AMC 20 Retube?l

[Petescj]

Long story short I got a AMC20 dirt cheap with the 3.73 ratio I wanted. The tubes are already notoriously weak and after the U joints were removed I found rust damage.

Assuming everything else is ok I thought new axle tubes may be a good way to go. I see it all the time on the shows but never with the AMC20 . Usually their building some kind of overboard front axle when doing this? Why not forgo a truss and re tube what I have. With some 1 piece axles I'd be as strong as a Dana 44 if not stronger when considering the larger ring and pinion correct? Is there something I'm not thinking of?

 

[Belizean]

I always hear it's stronger with the truss, wondering why it would be stronger without the truss? Just wondering about that. I would think you would install it since the axel is out

 

[HackFabrication]

Re: AMC20 Retube?

I seem to recall reading (on the internet), that AMC used beefier axle tubes on the 20 when it was put under the Wagoneers (or maybe their J trucks?). So, if that's true, thicker tubes would work. And adding the 1 piece axles goes without question. The major bug-a-boo with the AMC20 (other than the 2 piece axles), is that they may spin the tubes in the housing. Welding the tubes helps. And unless you're planning on 'jumping dunes' or dropping off waterfalls, I don't think normal/trail driving is going to bend them. But, anything is possible.

However, I think it's just a lot of work ($$$), compared to building up a Ford 9" or other comparable heavy axles. And I can plead guilty to dumping a boatload of money into my AMC20 (and Dana 30 ), when for an additional dingy load of money, I could have had a Dana 44 /60 under my CJ5 . Hindsight is 20/20, and the dollars add up quick.

 

[Petescj]

I always hear it's stronger with the truss, wondering why it would be stronger without the truss? Just wondering about that. I would think you would install it since the axel is out

Alot of the reason behind trussing the AMC20 is to prevent the relatively weak / thin axle tubes from bending. By re tubing with thicker tube I shouldn't have to worry about that.

 

[Petescj]

Re: AMC20 Retube?

I seem to recall reading (on the internet), that AMC used beefier axle tubes on the 20 when it was put under the Wagoneers (or maybe their J trucks?). So, if that's true, thicker tubes would work. And adding the 1 piece axles goes without question. The major bug-a-boo with the AMC20 (other than the 2 piece axles), is that they may spin the tubes in the housing. Welding the tubes helps. And unless you're planning on 'jumping dunes' or dropping off waterfalls, I don't think normal/trail driving is going to bend them. But, anything is possible.

However, I think it's just a lot of work ($$$), compared to building up a Ford 9" or other comparable heavy axles. And I can plead guilty to dumping a boatload of money into my AMC20 (and Dana 30 ), when for an additional dingy load of money, I could have had a Dana 44 /60 under my CJ5 . Hindsight is 20/20, and the dollars add up quick.

Here was my train of thought on the whole thing. Dana 44 /60 combo is pretty much Overkill for what I'm building. I shouldn't need more than 44's. Now if I go find a narrow 44 with 3.73 for say $600 that would be great. If not then I begin with the initial $25 I spent on the 20. Axles are somewhere around $250. Not sure how much the whole Retube would be but I still have $325 left before hitting the Dana 44 price. Finding the 44 with the correct gear ratio is also difficult.

 

[Lumpy Grits]

Where do you find these tubes?
Stock tubing will require lots of lathe work.
LG

 

[diddy2003]

Where do you find these tubes?
Stock tubing will require lots of lathe work.
LG

Agreed. I welded the tubes and did the one piece shafts. Maybe a truss next, but thicker tubes sounds like a lot of work.

 

[Hedgehog]

One more downer on the AMC20 are the relatively small bearings. Why not just weld on a truss? It would be quicker, cheaper and most probably add more strength to the entire axle. If you are worried about hard bumps bending the tubes themselves, weld a shield along the bottom of the tubes.

 

[Petescj]

Where do you find these tubes?
Stock tubing will require lots of lathe work.
LG

Ultimate 4x4 always shows that Ian cutting Dom tube to use for axles he builds. Never show the lathe work so maybe that's why I only really see it on TV

 

[Petescj]

Agreed. I welded the tubes and did the one piece shafts. Maybe a truss next, but thicker tubes sounds like a lot of work.

Hmm ok maybe there's more to this than I was lead to believe

 

[Petescj]

One more downer on the AMC20 are the relatively small bearings. Why not just weld on a truss? It would be quicker, cheaper and most probably add more strength to the entire axle. If you are worried about hard bumps bending the tubes themselves, weld a shield along the bottom of the tubes.

The one thing I'm worried about is where the one tube was bolted to the spring has some rust deterioration. I think it'll just outright break the way it is. I'll get a pic after work. I could also get the longer tube off the QuadraTrac axle cut down and use it to replace this rusty one?

 

[Lumpy Grits]

The axle tube has to be thick enough to allow boring for the axle bearing race and to fit the inner axle seal.
How are you going to press the tubes in place and at the correct specs?
Then, you have to weld the backing plate flange in place.
IMHO-The '20' ain't worth it.
Respectfully,
LG

 

[slomo]

From what I've read, I've seen zero documented info on any strength improvement from adding some truss. To me if the welds are not properly done, they "can" do more harm than good. Did they get good penetration? Grind all the rust, you know it's a Jeep, from the weld area? Use the correct welding rods and so on? Most I see are decoration pieces. Something to fool the eye.

Larger tubes, good luck on bearings and seals.

slomo

 

[Lumpy Grits]

From what I've read, I've seen zero documented info on any strength improvement from adding some truss. To me if the welds are not properly done, they "can" do more harm than good. Did they get good penetration? Grind all the rust, you know it's a Jeep, from the weld area? Use the correct welding rods and so on? Most I see are decoration pieces. Something to fool the eye.

Larger tubes, good luck on bearings and seals.

slomo

If that was truly the case about a truss. Why do you see it done by the professional desert racing teams and such.
Welding steel to iron is tricky, I've done it many times. When you truss and tube weld it does a great improvement in rigidity.
LG

 

[WHATROAD]

IMHO, the improvement was immediate. I'm not climbing rocks or near vertical walls. I am also no longer fearful of spinning my diff into a new and interesting position. Oh yah, and it looks good too!

 

[Lumpy Grits]

Nicely done!
LG

 

[Torxhead]

IMHO, the improvement was immediate. I'm not climbing rocks or near vertical walls. I am also no longer fearful of spinning my diff into a new and interesting position. Oh yah, and it looks good too!

Nice job! I do think you should try climbing rocks and near vertical walls though.

 

[Hedgehog]

It's probably an optical elusion but if you climb rocks the needed articulation of the rear end would beat the heck out of your exhaust pipe.

 

[jafo]

I guess I'm lost to the reasoning why. Better question is when are stronger axle tubings needed? At what point will stock axle tubings bend or twist? Unless you're dropping in a HP big block with loads of torque, or extreme rock crawling where suspension is under extreme amounts of flex, is it really a necessary mod?

 

[slomo]

IMHO, the improvement was immediate. I'm not climbing rocks or near vertical walls. I am also no longer fearful of spinning my diff into a new and interesting position. Oh yah, and it looks good too!

If you noticed some improvement, you have issues. Sounds like it was about to fall apart.

Like I mentioned, they are a piece of mind, weight add-on. Here is a first hand testimonial on it.

slomo