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My 2nd Busted D30a!!! Should I try for 3rd???
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Author:  2mopar_diesels [ Sun Mar 21, 2010 8:42 pm ]
Post subject:  My 2nd Busted D30a!!! Should I try for 3rd???
So far, this thing breaks 50% of the time when going offroad.........In 4 trailriding trips, the front diff has exploded twice. Before anyone says anything, I learned my lesson the 1st time around and so called "learned" how to wheel a KJ to try and make the front diff survive: Keep wheel speed to bare minimum, keep slight/steady pressure on breaks when in a bind, go as slow as possible, don't try taking the same lines that solid axle rigs do, and again, last, but not least............keep wheel speed to a bare minimum and try not to spin at all.

This still didn't work in my case. I was on a not too difficult trail, so wasn't "in over my head" the CRD was in a hard pull making a hill climb that had a bit of a left hand dog leg with a deep rut. Had the perfect line, modulating the front Truetrac with break pressure to get it to pull through. Wheels where turning of course (not spinning) cause the Jeep was moving, but very slowly. Then all at once, slid off the line I had hard into the rut, then high centered and BANG!!!! Rest is history.

Reasons for this, you are free to speculate and post, but my guess is that the torque output of the CRD while wheeling using 4lo and in a hard bind/climb/pull even without wheel spin is too much for the POS D30a. Heck, in a few climbs, with both front tires on the ground, you could hear a clicking/binding/popping in the axle cv's or diff one, especially if I noticed some wheel slip and I applied a little break to stop it, thereby the Truetrac would send torque to the high traction wheel. Unnerving to say the least, but figured it's just one of the quirks of the IFS, I don'd know, maybe it's the D30a's warning sign it doesn't like what it's asked to do.
Author:  cmohr [ Sun Mar 21, 2010 8:58 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Crikey!!!! Thats no good..... Might be a job for that new Steel 30 that als working on...
Author:  2mopar_diesels [ Sun Mar 21, 2010 9:28 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Now, for all you who love carnage, and trail pics, here you go!!! The 1st is a bone stock JK with open diffs front/rear for good size of scale in difficulty. He was the only one in our group that needed assistance getting past this spot (well, besides me of course) made up mostly of 4door JK's on 33's or 35's none of which had locker's at all, couple had OEM Traclocs. Besides me, only the leader and tail gunner (both TJ's) had locker's of any kind. Now, as you may see, my rear was not quite perfect on the line that was needed and that hump just ahead in the 3rd pic is what bumped me off line and was snapped just seconds before the carnage. 4th, 5th and 6th were the aftermath and the ensuing winch party that followed!!! If I had the rear tire about a foot or so further to the passenger side.......this may/may not have happened.........Who knows??????? For Obvious reasons, I wish I had a better spotter.


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Author:  67Customs [ Sun Mar 21, 2010 9:41 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Ouch man. That hurts. :(
Author:  Diggerfreek [ Sun Mar 21, 2010 11:18 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Ouch............. Time to call Marlin
Author:  JL Rockies [ Sun Mar 21, 2010 11:18 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Bad luck man. Thankfully, I've never had one go in all the hard miles I put on mine. I think tire selection has something to do with it.
Author:  2mopar_diesels [ Mon Mar 22, 2010 12:49 am ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Who is this Marlin guy, Digger???


You know, the sad part is that I wheel very smart........I don't do stupid things and know what I'm doing out there. But this has got me so turned around I can't figure it out!!! Maybe it's the Jeep Wheelin' gods getting their revenge for all the trouble free miles I put on my previous 2 XJ's. As built as they were, I babied them and took 'em through and across stuff that others I wheeled with would just scratched their head over. When people would try to egg me on and say "come on man, give her hell, you're being too easy, and you trailered it here anyway" I would say "nope, I don't like being broke" and would ask for a strap/winch/tug/stack rocks etc., or took a bypass. I had absolute certainty what their limits were and never exceded them!!!!! With the Liberty though, I'm lost!!!! It seems no matter what I try and regardless of other's experience and advice, it cannot be relied upon to do even the slightest technical offroad maneuvers. Breakage occurs at the most random and sometimes mundane times, it's like shooting dice at a craps game or something.

If the only way to guarantee it not to break is to stay on the level 1's and 2's (where 4wd is barely if ever needed) then I'd assume convert the CRD to 2wd, put some low resistance highway tires on it and lower it to the point it's basically a station wagon and have a 30+mpg suv. cause what's the point of having a low range t-case in something when you can't seem to take it on trails that even require it to be engaged?????
Author:  Diggerfreek [ Mon Mar 22, 2010 1:10 am ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
PM in a sec
Author:  2mopar_diesels [ Mon Mar 22, 2010 2:07 am ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Diggerfreek wrote:
PM in a sec


Yeh, gotcha!!! I'm taking it into the dealer tomorrow after I swing my stock rims and a/t tires back under it, to see if I can get lucky a 2nd time. If not, I've got a shop working up a price list on several different kinds of builds......a couple of SFA setups, and maybe a beta tester for one of JBA's steel housings!!!
Author:  Fulltimer [ Mon Mar 22, 2010 4:34 am ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Really sorry to hear about the damage. My guess is that when it slid into that rut the tires started spinny for a second and then hit bottom and grabbed traction. Boom!

