I think most of us know the choices for a Ford rear end in an older small or mid size Ford. If you have a Fairlane they only came with an 8” or 9” rear. Mustangs and Falcons did come with the smaller 4 bolt 6 cylinder rear. An 8” looks good next to those and is a fairly strong rear end.
One weakness of these rears is actually the size of the axle. 8” and 9” axles both came with 28 spline axles. The axle can be the weak link in these rears along with the 8.8”. High performance and truck 9” rears came with 31 spline axles. Any one looking to upgrade has also seen how much it costs to go that route. The 8 and 9” do have the advantage of the removable center section and no “C” clips holding the axles. I had an 8” rear that was open and now had enough power that it was a problem getting the car down the strip.
A posi unit and good axles would hold up well at my power level. All of the sudden I was over $700 just to upgrade it a bit. I wanted to “explore” my options at that point because most of the parts are similar in price no matter which rear. I have seen many references to 8.8 Explorer swaps.
A lot of the 4x4 guys swap them into Jeeps and other vehicles because of the strength and low cost. So what is the deal? The information I have seen would say a 31 spline 8.8 would be stronger than pretty much any 28 spline 8” or 9” rear because the axles are no longer the weak link. When I measured the smallest diameter on both shafts it told why.
![]()
The area of a 28 spline was .83” versus 1.35” for the 31 spline measured at the narrowest spot. So is there a strong inexpensive solution? I think so. It is the Explorer 8.8 rear. All have 31 spline axles and most have posi. Pick early or late to get drum or disc brakes depending on what you want. 1995 on up should have disc brakes with a nice parking brake that is a simple drum inside the disc. As long as I was doing it I went for the discs as one more befit to the swap.
Follow along to see how I did it. First I went to my local U-Pull to score a rear end. With special thanks to my brother Jon who stuck with me until we got all the parts we needed. Do a search for axle codes before you go so you can look at the door tag and make sure you get what you want. I also checked the axle tag just to be sure and the ring gears are marked as well. Ratios I have seen listed range from 3.08 to 4.10. Most I saw were 3.73 gears with posi.
This next trick is what makes this work. Explorers have one axle tube that is about 3” longer than the other and they are about 3” wider than my stock rear. Most cars are centered. Be sure to get 2 short axles because you are going to end up putting a stock short axle in that long tube. A stock 1964 rear is about 57.5” and the narrowed 8.8 will end up being about 1” narrower than stock. Time to remove the original 8” rear end.
![]()
$86 for a 31 spline posi rear with good disc brakes. I consider that a deal. If you do it yourself make sure you get all the cables to the front of the truck for the parking brake. Living in Minnesota I actually got a fairly low mileage cash for clunkers rear axle. I hate the whole concept of CFC but that does not change the fact that things can get very rusty.
![]()
You may get a rear with a sensor installed in it. You can pull the wire and leave it or I found a ½” pipe tap will run down the hole so a pipe plug can be used.
![]()
The next step is disassembly and cleaning. If you do it yourself make sure you take pictures or document where the shims and caps fit. If your bearings and gears are good you can just put it back together as is when done.
![]()
It seems there is often a tar like substance in the tubes after a while.
![]()
Here are some tools I used to clean the tubes. The copper is two pieces soldered together used to scrape the tube first. The brushes are on ¼” threaded rod that was run down the tube with solvent.
![]()
This is how it looks when clean. This also shows the nice weld on the shortened tube. Do not use a torch to cut off brackets you will not use since it will warp the axle tubes. I already had a sway bar or I may have looked a little closer at the one from the Explorer. The Explorer rear spring mounts can be used again. I ground the welds down and used a cut off wheel.
![]()
I tried the electrolysis rust remover that I saw in an article here. I did the whole axle and all the parts. The rear I picked was actually in very good condition other than the rust. I started with a Barrel and did the axle half at a time.
![]()
I flipped the axle and kept going until it looked good. I went over it with with a wire wheel on an angle grinder before I primed it. Then it went out for powder coating………until I saw a $3.99 can of semi gloss black at Menards. Hey it is a budget build right?
![]()
This rust thing is working well. I used some perforated angle to drop in a smaller tank and cleaned up the bolts. I was able to reuse almost all the fasteners.
![]()
I did not measure the long axle as a reference and I would suggest you do if you are not bringing it home with you. It would be nice for who ever narrows it. Cutting and welding the axle is one of those areas that I thought I could do it but knew there were shops set up to do it that have the tools and expertise to check and do it right. I chose Tin Man Fabrication in Oak Grove MN. Tin Man Fabrication, Inc. - Full service street rod and specialty vehicle shop. Jim shortened the one tube based on the short axle, straightened both tubes, and welded my spring perches on for a price that I thought was a value. After seeing the work I am glad I did not do it. I also could not have checked it for straightness. Check it out he also makes some parts for things like mod motor mounts in older cars.
