LOST JEEPS :: View topic - D30a replacement idea

Now, this would probably cost a fair bit of money, but it shouldn't cost anywhere near as much as a SFA...

Couldn't we find a front axle pumpkin that has the same critical dimensions as the D30a and modify it to replace the aluminum housing? My though process goes like this:

Same general locations of driveshaft tubes compared to the front of the diff (to prevent the axles getting pushed back or forward) and pinion (to try and avoid messing with the front drivshaft.

To mount it up you could make a plate that bolts inbetween the diff cover and the diff so that you can mount it to the stock brackets.

Then you can cut the drive shafts and tubes down to the correct lengths and go from there.

I know there would be lots of other little things to do but this might be a feasible idea. Any thoughts?

The D30a is Low pinion. Maybe use a low pinion D30 out of a TJ or XJ? I still think a fabricated steel housing using a 9" ford center section or similar would be easier to work with since all the brackets, etc would be welded on sheetmetal not cast iron.
Duplicate all these mounts on the New housing...

Mounts on the cover side could probably be easily incorporated Into a beefed up, custom cover. Mount at axle tube end could easily be added to the steel tube on that side. Rubber mount on side might pose some challenge but i bet could be figured out.

Not that its probably even possible.

But I was wondering what Diff Durango/Dakota's use and full size 1/2 ton trucks, thinking maybe those would be easily adaptable. that And does a Commander use a d30a?

Well let's see if we can get this to go anywhere. I am going to take a peek at a donor vehicle I have ('97 Expedition with 8.8's front(IFS) and rear).... I have the Expedition just sitting around so if it seems at all feasible then I'll pull them out and start tinkering.

So I figure that the following would have to be done(not including copious amounts of bracketry):

1) CV shafts made to go from new diff to stock knuckles
2) Diff will (most likely) be larger and, thus, will sit lower than stock, which will necessitate remounting LCA's which will also require taller or spaced knuckles to keep ridable geometry
3) Either lower or shim(angle) T-Case to cope with new driveline angles
4) Making new mounts for EVERYTHING haha

Anyone else want to add to the list?

durangotang wrote:

5) Rob a couple mini marts or a bank for funds. :wink:

Author:	JPaul [ Fri Nov 02, 2007 6:34 pm ]
Post subject:	D30a replacement idea
Now, this would probably cost a fair bit of money, but it shouldn't cost anywhere near as much as a SFA... Couldn't we find a front axle pumpkin that has the same critical dimensions as the D30a and modify it to replace the aluminum housing? My though process goes like this: Same general locations of driveshaft tubes compared to the front of the diff (to prevent the axles getting pushed back or forward) and pinion (to try and avoid messing with the front drivshaft. To mount it up you could make a plate that bolts inbetween the diff cover and the diff so that you can mount it to the stock brackets. Then you can cut the drive shafts and tubes down to the correct lengths and go from there. I know there would be lots of other little things to do but this might be a feasible idea. Any thoughts?

Author:	JJsTJ [ Fri Nov 02, 2007 6:42 pm ]
Post subject:
Totally possible and has been discussed numerous times in the past. Now go find one and get busy!!

Author:	tjkj2002 [ Fri Nov 02, 2007 7:24 pm ]
Post subject:	Re: D30a replacement idea
JPaul wrote: Now, this would probably cost a fair bit of money, but it shouldn't cost anywhere near as much as a SFA... Couldn't we find a front axle pumpkin that has the same critical dimensions as the D30a and modify it to replace the aluminum housing? My though process goes like this: Same general locations of driveshaft tubes compared to the front of the diff (to prevent the axles getting pushed back or forward) and pinion (to try and avoid messing with the front drivshaft. To mount it up you could make a plate that bolts inbetween the diff cover and the diff so that you can mount it to the stock brackets. Then you can cut the drive shafts and tubes down to the correct lengths and go from there. I know there would be lots of other little things to do but this might be a feasible idea. Any thoughts? I have been tossing the idea around for awhile and will see if it is feasable when I get USAFCOP's cradle out of his KJ.I would be using a HP Dana30 from a XJ.The only problem that I can see is clearance issues since you'd have to move the pumkin over about 3"-3 1/2" so your not trying to weld cast iron,then you'd need to take the stock inner axles and have them cut down and resplined to fit the CV's on them(again not going to be cheap).The biggest thing is clearance issues,could drop the diff down some but then a special front skid will be needed and you'd loose ground clearance,also from moving the center section over then you run into driveshaft clearance on the oil pan and tranny pan.Of course a new drive shaft will be needed,but then at least you'd have a better gear choice.I'm looking at about $2000-$3000 depending if you want a locker or not,but then bu the time you add a lift like Al's 4" or 6" lift,wheels and tires your looking at $5000-$7000 invested.Heck for that much you could almost do a SFA swap if your budget minded on the axles.

