“Super 8.8” a bit more than a name

[Pedaldude]

Then to add to the confusion. There’s not only one 9.75” diff.

Currently, there’s the regular 9.75” as well as the goofy 3/4 floating HD version. Then there’s the old regular HD version with beefed up parts and six bolts. Then there’s the old seven bolt 9.75” axle that made it easy to identify the older HDPP trucks.

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[Dale B]

Just a quick little overview of what “Super 8.8” denotes

So in 2015 with the releases of the S550 Mustang and 13th gen F-150 Ford decided to revisit and redesign the 8.8” Sterling axle that had been in production throughout the nineties. If you are not aware, the Sterling 8.8 is the “LS engine” of the axle world, it is commonly retrofitted in Jeeps etc for off-road builds. The original 8.8 was a 28, and then 31 spline setup. Adding splines necessitates a larger diameter in the axle, so the 31 spline 8.8 is the most sought after version. Enter the “super 8.8” in 2015, Ford went to a 34 spline axle, increasing the axle diameter yet again to contend with the higher torque demands of modern powertrains. Attached (Left) is the old 31 spline 8.8 and (Right) is the new 34 spline Super 8.8 pinion

So what are the key upgrades?

• Front/outer & rear/inner pinion bearings in the Super 8.8 were carried over from the previous 9.75” Ford rear-end
• Crush sleeve, pinion seal, and pinion nut all came from the earlier 9.75” model
• 34 spline axles and differentials

I have a RCSB 4x4, 5.0, 3.73 on order that is scheduled to be built in a couple of weeks. From what I understand is that it will have an 8.8 differential. Does that mean that it will have the Super 8.8?
I have wondered if the 8.8 was up to the task of adding a FP700 to take it to 700 hp? Dreams are free, hot rodding isn’t.

 

[JExpedition07]

I have a RCSB 4x4, 5.0, 3.73 on order that is scheduled to be built in a couple of weeks. From what I understand is that it will have an 8.8 differential. Does that mean that it will have the Super 8.8?
I have wondered if the 8.8 was up to the task of adding a FP700 to take it to 700 hp? Dreams are free, hot rodding isn’t.

5.0 with 3.73 automatically makes it a 9.75 rear end at least for 2021-2023.

Anything 8.8 is now super 8.8. Pre 2015 the 8.8 was only offered in the base V6, the point of the super 8.8 was a more robust package and it was extended to 2.7 & 5.0 as it shares everything with the 9.75 now except ring gear diameter. The axle carrier etc can take the same abuse as the 9.75 per Fords comments I’ve found. The big advantage of the 9.75 is heat dissipation and immediate input shock on the ring gear. The super 8.8 will hold up just as long as the 9.75 now though contorting and articulating off road and carrying high payloads, so I wouldn’t exactly worry if you did have the 8.8. The GT-500 runs 760 HP through the Super 8.8 just fine. I still believe yours is 9.75 though.

I’d be most worried about getting the 9.75 if I was towing long distance, the extra heat dissipation of the larger ring gear and housing is great for that, for some runs at the strip you’d be fine with the 8.8.

 

[Samson16]

5.0 with 3.73 automatically makes it a 9.75 rear end at least for 2021-2023.

Anything 8.8 is now super 8.8. Pre 2015 the 8.8 was only offered in the base V6, the point of the super 8.8 was a more robust package and it was extended to 2.7 & 5.0 as it shares everything with the 9.75 now except ring gear diameter. The axle carrier etc can take the same abuse as the 9.75 per Fords comments I’ve found. The big advantage of the 9.75 is heat dissipation and immediate input shock on the ring gear. The super 8.8 will hold up just as long as the 9.75 now though contorting and articulating off road and carrying high payloads, so I wouldn’t exactly worry if you did have the 8.8. The GT-500 runs 760 HP through the Super 8.8 just fine. I still believe yours is 9.75 though.

I’d be most worried about getting the 9.75 if I was towing long distance, the extra heat dissipation of the larger ring gear and housing is great for that, for some runs at the strip you’d be fine with the 8.8.

Great information kid!

 

[Dale B]

5.0 with 3.73 automatically makes it a 9.75 rear end at least for 2021-2023.

Anything 8.8 is now super 8.8. Pre 2015 the 8.8 was only offered in the base V6, the point of the super 8.8 was a more robust package and it was extended to 2.7 & 5.0 as it shares everything with the 9.75 now except ring gear diameter. The axle carrier etc can take the same abuse as the 9.75 per Fords comments I’ve found. The big advantage of the 9.75 is heat dissipation and immediate input shock on the ring gear. The super 8.8 will hold up just as long as the 9.75 now though contorting and articulating off road and carrying high payloads, so I wouldn’t exactly worry if you did have the 8.8. The GT-500 runs 760 HP through the Super 8.8 just fine. I still believe yours is 9.75 though.

I’d be most worried about getting the 9.75 if I was towing long distance, the extra heat dissipation of the larger ring gear and housing is great for that, for some runs at the strip you’d be fine with the 8.8.

Thanks for the information. I feel better now. I will report back when it gets here. The RCSB is only available with 5.0 and 3.73 e-lock in 2024.

 

[DHBPhoto]

So then all of our 3.73 trucks have a limited slip? In addition to the rear locker? That doesn’t make sense.

 

[The_Auto_Tech]

I had assumed the 8.8 was plenty robust at this point. Wonder if anyone has swapped a 9" in yet.

 

[JExpedition07]

I had assumed the 8.8 was plenty robust at this point. Wonder if anyone has swapped a 9" in yet.

I am pretty sure the 9” is weaker than the super 8.8” axle, the 9” was only a 31 spline shaft.

 

[The_Auto_Tech]

I am pretty sure the 9” is weaker than the super 8.8” axle, the 9” was only a 31 spline shaft.

Was just curious because TBM offers brakes for a 9" style axle ends, but not the 8.8".

 

[Dale B]

I have a RCSB 4x4, 5.0, 3.73 on order that is scheduled to be built in a couple of weeks. From what I understand is that it will have an 8.8 differential. Does that mean that it will have the Super 8.8?
I have wondered if the 8.8 was up to the task of adding a FP700 to take it to 700 hp? Dreams are free, hot rodding isn’t.

My 2024 XL RCSB 4x4, 5.0, 3.73 arrived a couple of weeks ago and to my surprise, it has a 9.75 rear end as standard equipment.
It would appear that all 2024 RCSB’s come standard with 9.75 rear ends.

 

[rugedraw]

I figured this might be a good place to ask. I'm sick of my 3.31 gears and ready to go 3.73 front and rear. Anyone know the correct part numbers of what I need to order? According to PTS, my truck has the 9.75" rear.

 

[JExpedition07]

I figured this might be a good place to ask. I'm sick of my 3.31 gears and ready to go 3.73 front and rear. Anyone know the correct part numbers of what I need to order? According to PTS, my truck has the 9.75" rear.

Your truck should be 9.75 correct

 

[rugedraw]

Your truck should be 9.75 correct

Yea, the rear set is pretty easy to find. I'm having trouble finding the 3.73 gear sets for the front diff.

 

[caverunner17]

So what's the difference between the 3400 and 3800 GAWR 8.8's? Specifically on the 2.7's that are rated for 6600 GVWR and the 5.0 with the same frame / 8.8 rear end rated for 7050.

 

[JExpedition07]

So what's the difference between the 3400 and 3800 GAWR 8.8's? Specifically on the 2.7's that are rated for 6600 GVWR and the 5.0 with the same frame / 8.8 rear end rated for 7050.

That is a great question that I have absolutely no answer for

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