![]()
I test fit things before I painted them just to be sure. It fit right in. My 8” had 5/16” bolts through the springs. The Explorer had a larger bolt that I could not use. The bolt centers the spring so I found some thick washers that fit inside the spring pads and put them on my existing spring bolts. The lower brackets in this picture were tossed. I am glad I tested them before welding them in.
![]()
A 64 Fairlane rear has springs that are not parallel. If that is true in your car allow a little extra width to accommodate the angle. In my case that was about ¼” wider than the spring width.
![]()
The Explorer rear also has larger tubes. My mounting plates would not work as is. I used the Explorer U bolts and they needed to be moved inboard to eliminate the original rubber isolated spring mounts. Here is a copy of my paper template.
![]()
Time to transfer to metal.
![]()
This is the top of the plates tacked in place.
![]()
Here is the bottom. I had originally eliminated the rubber spring isolators. That did bend this a little since it used to be bolted to another part. I needed to reinforce it so I added this angle bracket. I figured with the three holes I can adapt to slapper bars or cal trac like bars if need be in the future.
![]()
Here they are with a $3.99 powder coat.
![]()
Next it is a matter of getting the parts you need to finish the job. I used new explorer hose assemblies and bent a new line to go between them. If your backing plates need cleaning up there are two rivets holding them together. Drill them out to clean and paint and then pop rivet them back together. My used brake pads were half there but it was in my budget to spend $20 for new pads.
![]()
The hose to the body did not quite line up. The original bracket also held the fuel line in place. I used a clamp on the fuel line and cut and remounted the bracket. A coupling and a short line will make it work.
![]()
Due to the larger rear axle tubes my old sway bar brackets did not work. This is what I came up with. Basically muffler clamps with a bolt welded in for the mount.
![]()
The disc brake rears have a notch that grabs the cable from the little drum brakes inside the rotors. I plan on using the Explorer cable. It runs to the drivers side with a single cable. I then hope to connect it to my cable from the original with some kind of clamp.
![]()
A note if you buy a ring and pinion install kit. I bought a Ford Racing one for a Mustang. The Explorer has larger axle bearings and seals so get one for an Explorer. I also found that the two Ford Racing dealers in my area would sell 10% over cost to clubs. It was cheaper at the dealer than anywhere. All parts were also made in the USA unlike the Auto store bearings I picked up.
![]()
Every thing here could be done well under $500 with new bearings and seals. Try that with a 31 spline 9”.
![]()
Since I purchased mine from a U Pull they punch a hole in the cover to drain it. I welded a ¼” coupling to it so it could be a drain plug in the future. I also welded a couple rod couplings to the cover so I could mount an aluminum “M” just for grins. Hey it is an M cooler.
![]()
I now have better gears for my application. I also gained posi and 31 spline axles. The little bit narrower also rear makes it a little easier to get my tires on and off. Now it is time for some bigger tires.
.
One weakness of these rears is actually the size of the axle. 8” and 9” axles both came with 28 spline axles. The axle can be the weak link in these rears along with the 8.8”. High performance and truck 9” rears came with 31 spline axles. Any one looking to upgrade has also seen how much it costs to go that route. The 8 and 9” do have the advantage of the removable center section and no “C” clips holding the axles. I had an 8” rear that was open and now had enough power that it was a problem getting the car down the strip.
A posi unit and good axles would hold up well at my power level. All of the sudden I was over $700 just to upgrade it a bit. I wanted to “explore” my options at that point because most of the parts are similar in price no matter which rear. I have seen many references to 8.8 Explorer swaps.
A lot of the 4x4 guys swap them into Jeeps and other vehicles because of the strength and low cost. So what is the deal? The information I have seen would say a 31 spline 8.8 would be stronger than pretty much any 28 spline 8” or 9” rear because the axles are no longer the weak link. When I measured the smallest diameter on both shafts it told why.
The area of a 28 spline was .83” versus 1.35” for the 31 spline measured at the narrowest spot. So is there a strong inexpensive solution? I think so. It is the Explorer 8.8 rear. All have 31 spline axles and most have posi. Pick early or late to get drum or disc brakes depending on what you want. 1995 on up should have disc brakes with a nice parking brake that is a simple drum inside the disc. As long as I was doing it I went for the discs as one more befit to the swap.
Follow along to see how I did it. First I went to my local U-Pull to score a rear end. With special thanks to my brother Jon who stuck with me until we got all the parts we needed. Do a search for axle codes before you go so you can look at the door tag and make sure you get what you want. I also checked the axle tag just to be sure and the ring gears are marked as well. Ratios I have seen listed range from 3.08 to 4.10. Most I saw were 3.73 gears with posi.
This next trick is what makes this work. Explorers have one axle tube that is about 3” longer than the other and they are about 3” wider than my stock rear. Most cars are centered. Be sure to get 2 short axles because you are going to end up putting a stock short axle in that long tube. A stock 1964 rear is about 57.5” and the narrowed 8.8 will end up being about 1” narrower than stock. Time to remove the original 8” rear end.