Author:	JPaul [ Fri Nov 02, 2007 9:51 pm ]
Post subject:
Trust me JJ, if I had the money (or any at all right now) I would look into doing it. Sadly I'm having some difficulty with work and we're barely scraping by right now. I just like to think things out for when I do finally get enough money to do something. Hopefully in a year or so I will be back on track financially and can do more to my jeep than dreaming wistfully! I don't think I will ever lift it more than a few inches, I don't get out enough right now to warrant it. Heck, I don't even get out enough right now to warrant having a Jeep! But I know I will start doing more in the future, and I like to be prepared. I would just replace the front diff with a modded cast Iron if it ever broke on me, hopefully I won't have to bother, but if it does I would rather spend some extra money for insurance since at thtat point I would know I'm at the point where I'm doing stuff the stock KJ can't handle.

Author:	JJsTJ [ Fri Nov 02, 2007 9:56 pm ]
Post subject:
The D30a is Low pinion. Maybe use a low pinion D30 out of a TJ or XJ? I still think a fabricated steel housing using a 9" ford center section or similar would be easier to work with since all the brackets, etc would be welded on sheetmetal not cast iron. Duplicate all these mounts on the New housing... Mounts on the cover side could probably be easily incorporated Into a beefed up, custom cover. Mount at axle tube end could easily be added to the steel tube on that side. Rubber mount on side might pose some challenge but i bet could be figured out.

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Author:	tjkj2002 [ Fri Nov 02, 2007 10:18 pm ]
Post subject:
JJsKJ wrote: The D30a is Low pinion. Maybe use a low pinion D30 out of a TJ or XJ? I still think a fabricated steel housing using a 9" ford center section or similar would be easier to work with since all the brackets, etc would be welded on sheetmetal not cast iron. Duplicate all these mounts on the New housing... Mounts on the cover side could probably be easily incorporated Into a beefed up, custom cover. Mount at axle tube end could easily be added to the steel tube on that side. Rubber mount on side might pose some challenge but i bet could be figured out. The whole problem is shown in that 2nd pic,the uttur lack off material on the drivers side making it hard to adapt any other diff easily. Where do you plan on putting a 9" housing anyway? That thing is like twice the size of a D30. HMMMMMM,could call Currie about it when I order my RockJock 60 .

Author:	JPaul [ Fri Nov 02, 2007 11:54 pm ]
Post subject:
After looking at the pictures of the diff out of the KJ, and remembering pictures others have posted of the diff breaking, I think I'm noticing part of the inherent weakness with the housing. All the pictures I have seen are either the pinion bearing section blown apart or the bottom section cracked open. There seems to be an awful lot of bracing on the topside of the housing, but hardly any at all on the underside and around part of the pinion housing. I'm sure they did it for clearancing, but then you run into a weak spot on the housing, if everything else is nice and strong but it's not braced the same the whole diameter of the housing, you're going to get breakage in those specific spots. I don't know much about welding, but I wonder if you weld some reinforcing ribs to the underside and pinion are if that would help reinforce evrything. I don't know if the welding could possibly tweak the housing and cause alignment issues internally, but if it wouldn't that might be an option, then just put a skid plate underneath to protect the reinforcing ribs.

Author:	1300ZUK [ Sat Nov 03, 2007 12:19 am ]
Post subject:
Not that its probably even possible. But i was wondering what Diff Durango/Dakota's use and full size 1/2 ton trucks, thinking maybe those would be easily adaptable. that And does a Commander use a d30a?

Author:	Rush345 [ Sat Nov 03, 2007 2:03 am ]
Post subject:
1300ZUK wrote: Not that its probably even possible. But I was wondering what Diff Durango/Dakota's use and full size 1/2 ton trucks, thinking maybe those would be easily adaptable. that And does a Commander use a d30a? This raises an excellant point you fabricators please set me straight. I owned a '95 Dakota 4x4 but found that the drive train had problems sustaining the output of a 318CID or 5.2L engine but with a 3.7L V-6 would this senario be exceptable?? I admit that I ask this question out of pure ignorance. Therefore please don't spank me for being stupid. I have always admired the Chrysler 318 cid, Ford 302 cid, and GM 327 cid . All Classic race proven and admired power plants. If for no other reason than the history I would love to see a built up Liberty with a 5.2L V-8 with the RAM transmission, transfer case, front and rear diffs. What ever it takes to support this type of power. Just put this in line with the other WHAT IF's Columns!!

