|Axle Strength on the Cheap||Short Cuts|
By: Jeff Yokomura - 4/2000
|Danny White tries to extract his Jeep with the help of a tree. This is what happens when a Dana 35c's axle breaks. Notice, how happy he looks.|
Have you ever been in the backcountry and heard that unmistakable snap? With a broken axle shaft, bent tube, or chipped gear you're not going anywhere soon. It is not something you ever want to hear while in the middle of nowhere. Now what do you do? If you have a Dana 35c axle you watch your tire and axle squirt out. Your only option at this point is to three wheel out of the area and hope there is someone who can help at the trail's end. The solution is to get beefier axles. Currie and Dynatrac can custom build you any incarnation of a Dana or Ford axle to suit your needs. The only problem is they charge a premium for the best.
There are other options for those on a budget. Just like how Taco Bell sells inexpensive food, you too can have a inexpensive axle. The only catch is you need to do your homework and research your options. For this project we used a 1992 Jeep Wrangler (YJ) 2.5L with a Dana 35c. The axle already had 4.56:1 gears and a Detroit Gearless which were installed less then a year prior. The Stock axle had a overall width flange-to-flange of 60 inches and a 5 on 4.5 inch bolt pattern. This really limits your selection for axles since most trucks use the more common 5 on 5.5 inch bolt pattern. Many people do not know that during the late 80's and through to the early 90's, Chrysler used the Dana 44 axle in their Cherokee (XJ) and Commanche (MJ) lines.
|It may be hard to read but it says 605342 3 3VK 36 7 3x|
They were not on every Jeep but were only available for the Tow Package or Metric-Ton Package. For the Cherokee the Dana 44 was used from 1987 through 1990. Since the Commanche had a longer production run, it is safe to say that they may have used them till their end in 1992. There are a few notable differences between the Commanche and Cherokee axles. The Cherokee uses a Spring-Over axle suspension so the leaf spring perches are located on top of the axle tube, while the Commanche uses the Spring-Under axle suspension. This is not a big deal since in either case the perches would probably need to be removed. The donor axle was from an abandoned Cherokee. Since we were not there when the axle was recovered, it is unsure on the exact date of the Cherokee. Judging from the differential tag, the axle has 3.54:1 gears and an open carrier. This matches the model cast into the passenger side axle tube. The number is located on the passenger side axle tube and is usually buried under paint.
Model Numbers for Dana 44's
*courtesy of John Swink
|Model Number||Make||Gear Ratio|
|The Cherokee Dana 44 with an SM420 transmission.|
|Sam Purdy welding on the perches and shock mounts. Notice the slick footware.|
An important thing to note when comparing the Dana 35c with the Dana 44 axle is the axle tube diameter. The Dana 44 uses a two and three quarter inch axle tube diameter. This means that the old U-bolts and lower spring plates are not reusable. However, the lower spring plate can be ground out to clear the new U-bolts. To keep everything clean, we went with all new hardware. The new U-bolts, spring perches, shock mounts, and lower spring plate were all acquired from Currie Enterprise. The axle had 3.54:1 gears already in it. These would have to be removed and replaced with new 4.56:1 gears to match the front. Since a new carrier would need to be installed to use with the new gears, we found it a better choice to replace it with a Tractech Detroit Softlocker. With the help of our friend at Bar Offroad, we were sent new Spicer 4.56 gears along with a Yukon Master Install kit, new carrier bearings, and the Detroit Softlocker. It is a good idea to make sure the Master Install kit comes with new carrier bearings since those will have to be replaced, too.
The first thing that must be done is to remove all brackets, like the shock mounts and spring perches. To do so, it is best to remove the axle shaft and brakes then cover the bearing races and tubes from debris. To remove the perches and shock mounts, we had to grind the welds down enough to knock the brackets off with a hammer. Because the perches were stubborn, we switched from using the grinders to using a portable band saw. Once the tubes are cleaned and ground smooth, the new perches and shock mounts were ready to be welded on. Because the stock drivetrain and driveshaft were still being used, we went with the stock settings. For the shock mounts we did make some changes. The Currie shock mounts are about one inch shorter then the stock mounts. To help increase clearance we rotated the mount up to gain more ground clearance. This increases ground clearance but also limits your rear shock. We felt that the added ground clearance was more important than the loss in shock length.
Once the perches and shock mounts were welded on, next came the installation of the Detroit and 4.56 gears. This was relatively straight forward. We took some extra care in installing these. At first we tried to guess the shim pack. Since we did not have a arbor press, we put the carrier bearings into the oven at 350 degrees for 20 minutes. Theoretically, this would expand the bearings enough to slide them over the Detroit, but it proved to be a bad idea. We pulled the old carrier bearings and ground them out. This makes the old bearings slide easily on the carrier so you can set up the shim packs without trouble. Another problem arose when we found out the new bearings were one sixteenth narrower than the old ones, but after a while we were able to come out with a perfect gear pattern.
|The axle barely fit in the YJ with the rear seat removed and the front seat pushed forward.|
When the axle was done it was time to bring it home and continue the preparations. Once back home, we were able to give it a good cleaning. To get some of the deep grime off, we used a drill with a wire wheel. This made short work of the old paint and grime. Actually, it worked so well on the cover that it looked polished. This technique also removed much of the rust found on the drums and around the housing. Since we did not want to powder coat something that will be dragged against rocks, we decided to use Hammerite Rust-Cap Hammered Black instead. Hammerite is a great product. It has resins and glass in it that form a rustproof bond with the metal underneath. It holds up to rust and rocks as well. For this project only two cans were used to spray everything. The Hammered Black comes out a dark grey but looks really nice.
