Check Out My Rear End

[Boone]

I currently have issues with the rear 8.8 axle in my '05 GT. I have 3.55 gears, Eaton TruTrac, stock single piston brakes, and it is adjustable at every connection to the frame. Issues are a leak at the pinion seal, a leak at the passenger side axle tube at the pumpkin, and a general lack of confidence in the assembly.

I'm going to replace the whole axle as a unit, and advice is needed:
Stay 8.8 or figure out a way to get a Ford 9" to work?
Gears are going to 3.73 (high revving NA motor)
Stay with TruTrac or go Torsen?
Rear brakes - can I go 4P, and what parts should I procure?
Where do I get it? (I contacted East Coast Gear Supply in Raleigh, NC for an estimate)

I want this to be the last time I dig into this axle assembly. Also, I have the ability in the future to add a supercharger that could put me in the 800whp range, so I need some strength (but I won't dial it up that high, maybe 600whp on relatively low boost). I use the car for autoX, HPDE, and days where I just want to hear the rumble.

Thanks for your wealth of knowledge and willingness to spend OPM.

 

[Drlee50]

An 8.8 can handle 1000 hp easy. You would need larger spline axles but its fine. They do make 31 spline diffs that will do double duty. I ran 33 spline and a spool in my 8.8 1200 hp drag racing car. Wasnt an issue at all. Diffs are personal choice as they do have pros and cons but they should all be strong enough for your needs

 

[ArizonaBOSS]

TBH if you are going through the trouble of replacing the entire axle assembly, you might as well just go with the cambered unit from CorteX. There is no better time.
That would also transform the axle into a full-floater unit, so you could use a fixed (radial mount) rear brake caliper if you desired, however the stock caliper is generally good enough.
The axle tubes are welded to the diff pumpkin, and the end seals aren't the same design as Ford, so you won't see issues there. On top of that, the bearings in the outer ends are significantly beefier than stock, so on top of having negative camber in the rear, you don't lose camber in roll.
Cortex can deliver a complete assembly and all you have to do is shove it in the car and fill it with gear oil. That's what I did.

http://cortexracing.com/product/cambered-full-floating-cv-ball-drive-axle/

 

[thehueypilot]

https://www.currieenterprises.com/05-14-mustang-crate-rearends

Tim

 

[bpracer]

If you're tracking the car, good wheel bearings are boring but a necessity. A normal ball bearing rear wheel bearing has little side load capacity. The cortex unit looks like a floater axle setup that will have massive tapered roller bearings that will last forever. The Currie unit may be able to have a tapered, unit, roller bearing setup, but maybe not standard.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[Boone]

So I'm at $6200 for the Cortex cambered unit, and I'm at $4000 for the Currie 9"unit. I priced a Moser 8.8 at $4800. All are definitely higher than I was thinking going in, but I've always drooled over the Cortex cambered unit. I thought Mustangs were supposed to be inexpensive to track. Oh well, I'm not selling the car, so I may as well make it exactly what I want.

 

[ArizonaBOSS]

Get the CorteX unit. The 8.8 is more than strong enough; I don't know if there is a reason to go to a true "Ford 9 Inch" rear in these cars unless you are doing some serious drag-race stuff. On top of that, it's crazy to spend $4K+ and not have rear camber, unless they want to do some "heat the tubes" stuff that just ends up eating axles and bearings.

 

[Boone]

I sent an inquiry to Cortex today. We'll see how much the whole package will actually be, and I'll make a call. In the meantime, I'm going to fix the geometry of the rear axle and clunking noises with BMR parts that should arrive soon, and I'll monitor the leaks.

My crystal ball sees me buying in to the Cortex philosophy and going all in with their stuff. I don't think I'll ditch the 3-link rear, but their coilovers are impressive. I'll need to change mine sometime in the future, and having a plan counts for something.

 

[Boone]

I received my quote for Cortex for the cambered rear axle. $9K. Increases from the base price are T2R Torsen, shop set up, and OEM rear brakes. Pricey, but I still need to consider it since it is the best ass in the business.

 

[ArizonaBOSS]

Do eeeeeeeeeeet

 

[ArizonaBOSS]

Here is a good example of camber loss (positive camber when loaded) in the rear w/o camber, plus stock axle bearing deflection (black car) vs. cambered rear axle (red car):

 

[Boone]

You don't have to sell me on the advantages of the rear camber. My car is missing the sticker on the rear corner panel, which is why I pause at the price tag.