LP Dana 30 to HP Dana 30
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I would keep YOUR axle shafts (with unit bearings), and rotors.
This eliminates the possibility of getting a smaller U joint and also ensures that your rotor and unit bearing are correct for each other. There are some that are slightly deeper than others which can cause a problem. The other main benefit is that your brake pads and rotors are already worn/mated to each other.
Unless your gear ratio is the same, you will need to re-gear too. Depending on what gears you want, one might have the correct carrier to go to deeper gears, so you may want to look into that too to save from having to buy a new carrier.
You are lucky to be able to trade straight across.
This eliminates the possibility of getting a smaller U joint and also ensures that your rotor and unit bearing are correct for each other. There are some that are slightly deeper than others which can cause a problem. The other main benefit is that your brake pads and rotors are already worn/mated to each other.
Unless your gear ratio is the same, you will need to re-gear too. Depending on what gears you want, one might have the correct carrier to go to deeper gears, so you may want to look into that too to save from having to buy a new carrier.
You are lucky to be able to trade straight across.
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Can you please post a pic of the CV shafts? And CV, depending on what they are, could be much better.
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No TJ came from the factory with a HP30....
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Or with CV shafts.
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Depending on if they are custom cut from another vehicle or if they are bespoke CV shafts,
You can get quality alloy shafts for about $700, CV shafts from RCV off road will run $1050, they both have different strengths and weaknesses, really it depends on what your going to do in it and on what size tires.
You can get quality alloy shafts for about $700, CV shafts from RCV off road will run $1050, they both have different strengths and weaknesses, really it depends on what your going to do in it and on what size tires.
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353 Posts
There are 3 front axles found in XJ's (all 3 are Dana 30 or “D30” differentials in either the HP or LP design)
Credit should be given to Crash for much of this information
All of them use an outer Unit Bearing style hub assembly (the bearings are built into the hub and the hub and bearings are replaced as a unit) The hub is always turning the outer axle shaft that is bolted thru the Unit Bearing and the shaft is what keeps the Unit Bearing from separating and falling apart. (Useful to know if you have u-joint or shaft failure on the trail, you cannot just remove the entire shaft and drive the vehicle with nothing bolted thru the center of the unit bearing, it will fall apart)
1984 to 1992 XJ's came equipped with a HP30 vacuum disconnect front axle that has an intermediate shaft on the passenger side that physically disconnects from the outer shafts, saving on gas and wear and tear on the drive train. The vacuum shift is shifted by the transfer case.
1993 to 1999 XJ's came equipped with a HP30 front axle (non-disco) that has one piece inner axles and rotates the differential and front drive shaft whenever the vehicle is moving.
2000 and 2001 have a low pinion D30 front axle (sometimes referred to as the TJ axle)
Credit should be given to Crash for much of this information
All of them use an outer Unit Bearing style hub assembly (the bearings are built into the hub and the hub and bearings are replaced as a unit) The hub is always turning the outer axle shaft that is bolted thru the Unit Bearing and the shaft is what keeps the Unit Bearing from separating and falling apart. (Useful to know if you have u-joint or shaft failure on the trail, you cannot just remove the entire shaft and drive the vehicle with nothing bolted thru the center of the unit bearing, it will fall apart)
1984 to 1992 XJ's came equipped with a HP30 vacuum disconnect front axle that has an intermediate shaft on the passenger side that physically disconnects from the outer shafts, saving on gas and wear and tear on the drive train. The vacuum shift is shifted by the transfer case.
1993 to 1999 XJ's came equipped with a HP30 front axle (non-disco) that has one piece inner axles and rotates the differential and front drive shaft whenever the vehicle is moving.
2000 and 2001 have a low pinion D30 front axle (sometimes referred to as the TJ axle)
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Ten points for proper usage of "bespoke" in this context. DING DING DING!
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353 Posts
Found this on the Cherokee forum
Axle Joints:
Some 1984 to 1986 XJ's came equipped with CV (Constant Velocity) axle shafts. These are higher maintenance, hard to find, and most people swap them out for U-Joint shafts.
1986 to 1994 XJ's came equipped with the small (260 series) u-joint, EXCEPT All ABS and NP242 equipped XJ's came with the 297 size joint.
1995-2001 had 297 sized (larger and stronger) u-joints. 297 sized joints are the strongest of the three!
Housings:
The earlier disco housing has a two part tube on the right side with a separate cast piece pressed in the middle for the disco assembly, it is generally considered a slightly weaker housing then the non-disco housing and is much more difficult to install a truss onto. All disco housings have smaller 260 series u-joints and a three piece right axle shaft. (However it is possible to install a 2 piece axle shaft from a non-disco housing if the carrier is removed and a special seal is installed for the right side.)
The non-disco housing is the preferred housing stock, or as an upgrade to the disco housing and the Low Pinion housing. It is the easiest to install a truss system onto and very strong for it’s size. Many people have run 35’s with this housing by upgrading to Alloy axle shafts.
Axle Joints:
Some 1984 to 1986 XJ's came equipped with CV (Constant Velocity) axle shafts. These are higher maintenance, hard to find, and most people swap them out for U-Joint shafts.
1986 to 1994 XJ's came equipped with the small (260 series) u-joint, EXCEPT All ABS and NP242 equipped XJ's came with the 297 size joint.
1995-2001 had 297 sized (larger and stronger) u-joints. 297 sized joints are the strongest of the three!
Housings:
The earlier disco housing has a two part tube on the right side with a separate cast piece pressed in the middle for the disco assembly, it is generally considered a slightly weaker housing then the non-disco housing and is much more difficult to install a truss onto. All disco housings have smaller 260 series u-joints and a three piece right axle shaft. (However it is possible to install a 2 piece axle shaft from a non-disco housing if the carrier is removed and a special seal is installed for the right side.)
The non-disco housing is the preferred housing stock, or as an upgrade to the disco housing and the Low Pinion housing. It is the easiest to install a truss system onto and very strong for it’s size. Many people have run 35’s with this housing by upgrading to Alloy axle shafts.
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I lernt that wachin some fellers on tha BBC, ain't it sumthin when people know stuff n stuff
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That's a good thing...at least you know what you have.
Only other thing is the rotors.
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Everything but the ring & pinion are interchangeable, if your switching rotors be sure to replace the pads, or at the very least use the pads that are broken in on those rotors.
People usually take this opportunity to replace ball joints, pads and rotors, unit bearings, whatever you want and can afford, that way nothing is questionable later.
People usually take this opportunity to replace ball joints, pads and rotors, unit bearings, whatever you want and can afford, that way nothing is questionable later.
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