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Project 1 - Raptor > Rear Axle

Actual pictures coming soon

Next On Oprah - Why I Choose An Ford 8.8 over a D44, D60, Ford 9 Inch or Super 35 Kit.... Since everyone asks, here's the simple answer: they're readily available, they're strong and they're cheap and require very little prep work to install, compared to other options. Oh, and they weigh not much more than our D35 AND offer similar clearance. Now the guys we 4x with usually seem to have their high pinion 9 inch Currie's or their Dana 60's, etc but remember, this project is all about the average person with a modest budget can do to make their rig tough offroad while maintaining it's on-road driveability. No $20,000 budget here. Sure, if money weren't an object we may have chosen something else but the fact is, the Ford 8.8 is a great axle. If you don't see pictures on this report, I will eventually post them. You should see the 8.8 sitting next to the stock Dana 35. The darn thing is HUGE. The axle tubes look about 3.25 inches alone and the extra 4 splines give you an impressive increase in durability. Here are a few more reasons we choose the 8.8:

Price: we found a late model, low mileage Ford 8.8 for $250, plus about $100 shipping. Most other axle options we investigated were closer to $500-$1500. Note: we still need/needed to buy calipers, an e-brake cable and more, but overall the expense is still lower. We'll detail expenses below.

Features: Disc brakes...standard! You can also often find ones that have a limited-slip differential. While not nearly as good as a locker, limited-slip is better than nothing and in our case, it will hold us for a little while until we're able to buy the ARB air locker for this axle.

Ease of installation: It's not "bolt-on" but modifying the 8.8 for installation in Raptor doesn't require a significant amount of modification. Plus, the width is only 1/2 inch shorter on each side. This is barely noticeable and can be fixed with half-inch spacers.

Before we get into the rest of the details, I'm sure some of you are wondering why we even are interested in swapping in a new axle in the first place and is this something the average Jeeper should really consider. Consider this: you're out 4 wheeling with your Jeep riding on 33 inch tires. You power up a hill and finally power over some rocks to crest the hill when BAM, your Jeep stops. You broke the weak 27 spline axle from your stock Dana 35. Now unless you have a spare with you or are able to let your Jeep sit there until you can get one, you're looking at a possible tow job, miles out in the wilderness, plus the cost of a replacement axle, plus installation, etc. The cost of all this together could easily end up around $1,000 and then you end up with the same stock axle and you'll be afraid to drive you Jeep in tough places. It really isn't very hard to break an axle when you're running tires 33 inches or above. You don't even need to be a hardcore rock climber (we're not). So we figure for about $500 or so we can proactively prevent such weakness and at the same time pick up the added safety of rear disc brakes. We also wanted to complete this upgrade prior to lifting Raptor. This is one of the building blocks of future upgrades. Sure it won't make Raptor look any better and it won't add significantly to it's 4x4 abilities today, but we feel it's an important start.

Misc notes:

• The Ford 8.8 that comes on Ford Rangers is apparently 28 spline as opposed to the 31 spline axles from the Explorers. Also, Ranger axles may only come with drum brakes whereas the late 90's Explorers came with disc brakes.
• A weakness of the 8.8 seems to be where the axle tubes are attached to the differential. Some people seem to weld around the axle tube on each side to strengthen the connect while other suggest spot welding in a few places. I need to investigate this further.
• If you pull an 8.8 from an Explorer, you'll need an adapter to attach your driveshaft. M.O.R.E. sell these but you can also buy a Spicer adapter from Napa. No part number yet.
• Axle strength for a 31 spline Ford 8.8 is reported to be 5,707 pounds-ft yield torque. Yield strength is the point at which the metal deforms, before breaking, which makes it a more relevant figure for determining axles strength. The axle size is 1.29 inches and the material is usually 1040 carbon steel in stock format. 1050 carbon steel is 10% stronger, 1540 carbon steel is 15-20% stronger and 1341H, 1541H and 4340 carbon steel are 20%, 20% and 40% stronger than 1040, respectively. Comparitively speaking, the 27-spline Dana 30 and Dana 35 have a yield torque of only 3,640 lbs-ft., partially due to their smaller 1.11 inch size. (Summary: Ford 8.8 - 5,707 lbs-ft and Dana 30 and 35 - 3,640 lbs-ft) Source: Off-Road Adventures, June 2003
• Some who have done the Ford 8.8 swap have suggested that there needs to be a change in front and rear hydraulic proportioning in order for the brakes to work properly. I haven't figured this part out yet but Wilwood offers an adjustable proportioning valve that may be useful in getting the ratio right. 4-Wheel & Off-Road mentioned the valve in their December 2002 issue (page 48) saying, "With most four-wheel disc brake conversions there is no need to keep the factory-proportioning valve at all. You just run full line pressure form the master cylinder to the front brakes and then run the rear brake line through the adjustable proportioning valve to adjust the feel as necessary." Of course if you do this, you'll want to test it all in a safe area before venturing out onto the road.
• I'm considering using axle shafts for the 8.8 that are drilled for a 5 on 5.5 bolt pattern. Not only is this stronger but since I'm considering upgrading my front axle pattern to 5 on 5.5, it's important to match front and back. I spoke with Eric at National Drivetrain who said they can build the axle shaft that was, of course for a price.

12/11/2001 - A couple days after it was shipped, our axle arrives at Yellow Freight where we happily pick it up in the middle of the night. A couple of guys stop to talk Jeep and axles and seemed impressed with our find. At this point, we're feeling pretty good. We bring it home and set it on some jack stands in the garage where it will wait to be prepped. Our 8.8 came from a wrecked (in the front) 1998 Ford Explorer with only 38k miles on it. The axle has been sitting outside for a while and it's not very pretty at this point - lots of surface rust. But when we're done with it, it will look almost new.

We're planning for a late February install so we can test the axle out at the 2002 Tierra del Sol event in early March. There are a couple of steps before we get to the install and I'll detail them along the way.

10/23/2003 - An update. Yes it's been almost two years since I acquired this axle but I've decided to install it when we install the lift so we get the pinion angle correct when welding the spring perches. Additionally, I needed 3.73 gears for our front Dana 30 and recently located a YJ high pinion Dana 30 with 3.73 gears already installed that we'll be using in the front. This way I can work on both axles to prepare for the install while continuing to drive our Jeep on a daily basis. For more on the front axle, visit this page.

more soon...

For more information on installing a Ford 8.8 axle in the rear of your Jeep, click this search query.

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