Front diff failure

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eleblanc

eleblanc

10 Year 15 Year
Joined
Jul 4, 2006
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Montreal
Well yesterday i drove from the shop about 1 miles when suddenly my front end locked up totally. drive / neutral or backup...nothing the truck wouldn't move.

We look under and oh my...the front diff is hanging under the truck. supports broke and everything.

The truck is on the lift and the oil drained out with chunk of metal.... I've read about the front diff failures, i don't know what could have caused this. Maybe this problem https://forum.ih8mud.com/100-series-cruisers/453807-minor-assembly-fail.html
Somehow weaken something and it eventually failed and lockup.

Anyhow, should i rebuilt this stock or it will fail again?

finding R&P 4.10 will also be fun!
 
What year is the diff? If it is a pre 2000, only 2 pinion spider, you definitely don't want to go stock.
As you know, prevailing wisdom on MUD is ARB the front as soon as possible. That HDJ probably has more torque than the gas setup, just saying…
 
If you're running stock diffs in your '01 the R&P ratio is 4.30; they're tough to source and OEM is not cheap. 4.10 came '03+

Regardless if you decide to stay same gearing or not you would be well advised to go to the ARB up front...
 
The diff is from a HDJ100 using a 4.1 ratio, it is IFS. Well that is what the EPC says. But will confirm once opened. The diff comes from a 2000 HDJ100 (manufacture mid 1999) So that would be a 2 pinion spider?

I also have the front diff of a 2001 UZJ100 (us market), would that be 2 pinion spider or 4?

I don't really need a ARB, unless the majority says that it will fail again, by simply driving dirt road, and very light offroading...
 
2000UZJ said:
I think were jumping the gun and blaming the differential. The support failed, the OP already posted pictures of the support weakened. I say replace that and go from there.
Click to expand...

I have a hard time beleiving the support would have failed THEN broke the diff. There is definitivly a teeth or two missing.

for those who know how it is supported, there is a leg on the front diff cover. And a bolt that goes through that front support bolted to the frame. And between the bolt head and the support on the diff cover there is a large washer.....well the poor cup washer went right through the hole due to diff wanting to rotate going down.

I do not beleive the support failed then the diff went down and then broke teeth on the ring...it is a open diff.

the diff inside broke, locked up the front end and by going 40 mph the rotational moment broke all the support.

Now why did the diff inside failed, i don't know, could it be because i drove the truck 2-3 week with one support badly installed? i really don't know.
 
eleblanc said:
I have a hard time beleiving the support would have failed THEN broke the diff. There is definitivly a teeth or two missing.

for those who know how it is supported, there is a leg on the front diff cover. And a bolt that goes through that front support bolted to the frame. And between the bolt head and the support on the diff cover there is a large washer.....well the poor cup washer went right through the hole due to diff wanting to rotate going down.

I do not beleive the support failed then the diff went down and then broke teeth on the ring...it is a open diff.

the diff inside broke, locked up the front end and by going 40 mph the rotational moment broke all the support.

Now why did the diff inside failed, i don't know, could it be because i drove the truck 2-3 week with one support badly installed? i really don't know.
Click to expand...

Seems like either one could of happened.

support failed causing the assembly to rotate, bind up and pop the diff teeth.
or the diff failed, causing the assembly to stop rotating and spin the support breaking it.

Either way...
 
Some pictures, i don't think the pinion support and the front cover support can break like that driving on the road 40 mph..
IMG_2431.webp
IMG_2432.webp
IMG_2434.webp
 
Brock has the answer for US rigs, not sure about non-US or if HDJ models are different.
 
4 pinion front diff from August 1999 production.
For UZJ from frame # 5003980
For HDJ from frame # 8011850

And that's:
4.3 for UZJ, p/n 41110-60821
4.1 for HDJ w 4-sp-auto, p/n 41110-60801
3.909 for HDJ w manual, p/n 41110-60811


Do you still have the 4.3 at the rear?
And the 4.3 from the uzj available?
And 33 to 34 " tires?
...
 
You guys are just kidding about having different ratios front and rear, that would drive ATRAC nuts and probably break something.
Think you could get by with stock 4 pinion for the type driving you are talking about, but with that HD torque you don't want to get a heavy foot in tricky stuff.
 
No atrac on HDJ.
Would break something in the end.
 
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