Terry
Author:  tjkoen01 [ Mon Mar 22, 2010 9:25 am ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
if you are hearing clicking when wheeling, maybe your cv's are binding and that is what is causing your front diff to break. if you are being as conscience as you say you are (which i would believe after breaking one already), i'd say there is something else wrong....or at least contributing to the breakage other than the extra torque from the crd. just my :2cents:
Author:  MP Jeeper [ Mon Mar 22, 2010 12:41 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
1st of all, sorry for your ill fortune. That's absolutely frustrating man.

2nd, i really question how much the spinning/grabbing thing plays into it. Not that it doesn't, but just how much?

Bunch of us were wheeling at the Badlandz a couple years ago and AndySRT was going up this easy incline, not extreme at all, nice easy pace and driving smart as you describe and . . . BANG! :shock: There it went. Needless to say we were all scratchin' our heads a bit.

i've driven some obstacles that required me to get into the skinny a little more than i wanted, bouncin up & down and just knowing that D30a was going to grenade for sure but . . . nothing. i've watched others do the same and survived as well.

No doubt the D30a is the weak link on the KJ but when it comes to breakage it seems it's, as you say, kind of a crap shoot. My :2cents:
Author:  CRDMiller [ Mon Mar 22, 2010 5:46 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
I wheel the snot out of my crd and always fear the d30.

I know photo's never do em justice but that trail looks pretty mild, i think something else is up.
Author:  1996xj [ Mon Mar 22, 2010 6:41 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
2 mopar_diesels, sorry about your diff. situation's !! I belieave there has to be more pressure and force put on the front diff. case with a locker in the front !! And haveing the diesel on top of the locker prob. is too much for the dana 30a to take !! I have wheeled my 04 Gas KJ with 32's and a rear powertrax, pretty hard in the past with wheel spin and steep grades and never had a probem in the 60k I have driven it !!
Author:  2mopar_diesels [ Mon Mar 22, 2010 6:57 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
tjkoen01 wrote:
if you are hearing clicking when wheeling, maybe your cv's are binding and that is what is causing your front diff to break. if you are being as conscience as you say you are (which i would believe after breaking one already), i'd say there is something else wrong....or at least contributing to the breakage other than the extra torque from the crd. just my :2cents:



Yes I do hear that, and maybe there is something to this theory, as it's always worse when going uphill and the suspension is obviously unloaded, leading to a slightly steeper CV angle. But what exactly would that have to do with the diff? As the axle shaft going into the diff case is stationary. Could it just be binding and shock loading the diff or something??? I know they are not bent or anything, cause I have 0 vibes at any speed regardless of t-case position. I know the original dealer who did the warranty work last year reused the CV shafts cause the service manager said they weren't affected. So, there maybe something to this......I know one thing!!! Regardless of what the dealer does or what I do, if it stays IFS, I'm getting new CV shafts if I'm told I need them or not.

Another thing maybe that when it slid off on top of the rut, it slammed right where the diff is onto the skid plate that might have deflected enough to cause it to bind and break. I mean, there was a bit of forward momentum going up, but no spinning. But there was an abrupt stop when it high centered. Regardless, it shouldn't break so easily!!!!
Author:  2mopar_diesels [ Tue Mar 23, 2010 3:03 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Well, found what the "other" contributing factor was/is........deflection of the diff skid had/has everything pushed back and upwards by about 1" to the rear and nearly 2" up. Therefore causing the severe binding. It was hard to see just how bad the skid had bent until the dealer showed me what a stock one looked like. So, if I decide to stay with IFS, I'll be looking at a stronger front skid plate!!!
Author:  rescu2000 [ Tue Mar 23, 2010 7:21 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
Why these things do or don't break is a mystery to me. I beat the HE double hockey sticks out of mine and haven't borke it. It could break tomorrow, but I've been rough on it. I even snapped a cv axle shaft (right outside the diff, broke about 1 1/2 " off of it right past the splines). I have a video on YouTube of me climbing a 4 or 5 foot rock with the front passenger side tire.

Then on the other end of the spectrum, we have another local (Wilmington) guy who DOES know how to offroad and owns a lot of 4X4's and his broke on a small 6 or 7" rock on an uphill climb.

Some castings just appear to be stronger than others. I think the dent/alignment issue you mention probably does create some problems too though.
Author:  LibertyCRD [ Thu Mar 25, 2010 12:46 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
I agree. It's strange. I've had two KJ CRDs....neither has ever given me a problem offroad. The D35 in the rear of almost all Jeeps ever made....supposedly those are junk too but I never had one break even with 33s and none of my friends ever had one break and we were hard on them. So some people just have bad luck I guess because these Jeep axles are not really that weak.
Author:  ATXKJ [ Thu Mar 25, 2010 12:56 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
I ordered a replacement front skid and it was thicker than the original
Author:  2mopar_diesels [ Thu Mar 25, 2010 4:57 pm ]
Post subject:  Re: My 2nd Busted D30a!!! Should I try for 3rd???
ATXKJ wrote:
I ordered a replacement front skid and it was thicker than the original



And I either plan to reinforce a factory skid by welding some 3/16 plate to it, or get a Skidrow skid if I stay with IFS.

I'm still trying to decide on this or SFA, as the shop wanting to do the conversion work just quoted me $5200 total contract price for a HP D30, Eaton E-Locker front, and 4.56 geas f/r. And, of course, all the related and necessary parts and fabrication to complete the swap.
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