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Solid axle conversion in YJ D30 questions...

10K views 42 replies 13 participants last post by  calpbs 
#1 ·
I'm getting everything together to do a solid axle conversion in a YJ Dana 30, and have a few questions. My YJ currently has an 8.8 3.73 in the rear, and I am in the process of converting to 4.10s. I have a D30 out of a '90 or '91 4cyl YJ, and will be building a 2nd 8.8 for the rear.

I was able to snag a Cherokee donor axle for the solid outer shaft, and have pulled everything off that I think may eventually use. Question is, should I go ahead and swap in the Cherokee's driver's side axle shaft as well? I remember reading somewhere that they used larger U-joints, but not sure. I *believe* the Cherokee D30 is a '94, but can't remember for sure.

Also, for those who have removed the CAD, what did you do with the vacuum lines, and are you able to still keep the "4wd" light in the dash?
 
#2 ·
The XJ's used a larger u-joint in '95 and up, if you have '94 shafts the driver side wont be any different than you have already. If it does have the larger joints I'd swap both sides.

I removed the CAD altogether and put a plate over the hole and then swapped the vacuum switch on the t-case with one from a TJ and ran wires to the light. Anticaman had a good write up on how to do that part of it, you'll have to search for it though I don't have a handy link.
 
#6 ·
Ok, finally started the conversion today. Good news, looks like I have post-'95 XJ shafts as the universal joints are a larger diameter than the ones currently in the assembly. I'm going to go ahead and swap out the u-joints, as it will be much easier now than later on once they are in the Jeep. I picked up an inner oil seal, except it was not the passenger side inner seal for the conversion. No problem, I can go ahead and swap out the driver's side inner seal now that the carrier is out. Haven't been able to locate a NAPA 11800 oil seal (or any other seal that cross references to that number) locally, so may have to get one shipped.

My question is, is it necessary to place an outer seal in the disconnect housing? I noticed Rusty's Offroad kit doesn't offer an outer seal (only the inner seal), whereas the Yukon kit offers an inner seal, CAD housing seal, and what looks like an additional seal at the end of the housing near the passenger side tire.

If it is a good idea to add the seal at the CAD housing, anyone have a part number other than the NAPA 11800 and 15843? NAPA doesn't have them, and I've had trouble trying to get them cross-referenced at other parts stores. Does anyone know a vehicle that the NAPA 11800 number is actually OEM for, may make searching for it a little bit easier.
 
#7 ·
Search for "NOS 11800" on google. My Napa store didn't have it in stock but got it the next day from the warehouse for me. I used the 11800 seal as the inner seal. I installed it at the pumpkin. I left the seal at the CAD installed although theoretically it serves no purpose if the diff fluid is contained by the inner seal. I do not have an outer seal. I have just the stock plastic dust cover or whatever it is called.
 
#8 ·
You CAN put a seal at the CAD and I'm sure there's a number floating around here, but the shaft isn't machined there so it may or may not last. I didn't put one there way back when I did this.
 
#10 ·
Is the housing/tube also machined for the seal? I would think the CAD housing is machined for the seal but the axle isn't and at the differential the axle is machined for the seal but the housing isn't. Just curious.
The inside of the front pumpkin (on the passenger side) is not machined for a seal, but the 11800 is supposed to fit in place anyway (and still have the correct ID to seal around the shaft). As far as the CAD housing goes, it is machined (and a replacement seal is easily sourced). Problem is, the outer shaft (of the 2pc axle assembly for the YJ) is a larger diameter than a 1pc XJ/TJ shaft...so while the seal will fit in place, it won't seal around the XJ/TJ shaft. My assumptions are the NOS 15843 has the correct OD for the CAD housing side and correct ID to seal around the 1pc XJ/TJ shaft.

From what I have found, the only purpose for the CAD seal is to keep water from filling and sitting in the CAD housing. The inner seals keep the gear oil in place, and keeps water and other fluids from contaminating the front pumpkin. Its just that sourcing these seals locally has turned out to be more difficult than expected.
 
#13 ·
I ordered the seals through NAPA today, should have them tomorrow afternoon. Also went ahead and ordered a 4wd switch for the transfer case, and the Duralast 259 connector for the switch. I decided since I already have to axle apart, might as well clean it up an paint it....no point in not since I am rebuilding just about everything.

Those end seals look interesting, may have to give them a try if the other seals don't work.
 
#15 ·
I found a connector s712 which is supposed to be a direct replacement for the tj switch.
It looks to be identical to the Duralast 259 connector from AutoZone, just more expensive (at least at Summit).

My seals came in yesterday evening, and the 11800 looks correct (haven't had a chance to seat it yet). The 15843, on the other hand, was not...at least not for what I need. It looks like the standard seal for a 2pc outer shaft, as the ID is larger than the 11800. Of course, the 1pc TJ/XJ shaft is much smaller than the 2pc outer shafts in the YJ, so it would be pointless for me to use this seal.
 
#17 ·
color me crazy, why not just swap in the entire XJ axle?
Entirely too much work. While the axles themselves are pretty much the same (although I think the XJ is HP, YJ is LP), the XJ uses coil springs links up front, wheres the YJ just uses leaf springs and sway bars. You would have to either convert the YJ to coil springs and links, or cut off all the extra stuff on the XJ D30 and weld on spring perches for the leaf springs...either process is time consuming, potentially expensive, and not sure worth it in the end.
 