$86 for a 31 spline posi rear with good disc brakes. I consider that a deal. If you do it yourself make sure you get all the cables to the front of the truck for the parking brake. Living in Minnesota I actually got a fairly low mileage cash for clunkers rear axle. I hate the whole concept of CFC but that does not change the fact that things can get very rusty.
You may get a rear with a sensor installed in it. You can pull the wire and leave it or I found a ½” pipe tap will run down the hole so a pipe plug can be used.
The next step is disassembly and cleaning. If you do it yourself make sure you take pictures or document where the shims and caps fit. If your bearings and gears are good you can just put it back together as is when done.
It seems there is often a tar like substance in the tubes after a while.
Here are some tools I used to clean the tubes. The copper is two pieces soldered together used to scrape the tube first. The brushes are on ¼” threaded rod that was run down the tube with solvent.
This is how it looks when clean. This also shows the nice weld on the shortened tube. Do not use a torch to cut off brackets you will not use since it will warp the axle tubes. I already had a sway bar or I may have looked a little closer at the one from the Explorer. The Explorer rear spring mounts can be used again. I ground the welds down and used a cut off wheel.
I tried the electrolysis rust remover that I saw in an article here. I did the whole axle and all the parts. The rear I picked was actually in very good condition other than the rust. I started with a Barrel and did the axle half at a time.
I flipped the axle and kept going until it looked good. I went over it with with a wire wheel on an angle grinder before I primed it. Then it went out for powder coating………until I saw a $3.99 can of semi gloss black at Menards. Hey it is a budget build right?
This rust thing is working well. I used some perforated angle to drop in a smaller tank and cleaned up the bolts. I was able to reuse almost all the fasteners.
I did not measure the long axle as a reference and I would suggest you do if you are not bringing it home with you. It would be nice for who ever narrows it. Cutting and welding the axle is one of those areas that I thought I could do it but knew there were shops set up to do it that have the tools and expertise to check and do it right. I chose Tin Man Fabrication in Oak Grove MN. Tin Man Fabrication, Inc. - Full service street rod and specialty vehicle shop. Jim shortened the one tube based on the short axle, straightened both tubes, and welded my spring perches on for a price that I thought was a value. After seeing the work I am glad I did not do it. I also could not have checked it for straightness. Check it out he also makes some parts for things like mod motor mounts in older cars.
I test fit things before I painted them just to be sure. It fit right in. My 8” had 5/16” bolts through the springs. The Explorer had a larger bolt that I could not use. The bolt centers the spring so I found some thick washers that fit inside the spring pads and put them on my existing spring bolts. The lower brackets in this picture were tossed. I am glad I tested them before welding them in.
A 64 Fairlane rear has springs that are not parallel. If that is true in your car allow a little extra width to accommodate the angle. In my case that was about ¼” wider than the spring width.
The Explorer rear also has larger tubes. My mounting plates would not work as is. I used the Explorer U bolts and they needed to be moved inboard to eliminate the original rubber isolated spring mounts. Here is a copy of my paper template.
Time to transfer to metal.
This is the top of the plates tacked in place.
Here is the bottom. I had originally eliminated the rubber spring isolators. That did bend this a little since it used to be bolted to another part. I needed to reinforce it so I added this angle bracket. I figured with the three holes I can adapt to slapper bars or cal trac like bars if need be in the future.
Here they are with a $3.99 powder coat.
Next it is a matter of getting the parts you need to finish the job. I used new explorer hose assemblies and bent a new line to go between them. If your backing plates need cleaning up there are two rivets holding them together. Drill them out to clean and paint and then pop rivet them back together. My used brake pads were half there but it was in my budget to spend $20 for new pads.
The hose to the body did not quite line up. The original bracket also held the fuel line in place. I used a clamp on the fuel line and cut and remounted the bracket. A coupling and a short line will make it work.
Due to the larger rear axle tubes my old sway bar brackets did not work. This is what I came up with. Basically muffler clamps with a bolt welded in for the mount.
The disc brake rears have a notch that grabs the cable from the little drum brakes inside the rotors. I plan on using the Explorer cable. It runs to the drivers side with a single cable. I then hope to connect it to my cable from the original with some kind of clamp.
A note if you buy a ring and pinion install kit. I bought a Ford Racing one for a Mustang. The Explorer has larger axle bearings and seals so get one for an Explorer. I also found that the two Ford Racing dealers in my area would sell 10% over cost to clubs. It was cheaper at the dealer than anywhere. All parts were also made in the USA unlike the Auto store bearings I picked up.
Every thing here could be done well under $500 with new bearings and seals. Try that with a 31 spline 9”.
Since I purchased mine from a U Pull they punch a hole in the cover to drain it. I welded a ¼” coupling to it so it could be a drain plug in the future. I also welded a couple rod couplings to the cover so I could mount an aluminum “M” just for grins. Hey it is an M cooler.
I now have better gears for my application. I also gained posi and 31 spline axles. The little bit narrower also rear makes it a little easier to get my tires on and off. Now it is time for some bigger tires.
.
