[kevchev]

I just got an old rusty '79 cj-7 w/ a 6 cyl., 400 auto and quadratrac. i am doing a complete brake job including new s.s. lines. Fun! Fun! Fun!
The more I dig into this thing the more I find to do! I know! That is life!
O.K. I see that the axle seals are leaking and have finally been able to get the hubs off the axles and the axles out of the rear end housing. The hubs don't seem to have very much spline in them. Do they have more spline when they are new or does the 250 ft. lbs torque on the nut cause them to be drawn into the splines on the axle itself and the strength is then in the amount of torque?
I have seen where they sell after market 1 peice axles and am thinking that will be the way to go. Can anyone recommend a strong, cheap version or company to go with? Also, Please explain to me the thought of a 2 piece axle in the first place?
thanks!
Kevin

[PavementPounder]

Moser makes a good 1-pc kit for Quadtratrac C20's.

Moser Engineering

[CJhollic]

Moser, superior and Yukon. I have the Yukons and so far am happy. I cant imagine why they had a 2 piece design. Before I finally purchased the 1 piece, I spun a hub on the drivers side and broke the passenger side just outside the wheel bearing. You are making the right choice by replacing them.

[Jim1611]

Definately go with the one piece axle. You won't be sorry one bit because if you put on bigger tires and start pushing it the 2 piece will end up spinning in the splines and you'll have to replace them anyway.

The reason for the 2 piece design is because they are cheaper to manufacture. In a one piece axle you start out with a solid piece of material and it has to be turned down on a lathe, lot's of wasted material. Some one piece axles are made from forgings and though they are cheaper than the solid billett they still require more money to make than the 2 piece kind.

All in all the model 20 is still a light duty rear axle. Instead of spending much more on it maybe you ought to consider swapping in a dana 44 or Ford 9 inch. The 9 inch is a great choice. Currie Enterprises sells them. Kinda pricey though. Another thing you could do if you have the mechanical ability is buy a junk yard axle and have it narrowed at a good machine shop.

[chromegrille]

the new rear hubs don't have splines; as you tighten the nut down, it makes the splines.
just make sure you get the nut tight when you re-install.
I'd run them if they weren't loose (spline wise) to begin with.

[kevchev]

Thank you all for the input. I ordered a pair of 1 piece axles last night.
I really do not want to take this apart again if I can help it. Except to grease the bearings I guess.
Thanks again!
Kevin

[CJ Rick]

Kevin, you should post pics and a write up on the install. This seems to be an area that gets alot of questions.

[kevchev]

I mock fit my 1 piece axles and measured them, then took them to have the bearings and bearing spacer pressed on the axle as well as having the backing plate, retainer and spacers, behind them according to the instructions, etc...
As I started to bolt the 4 bolts down, the axles are binding up and tough to turn by hand. Does anyone have any experience with this?advice? I heard about removing the block on the cross shaft?
How does this affect the axles and why? Nothing is easy with this thing so far!
Thanks in advance!
Kevin

[79jeepguy]

I had this personal decision long ago. I decided to go with a Dana 44 and have been happy with it.

[Totallymetal]

I didn't remove the thrust block with my Superior one piece axles and ended up burning up my right rear bearing and seal in short order. I believe they are actually pushing on the thrust block and the bearing was the weak link. I wish I would have just taken the extra time and removed the thrust block, I have read tons of info on the one piece installs since then. The thrust block is only needed with the 2 piece axles.

[kevchev]

Thanks for the info!
What purpose does the thrust block serve? I have seen on some posts where people have said they left theirs in. I am sure some applications have more tolerance. I too have a t400 and quadratrac. i am going to pull the rear diff cover back off tomorrow and see about taking the block out. Yes, I put it back on before I knew everything about it. I knew it went right back on way too easy.
Can you tell me more about the MM part time kit? I had one put in a Chevy 203 a long time ago. Just got this jeep recently and am thinking about putting one in myself. Is it difficult and time consuming or is it pretty standard stuff?
Also, is there more to the front end than just changing hubs?
Thanks!
Kevin

[RobP]

I spent a ton of cash on one pc. axles and 4.88 gears in a AMC 20 housing to run 35's. I would never do it again, but this was my first project. Dana 44's would be much much much cheaper, but I could not weld so I could not do it. I did truss the thing though. Good luck on yours.... my 2 cents/

[26679cj5]

the reason for the 2 piece axle was price but a big part of that was they could make different length shafts and mount them all to the same spindle.

if you convert to single piece shafts, weld the tubes to the housing and possibly make a truss, the amc 20 will be stronger than a 44 due to the 20 having a bigger ring and pinion. the 20 does have thinner tubes but with the truss the problem should be solved. you'll handle 35s and possibly larger depending on how you drive (i know a guy who runs an ox in his amc20 with 37s and has never broken one of his moser shafts and he dogs it like crazy).

your dana 30 will probably break something before the amc20 would if you go 35s or larger.

[5-90]

Originally Posted by kevchev

Also, Please explain to me the thought of a 2 piece axle in the first place?
thanks!
Kevin

That's an easy one - manufacturing cost.

You can either take a shaft and cut it to length, roll/grind the bearing surface, roll splines on it, and dress the ends, OR you can cut it to length, roll/grind the bearing surface, roll splines on it, dress the ends, and then friction-weld the flange on the end.

To fricction weld, you essentially spin the shaft up to 20,000-25,000rpm, then press the flange on the end with enough force to stop the shaft (thus welding it on.)

Then, dress the weld, balance the shaft, and make damned sure you got the flange on centre (or just do an oversize flange, then machine to final and bore out the lug pattern. Too precise to drill.)

Guess which one costs less?

[jwhite_00]

One-piece axles have unit bearings, they do not require any sort of end-play adjustment like the bearings with the factory two-piece. Therefore, if the ends of the one-piece axles contact the thrust block they will put a side load on the bearings and shorten the life. It is wise to take the diff cover off and make sure that there is some thrust block end-play after the install. Most axles are short enough that the thrust block removal isn't required but all of the manufacturers recommend checking just to be sure.

Just to set the record straight. There are a couple of ways to make the one-piece axles. The cheap one-piece are made from a hub and shaft that forced together under a great deal of pressure and spun. The resulting friction welds them together into one piece. They are stronger than the factory item but usually come with a disclaimer recommending that they are not to be run with a tire greater than 32".
The better ones are forged from a piece of round stock with one end mashed to roughly form the hub and then machined. Forgings are far superior metallurically and less expensive per unit than maching from a solid block of steel. Moser, Superior and Yukon axles are all made from forgings.