Dana 30 gears
I finally completed the regear of Jennifer’s XJ the weekend. This has been a much longer project than I first expected.
She has had a gear set on her shelf for a few months now waiting for me to install it. However, we had to collect all the various parts needed. The first being a matching set for the rear. Once the rear gears were in, I finally proceeded to work on the front.
I began by stripping down the old gears. This swap involved going from the stock 3.55 gears to 4.10 ratios. There is a different carrier required for the 4.10 gears due to the thickness of the ring gear.
The first step was to move the spider gears from the old carrier to the new one. The ring gear had to be removed to provide clearance for the cross pin to be removed. The cross shaft is held in place by a roll pin that has to be driven out with a punch. My proper sized punch seems to be missing, so I used an old drill bit instead.
With the spider gears transferred, I then mounted the new ring gear on the carrier. I removed the bearings from the old carrier to retrieve the shims being careful to keep them on the correct sides. I took a set of slightly worn bearings and reamed out the inner race with my die grinder until they slipped on easily. I used these for the trial fits before installing the new bearings.
I pressed off the old pinion bearing to retrieve the slinger under it. I then heated the new bearing and slipped it onto the new pinion with the slinger under it. I noticed after it cooled that I could rotate the slinger slightly so I tapped it down tighter with a punch and hammer.
I used a punch to drive out the races from the housing. There is an oil baffle under the inner pinion bearing that will be destroyed in the removal process. We had some trouble locating a new baffle. Although they cost less than two dollars, no one in town had one in stock. Most 4×4 places wanted $8 to $16 to ship one. We finally found a place with reasonable shipping and bought two just in case.
One of my XJlist members gave me the tip to measure the oil baffle and replace it with a shim during the set up process. This keeps you from destroying more of these baffles while performing the set up tests. My baffle measured exactly 0.020 inches so I used a 20 thousandths shim in place of it during set up.
The pinion depth on the Dana 30 adjusts by shims under the bearing race in the housing. This means driving the race in and out until you get the shims right. I took and old outer pinion bearing and reamed it out so it would easily slip on an off during set up. I assembled the pinion with bearings and slingers but no preload shims. I snugged up the yoke nut to take out all end play.
I then set the carrier in place. I used a soft hammer to drive it into the housing rather than using a case spreader. I set the caps in place and tightened them down. I then coated some of the teeth with the yellow marking compound that came in the overhaul kit. I then rotated the assembly around to get a pinion depth pattern.
I had used the chart in the Jeep FSM to select the pinion shims. Basically each pinion gear is marked with its variance from zero depth. In this case the old gear was marked 2 and the new gear was marked 6. This meant I needed to remove 4 thousandths of shim from the shim pack under the bearing race. I measured the shims that came out and removed a 10 and added a 5 to make up close to 4 difference. I then added a 20 to substitute for the baffle.
I almost cheered when this shim pack gave a beautiful wipe pattern showing the contact patch right in the middle of the gear. I also found that the yellow gear marking compound which is actually made by GM makes a much better mark that the Prussian Blue I have used in the past.
I set up my dial indicator and verified the back lash. It was a bit hard to read the indicator but it was well within the .006 to .009 spec in the manual. That meant the same shims from under the old bearings would work.
I almost wished I had put the baffle in. I carefully drove out the race and replaced the shim with the baffle and reinstalled it.
I prepared to set the pinion preload with the new bearings. That is when I noticed that the rebuild kit contained the wrong outer pinion bearing. It was one for a low pinion Dana 30 rather than the XJ style high pinion. This difference has plagued this install from the beginning. (See the earlier posts.) I obtained a replacement from Advance Auto but not without some difficulty getting the right part even with the old bearing in hand.
I prepared a set of shims based on what had come off the old pinion. These proved to be way too tight. I then built a thicker stack of shims. These were too loose. The pinion preload is supposed to be between 20 and 40 inch pounds when installing new bearings. The preload is adjusted with shims on the XJ contrary to what the FSM says. Some Dana 30s use a crush sleeve like the Dana 35 but not this axle.
I then made up a shim pack that measured 55 thousandths. This was too tight, so I made one that measured 60 thousandths. This was just a bit too loose. Luckily, I do have an inch pound torque wrench so I could make accurate measurements. I would have been very frustrated if I were trying to use weights and a string as some forums recommend.
I came down to where 55 was too tight and 59 was too loose. I was not able to build a pack in between with the shims I had. I finally gave up a made it just a bit loose. I hammered in a new seal and made the final install of the yoke. I had upgraded her to the U bolt style yoke from the strap style while we were in there.
I then replaced the set up bearings on the carrier with new ones from the rebuild kit. I once again used my soft hammer to tap the carrier into the housing and torqued the cap bolts to spec. I rechecked the backlash and pinion wipe pattern with the new bearings. Nothing changed.
With everything in place, I left her put the new gasket on the newly pink diff cover. She bolted it up and filled the housing with oil. She then put up her drive shaft and skid plate.
A test drive indicated that the new gears ran nice and quiet. We then took it for a quick run in the woods and enjoyed the new crawl ratio.
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