• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Dana 30 Tech

CRASH

NAXJA Forum User
NAXJA Member
Location
Foresthill, CA
I promised front axle advice in another thread, so here goes.

First, let me reiterate the premises we are working under here. We are talking an XJ with a 4.0-4.7 liter motor, weighing about 5,000 pounds loaded for a weekend of trail running in the rocks. Rocks are what I have experience in, and they are generally harder on parts than the slicker conditions in the East, the PNW, and the South. If you stick with these guidelines, you’ll be fine in the gooey stuff.

Front axle choices are simpler than the rear. There are basically three choices:

Dana 30: This is the stock axle that came in XJ’s from 1984 to 2001. There are many variations, with some parts being interchangeable and others not.

Dana 44: This axle is used in many different ½ and ¾ ton vehicles, as well as export Cherokees (RS) and Rubicon TJ’s (low pinion)

Dana 60: Found on Ford F-350.

More on the last two in a later article.

Disconnect 30:

This axle uses a vacuum actuator on the passenger side to slide a locking collar between an intermediate shaft and an outer shaft. This feature keeps the driveshaft from spinning on the highway, thereby yielding a vibe free ride. This axle came with 260 sized u-joints (more on that later), and 27 spline shafts, just like all other Dana 30s. You can use a 95 Wrangler ABS shaft to upgrade this axle to 297/760 joints and keep the disconnect feature. Dana part numbers for this are 75589-1x for the right side and 75815-1x for the left. You can also upgrade to 297/760’s with late model non-disconnect shafts by using any TJ or XJ shafts from 95 and up vehicles, but you will need to order a special seal from Warn Industries in Clackamas, Oregon in order to seal the diff, since the old seal used to ride on the disconnect portion of the outer shaft. The weak link of the disconnect axle is rarely the U-joint once it is upgraded to 297/760 size. The intermediate shaft is fairly short in these applications, and it has a large spline section where the actuator rides. This design makes the shaft excessively torsionally stiff, causing it to break the splines on the differential side. The broken part usually sticks in the diff, forcing a complete disassembly on the trail. Pleasant. This axle is a reverse spiral unit, commonly called hi-pinion or reverse cut (more on this below).

Non-Disconnect, RS:

This axle first made it’s appearance in early XJs with the advent of the Select-Trac t-case. It does not use a disconnect, so the front driveshaft spins even in 2wd. The early axles came with 260 u-joints or an interesting CV design that tends to be pretty fragile. Sometime in the mid-90’s, the switch was made to 297/760 joints. Identical to the disconnect 30, it uses a 7.5” ring gear and 27 spline axles, and is a reverse spiral unit. Max gearing available is 4.88. Differentials and axle shafts are available to upgrade any Dana 30 to 30 spline, but a word of caution, when used in the rocks with aftermarket U-joints (more on this later), the weak link with this setup becomes the ring and pinion. This has to do with the inherent problem with the Dana 30 when used with big tires and low gearing, housing flex. When you apply torque to a pinion shaft, it tries to force the ring gear away from itself, and causing the pinion to ride up the gear teeth of the ring gear. This torque loading flexes the carrier and the housing unless both are stiff enough to resist it. With the Dana 30, the carrier takes a lot of abuse, which is why we see a lot of the 3 piece ARB carriers with broken and backed-out bolts. Eventually all this torque will weaken the ring gear and break teeth off of it or the pinion. Another weak link of this and later axles is the passenger side UCA mount. They fold like a cheap suit when abused. Do yourself a favor and weld a reinforcement plate to the front.

Non-disconnect, “Low Pinion” 30:

This axle made its debut, much to the chagrin of enthusiasts, in 2000. This axle uses geometry common to rear axles. The pinion rides below the ring gear centerline, and when used in a rear application, rides on the drive side of the gear. However, when used in a front application, the pinion rides on the coast side of the gear when driving forward. The coast side of a gear set has a greater slope to it than the drive side, so this accentuates our problem of ring gear deflection described above. When driving on the coast side of a gear, the ring and pinion is about 25% weaker than when running o the drive side. A reverse spiral gear as found in earlier XJ axles solved this problem by cutting the ring gear with the drive and coast side of the gear swapped. This design was conceived by Dana and Ford in the late 60’s to improve driveline angles and strength in their front axles. It does both well. In a sense, the 2000 and 2001 model axles are a de-evolution in technology. They do, however, all come with 297/760 joints.

A word on U-joints.

