Fox Ford 8.8"/9" Differential/Rear End Thread?

ShedBuiltMS

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What's going on Stangnet. Saw there were a few other threads for people to post their setups when it comes to other components on their fox but none with dif specific info. If I missed it I will defer and crawl back into my hole!

With that being said I wanted to see what everyone here is running for difs. I have my eyes on a full list of parts and brands to pick up this winter for my re-build, My Progress Thread Seeing what ya'll do and don't like. I know there's some mismatched stuff out there that can be crossed and used with other stuff as well as stuff for new edge cars that will and will not work, dif covers, etc. Even post up a custom or hybrid setup that you may have or made.

Some info to throw down,
Street car, Drag car, Daily, weekender, All of the above? Year/V8or2.3
Size/Brand/Type (lockers, slip, spool etc.)/Ring and pinion setup/Cover setup/Transmission used

Quick review good or bad, likes and dislikes

Links to threads or your builds with rear end setups with a brief description is also a plus.

Thanks Stagnet,
Pat
 
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Mustang5L5

Put lubricant all over the balls
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For the most part, the 8.8 tends to be the most robust component on the car from the factory. Hard to really "blow one up" short of a dedicated drag beast launching on slicks. You tend to snap an axle shaft first. That's why you don't see much info on differential builds here. If anything, the trans will blow up long before the diff does.

Good center pumpkin, 31 spline setup with quality axles, and maybe even welding the housing is plenty strong enough for most drag builds. By that I mean getting down to the 11-10 second mark. As you go beyond that, needs may change slightly based on rising level of HP.

No real reason to change to a 9" rear. Yes, it allows for quick gear changes with the removable center, but it's heavy and has a lot of parasitic loss.

Other than a diff cover, and a change to 3.73's, my 8.8 is stock.
 
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ShedBuiltMS

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For the most part, the 8.8 tends to be the most robust component on the car from the factory. Hard to really "blow one up" short of a dedicated drag beast launching on slicks. You tend to snap an axle shaft first. That's why you don't see much info on differential builds here. If anything, the trans will blow up long before the diff does.

Good center pumpkin, 31 spline setup with quality axles, and maybe even welding the housing is plenty strong enough for most drag builds. By that I mean getting down to the 11-10 second mark. As you go beyond that, needs may change slightly based on rising level of HP.

No real reason to change to a 9" rear. Yes, it allows for quick gear changes with the removable center, but it's heavy and has a lot of parasitic loss.

Other than a diff cover, and a change to 3.73's, my 8.8 is stock.

Thanks for the info, the OE 8.8 rear end is solid for sure. I was hoping to maybe see what brands people were running mostly and see if they had had good or bad things to say. I'll more then likely be getting a 31 spline locker with upgraded axles to 5 lug. (data base of sorts).

Edit: we are also trying to build our site up to include V8 and domestic/ RWD platforms so it'd be a good help on what to stock that people might want at a discounted price for the community.
 

junkyardwarrior

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throw an aluminum center section in the 9" and it gets lighter. Similar for the spool if you are going to run a spool. Does not solve it's power hungry nature, but does lighten it up considerably. I want to say about 25 lb lighter.

8.8 is a good rear end until you get into hard launches on slicks; when you start making good power you're gonna need to address the axle tubes' attachment to the center section. Really at that point, you'd probably be wise to think about tossing a set of 9" ends on the 8.8 housing at the same time, which will let you do away with the c-clips (just run 9" style axles)
 

ShedBuiltMS

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throw an aluminum center section in the 9" and it gets lighter. Similar for the spool if you are going to run a spool. Does not solve it's power hungry nature, but does lighten it up considerably. I want to say about 25 lb lighter.

8.8 is a good rear end until you get into hard launches on slicks; when you start making good power you're gonna need to address the axle tubes' attachment to the center section. Really at that point, you'd probably be wise to think about tossing a set of 9" ends on the 8.8 housing at the same time, which will let you do away with the c-clips (just run 9" style axles)

I think y'all are misinterpreting my post. I already know what I am putting in the car. That part is figured out. I'm not here asking for advice per say. Just input or data.