|Here the housing gets a good cleaning with brake cleaner and a wire wheel on a hand drill.|
To make it easier to move the axle out and around the garage, we left the leaf spring and tires on. The leaf springs made it possible to keep the pinion from rotation downwards and hitting against anything. By removing the emergency brakes, T block, and the shackle and spring hanger bolts, the axle easily rolled out. With the axle removed, we proceeded to transfer the tires over to the new axle. The wheels went onto the new axle fine, and we decided to leave off the wheel center caps. Once the tires were on, the new axle was mobile for the first time. Next up was to remove the U-bolts and move the leaf springs over to the new axle. Since the leaf springs needed some cleaning, this was the time to do it. A quick scrub down and some coats of paint made the leafs look new again. With the leaf springs on the Dana 44 is was time to see if everything fit together with the frame mounts. Because the axle had a Detroit Softlocker installed it required two people to maneuver the axle into position. This took a few attempts since the locker kept wanting to go straight. Once it was in the general position and the leaf springs have been moved into position with the spring hangers we were able to put the bolts back into the hangers. This will be enough to hold the axle into position and the pinion yoke pointed the right way. Because the we knew there would be more adjusting we just hand tightened the hanger and shackle bolts for the time being.
With the tires on we later noticed that the axle was one inch too far on the passenger side. Since everything was bolted together, it was easier to remove the tires and let the axle center itself naturally then to roll the axle out again. Once the tires came off the axle centered and was ready for the hanger and shackle bolts to be torqued We typically go lighter on the torque ratings stated in the Factory Service Manual since ride and suspension flexibility will suffer if they are too tight. Once the axle was into place we were able to reattach the shock mounts and driveshaft. Because the Cherokee used the Dana 35c and Dana 44 the pinion yoke fit the Wranglers driveshaft without any problems. Be sure not to over tighten the yoke straps or else there may be problems later on. Such as sheared yoke strap bolts. This would be a good time to replace the yoke straps with U-bolt style straps. These are stronger and will hold up much longer then the regular yoke straps.
Here you can see what may have taken a few hours condensed into four pictures.
It was time to dive into the brakes. From the looks of it they were in good shape. The pads had more than enough life in them. One problem with the brakes from an Cherokee is that the they use a center emergency brake lever instead of using a pedal like the YJ. This means that the two cables are of even length and will not work with the YJ's set up. However, this is fairly easy to fix. We decided on using the Cherokee's driver side cable and the Wrangler's passenger side cable. This was done because the Wrangler's driver side cable was very short. This would most likely reduce suspension travel, so the longer Cherokee cable was used. The only problem with using the longer cable is routing it so it would not get squished or caught on anything. Here is a tip that could save you a lot of time. To be able to remove the emergency brake cable without having to remove the brakes disconnect the clips that hold the sleeve to the frame and back plate. Once that is done we pushed the cable into the sleeve from the fame mounted end.. This gave us a lot of slack on the cable and usually pushes the spring which locks the emergency cable to the shoe out. With a screwdriver we were easily able to pop the cable out from the brake pad.
Other things to note since we are on the subject of brakes is that the Wrangler uses a combination T block and axle breather while the Cherokee uses separate breather and T block. Also, the breather for the Wrangler has much larger diameter tube then the Cherokee's. This has not been fixed yet but should be by the time you read this. Because the Cherokee uses a breather separate from the T fitting for the brake, the block was in a different location. The old brake hardline would not come free from the T block, and we were not able to reuse it. So, the T block and hardline was reused from the Dana 35c. Care must be taken when rebending the line. If you bend it too many times, it can cause cracks in the tube and will leak. At that point the hardline should be replaced. Another option to bending the line is to buy a replacement pre-bent hardline. The Dealer typically sells these. Or else you can go to the local Auto Parts store and but straight hardline in various lengths. You will also need a tube bender if you go with the hardline. Once the line was bent everything went together and there were no leaks.
|Make sure to cut the extra length from the U-bolts before they snag something on the trail.||This is the re-bent brake hardline. It doesn't look too bad.||The tires came off again to make certain that the axle was centered correctly.||Here is the Cherokee Dana 44 in the Wrangler|
The last steps were simple. We needed to remount the wheels and tires and put gear oil in the Dana 44. We did not put oil in earlier because were were still moving the axle around and did not want to end up leaving a mess anywhere. The Master Install kit came with a paper differential cover seal but we decided to use Permetex Ultra Blue RTV Silicone sealant instead. While the RTV cured a bit we took the time to bleed the rear brakes. Because we had to remove the rear lines air was trapped in the system. To remove the trapped air we used a Mighty Mite vacuum pump. This made it possible for one person to bleed the system alone which saved time and got the brakes firm and without air. Because we did not replace the old brake cylinders this is the time to check if they are leaking. Our axle had good looking boots and the seals were OK to use. With everything put back together it was the moment of truth.
We backed the Jeep out of the driveway slowly and there were no strange noises. The brakes seemed to be working fine. The emergency brake still needed to be adjusted but everything else looked OK. As we got the Jeep on the street, grinning from ear to ear, a months work had finally been acomplished. A few days later we ended up replacing the balding 32's with 35x12.5R15 Goodyear Wrangler MT/R's. It would not have been advisable with the stock Dana 35c but with the new strength of the Dana 44 we were ready.