Stupid is as stupid does bud. If you want to f with a rear that inferior thats up to you. I've seen 8.8 rears end up bending on a high 9 sec car......bent the housing. Now with that said if i had a mustang i would run the 8.8 as far as i could. But most people on this sight have fcars so i see no reason to waste $ on a weaker rear that will end up costing you more.

No matter what you do that 8.8 will never be as strong as a comparable 9".

Btw there has been many tests to show a 9" will only lose about 6-8 hp. The % thing is bs.
With many ratios of gears out there that has been lightened and rem polished for a 9" I'm sure the hp loss is even more minimal. The 9" gears i just installed are actually 8.625 and weigh about the same as the 7.5 gear set.


I can weigh my tq arm. But I'm sure yours will weigh more as you will have to also have an adapter to use the oe style tq arm or make some conglomeration to hang off the 8.8 for a tq arm. The fab 9 lends itself to this easily with only 4 small tabs.

My hp was with the 10bolt....and would be around 430whp on a dj. I haven't dyno'd it with the 9".

From the way it sounds your 8.8 may be heavier. If your 54" rear weighs 65lb my full width fab 9 fcar rear housing weighed like 68lb.....and is stronger.

And like i have already said.....twice. If the power loss bothers you so much run a 12bolt center in a 9" housing

 

Ran a 6.81@104.x. Rain kept us from getting more passes. I have to raise my revlimiter now and try launching at different RPMs, I only left off of idle and didn't stall it up any. I also need to do some adjustments on the DA rear coilovers.

 

And you can do the same lightening and gear treatments to an 8.8. Face it, the 9" gearset's design with more hypoid offset is less efficient than the 8.8. Not until you exceed the 8.8"s capacity does the 9" become superior.

Yea, you will lose less than 10hp if you are making less than 300hp. The % thing isn't BS just because you say so, efficiency is typically expressed in %.

Here's a comparison of an 8.8 and a 9", both with exact same brackets and same width. I made these for a non-torque arm application, but it is a valid direct comparison between 8.8 and 9" housing/centersection weights...
52" wide 8.8 "Crown Vic" 3" tube housing with brackets and 9" billet ends installed = 69lbs
52" wide 9" oem housing (no back brace) with brackets + bare single rib centersection (no pinion support) = 79lbs

This is two rears configured exactly the same at the same width, and the 8.8 has a 10lb advantage over the 9". My torque arm weighs 18lbs 12oz, a 9" torque arm would need to weigh less than 8lbs 12oz in order to come up with a weight advantage over an 8.8.

In the process of swapping gearsets, you lose the additional bearing on the nose of the 9" pinion. Your 9" will be more efficient, but the gearset strength will be all 12 bolt.
.

 

i'd like a pic of this mount in a f-body, maybe even a link if its not too much trouble.....

 

I agree.

The appeal of a 8.8" is that you can take a $150 used axle, chop off the tubes, weld in your stock tubes and a TA mount and have a cheap axle that's stronger.

The funny thing is that people started marketing prefabbed housings and by the time you throw a bunch of new parts in it, you might as well buy a D60 or 12 bolt.

 

I'd rather have an 8.8 than a 12 bolt,and a d60 is tough but heavy.

 

Do the same lightening to the r&p of the 8.8....fine. But it's still not as strong. And i can buy the 9" gear that is already lightened and polished for less than $200 shipped. Try that with a 8.8.

Yes the 9" has more offset in the r&p which equates to more tooth contact....which equates to strength. We are only talking using 6-8 hp here for the 9". Now that 8.8 is gonna use 3-5 vs a 10bolt. You are arguing over 3hp here vs a rear that in the end is cheaper/more parts available /stronger.

The percentage is bs....it's only gonna take certain amount to run the drivetrain. And with a stronger rear like the 9" as pressure is applied it will deflect less. So even if it is a percentage at some point the 8.8 will use more.....and more $....and more time fixing it. Again.....we are looking at about 3hp here.

My mwc tq arm weighs 13lb....with all ends on it. The short arm they make is lighter than my long arm. The xmember is lighter than stock where it attaches. I gained less than 10lb goin to a fab 9 vs the 10bolt overall. With lightened gears even less. Try that with your 8.8. Be sure you have one of those fancy heavy reinforcement covers on it too

Loke i said if i had a mustang....and i do. Then i would let the 8.8 go as far as it could. In fcar application 9" all the way. It ends up being stronger,lighter and more cost effective.
I can see someone wanting to use a 8.8 if they have one and making it themself. But one could easily do the same with a 9". There are used fcar 9"s out there for 2-2500k...with tq arms.
Why do a 8.8 over a 12bolt? They are virtually the same

 

In for educated response.. Lol

 

8.8, 12 bolt, 8.5 10 bolt all have the same hypoid offset and use the same bearings. The 8.8 came with 28 or 31 spline axles depending on application, the 8.5 10 bolt came with either 28 or 30 spline axles, the 12 bolt came with 30 spline.

