Dana 30a...

[yellocoyote]

When the front diff is open, you can get different rates of wheel spin at each wheel. When they both catch, the pinion trys to walk up the ring gear and because the case is weak it breaks, splits just about right under the pinion at the output shaft

Correct - which was the case this time too.

So Jayme, Doesn't Esteban still have a D30a with an air locker all ready to bolt up? Don't think he has installed it yet.

I think he does, but I'm pretty sure he wants it on his KJ. He certainly did the last time I talked to him about it.

 

[yellocoyote]

After opting to pull the diff out when we have a weekend to do it, I did get under and take a few photos of the carnage. eek2.gif

You must be registered for see images

You must be registered for see images

This photo leads me to think that without the aluminum collar, the front differential would have fallen to pieces on the trail. The collar appears to have held the pieces together. It'll be interesting to see the chain of events once I remove the collar...

You must be registered for see images

 

[Dave]

^^cracked it all over the place.......geeeeezzz

Dave

 

[Ry' N Jen]

Holy:favorites68: Jayme!
Looks like a bomb went off in that diff!

 

[Marlon_JB2]

Man and the collar was supposed to be the fix for diff troubles. Guess there's no reason to have the darn thing at all!

 

[LibertyTC]

Woh!

And I was expecting a small 2" crack along collar!:favorites68:
They should redesign the collar in steel and rest of body in aluminum?:shrug:
This just proves that wheel spin and landing= detonation ! notcool.gif
Somethings were built tough, I am afraid this simply is not one of them.:freak3:
Going to wheel hard= JBA steel front D30A+locker.:smokin:

 

[yellocoyote]

Man and the collar was supposed to be the fix for diff troubles. Guess there's no reason to have the darn thing at all!

It's not a fix, but I've read of other people that also noticed that their diff "held together" better with the collar on instead of falling to pieces on site. If mine would have simply fallen apart, the recovery of my KJ from the place where the diff cracked would have been a lot more interesting. p:

 

[tommudd]

I have seen them broken with and without the collar on there, yes you're right Jayme it would of been more fun due to without it does fall to pieces.
The one I swapped out without a collar was cracked more as well, ( but who knows if the collar helped with that or not)
The one with the collar held together pretty much until I removed the collar after I took it out

 

[yellocoyote]

I'm kind of anxious to see what happens when I remove the collar... if it'll just fall apart on the driveway or...:shrug:

 

[Nooby]

Looks like a job for a few packs of JB weld


but dang, hope you get it fixed soon

 

[ridenby]

Damn.

 

[yellocoyote]

Question: When the CV joints are out, does the front driveshaft still turn when you drive? Or is this a waste of my time to go out and remove it?

 

[tjkj2002]

Question: When the CV joints are out, does the front driveshaft still turn when you drive? Or is this a waste of my time to go out and remove it?

No but I'd pull the driveshaft anyways,and diff.Less chance of accidentally shifting into 4wd and causing more issues.

 

[Jo6pak]

jo6pak -- diff is pretty well tucked up, possible but improbable to break it by coming down ******* something. Beside, Jayme has full skids. known issue with any vehicle with aluminium diff. H3's and chevy 4x4 pickups have the same issue.

When the front diff is open, you can get different rates of wheel spin at each wheel. When they both catch, the pinion trys to walk up the ring gear and because the case is weak it breaks, splits just about right under the pinion at the output shaft

OK, I understand now. I was wondering how it would be damaged from an impact when it's protected by those nice yellow skids.:smokin:
Great explaination. Thanks, I'm a little less stupid nowp:

I don't mean to hijack the thread, but would a LSD up front increase or reduce that probability?

 

[yellocoyote]

No but I'd pull the driveshaft anyways,and diff.Less chance of accidentally shifting into 4wd and causing more issues.

Understood - thanks.

 

[bugnout]

would a LSD up front increase or reduce that probability?

Not sure what kind of stresses you'd get with an LSD when one wheel was off the ground, but IMHO, a selectable locker will decrease the chance of the diff blowing up, (that is if you remember to engage it When both wheels are spinning at the same speed, you should have relatively constant and predictable loads.

 

[LibertyTC]

How is it going now Jayme? Got it all apart and able to do 2 WD now?
Updates on choice of case?
Hope you are still not in the In-Op club.

 

[yellocoyote]

How is it going now Jayme? Got it all apart and able to do 2 WD now?
Updates on choice of case?
Hope you are still not in the In-Op club.

Oh no - I've been driving it in 2wd all last week. No issues and not in-op. We had to take the CV axles off the KJ with the knuckles still attached, take the whole thing to the local driveline shop that we like, and they had to separate everything with an air hammer... that's how over-torqued the suspension was when it came back from re-gearing back in March. eek2.gif Never again.

Likely going with the steel diff, but we've had other projects going (The Boy has been helping friends with their vehicles and is lifting his Astro van... and I have my own projects as well)... so we haven't ordered it or done any other work yet. CV's and front DS are out, and that's it for now.

I'll keep this thread updated with what we're doing.

 

[yellocoyote]

UPDATE:

The initial plan was to have the diff removed on Saturday to have the innards sent to JBA on Monday...

Saturday: Started working on removing the differential. Aaron really had issues removing the cam bolts for the LCA. Ended up breaking one, got 2 more out, and the last one was rusted into the metal sleeve within the bushing. Fortunately we had the foresight to pick up some replacement bolts ahead of time. So, Aaron replaced the broken bolt with one of the new ones, and opted to put everything back together and see if a nearby shop might know of a way to get the resistant cam bolt out.

Sunday: We took the KJ to our Firestone that we always go to for alignments... thinking that they may have a better way than using the air hammer that we had borrowed. They ended up being under-staffed and suggested that we try heating the LCA to get the bolt out. With this in mind, we weighed options. Buy a new set of bushings for my existing LCA, wait the few days to have it shipped to us, another afternoon to have them pressed in by someone with the correct tools, and then reassemble... OR... pick up a used LCA at a local yard to use in case the stubborn bolt couldn't be removed and it had to be cut out.

Monday: Aaron picks up a donor LCA out of a 2005 from a local yard. He then tried the heating method until he runs out of fuel. Decided to scrap the idea and take it to a local welder to see if they had better torches or would be able to cut it out.

Today (Tuesday): Welder tells him that he wouldn't heat/cut (I assume it's because he didn't want to compromise the surrounding structures), but suggested taking a sawzall to the existing cam bolt. Aaron has a non-working sawzall in the garage. Spends the better part of the afternoon repairing it. He had just started cutting the bolt shortly before I got home from work. He successfully removes the old LCA, and getting the differential removed was easy after that was done. For now, my KJ is reassembled (minus a diff) and is drivable again. It will be taken in for alignment tomorrow.

Aaron plans to gut the diff after work tomorrow so we can send the internals to JBA (hopefully) on Thursday. Already spoke with Marlin, so he knows it's coming and he has the steel diff in stock and ready.

To be continued...

 

[streetglideok]

You cant get a break huh? Sounds like the road salt blues, ick. I hated dealing with those headaches in wisconsin, and iowa when I wrenched up there. You got used to pulling the blue wrench out to do anything. A guy good with a torch should be able to cut those bolts off without damage to the subframe. You can always move out here, we dont have that stinkin stuff.