Author:	durangotang [ Sat Nov 03, 2007 9:39 am ]
Post subject:
Well let's see if we can get this to go anywhere. I am going to take a peek at a donor vehicle I have ('97 Expedition with 8.8's front(IFS) and rear).... I have the Expedition just sitting around so if it seems at all feasible then I'll pull them out and start tinkering. So I figure that the following would have to be done(not including copious amounts of bracketry): 1) CV shafts made to go from new diff to stock knuckles 2) Diff will (most likely) be larger and, thus, will sit lower than stock, which will necessitate remounting LCA's which will also require taller or spaced knuckles to keep ridable geometry 3) Either lower or shim(angle) T-Case to cope with new driveline angles 4) Making new mounts for EVERYTHING haha Anyone else want to add to the list?

Author:	JJsTJ [ Sat Nov 03, 2007 10:32 am ]
Post subject:
durangotang wrote: Well let's see if we can get this to go anywhere. I am going to take a peek at a donor vehicle I have ('97 Expedition with 8.8's front(IFS) and rear).... I have the Expedition just sitting around so if it seems at all feasible then I'll pull them out and start tinkering. So I figure that the following would have to be done(not including copious amounts of bracketry): 1) CV shafts made to go from new diff to stock knuckles 2) Diff will (most likely) be larger and, thus, will sit lower than stock, which will necessitate remounting LCA's which will also require taller or spaced knuckles to keep ridable geometry 3) Either lower or shim(angle) T-Case to cope with new driveline angles 4) Making new mounts for EVERYTHING haha Anyone else want to add to the list? 5) Rob a couple mini marts or a bank for funds.

Author:	InCommando [ Sat Nov 03, 2007 11:08 am ]
Post subject:
Seems like an S-10 or K1500 diff would be great, if do-able. They are readily available. I gotta say that I hardly take my KJ off-road any more. The constant worry of busting that junk front diff takes all of the fun out of it. That is really too bad, as I almost always get comments from people who are surprised over the KJ's capabilities. Capable? Yes. Durable? No. I wonder why they bothered with a 241 t-case in mine, and still used the garbage D30a up front.....

Author:	durangotang [ Sat Nov 03, 2007 12:26 pm ]
Post subject:
JJsKJ wrote: durangotang wrote: Well let's see if we can get this to go anywhere. I am going to take a peek at a donor vehicle I have ('97 Expedition with 8.8's front(IFS) and rear).... I have the Expedition just sitting around so if it seems at all feasible then I'll pull them out and start tinkering. So I figure that the following would have to be done(not including copious amounts of bracketry): 1) CV shafts made to go from new diff to stock knuckles 2) Diff will (most likely) be larger and, thus, will sit lower than stock, which will necessitate remounting LCA's which will also require taller or spaced knuckles to keep ridable geometry 3) Either lower or shim(angle) T-Case to cope with new driveline angles 4) Making new mounts for EVERYTHING haha Anyone else want to add to the list? 5) Rob a couple mini marts or a bank for funds. Nah.... mini marts rarely keep more than $100 in the register.... we'll have to find another solution

Author:	durangotang [ Sat Nov 03, 2007 6:29 pm ]
Post subject:
OK well here's my contribution for the day: This is the IFS version of the Ford 8.8" axle. The biggest problem that I can see with this one is the fact that the mounts are fore and aft as you can see (and it's just a bad angle... the rear mount isn't actually lower than the diff). The offset is pretty close to that of a CRD with 3.5" coming out of the driver's side of the diff. The other side is about 13". The hub-to-hub difference on this assembly is about 10" wider than ours. I haven't torn into the front of the KJ just yet but I doubt if there is room to build mounts on the front and rear for this. If someone else knows better then let me know.... The rear end is another story though.... I had no idea how similar our rear setup is to the Expedition. This huge rear has coils and trailing arms just like ours but they use a cool looking I-Beam panhard bar instead of our wishbone. You would lose 1" of clearance at the pumpkin with this axle. The only modifications needed (aside from driveshaft would be to move the shock mounts, perches, and control arm mounts. I also like the idea of that panhard bar (assuming you could find a place to weld the mount) a lot more than our wishbone thing. The control arms on the expeditions look like they would bolt right onto the KJ but are 2.5" longer.... hmmmm The rear coils are a good size too... they may just work for a lift on ours if the spring rate isn't outrageous.... Well that's it... I'll find another vehicle to poke around underneath tommorrow hopefully.

Author:	Rush345 [ Sat Nov 03, 2007 7:56 pm ]
Post subject:	I eagerly Await
I eagerly await the further adventers of DURANGOTANG

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