8.8" / 9" Comparison Questions

[Robb]

Hey Guys!

I got a buddy who is doing a little axle swapping on his Yota has come to a little of an axle choice delima. He is going with a Ford 8.8" or a 9" because both are readily available and inexpensive. I should rephrase that, he can get hold of a drum brake 9" or a disc brake 8.8" for about the same price. He wants to run discs. This is how we are looking at the comparison.


Ford 8.8":

- big advantage, already disc'd
- smaller ring and pinion
- lockers tend to be a little more expensive (as far as eBay goes, 9" lockers seem to be more plentiful)
- regearing costs will be higher (the 9" has the removable center section)

Ford 9":

- big disadvantage, drum brakes and conversion kits aren't really cheap
- larger ring and pinion
- lots of cheap aftermarket stuff (lockers) available
- cheaper to regear, or just buy a "set up" center section

How would you score this? Which route seems more attractive?

Thanks Guys!

 

[udmsvt]

i think the more accurate question would be, for the setup he wants (disc/regear/locked), which would be cheaper. from what i understand, our 8.8 can be a tough bugger (granted not quite the 9")...should be more than enough for a yota, but it all depends on cost start to finish...look at the big pic.

 

[Alec]

Yup:

cost of 8.8 + regear + locker

cost of 9 + discs + regear + locker

If he wants discs, don't "settle" for drums, especially on a DD.

 

[mrboyle]

One thing you failed to mention/consider, wheel bolt pattern. If he doesn't mind running different wheels, no problem. But unless he is planning to run a front axle with the 5x4.5" pattern (Dana 30?) or is willing to run the risk of using adapters, he needs to think about the cost of aftermarket axles, rotors, etc....

 

[Alec]

Oops, forgot about that

 

[Robb]

Both would be 5x5.5.......he is running a Ford D44 up front.

I will try to come up with a "best guess" cost of both of them tomarrow. They should come close with everything, but we need to run the actual numbers ourselves.

 

[tdavis]

Some differences:

The 9inch will be shovel, in comparison to the 8.8inch.

You can build a stronger 9inch than you can build a 8.8inch. Bigger everything.

 

[udmsvt]

its for a yota. personaly, i think the 9" would be overkil...unless its behind some massive engine.

 

[Hotweels]

After alot of talking with some mechanic friend's of mine (both wheel and work for ford) we hashed out that the 8.8 is just as strong as a 9" in every aspect but the pinion support.
#1 Ring gear diameter is .2" smaller ya big deal.
#2 8.8 is factory 31 spline in explorer's compaired to 28 in early bronco 9".
#3 factory disc's on the 95+ explorers
#4 8.8 uses a stronger factory carrier (this is what they told me)
#5 The 9" has a very low pinion placement... like almost 4" lower than a 8.8
(this is all based on a bone stock factory diff)
Some of the down side stuff on a 8.8 is the c-clip's, expence of lockers and it full width pickup's the housing's are known to bend with hard use.

I will be be breaking out the 7018 this winter so i can test the true strength of a 8.8 in early spring.... mmmmm spool

 

[Alec]

I'd personally go with an Explorer 8.8 and good wheel spacer/lug adapters.

 

[Brian1]

If it was my decision I would go with a 9in. There is a huge aftermarket for the Ford 9". I also like the idea of a removable 3rd member.

#2 8.8 is factory 31 spline in explorer's compaired to 28 in early bronco 9".
What are the diameters of the shafts? I dont know, but spline count doesnt mean everything if the shafts are bigger or dont neck down anywhere. If the shafts are both the same diameter then you have a point. There are many aftermarket shafts available for the 9 that would increase the strength.

#5 The 9" has a very low pinion placement...
If he is concerned about the pinion being lower, Currie and other places make a hi-pinion housing. It is always an option in the future.

#4 8.8 uses a stronger factory carrier (this is what they told me)
This wont matter if you lock it up with a detroit, spool or ARB.

What size tires is he using and what type of wheeling does he do? What plans does he have for it in the future? These are important factors when deciding on axles.

If the price of the 8.8 is reasonable (less than the cost of a disc brake kit) I would also buy it and take off the discs and adapt them to the 9" then sell the 8.8 for whats left of it. The Explorer discs are a common swap for many types of axles and should work on the 9" with some modifications.

 

[Robb]

Excellent Advice Guys!! Thank You for taking the time to help!!

I only had a chance to talk to by buddy for a few minutes today, so we didn't go into a lot of detail. I think he has his mind set on the 9"tho. He came to the conclusion that he will try out the drums for awhile and see how he likes them, if if he doesn't like them, he will do the conversion in the future.

Spline count isn't much of a concern. He has access to a machine shop, and the 9" that he will probably get will be a cut down 31 spline.

Not sure on axle shaft size. Could be 1.19" or 1.31", anyone know how to tell (without pulling it apart)?

He is running 36"s right now, but wants the freedom to move up in the future. Another reason why he leaned toward the 9. He wheels it about as hard as you can here in the mid-atlantic states.