 

The deeper ratios of 8.8 ring gears from Ford are now "lightened" from the factory, as the design of the gear blanks have changed to eliminate most of the "extra" material from the back side. $170/set brand new, even cheaper used.

At 700whp, i don't use a cast cover. Never broke anything rearend related in 13 years with the exception of a stripped locker. Same set of 3.73 gears/bearings for the last 9 years.

 

MWC Fab 9, and be done with it.
The MWC Fab 9 will find your other weak links.

 

Good info. I knew they were all very close to being the same. I used set up alot of rears.
I bet they aren't lightened like these.....or polished. I don't have a pic of the machining but they're pretty nice.

I've seen plenty 8.8s fail. They would be fine behind most autos.
Yup. For fcars it really is the best option.

 

I'm sure you've seen plenty of 9" failures as well. Usually it's the pinion support getting shoved out the front of the case, which can easily hurt the driveshaft and transmission. It's a combination of the 9"s lower pinion and the more worm like gear mesh, the pinion is basically pushing from a low angle on the ring gear, the equal and opposite reaction to that is a force that's trying to push the pinion out the front of the case. The typical stock single rib 9" case has a weak pinion support and five 3/8" bolts containing that force. Unless you have upgraded to a bigger bearing pinion support and installed studs to hold it in the case, your common "free" 9" pumpkin won't be as strong as an 8.8.

 

The Ultra-Lite ring gear option can remove up to 2.6 lbs from a 9" ring gear for appx $100, depending on ratio. Keep in mind that the 9" gear blanks were never formed to be lightweight like the current 8.8 ring gears, so doing the same lightweight machining to the 8.8 ring gear won't net much weight savings.

That said, there are aftermarket 8.8 gearsets that are not being made as lightweights. I installed a set of Italian Motive 5.71's in an 8.8 a couple weeks ago, that ring gear seemed like it was double the weight of a FMS 8.8 3.73.

 

I have daytona pinion support. But no i have not seen a 9" fail. I'm sure they do and yes the factory case has it's limitations.....mostly beyond what most of us run. A auto car can go further with one of those than they can a 10bolt which is fine till you start running into the 10s with a auto.

If i remember right my lightened 9" gears were 3lb and a few oz lighter. They also measure 8 5/8". Sure the lower the gear the heavier the ring gear....it gets thicker.

I have no issue with a 8.8. A 9" is just a better option for these cars.

 

Now i'm curious. If you've not seen a 9" fail, what were the failure modes of those 8.8's?

 

I would love to have an 8.8 because of the virtually unlimited gear ratios and posi options. The problem is any ford housing was not build for a TA. It was not engineered to take the stress. If someone like Strange or Moser could build an 8.8 housing with cast TA mounts to fit in an F-body I would strongly consider it over a 12 bolt for the same cost because of the reasons I already stated.

 

Axles, ripped teeth.....and a friend bent the **** outta his housing on the launch. There is also only about 10 million mustangs running around wuth 8.8s to. So it only stands to reason you will see more of those fail.
If you think a 8.8 has unlimited gear sets look at a 9". Almost any ratio you can think of. I recently put 4.00 in mine. Kinda wish i woulda went with 4.22....there's even a 4.40 and gears in between all of those.

 

You can't really say the 8.8's axle strength is inferior to the 9", as both were available with either 28 or 31 spline axles. Sure the 9" axles are bigger at the bearing than the Mustang 8.8, but the Explorer and F150 8.8 axles are even bigger at the bearing than the 9".

"Ripped" teeth are usually the result of either something passing between the gear teeth, or poor setup where contact is out near the tip of the ring gear's tooth, adding stress to the tooth's root. There are guys getting 1000+ thru stock Ford 8.8 gearsets without ripping the teeth out. If you make enough power to actually rip teeth out of a properly set up 8.8 then yea, you need to step up to a stronger gearset.

Your friend's bent housing was likely an un-braced Mustang housing, with it's small 2-3/4" dia axle tubes. The small tube 9" housing from the early Mustangs will bend just as easy until you add a back brace. Crown Vics use a stiffer 3" axle tube, Explorer/F150 8.8's use a 1/4" wall 3-1/4" dia tube that's equal to most any 9" tube. It's also easy to add a brace to any 8.8 if it's needed.

 

All good info....
All of which convinces me a fab 9 was the best choice.