what are my stock axles?

Well in an 84 your rear should be an AMC20 the front I'm thinkin will be a Dana 30 check the site the information is already out there as to what is stock. as far as ratios if the tags are not there you have to open the diffs to see it . These guys on here can advise you better but remember the search button is your friend. As far as 33's there are some that will say go for it and some that will say you will spin a rear axle.
 
How you drive will ultimately dictate life expectency.
 
battleship had it right. The front should be a Dana 30 and should look like this:
D_dana30.jpg

The rear should be an AMC20 . It should be very round and look like this:
d_model20.jpg

They should handle 33 inch tires but the weak link is the 2 piece axle in the rear. You should swap in one piece axles if the PO hasn't already. Look at the rear hub. If there is a big nut in the center then you have the troublesome OEM 2 piece axles.
 
I have a 1984 CJ7 . What are the stock axles and will they bold up to 33s? How do I correctly identify them?
Thanks!

Here's a pic of a Dana 30 , since Daves didn't show.

With one piece axles in the AMC20 , they will hold up to mild use. I still run mine.
 
As said, your stock axles are a front Dana 30 and a rear corp20. If your Cj is a 4cyl, the stock gearing is 4.10's. If you're running a AMC 258 i6 / 4.2l , your gearing is either 2.72 or 3.73, or possibly 3.55. Check the tag, pull the diff cover and count teeth, or jack up the rearend and rotate a tire one full revolution. The number of driveshaft rotations per one full turn of the tire is your approximate gearing. example: If your driveline turns approx 3½ turns, your gears are 3.55. 3 and 3/4 turns, and you have 3.73's.

Also, as was already said, the addition of a one piece axle kit for the corporate 20 is almost a must...especially if you go over stock size tires.
The 20 is a surprisingly strong axle once you address the 2-pc issue. The addition of a truss and welding the tubes to the diff will create an axle arguably stronger then a Dana 44 .

Im running 36" Swampers on a locked corp20 and have had no issues with it. I ran 33's on the same axles for years and beat the hell out of them again, with no issues. The front Dana 30 however, broke the first weak I ran the 36's (my spotter's fault :D ) No issues running 33's, but it's all about tire placement and staying off the throttle when the steering is bound up.
 
Would a D35 in the rear hold up 33s and some rougher use?

That would be going backwards. The rear model 20 with one piece axles will handle the 33's just fine. I have had them for almost 20 years with no issues and a v8 under the hood.
 
How much work is involved in making the 20 solid?

Not a lot. The axles are about $250 for the kit, then you can buy a pre made truss for around $125 and have e tubes welded when the truss is welded on. Cost for welding will vary, but you are looking at a little over $400 if you do all the work except the welding.
 
Would a D35 in the rear hold up 33s and some rougher use?
As already noted, the AMC20 is a much better axle than the Dana 30 as long as you get one piece axle shafts.
m20-350x250.jpg

Here there are for $190
Crown Automotive Jeep CJ AMC 20 One-Piece Axle Kit (76-81 CJ7, 76-83 CJ5)
The AMC20 has a bad reputation as a weak axle but that is mainly because of the two piece axle shafts. The next weakest part is the axle tubes. Especially where the tubes go into the pumpkin. It's not a big problem but if you really abuse your jeep you might want to weld on a brace.

AMC20 Ring Gear is 8.875 inches
Dana 35 Ring Gear is 7.5 inches

A one inch difference in the ring gear is a huge difference.
 
Good info here, I found a whole AMC20 rearend after i busted my yoke on rear axle for $20, it had 1 piece alloy shafts, wondering how good they were, the axle came out of a cj with a hopped up v8 and it only had 1 bearing still somewhat in tact but a screwdriver took care of that, and so far other than the dent in the diff. cover thats all that was wrong with the thing, guy just got tired of workin on it i guess and sold it to me, so all the parts are goin into my cj now and if anyone needs a 3.54 i have the carrier and all layin around.
 
As already noted, the AMC20 is a much better axle than the Dana 30 as long as you get one piece axle shafts.
m20-350x250.jpg

Here there are for $190
Crown Automotive Jeep CJ AMC 20 One-Piece Axle Kit (76-81 CJ7, 76-83 CJ5)
The AMC20 has a bad reputation as a weak axle but that is mainly because of the two piece axle shafts. The next weakest part is the axle tubes. Especially where the tubes go into the pumpkin. It's not a big problem but if you really abuse your jeep you might want to weld on a brace.

AMC20 Ring Gear is 8.875 inches
Dana 35 Ring Gear is 7.5 inches

A one inch difference in the ring gear is a huge difference.

Busadave,

Do you think the crowns would be as good as some of the more expensive kits?

Thanks,

Coach
 
Busadave,

Do you think the crowns would be as good as some of the more expensive kits?
Thanks,
Coach
I recently had an axle bearing go out. The PO put in one piece axles but I didn't know who made them. So I started to check around. I called up Moser Engineering. They were a great help. They told me it doesn't matter who made the axle. There are only two manufacturers of those axles. And the bearings (and seals) are all the same. But there is old and new style bearings.
The axle shafts are made by 2 companies. Supierior Axle makes the Crown Axles.
If you want to go for the more expensive axle shafts go for Moser. The cheapest place I found them is at Summit Racing - $270
Moser Engineering CJ-S - Moser Engineering Jeep Axle Kits - Overview - SummitRacing.com
Another reason to go with Moser is they have excellent tech support. When I needed bearings they helped me out and sent both old and new style bearings and let me return what I didn't need.
 
I recently had an axle bearing go out. The PO put in one piece axles but I didn't know who made them. So I started to check around. I called up Moser Engineering. They were a great help. They told me it doesn't matter who made the axle. There are only two manufacturers of those axles. And the bearings (and seals) are all the same. But there is old and new style bearings.
The axle shafts are made by 2 companies. Supierior Axle makes the Crown Axles.
If you want to go for the more expensive axle shafts go for Moser. The cheapest place I found them is at Summit Racing - $270
Moser Engineering CJ-S - Moser Engineering Jeep Axle Kits - Overview - SummitRacing.com
Another reason to go with Moser is they have excellent tech support. When I needed bearings they helped me out and sent both old and new style bearings and let me return what I didn't need.

Interesting, now I guess I would need to decide how much customer service is worth. I haven't heard anything bad about the Mosers, thanks for the help.
 
Moser FTW. They will warrantee your shafts from breakage no matter what motor you run. They are the only shaft I will buy. Like I said. i have 18 something years on my Moser axles with a 350 small block. I drive it pretty hard and they are going strong. I have even roasted my 33 mudders more than once.
 
I got my Superior kit around 15 years ago, great product also and I paid $199...but the other kits were going for around $250 at the time.

Always had great support and these axles have held up through a locked rearend running a V8 and a lot of torque. They seem to be holding up to my 36" TSL's just fine.

I think Either Moser or Superior would be an excellent choice. And Crown axles, being built by Superior, would also be good quality but I'd be carefull with the customer service since you aren't dealing directly with Superior.
 

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