There are three common sizes of U-joints in light truck applications: the ¼ ton 260 joint which uses a 1.063” diameter cap, a ½ ton 297/760 joint which uses a 1.188” diameter cap and correspondingly larger trunion (the part that the cap rides on), and the 1 ton 332 joint which is a Dana 60 joint. The 297/760 is a strong and popular upgrade for the 260. All of these are made by Spicer corp. Lately, a slew of aftermarket joints have become available in the 297/760 size. OX, CTM, Jantz, Longfield, etc are all making joints which in one way or another increase the strength of the units. All have benefits and weaknesses, but most replace the needle bearings in the caps with bushings. This allows an increase in trunion diameter and a corresponding increase in strength. The downside is that the joints may see increased wear when driven in a vehicle that does not have hubs that unlock.

These joints should be used in high strength axle shafts such as a Warn or Superior. They can be used in an OEM shaft, but the ears of these shafts are fairly soft, and routinely rip off of shafts when using even OEM 760 joints. If you use these joints in any shaft, you must use a full circle clip to retain the cap. As axleshafts stretch, especially OEM Spicer shafts, they allow the cap to loosen and walk its way around. Eventually the little half-clip that retains them falls out and the joint is expelled from the shaft with extreme prejudice. That, folks, is what we call a show stopper. Running a full-circle clip on an OEM shaft requires some clearancing of the shaft ears to allow room for the clip. This requires actual work, which I am generally adverse to, so we used to weld the caps to the shaft. Which brings us to yet another point.

OEM Spicer shafts are like condoms. You use them once and then you flush them. The axleshaft itself rarely survives a U-joint break intact, as the four ears usually collide at a high rate of speed deforming them beyond recognition. Sometimes, though, you may think to yourself “Self, I could get a new joint in there. That Crash guy is off his rocker.” Trust me, the shaft is a goner, as it will usually be stretched and stress fractured. You may be limp it off the trail, but replace it ASAP. This is why I’ve never hesitated welding caps in, they are a permanent installation anyway. Unless you like using your condoms twice.

Two more words on shaft breaks. If you hear the dreaded “Snap, Crackle, Pop”. STOP RIGHT WHERE YOU ARE. If you drive even 5 feet on a broken u-joint, you run the risk of the shafts riding up on each other and popping the ball joints out of their sockets. If you don’t have a spare shaft with you, and you need to move, you may be tempted to pull just the outer shaft out. DON’T DO THIS ON A D-30. The Dana 30 used in TJ’s/XJ’s/ZJ’s/MJ’s/WJ’s is a semi-floating axle, that is, the shaft itself carries the weight of the vehicle. With the shaft removed, the bearings will fall apart, leaving you wheel-less.


What does it all mean?

This is where I know I’m going to catch some flack. I am not a very big believer in the Dana 30 for rock use. Jes and I have a pile of broken shafts and a broken carrier to prove it. So, I cannot recommend running a tire larger than 33 inches with a locker in the rocks. Larger than this, and several things become very apparent. Your braking ability becomes horrible, the unit bearings really begin to suffer, the ring and pinion are screaming for mercy and you may start having ball joint troubles.

Polishing the turd.

OK, so you’ve got some money in your 30 and want to keep it. Understandable. What’s the ultimate 30? If I had to keep a 30, and I wanted to run 35;’s on it against my better judgement, I’d build it this way.

I’d start with an RS non-disco housing, beef up the passenger side UCA mount, run 4.56 gears, and an OX locker. Why the OX? It’s been my experience that the OX billet steel cover does a very good job of increasing housing rigidity, and the lockers themselves are at least as stout as an ARB. I don’t like any automatic locker for the 30 because of the extra stress that is put on the axle at all times when you are in 4wd. At least with a selectable locker you can leave it off until you need it and save the unit some wear and tear.

Next, I’d run WJ Grand Cherokee outers so I could move the steering up to the drag link hole which is about 2 inches higher than the OEM XJ 30 arm. I’d run a WJ outer from a right hand drive vehicle on the drivers side so I could run the tie rod up high as well. The WJ brakes are a no-brainer, twin piston calipers with beefy rotors improve performance tremendously. I’d use the Warn 5 on 5.5” hub kit and have the rotors machined to fit. This would get me the desirable locking hubs so I could comfortably run a CTM joint in Warn or Superior axles. I think I’d keep the 27 spline axles just so that the ring and pinion wouldn’t be the weak link, but it would be hard to resist the 30 spline units.

Please understand that if you build a 30 as described above, you can build a Dana 44 for about the same money.

More on building a front 44 for XJ use next week.
 
Excellent write up. This answers allot of questions I've had on where to sink $$$ into. Thanks
 
Excellent tech and humor! Thank you!
 
ChuckD said:
How would you compare the cast disco UCA mount to the non-disco? Like the one Gary E and I run?
I've always heard it was much stronger, and I think this comment eludes to that:

CRASH said:
Another weak link of this and later axles is the passenger side UCA mount. They fold like a cheap suit when abused. Do yourself a favor and weld a reinforcement plate to the front.
 
