The Ford 8.8 or Explorer 8.8 is becoming a very popular axle to install to just about everything. With the availability of practically “everywhere”, high support, and ease of mod, it is no surprise why people are turning to the Ford 8.8 as their solution to differential upgrades.
Tons of information exists regarding the 8.8, but only “talk” about the task of narrowing the Explorer 8.8 seems to exist no matter how much searching you do. This article is not written to discuss all the vehicles you can use it on, which is best, or any opinions regarding “the best” for the job. This is simply a “How-To” get the job of narrowing done and into your ride.
Why the Ford 8.8?
There are many reasons to use a Ford Explorer 8.8 from the 1995-2004 Ford Explorer. Here are a few key “pluses”
- Easily found at almost any junk yard
- Variety of gear ratios and options (LSD, open diff, etc.) available
- Easy to fit into most RWD vehicles
- Rear disc brakes (typically an upgrade)
- Common 5 x 114.3 0R 5 on 4 ½ lug pattern
- Plenty of Aftermarket support for future upgrades
- Very strong. Handles abuse from track racing to offroad and everything in between
(located in driver door jamb or on differential tag)
43 = Open 3200 3.08
41 = Open 3200 3.27
42 = Open 4.10
46 = Open 3.73
45 = Open 3200 3.55
D4 = Limited Slip 3200 3.73
D2 = Limited Slip 4.10
L73 = Limited Slip 3.73
Common Dimensions and Weight
Ring Gear Diameter - 8.8 inches
Axle Tube Outside Diameter - 3.25 inches
Axle Tube Wall Thickness - 0.25 inches OR 0.188 inches
Axle Diameter - 1.320 inches
Axle Spline Count - 31 splines
Assembly Width - 59.625 inches
Assembly weight - 175 pounds (approximate)
Assembly Width After Narrowing
**Note: Measurement is wheel mounting surface to wheel mounting surface and may differ slightly depending on brake rotor manufacturers thickness of rotor hat surface.
Q: Where do I find the correct Ford Explorer 8.8, 31 spline axle?
Start searching for:
1995-2001 Ford Explorer
1995-2001 Mercury Mountaineer
*Tip* To narrow down your search, if you find rear disc brakes, you are on the right track. Earlier models were equipped with drum brakes and different splined axles.
Q: How do I ensure I have a 0.25 inch axle tube?
Unscrew the vent fitting on the passenger side axle tube. You will be able to see the wall thickness of the tube.
Q: How do I find the axle code?
Look in the Drivers side door jamb (on the door). All the vehicles information is listed on the tag including the “Axle Code”
The Differential tags are coded with either an “L” for Limited Slip, or a “C” for Conventional (open differential)
4L10 = Limited slip differential with 4.10 gears
3C08 = Open Differential with 3.08 gears
Q: Can the Explorer 8.8 be Narrowed?
Yes. The Explorer 8.8 is almost famously narrowed easily.
Q: I heard you can narrow the Explorer 8.8 by making only one cut. Is this true?
Technically, no. It takes two cuts to narrow the Explorer 8.8. You also need to weld the tubes back together. The Explorer 8.8 is sometimes known as the “one cut diff” because you only need to cut one side down to narrow it. It takes 2 cuts to remove the correct length of tube needed to narrow the axle and one weld to stick it back together.
Q: Which Side Needs to Be Cut To Narrow the Explorer 8.8?
The Driver’s side. If you look at the Explorer 8.8 rear axle, you will notice the driver’s side axle tube is longer than the passenger side. This actually offsets the differential “pumpkin” to the passenger side. The Explorer 8.8 is narrowed by cutting out 2.875 inches from the driver’s side axle tube, welding it back together, and installing a separate passenger side axle in the now shortened driver’s side axle tube.
Q: Where do I source a shorter axle to match the narrowed Driver's side?
You need to grab a second axle from the Passenger side of a separate/different Ford Explorer with the 8.8. You are basically narrowing the Driver's side to the same length as the passenger side, so you need 2 passenger side axles. Once you narrow the Driver's side, you will install the shorter axle just as it would be from the factory.
SPECIAL NOTE: Since most people will be purchasing a used Ford Explorer 8.8 from a scrap yard, take a few extra minutes to remove the second passenger axle, remove the long driver's side axle, and purchase the whole assembly with the shorter axle. There is no use at all for the longer Driver's side axle.
Q: Is Narrowing a Ford Explorer 8.8 Axle Easy?
“Easy” depends on experience and ability. Generally speaking, it is easier than most rear ends and is often considered a DIY weekend job.
Q: Do I Need Any Special Tools to Narrow the Explorer 8.8 Rear End?
You need general metal working tools such as a grinder and a welder. You should also have the knowledge regarding use of your tools and experience with them. Remember, if your cut is crooked and your weld is crappy, you could split the axle tube while driving and cause serious harm or even death to yourself or people around you.
BE SERIOUS about your ability. If you have never welded before, you should not take on narrowing a rear end as your first project (or second, or third, etc.) You should have a few years of experience, a strong capable welder, and confidence in your work.
Q: What Kind of Welder Should I use?
MIG, Arc, or TIG welders are capable of doing the job. A little flux cored hobby welder (aka “Shock box”) from your local bargain store is NOT considered a capable welder. Your welded should be able to weld ¼” steel, but not at a “max” rating.
- A welder rated for 20 Gauge sheet metal to ⅜” steel is a capable welder because ⅜” is the max, which is more than ¼”.
- A welder rated for 26 Gauge sheet metal to ¼” steel is technically not a capable welder because you are welding at the maximum rating. Welding at max can lead to a weak weld due to low duty cycle. It is possible, but not recommended.
You should use a capable welder and be proficient with the welder you intend to use.
Q: Do I Need Extra Brackets, Perches, Tabs, or Anything After Welding?
You might. Every install is different. You should know what you are installing your narrowed diff into and what is needed to adapt it to your vehicle. Leaf spring perches, coil spring buckets, 4 link tabs, and so many more parts can be purchased online from a multitude of vendors. Just remember to order parts for a 3.25 inch axle tube. Parts are usually listed for the diameter (3.25 or 3-¼”), but some are listed with a radius of 1.625”
Q: What kind of upgrades can be made to the Explorer 8.8?
Everything can be easily purchased from upgraded brakes, to stronger axles, different gear ratios, upgraded gears, different lockers, and so on.... It literally is near endless because the Ford 8.8 is a common differential. Just remember you will have TWO passenger side axles if you choose to order upgraded axles.