I'm just trying to get a list together or something searchable that when a user types in "what rear end" or "what dif" that they're able to look here and see what people do and dont like just like most other components.
 

TOOLOW91

If you're the village idiot what's that make me?
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Street / strip / show / take it to work driver :cool:

8.8
Welded tubes
Moser 31 spline c clip axles
Frpp 31 spline posi unit .
3.55 frpp gears
Arp Hardened axle studs

Been high 10s on a radial with it At 580hp With a tko 600 , it makes a wee bit more now with a FB AOD .


Haven’t ran it with the new combo yet , old combo only went 1.55 60 which was miserable .

Plans are 9 inch ends
Moser 33 splines
33 spline tru trac
Most likely keep the 55s.
 
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revhead347

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Kurt
 
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96pushrod

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I think the reason people don’t really talk about their rear end setups is because they’re really not all that extravagant lol.

8.8 here with a Detroit locker and 31 spline axles. Haven’t even welded the axle tubes yet. Don’t know if I’ll ever get around to it on this rear. 4.10s with an a5 on either a 275/60r15 or a 27x10.5. Car gets street driven a lot.

28 spline stuff has been known to hold up well, even with limited track use on 400+whp stick cars. Not exactly highly recommended though. Once you’re able to get into 1.5/1.6 60ft territory it’s a wise idea to upgrade.
 

CarMichael Angelo

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I think y'all are misinterpreting my post. I already know what I am putting in the car. That part is figured out. I'm not here asking for advice per say. Just input or data.

I'm just trying to get a list together or something searchable that when a user types in "what rear end" or "what dif" that they're able to look here and see what people do and dont like just like most other components.
That makes Zero sense..
 

CarMichael Angelo

my rearend will smell so minty fresh,
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how does it make zero sense?
Zero sense = You know what you‘re doing already . you're just wanting to check if everybody here will give you input to offset/corroborate what your plans are.

i.e. “ I plan to jump off a cliff,...( and I’ve already decided to do that) as I make my way to the edge, should I walk, or run?”
 

ShedBuiltMS

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Zero sense = You know what you‘re doing already . you're just wanting to check if everybody here will give you input to offset/corroborate what your plans are.

i.e. “ I plan to jump off a cliff,...( and I’ve already decided to do that) as I make my way to the edge, should I walk, or run?”

I am not trying to get anyone to confirm anything for me. I'm attempting to create a thread just solely for the sake of people being able to see (in one thread) a list of what people are running. There's a thread list for half the :poo: on any car forum. Let me apologize for trying to create another one. Wouldn't expect any less from someone with a political signature in a car forum though lol
 

General karthief

wonder how much it would cost to ship you a pair
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It's a thread for when someone is looking for what is successful,
As in ' are people running or walking off the cliff'
Just for fun I googled 8.8 vrs 9" and got a lot of ' this is better/faster/lighter' but not a lot of 'I run this stuff in my 8.8/9" and run this on that tire'.
The search did list this thread so it's a start. :nice:
 
