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4x4 conversion is nearly done, but need help on ft. axle plz


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Hello all,

 

It's been a long, long time since my mechanic started on my conversion, but it's almost complete. He's transferred the front and rear axles and drive shafts from my donor 1988 4x4 MJ (it had a 4.0L, auto tranny).

 

I complicated matters a bit by using an NV3550 from a 2000 XJ, and an NP242 from a 1998 Grand Cherokee. My mechanic has the tranny and transfer case in but he's having a problem connecting the front axle vacuum connection. He is saying that the automatic system that was part of the donor MJ will not work because it will not connect to the new NP242. He says I need a manual connect/disconnect vacuum switch. Is anyone familiar with this? Thanks.

 

Clarke

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Your easiest option will to take the vac housing off the axle, and simply shim the shift fork over so it's always engaged. Since you have a 242, you'd want it like that with the AWD anyway. Even the older XJs with the 242 from factory had the non-disco axles.

 

I agree. Lock the shift fork over and forget it.

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Your easiest option will to take the vac housing off the axle, and simply shim the shift fork over so it's always engaged. Since you have a 242, you'd want it like that with the AWD anyway. Even the older XJs with the 242 from factory had the non-disco axles.

 

I agree. Lock the shift fork over and forget it.

 

3rd.

 

 

 

 

Clarke, would you happen to have a picture of the tailhousing of the XJ NV3550?

 

I am doing the same as you with a TJ NV3550 and 98 XJ 242, i understand the XJ NV3550 is clocked differently, and would like to be able to see the difference.

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If you go with some sort of selectable lock for the front axle, be aware that, should you ever shift into awd without for sure locking the front axle, bad things will happen in your t-case. I feel it's better to just shim the fork over and not risk anything.

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What is the downside to having the front axle locked all the time? Extra wear? Worse mileage?

 

Your more ready to use your 4x4, so your more tempted to go onto the road less travelled and get yourself stuck and/or break something...

 

I don't see it as a downside though :cheers:

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So if I were to replace the axle, what would you guys recommend I use?

A high-pinion D30 from a '92 or newer Cherokee with ABS (to get the larger u-joints). Don't go newer than 1999 -- in 2000 they changed to a low-pinion front axle.

 

However, that'll get you the crappy composite brake rotors that warp if you look at 'em cross-eyed. I'd keep what you have and just shim the disconnect to make it full-time.

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  • 2 weeks later...

My 4x4 swap is now complete, but the front axle has two problems. 1st, the vacuum disconnect will not fit in the new setup, but I can just shim it and move along. The other issue is that the seals are leaking and my mechanic can't fix it. He's saying "the kingpin has to be heated with a torch and pressed out", a job he can not handle at his place...

 

I've looked at some of the write-ups on converting to the larger U joints at madxj.com (thanks PETE!), and I'm not really seeing what the problem could be here. Now, this guy is a good shade tree mechanic and he's tackled the entire 4x4 conversion as well as adapting the NP242 and the NV3550. I tend to believe him, but I can't understand what the issue could be. Can someone help shed some light on this?

 

Thanks.

 

Clarke

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Kingpin? What on earth is he calling a kingpin on the Dana 30?

 

Shim the fork yourself. Stop paying this guy to do stuff you can handle. :D

 

I'm not paying him to shim the Dana... I just have it at his place which is 2 hours away so I'm trying to decipher what he is telling me needs to be done before I pick the truck up.

 

I'm GUESSING he's talking about the axle nut needs to be heated to get it off, but who knows. All I know is that the seals are leaking and he does not recommend I drive it for 2 hours.

 

On this note, where would one recommend getting replacement axle shafts with new U-joints and seals? Thanks.

 

Clarke

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I don't have any idea what he is talking about. I am old enough to have owned cars that actually had kingpins, so I know what they are, and I know for an absolute certainty that an XJ/MJ/ZJ/TJ Dana 30 front axle does not have kingpins. And if it did -- it wouldn't in any way relate to leaking seals.

 

Those front axle nuts get torqued to something like 175 foot-pounds, IIRC, so it's not surprisng he's having a hard time getting them off. It just needs a LONG, heavy-duty breaker bar (or a cheater bar).

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  • 4 weeks later...
Kingpin? What on earth is he calling a kingpin on the Dana 30?

 

Shim the fork yourself. Stop paying this guy to do stuff you can handle. :D

 

 

OK, so he was talking about the Kingpins on the hub carrier. I think he was going to take the axles out by removing the entire steering knuckle and separate the U-Joint from the shafts... From the MadXJ page it looks like it stays in place and you just remove the three hub bots and it all comes out...

 

Regardless, I feel good about the work the guy does, and he said he can replace the U-Joints and the inner seals for under $300. that included the seals and new U-Joints... At that price should I just let him do it? Thanks.

 

Clarke

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