Upgrading Axle
Upgrading Axle
- Thread starter tycoon90
- Start date
LongHorn
Always Off-Roading Jeeper
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- Washington Co.,Texas
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- 83'CJ-8 Scrambler Slightly Modified;),48'CJ2A, 54'CJ3B 67'Jeep M-725, 88'YJeep Wrangler Slightly Modified;)
It depends on who you ask. I personally have welded the axle tubes then after time the weld broke. because the difference in cast iron & steel. I also replaced the weak two piece shafts with 1pcs. forged & broke them. I found that Scout 2 axles work nicely & have the same bolt pattern. With a 360 V8 & 35" tires they work well. But bigger tires , bigger motor & big rocks made me move up to front & rear Dana 60's.
TeamRush
Active Jeeper
Actually, the center section of a AMC20 is cast STEEL, not cast iron.
The reason most welds break is people do a number of things wrong when welding the cast steel to the welded steel tubes inserted into the housing...
First, you need to clean off the joint with pressure.
Blow out as much grime as you can between the tubing and housing.
Then you need to COOK the joint between the tubes and housing to get any liquid oil out of the weld area.
Then you need to clean off the axle tubes, and area to be welded with a grinder, and I usually sand blast the areas to make sure there is no rust that can contaminate the weld.
Clean off the metal with a solvent.
Brake parts cleaner, paint thinner, ect. to remove any dust, grindings, ect.
PRE-Heat the cast STEEL housing where you are going to weld, then stitch the welds... Make three or four evenly spaced welds around the tube to housing, with the same number of evenly spaced areas that ARE NOT welded.
Allow the welds to solidify proplery,
Then go back and weld up the open spaces.
Stitching the welds makes for a good stop if a crack gets started.
Remember to PRE-HEAT the housing before welding again, and I usually POST HEAT the weld to make sure it doesn't cool too fast.
Since the housing is CAST STEEL, you can use a MIG welder,
BUT!,
I have had much better results with a stick welder using HIGH NICKEL/LOW HYDROGEN rods.
They are EXPENSIVE, around $50 a pound, but worth every penny for this application!
Once post heating/controlled cooling is done, and if you used the proper stitch welding with the correct rods, you shouldn't have any problems with cracking...
-----------------------------------------------
In my opinion,
The AMC (Spicer) Model 20 differential used in CJ's is weak and not worth the time/effort to work it up correctly.
The AMC/Spicer center section is strong enough, and rigid enough, and has a large enough ring and pinion gear to say alive in most jeeps, but those are the ONLY good points...
Jeep used a cheesy welded steel tubing in the axle tubes that likes to bend, split, sometimes even completely break!
The wheel bearings are TINY for an off road axle!
They are problematic, and leak/failure prone, and difficult to change.
Brakes on the CJ axles were a JOKE,
Weak two piece axles are an accident waiting to happen,
and the only traction aid was a 'Posi' with a clutch pack that looks like it belongs in a Tonka Toy.
Over all, by the time you replace the carrier with a locker or good posi, replace the axles with one piece units,
Install a good set of brakes,
Replace the axle tubes with something that doesn't bend when sneezed on,
And truss the differential up so it doesn't bend like Play-Doh, you may as well have inserted a Dana 44 in (available from many places) or a Ford 9"...
Both have more ground clearance, both can easily be built to Dana 60 strength fairly easily and cheaply,
And both will out live the AMC20 in rough service.
(Both have MUCH better ground clearance, and are lighter than the Dana 60 also!)
------------------------
If you want to keep an AMC20 for 'Collector' sake,
Consider narrowing one from a full size Jeep.
They have MUCH better tubes, axles, bearings, ect. than what was used on the CJ.
The reason most welds break is people do a number of things wrong when welding the cast steel to the welded steel tubes inserted into the housing...
First, you need to clean off the joint with pressure.
Blow out as much grime as you can between the tubing and housing.
Then you need to COOK the joint between the tubes and housing to get any liquid oil out of the weld area.
Then you need to clean off the axle tubes, and area to be welded with a grinder, and I usually sand blast the areas to make sure there is no rust that can contaminate the weld.
Clean off the metal with a solvent.
Brake parts cleaner, paint thinner, ect. to remove any dust, grindings, ect.
PRE-Heat the cast STEEL housing where you are going to weld, then stitch the welds... Make three or four evenly spaced welds around the tube to housing, with the same number of evenly spaced areas that ARE NOT welded.
Allow the welds to solidify proplery,
Then go back and weld up the open spaces.
Stitching the welds makes for a good stop if a crack gets started.
Remember to PRE-HEAT the housing before welding again, and I usually POST HEAT the weld to make sure it doesn't cool too fast.
Since the housing is CAST STEEL, you can use a MIG welder,
BUT!,
I have had much better results with a stick welder using HIGH NICKEL/LOW HYDROGEN rods.
They are EXPENSIVE, around $50 a pound, but worth every penny for this application!
Once post heating/controlled cooling is done, and if you used the proper stitch welding with the correct rods, you shouldn't have any problems with cracking...
-----------------------------------------------
In my opinion,
The AMC (Spicer) Model 20 differential used in CJ's is weak and not worth the time/effort to work it up correctly.
The AMC/Spicer center section is strong enough, and rigid enough, and has a large enough ring and pinion gear to say alive in most jeeps, but those are the ONLY good points...
Jeep used a cheesy welded steel tubing in the axle tubes that likes to bend, split, sometimes even completely break!
The wheel bearings are TINY for an off road axle!
They are problematic, and leak/failure prone, and difficult to change.
Brakes on the CJ axles were a JOKE,
Weak two piece axles are an accident waiting to happen,
and the only traction aid was a 'Posi' with a clutch pack that looks like it belongs in a Tonka Toy.
Over all, by the time you replace the carrier with a locker or good posi, replace the axles with one piece units,
Install a good set of brakes,
Replace the axle tubes with something that doesn't bend when sneezed on,
And truss the differential up so it doesn't bend like Play-Doh, you may as well have inserted a Dana 44 in (available from many places) or a Ford 9"...
Both have more ground clearance, both can easily be built to Dana 60 strength fairly easily and cheaply,
And both will out live the AMC20 in rough service.
(Both have MUCH better ground clearance, and are lighter than the Dana 60 also!)
------------------------
If you want to keep an AMC20 for 'Collector' sake,
Consider narrowing one from a full size Jeep.
They have MUCH better tubes, axles, bearings, ect. than what was used on the CJ.
LongHorn
Always Off-Roading Jeeper
- Posts
- 5,325
- Media
- 39
- Thanks
- 1
- Location
- Washington Co.,Texas
- Vehicle(s)
- 83'CJ-8 Scrambler Slightly Modified;),48'CJ2A, 54'CJ3B 67'Jeep M-725, 88'YJeep Wrangler Slightly Modified;)
[FONT="]So basically your just polishing a[/FONT] turd. 
mylittlecj5
RIP Mike, we'll all miss you
Longhorn, this has nothing to do with the thread, but could you adjust your font size to something those of use with normal (old-man) vision can actually read? Please?
LongHorn
Always Off-Roading Jeeper
- Posts
- 5,325
- Media
- 39
- Thanks
- 1
- Location
- Washington Co.,Texas
- Vehicle(s)
- 83'CJ-8 Scrambler Slightly Modified;),48'CJ2A, 54'CJ3B 67'Jeep M-725, 88'YJeep Wrangler Slightly Modified;)
Sorry about that I'm better w/Jeeps than Computers.
mylittlecj5
RIP Mike, we'll all miss you
I wish I could say that (and not be lying) 
but thanks
but thanks