ChuckD said:
How would you compare the cast disco UCA mount to the non-disco? Like the one Gary E and I run?


That's what I run too. :cheers:











And in the disco part, when converting to non-disco. The seal is not a special one from Warn, I ordered the 2 that warn wants, they didnt fit, and why would you need 2?

The correct seal # is 11771, and can be purchased from any parts store for around 7$.

(Thanks to Chuck D for that #).

I have been running mine for about 6 months, no leaking. Im not sure what its originally ment for though.
 
ChuckD said:
Thanks for the comment Brett, but I was hoping the Guru of Turdy Polishing would elighten me. :D


The casting simultaneously solves and creates problems. It is infinately stronger than the welded sheetmetal mount on the late model thirthies. The problem with it is that the tubes flex within the housing a bit. Over time you can see they get a little bent. I think this more due to stress from stupid activities like jumping and racing through the desert at high speed than from torque loading. I have never tried this, but I guess if you have a nice straight housing, you could run a nice bead all the way around both side of the forging/casting to try and help the stiffness. Go slow with the welder, though, and follow good cleaning, pre- and post-heating practices. THe tubes are thin enough on these axles that too much heast could cause some heat affected zone brittleness in the tubes adajacent to your welds.

I say forging/casting because to tell the truth, I don't know which it is. I would hope its a forging because of it's position, but I can't say for certain.

CRASH
 
CRASH said:
The casting simultaneously solves and creates problems. It is infinately stronger than the welded sheetmetal mount on the late model thirthies. The problem with it is that the tubes flex within the housing a bit. Over time you can see they get a little bent. I think this more due to stress from stupid activities like jumping and racing through the desert at high speed than from torque loading. I have never tried this, but I guess if you have a nice straight housing, you could run a nice bead all the way around both side of the forging/casting to try and help the stiffness. Go slow with the welder, though, and follow good cleaning, pre- and post-heating practices. THe tubes are thin enough on these axles that too much heast could cause some heat affected zone brittleness in the tubes adajacent to your welds.

I say forging/casting because to tell the truth, I don't know which it is. I would hope its a forging because of it's position, but I can't say for certain.

CRASH

Well, I hope FarmerMatt knows how to weld. :D I have identical trussing as Gary E. I'll try to dig up some pictures, if anyone else is interested.
 
Another soft spot on any D30 is the lower control arm brackets. These four thin sheet-metal bits hang way down in munchkin land. Depending on the gusto of the hit, maybe not a show-stopper, but for sure an attention-getter.

JKS sells weld-on 'mini-skids' that box the leading edge and offer some rigidity. If one were handy, they could do their own reinforcing.
 
Thanks for the write up. This info helped me learn more about my axle. I am only running a 2.5 inline four and don't think that I will be putting as much pressure on my axle as some other people. I have only had to replace my driver side cv axleshaft since owning my truck. The only reason that it had to be replaced was because the boot ripped open and dirt and water got in there and ruined the bearings. Replacement was $70.00. Again thanks for the awesome threat. Alot of people should learn alot from this.
 
Crash your recent right ups have been verry informative. You should really consider submiting these to the Tech Archives in the members forum.
 
woody said:
Another soft spot on any D30 is the lower control arm brackets. These four thin sheet-metal bits hang way down in munchkin land. Depending on the gusto of the hit, maybe not a show-stopper, but for sure an attention-getter.

JKS sells weld-on 'mini-skids' that box the leading edge and offer some rigidity. If one were handy, they could do their own reinforcing.
very true! i have a friend that yesterday ripped one of his LCA mounts off his axle just playing in the mud in his yard. my understanding is they are only welded on the outside, welding the inside too would help.
 
Nice write up Crash. Don't abs equiped XJs before 95' or 96' also have 297 u-joints stock? Keep up those write ups. Although I have read similar stuff, it is nice to have you and the other guys who torture test yours rigs comment on what you run and what works and doesn't work.
 
misty said:
Nice write up Crash. Don't abs equiped XJs before 95' or 96' also have 297 u-joints stock? Keep up those write ups. Although I have read similar stuff, it is nice to have you and the other guys who torture test yours rigs comment on what you run and what works and doesn't work.


89+ w/ABS have the 297 Ujoints.
 
hjeepxj said:
89+ w/ABS have the 297 Ujoints.
my 92 xj with ABS has the 297's in it (bearing cap measuring 1 3/16")

thanks for the good read all in one concise location...

and - why wouldnt you use a condom twice?
 
why even use it once?

once again, nice write up
 
Back
Top