Has anyone here placed a limited slip differential in the front on a F150 4x4 with the 8.8 and ifs? I want this, but have heard from a few shops in the area here that it can't be done. Detroit TrueTrac has one for this application but I don't want to install it if it is just going to cause problems. Thanks for the help.

 

You can get quite a few limited slips for it. Anything that will fit a 28 spline 8.8 inch rear end (used on 4.0 rangers, explorers, crown vics etc.)

As soon as the Detroit is available (supposedly 2 weeks now) I will be getting it for the rear 9.75" and getting an eaton e-locker for the front and 4.10 gears.

The eaton is electric, open until you pushed the button then it is locked tight.
Auburn makes an electric one too limited slip then push the button to lock it.

I like the Eaton see it here http://www.traction.eaton.com/prod1.htm
http://www.traction.eaton.com/prod7.htm

The eaton is about $550 if you shop around. Thats about the cheapest I have found but still calling around.

 

I don't think a conventional clutch-based LS will work in the front of any vehicle with a Center Axle Disconnect, which your '98 has. Someone can correct me if I'm wrong, but I think when you're in 2wd, the two side gears in the differential are actually spinning in opposite directions. In other words, the differential is "differentiating" 100%. A clutch-based LS would try to oppose this effect, and one of two things would happen, I'm not sure which.

(1) the clutches would grab hard enough to spin both side gears the same direction, which would cause your front driveshaft to spin even when in 2wd.

or (2) the clutches would slip enough that they would wear prematurely.

As 93f150 pointed out, a selectable locker might be a better choice, although a more expensive one.

The Truetrac you mentioned might work, too, since it is a gear-based LS, not clutch-based. It might allow 100% differentiation when under no load (i.e. 2wd).

 

Correct. With the CAD, it'll cause problems.

If you went to a live front axle out of an expedition, or manually locked the CAD in the engaged position, that should solve that problem at the cost of a MPG or two, and some longevity of the front axle components.

-Joe

 

yes if you put a clutch type LS in the front axle that has CAD (center axle disconect) when you are driving and you try to turn it will feel like you have two flat tires up front, my buddy put a trak lock in his bronco with cads and i had to change out his whole system to manual hubs so he could drive it, what you need is a selectible locker that is open untill you want it to be locked like a ARB, good luck

 

The bronco never had a center-axle disconnect, it had automatic-locking hubs. It's the action of driving the axles that caused them to lock, hence the reason he needed manuals.

The system on our trucks works completely different, but you're right about the mechanicals. The problem it would create, however, is that it would always be dragging the driver's side wheel, and would always want to pull to the left at speed. Locking the CAD to link both sides would stop the pull, but would convert it to a live axle, costing the mileage, and with a locker, would cause all the problems you mentioned, typical of a locked and live front end.

Like you said, a selectable locker that's OPEN when disengaged would work fine, and those operating criteria scream ARB from the rooftops. Eatons are nice, but being a limited-slip when disengaged won't work in the front end of our trucks.

-Joe

 

Actually the Eaton elocker is open when not activated, like the ARB. The Detroit electrac and the auburn ected are both LS when not activated.

 

What year uses the CAD? The reason I ask is, I want to put the Detroit TrueTrac in the front of my 99 F-150, but I won't if it will spin the driveshaft all the time.

 

I could have sworn I remembered reading when it first came out that it was a limited slip when disengaged.... I can be wrong. It's happened before.

:P

All '97-'03 4x4 F-150s used the CAD.

-Joe

edit: With that in mind, I stand corrected.... and maybe that's why I had it in my mind that the E-locker would work for the front end all this time....

Now, if they just made one for the rear..... The ElecTrac might be what I want there....

-Joe

 

The Truetrac (and the Electrac, come to think of it) might work, since they are gear-based limited slips. The problem with clutch-based limited slips for a CAD front axle is that the clutches are spring preloaded, which causes some "grab" (resistance to differentation) even with no load. Tractech (maker of the Truetrac and Electrac) advertises that they act "open" until needed. In other words, they should provide no resistance to the 100% differentiation that occurs when a CAD is running in 2wd.

Check out www.tractech.com and perhaps contact them for a detailed explanation of why they would or would not work.

 

Indeed, any selectable locker will work as long as it's completely OPEN when disengaged. A limited-slip in the front end just won't do.

-Joe