant if you can find a junkyard with a scout or two, i know my local ones always have one or two scouts). or if you used an 8.8 you would have to run 2" spacers up front

The AMC 20 one piece axle swap is not a hard swap at all but, you might have to pay someone to do gears in the axles, so dont forget if you do one, you have to do the other. IMHO the best route to get is to just rebuild the 20 with one piece shafts and regear it with a good LS or air locker. you can do the one piece axles yourself but gear installation is a tricky thing. it requires lots of attention, lots of patience, and plenty of time especially if its your first time. it is definately not something taht is recommended for the garage mechanic to do with a limited amount of tools.

in conclusion, my opinion is->

look for a 44 out of an 86 cj and jump on it if you find it. check ebay night and day, they dont go for too much usually.

otherwise, rebuild the amc 20 yourself with new one piece shafts (it will come with new bearings and seals in the kit), buy a limited slip or selectable locker and have someone regear your axles for the bigger tires. go to 4.10s and youll be plenty happy.

edit, theres one on ebay right now if you live in or near illinois, its in good cond and local pick up

jps4jeep · #11 (**permalink**) 02-22-2006, 02:52 PM

Keep the 20, one piece axles, maybe a locker if you plan to wheel hard. If this is a weekend warrior, save your self the cash and skip the locker, running with open diffs will not only be easier on your wallet, but will also let you learn how to wheel and hone your skills.

If memory server me, 82 was the last year for the narrow trac axles, you could look for a 86 CJ and swap in a D44 rear and the D30 front (same D30 you have just a little narrower) or get just the D44 rear and either cut the rear down or run spacers up front.

At this point, If your largest tire choice is 33"s, keep the modle 20! I am going to be running 37" tires on a model 20 axle with nothing but a One piece axle conversion (open of course) also to note, the axle Diameter is the same, D44 is a 30 spline while the Model 20 is 29 spline, and the ring gear in teh 20 is larger.

KEEP THE 20