#19 ·
Entirely too much work. weld on spring perches for the leaf springs...either process is time consuming, potentially expensive, and not sure worth it in the end.
A few cuts, measuring, welding. I probably have about $50 all in when I did my axle swap but I also had a welder prior. As far as time, I spent more time waiting for the paint I put on it to dry then anything else. If you already have the axle then you are mostly there already.

Why keep the stock disco housing when you can also clean up that portion as well? Looks cleaner and less to get hung up on the rocks.
 
#21 ·
Here's what I have done so far. Since I had the axle disassembled, I figured I would go ahead and clean it up and repaint. The ball joints had been recently replaced, so there was no need to pull the steering knuckles.

Here's what I started with...


...couple coats of primer...



...and a couple coats of Rustoleum spray enamel...

 
#22 ·
I had to fab up a block off plate for the CAD housing, which wasn't too difficult. Still have to seal it with a little RTV, or I actually may make a gasket...still haven't decided. I wanted to order the kit from Rusty's Offroad, as the kit was only $18 for the plate and inner seal, but the $15 shipping encouraged me to make my own. I'm debating on swapping out the hub assemblies, but not sure if they need to be changed or not...figured doing it now would be pretty simple. I've found hub assemblies from $55 shipped for a pair of generic hubs to $180 shipped for a pair of Timken assemblies.

I may have found an oil seal that will work in the outside of the CAD housing and still seal around the XJ/TJ 1pc shaft. I spoke with a rep at Timken today, and gave them the dimensions I needed and they have a seal that sounds like it should be perfect. I'm not going to post the seal number yet, as I want to make sure its correct before I clog up the thread with incorrect part numbers. If it does work, I'll post the number. I had to order it online, as none of the local parts stores could get it any quicker than I could...plus it was cheaper on eBay. Its a Nation oil seal, and I have a corresponding NAPA number, so hopefully it will work (won't know before next week).

Calpbs, I'm also in Georgia if you need any help with your axle conversion...
 
#25 ·
I so want to do this, I have bought about half the parts but changing the gearing is a big part of it. Do the tubes need welding ? Thanks for the help offer, according to when I green light this project I'll let you know. Your work looks great. Have you considered a gusset? I have seen some nice looking ones.
 
#26 ·
Relax. It's not that big a deal. Parts are only the seal and a TJ right shaft. Yes, you have to pull the carrier, but it's just out and in, no shim changes. I did my first r&p swap after getting instructions from a club buddy on the phone for an hour. Those gears are still in service, that was 1999. It's science, not religion, don't let it make you afraid.
 
#28 ·
I see you painted your outer knuckles where the wheel bearing seats in. You should really sand all that off as it is a tight fit, use a generous amount of anti seize when reassembling.
Yeah, that actually crossed my mind when I was painting....I'm going to go back in and clean up/polish all the contact points, and EVERYTHING will get a healthy dose of anti-seize.

Why? The seal will be at the diff now, so nothing to leak out of the CAD hole. Just get the inner axle seal.
I'm entirely too OCD to not put a gasket there. ;)
 
#30 ·
I have bought about half the parts but changing the gearing is a big part of it. Do the tubes need welding ? Thanks for the help offer, according to when I green light this project I'll let you know. Your work looks great. Have you considered a gusset? I have seen some nice looking ones.
Unless you are regearing, all you need to do is pull the carrier assembly. Most of the times its pretty easy, but I have seen some that are a little more stubborn (and require a bit more persuasion). Just make sure you put everything back in the exact same spot...no exception! Bolts, bearings, and bearing caps must go back in the same way they came out.

I thought about welding up a gusset just for the fun of it, but not sure it is really necessary.

I wish you were closer I'd want to take that 3.73 D30 off your hands!
I haven't really decided what I am doing with the 3.73 D30. I have a matching 8.8 in 3.73 that I also built, but not sure if I am going to save the set for potential YJ projects down the road or not...
 
#31 ·
I have set gears plenty of times. I am regearing to 4:10 and an 8.8 swap of which I have some parts, also a sye and clutch and maybe an external slave. I may go as far as the cherokee axle and locking hubs. It all gets interconnected. I may have a free spare dana 30 which I will build paint and ultimately swap when I do the 8.8. Naturally when I go down this path I will clean and paint all the components as well as welding and stiffening. I will want it to look tip top. So ultimately it becomes a financial decision which is in tight supply so I source parts based on cost and cost and I take cost into consideration but I never sacrifice quality but if you were not aware I consider cost.
 
#32 ·
I've always wanted to learn regearing, to the point that I have all the tools (short of bearing press)...just haven't had a reason to try (yet). One day, I'll force myself to learn!

The SYE isn't too bad, just make sure to not leave one of the internal snap rings on the bench after you get everything reassembled and trying to mount back to the transmission...I learned that one the hard way. When you do the SYE, might as well swap out the chain....its cheap insurance, and a lot easier to do once the case is apart. Luckily, a 4" lift & 33" tires gets you reasonably high enough to work under the Jeep, but I still set mine up on 6 ton Jack stands. I could actually sit partially upright and pull the transfer case, made it easier.

Next time I do it, though, I won't be using no stinkin' jack stands... ;)



Any particular reason you want to go with manual hubs?
 
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