Jeep Grand Cherokee Dana 30 Front Axle - Project Ain't It GranderPosted in Project Vehicles on April 1, 2008 0) (
We went over the buildup of our rear axle last month, so now it's time to cover our front axle buildup which was a bit more extensive. Custom Dana 44s and 60s are really nice, but out of our budget. Yeah, we would love to have them too, but we decided to go with something that the average guy could easily duplicate in his garage at home.
While our Grand came with a Dana 30 front end that has served us some 95,000 miles, we had only been using an open differential and 31-inch tires. With 33s, and possibly 35s in the future, we felt something stronger was in order. While Dana 30 is not ideal, a buddy gave us a high-pinion 30 out of a Cherokee XJ. The high-pinion gains us two things: the ring gear is being driven on the proper side, and we would have less front driveshaft angle with the pinion coming out the top of the housing instead of the bottom. For gears, we again went to Motive Gear, company that has a long history as an OEM supplier, as well as to the aftermarket and to full-on racing of all kinds. A set of 4.10:1 gears was our choice, which with 33s would be the same as our previous 3.73:1 gearset and 31-inchers, though now we wish we had gone to 4.56:1s.
We wanted to have something to drive them equally, and the logical choice was ARB's relatively new 30-spline Air Locker. One of our biggest hang-ups with the ARB unit in the past was the fact that you had to notch the carrier bearing cap for air line clearance. To us, this just wasn't right. Well, guess the engineers Down Under finally also figured this out, and found a way to route the air line without notching the cap. Plus, there have been some more engineering updates to improve the overall strength of the unit. It's tough to find a place to mount the necessary air pump to operate the Air Locker, but we finally discovered just the right amount of room next to our K&N air filter.
For axleshafts, the original booted CVs were not going to hack it with all the new traction we were developing, so in went a special set of Superior's 4130, 30-spline shafts that use the larger-style 297 U-joint. However, we still had to run the smallerdiameter outers to fit in the stock-sized unibearing hubs. These are also made from 4130 material, so we really don't expect any problems. We replaced our original unibearing hubs with a pair from Crown Automotive. We also installed new ball joints sourced from Crown in the steering knuckles. Definitely quality stuff from Crown, not some cheap off-shore knock-off. We have used a lot of Crown's products in the past and have been very pleased with the results. OK, you can't buy directly from Crown, but Quadratec is our supplier.
Speaking of ball joints, don't try to pound the ball joints in and out with a big hammer! Use the proper ball-joint press tools to do the job right. Our low-cost tool set came from Harbor Freight and works great.
With Superior's new larger-diameter 30- spline axles come new inner tube seals. The short side is a '03-'06 Jeep Rubicon seal, and the long-side tube is a National seal (PN 473210). However, on the disconnect axle, a seal seat was never machined on the long-side axletube within the housing, as oil sealing was done at the disconnect housing. This means that there is nothing to support the long-side inner seal or to keep it square within the tube. Chris Overacker of Code 4x4 (www. code4x4.com) shared with me a little trick. I machined a chunk of aluminum bar down to .0025 inch over the axletube inner diameter and pressed it into the axletube. Now, the seal can rest solid against this bar and there is no chance of knocking it out when installing the axleshaft. Oh yeah, there is a 1.40-inch hole in it with a tapered "ramp" for the axle to slide through.
After this was done, we found that our Dana 30 came out of a very early Cherokee, and for some reason, the axletube inner diameter was a few thousandths of an inch larger than those of later vintage. That meant that the OD of the axleshaft seal we were supposed to use was too small. The proper-sized seal was not available anywhere. (Believe us when we say we searched.) After many sleepless nights, we finally figured out a way to make a tool that would slightly expand the OD of the seal to the proper size. And darn if it didn't work. One of the things we did to increase the axletube's strength was to make up a two-piece sleeve that we welded over the short span of axletube between the axle disconnect and the differentialhousing.
We also built a new taller mount for the track bar, and reinforced it both on the front and back side for added strength. This is important because there is a lot of side-to-side force applied to it as the axle travels through its suspension cycle. We spent a considerable amount of time, and the end results were worth it. The track bar follows almost the exact arc of travel that the steering drag link does for "bump"-free steering response. The mount also serves double duty as a steering damper location point. On the frame side of the track bar, we used a mount supplied by T&T Customs that moved the sway-bar mounting point downward about 2 inches.
