Cracked Duff radius arm


whitetrash96

whitetrash96

15+ Year Member

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Recently while servicing my front diff I noticed another crack in my rod ended Duff radius arms. Last year I had a crack welded up on my ears and now it seems I have another crack in a new location. My question is what are people doing to beef up their Duff radius arms?

Unfortunatley photobucket isn't allowing me to upload any new pics:dunno:
 
Here's where I had the ears welded up last year.
Cracked Duff radius arm


Cracked Duff radius arm


Here is the new crack I found. Not catastrophic but definatley worth looking after.
Cracked Duff radius arm


I've got to get my welder buddy to have a look at the new crack but was wondering if people have braced their arms.
 
i think there is something in the tech library about the duff arms cracking and a fix for it.... might be worth a look for you.
 
i'd just add some 3/16" plate to them for extra bracing
 
on the old style i was always twisting and craking/bending them along with wasting d35 beams.


but i was way off the expected path as well as far as power weight and tire size.

for what they are i cant complain. as you beat the fawk out of them you constantly monitor and maintain your whole suspension or build bigger etc....


i just consider it general maintenance.
 
pillen140 said:
i think there is something in the tech library about the duff arms cracking and a fix for it.... might be worth a look for you.
Click to expand...

I had a look but didn't find anything specific to repairing duff arms, thanks though.

I spoke with my welder this morning and picked up some 1/4" flat bar to brace the arms, hopefully have the cracks repaired and new plate installed this weekend. I'll post pics when they're done.
 
I've seen reports (with pics) of that exact failure a couple times already (failures where the box section tapers down toward the tube section).

Agreed, I would grind out & weld up the crack, followed with a couple pieces of 3/16" plate bent to fit against the arm over where the crack is (a gusset along the top wouldn't hurt either).

How old is that Duff kit?
 
I would throw some plate on there instead of just welding it. Another thing that to stop a crack you need to drill a hole in the end of the crack to keep it from running after a weld/fix.
 
Got the gussets welded on, while grinding out the ear cracks we found them to be much worse than anticipated and were like spider webs with cracks running everywhere. We cut out the rotten metal and built the area back up with weld, then ground everything smooth and formed radiused corners rather then the orginal 90 degree ones so as to not create any stress risers.

Cracked Duff radius arm


Cracked Duff radius arm


Cracked Duff radius arm


Cracked Duff radius arm
 
Very nice work! :icon_thumby:

I'd probably even go a step further and double-plate the ears with another piece of 3/16" plate so they're 3/8" thick, just to make sure it doesn't crack again (at least on the driverside which supports the diff housing).
 
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