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CarMichael Angelo

my rearend will smell so minty fresh,
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It's a thread for when someone is looking for what is successful,
As in ' are people running or walking off the cliff'
Just for fun I googled 8.8 vrs 9" and got a lot of ' this is better/faster/lighter' but not a lot of 'I run this stuff in my 8.8/9" and run this on that tire'.
The search did list this thread so it's a start. :nice:
Anybody who has considered them knows the pros and cons. Like everything else on a Fox Mustang, it’s nothing new.
But since it’s an “information thread”, Ill add this.
An 8.8 is more than capable of withstanding significant power, well beyond what it would see in everyday street car use. The benefits to the rear are that it fits, it came in the car OEM and there are multiple brake upgrade options from the salvage yard that easily fit, as well as a great aftermarket. a 9“ on the other hand, doesn’t w/o welding on the upper and lower fox CA mount points. Finding a brake system almost always involves the aftermarket, as most came with drum style brakes, unless the rear came with disc brakes.. An 8.8 has a “ centered pinion”, as opposed to a 9” where the pinion engagement points is positioned much lower on the ring gear. The benefit of the centered pinion puts the rear end much more likely to be centered in the vehicle as opposed to the 9” which has a significantly longer axle on one side. The additional negative to the 9” pinion location is that there is parasitic loss. The pinion tries to climb the ring gear due to its low placement and potentially robs power.
The 9” is heavy compared to the 8.8, but because of the removable center section, is much easier to service. The 9” rear has bolted in axles, and when compared to the C-Clipped versions that an 8.8 comes with, a 9” axle remains in the housing if it breaks..Conversely, an 8.8 axle will be free to come out of the housing if it breaks. For that reason, Most people using an 8.8 with slicks and higher power opt to convert the C clip axle to either a C clip eliminator kit that makes the axle a bolt in, or cut the housing ends off, and weld on 9” housing ends and go to a 9” style axle in an 8.8. Most sanctioned tracks require one or the other solution.
Because its solid steel construction, a 9” housing is almost un-breakable, and with a back brace welded in place can be made even more robust. It is the go to for extreme power handling. Since that rear has been in use since the dawn of time, numerous options exist for center section upgrades, as well as the diff itself. An 8.8 will be susceptible to bending at the center, as the axles tend to pull forward of the center section. Axle brace kits are made to control that, but the room required to use them make putting an exhaust system in the car extremely difficult. You are relegated to using the housing as ford made it, there are upgraded caps, and rear end covers that are available to help keep everything inside supported.

Have I left out anything?

Me; 8.8 w/ Moser 28 spline axles, rebuilt t loc, 3.73; Some rear end girdle/cover, SN 95 rear brakes.
 
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TOOLOW91

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Anybody who has considered them knows the pros and cons. Like everything else on a Fox Mustang, it’s nothing new.
But since it’s an “information thread”, Ill add this.
An 8.8 is more than capable of withstanding significant power, well beyond what it would see in everyday street car use. The benefits to the rear are that it fits, it came in the car OEM and there are multiple brake upgrade options from the salvage yard that easily fit, as well as a great aftermarket. a 9“ on the other hand, doesn’t w/o welding on the upper and lower fox CA mount points. Finding a brake system almost always involves the aftermarket, as most came with drum style brakes, unless the rear came with disc brakes.. An 8.8 has a “ centered pinion”, as opposed to a 9” where the pinion engagement points is positioned much lower on the ring gear. The benefit of the centered pinion puts the rear end much more likely to be centered in the vehicle as opposed to the 9” which has a significantly longer axle on one side. The additional negative to the 9” pinion location is that there is parasitic loss. The pinion tries to climb the ring gear due to its low placement and potentially robs power.
The 9” is heavy compared to the 8.8, but because of the removable center section, is much easier to service. The 9” rear has bolted in axles, and when compared to the C-Clipped versions that an 8.8 comes with, a 9” axle remains in the housing if it breaks..Conversely, an 8.8 axle will be free to come out of the housing if it breaks. For that reason, Most people using an 8.8 with slicks and higher power opt to convert the C clip axle to either a C clip eliminator kit that makes the axle a bolt in, or cut the housing ends off, and weld on 9” housing ends and go to a 9” style axle in an 8.8. Most sanctioned tracks require one or the other solution.
Because its solid steel construction, a 9” housing is almost un-breakable, and with a back brace welded in place can be made even more robust. It is the go to for extreme power handling. Since that rear has been in use since the dawn of time, numerous options exist for center section upgrades, as well as the diff itself. An 8.8 will be susceptible to bending at the center, as the axles tend to pull forward of the center section. Axle brace kits are made to control that, but the room required to use them make putting an exhaust system in the car extremely difficult. You are relegated to using the housing as ford made it, there are upgraded caps, and rear end covers that are available to help keep everything inside supported.

Have I left out anything?
That strange makes a brake backing plate for 94-04 factory ford disc and 05-14 brakes .
Just requires the “ late “ big end (1137 p/n for strange )

Part numbers

B1706MC - 94-04 GT (tapered axle bearings )
B1706MCC- 94-04 Cobra (tapered axle bearings)
B1706NC 05-14 GT ( tapered axle bearing )
B1706NCC 05-14 GT ( ball style bearing )
B1706NCG - 13-14 gt500 ( tapered style bearing )
 
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