We figured that stock brakes up front were not going to do the best job with tires and wheels that weigh about twice as much as the originals and that have a much larger rolling radius. Stainless Steel Brakes Corporation provided us with new quality cast rotors that have what are referred to as "Turbo Slots." These slots are specially designed to remove the gas buildup that occurs between the pads and the rotor during hard braking. A side advantage is that they also remove water and dirt that can get between the pads and rotors during off-highway travel. They also had just the right brake pads to ensure that our Cherokee's stopping distance would be improved in all driving conditions.
Rusty Megois of Rusty's Off Road knew just what coils we needed to get the 5 inches of increased ride height we wanted, taking into account the added weight of the ARB bumper and Warn winch, as well as our aggressive driving style. Rusty's model ROR508 coils worked perfect. Yes, going down the highway as a daily commuter, the front end is about an inch lower than the rear-we like the look-but when the back is loaded with a fullsize spare tire, a chainsaw, recovery gear, an ice chest, and other gear, it sits level and still looks good.
On our first buildup, we had used JKS upper stud-eliminator shock mounts as well as their pin-bar eliminators on the bottom mounts so we could use a more readily available and wider range of shock lengths that used the more common EB1 type eye. They had worked excellently, and we saw no reason to change them out. In our opinion, the lowers are almost a must-have, as they do an excellent job of capturing the shock bushing and preventing it from distorting and an early demise. We also used JKS adjustable bumpstops. These are pretty cool in that they allow for seven different height adjustments.
To get the power from the transfer case to the front axle, we again went to J. E. Reel Drivelines, who made us up one of its long-travel slip-yoke shafts and equipped it with the waterproof U-joints. Not only do these have better seals than a standard auto-parts-store joint, but the body is cold-forged and cryogenically treated for additional strength.
We definitely needed to improve the steering linkage to maintain good highway manners as well as the strength. Tera- flex offers a crossover-steering setup for the TJs that consists of a new right-hand steering knuckle that offered a provision for crossover steering, a very large hexshaped tie rod and drag link, and some really trick heavy-duty tie-rod ends. These tie-rod ends offer an offset that moves the tie rod outward so that you can still have full steering left and right without the tie rod hitting the diff cover. We also used them on the drag link to provide proper clearance for our track bar.
To control body motion, we went with one of Addco's 11/8-inch replacement sway bars, and modified a Teraflex TJ mount for the right side while using the factory axle mount on the left. The sway bar worked great, both on and off the trail, and we don't disconnect it unless we want maximum articulation. However, the added stiffness, along with the additional wheel travel the T&T suspension offered, bent the flat-bar connecting links into pretzel shapes. To solve it, we used the same Tera- flex ends but welded them to a section of 3/4-inch tubing. Teraflex offers some great adjustable tubular units that we will replace ours with one of these days.
During our "testing," the original power-steering pump decided it had had enough of a workout and the front seal failed. We also had noticed quite a bit of looseness in the pitman shaft, which contributed to not exactly positive steering. We replaced the steering pump with a local parts-store replacement but really wanted something a bit better than a mass-produced rebuilt steering box. We had been running some PSC components on one of our other Jeeps and were really impressed with the attention to detail and the quality of workmanship, as well as the support we had received. So we ordered up one of PSC's SG-621MR steering boxes. This is a precision rebuild with the added advantage of having the ports available to connect to a cylinder assist if we should so desire in the future. We can't believe the difference the PSC box made not only in road feel but in the lack of turning effort.
We wanted to make our Dana 30 as strong as possible and we feel we accomplished it. One thing that did bother us a bit was the housing strength. We've seen broken ring-and-pinion gears that we attribute to axlehousing flex, allowing the ring gear to pull away from the pinion. We explored several options and at first used Superlift's Rock Ring. It's a great product, and the one on the rear (as well as the ones on the front and rear of our other Jeep) have proven themselves many times over. We had seen a prototype nodular-iron cover built by ARB some time ago that had two unique crossbraces as well as a magnetic drain plug-and get this, a dipstick to check the lube level. We had to have one, and when Jim Jackson, president of ARB USA, told us they were available, we ordered one up. Yep, we are impressed with it. It's the next thing to go on.
Overall, we are pretty darn happy how the front end turned out, even though it took a lot of modifications, a lot oftime, and a bit more money than we had planned on. Next time, we'll discuss a few things that we did to finish up the project and make Ain't It Grander a lot more trailfriendly and comfortable.