Drivetrain Tech General discussion of drivetrain for the Ford Ranger.

Mystery 8.8/7.5 differential question…

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Old 12-19-2022
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Mystery 8.8/7.5 differential question…

Hey everyone. I’ve got a question regarding the rear differential in my 2006 Ford ranger 4L FX4. I am redoing the clutch pack in the limited slip differential and decided to do the axle seals while I’m there. The body and rear axle tag both say that the differential is an 8.8, however, all three parts stores I went to tried to give me a much larger axle seal. I brought in my old axle seal and it is sized identically to the part listed for a 7.5 rear axle. Any thoughts on the matter? It’s hard to imagine that somebody swapped out the differential and even put the old axle tag on to cover it up… is this just a case of out of date part numbers perhaps? Thanks everyone.
 
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Old 12-19-2022
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7.5" and 8.8" used the same axle bearings and seals since both used the same 28-spline axles, and axle tubes
So yes that would be correct

Explorers used 31-spline axle 8.8" and sometimes parts store will give you parts for those which are bigger

Ranger FX4 Level IIs got the 31-spline but no clutch packs, it was Torsen gear limited slip
 
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Old 12-19-2022
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Thanks, I thought that the two would have had the same axle tubes. So it’s probably the case that all of the parts stores around here are using the same database, and that database has the explorer 8.8 part number in place of the ranger 8.8. It is surprising then how much bigger the 31 spline axle is though because the seal they wrongly gave me at first was markedly bigger than the proper seal. With that said, however, my truck has done a fair amount of 4 x 4 time, and that slightly smaller axle has never provided any problems…
 
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Old 12-20-2022
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RockAuto shows 2 part numbers for the 06 8.8 wheel seals. Like RonD mentioned, there are two due to a package option.

If you are curious if you do have an 8.8, and not a 7.5, just take a look at the rear diff cover, and that will indicate which one you own.

Ford Rear Axle Identification
 
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Old 12-21-2022
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Originally Posted by Turismolover22
RockAuto shows 2 part numbers for the 06 8.8 wheel seals. Like RonD mentioned, there are two due to a package option.

If you are curious if you do have an 8.8, and not a 7.5, just take a look at the rear diff cover, and that will indicate which one you own.

Ford Rear Axle Identification
Thanks, yah I double checked, it definitely is the 8.8(28). It would appear that the 8.8 part number they list must be for the 8.8/31spline and the 7.5 part number they list is for the 8.8/7.5/28spline. Either way it back together and should make a world of a difference. Previous to the clutch rebuild my axles had nearly a half inch of outward play due to the worn clutch pack, there is now zero. I’m excited to see how well it does in the one wheel low traction scenarios now, it used to run like an open carrier! 🤦🏼‍♂️
 
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Old 12-21-2022
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Originally Posted by Turismolover22
RockAuto shows 2 part numbers for the 06 8.8 wheel seals. Like RonD mentioned, there are two due to a package option.

If you are curious if you do have an 8.8, and not a 7.5, just take a look at the rear diff cover, and that will indicate which one you own.

Ford Rear Axle Identification
I believe there is a bit of a misprint on that link you sent. It reads:
The Rangers use a 28-spline 8.8-Inch axle on 4.0 Liter engine applications and a 31-spline axle on FX4 applications. All Explorer’s are equipped with a 31-spline 8.8-Inch axle.”
That should read ‘31-spline axle on FX4 Level 2 applications’…
 
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Old 12-21-2022
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+1 ^^^

31-spline were Torsen model with a limited slip thats gear driven as well. not Ford/GM style clutch pack limited slip
 
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