Good day -

I'm strongly considering a new 2014 F150 - assuming I can find one I like and I can get financing together quickly. Obviously time is running out ... and I may end up waiting for the 2015s.

I haven't decided on an engine, but it will definitely be 4WD, and I'm confused by the multiple options for the rear end. When I bought my 1998, I think all that was available was open and limited slip. For 2014, we have limited slip, non-limited slip and electronic locking.

What are the pros and cons of each? For reference, the towing and hauling I'll do will be minimal and light duty.

[I did a limited search for this topic, but couldn't find such a discussion. If it exists already, please point me there.]

Thanks,
dogfood

 

The open and limited slip are pretty self explanatory. The locking option is (as I understand it) an open diff until you pull the switch to engage the lock and it's only good up to something like 30 or 40 MPH or something like that (can't remember the exact speed limit) and then it'll automatically disengage even if you still have the switch pulled out. So, the electronic locking option is pretty much for slow speed operation and not really intended for pavement....just snow, gravel or some other slippery situation.

 

Limited slip and locking is not as important as it used to be now that we have advanced traction control.

 

There is a variation with the locking differential with the Raptor.

The Electronic locking differential (ELD) is available at any speed, thresholds for the ELD are lifted for the Raptor. The ELD will remain locked up to the maximum vehicle speed when engaged.

Also the modified rear differential capable of locking in 2H, 4H and 4L. This is completely different from the regular F-150.

 

I believe they changed it for 13. On my FX4 you can lock the rear diff in 2H, 4H, and 4L. I thought I read somewhere the cutoff is 20 or 25 mph on non-raptors.

 

Ok, thanks for the input so far ... but at the risk of appearing like a complete doofus, please entertain two probably simplistic questions:

(1) If open differential is available on a 4WD vehicle, how does it work? Doesn't "open" imply that one wheel per axle is just along for the ride (i.e. doesn't do any real driving)?

(2) How do "traction control" and "advance trac" work with each type of differential? It seems that there could be redundant - or competing - systems at work here.

Thanks,
dogfood

 

My comments are based on my 2012 XLT with ecoboost, 4WD, open rear diff with elocker.
(and I used to have a 2004 FX4 with limited slip)

The e-locker automatically disengages at 20 MPH.
The open rear diff forces you to use 4WD much more often in the snow. And sometimes in the rain if you want hard acceleration.
(Yes, you are right that in 2WD with the open rear diff you are basically powering just 1 wheel.)

After driving it for a couple years I find that I would prefer to have the limited slip diff. It is extremely easy to break the one wheel loose when the pavement is wet, snowy, loose gravel, dirty, shiny road stripes, etc.

On to the traction control / ESP system - I think the reason they are going to open rear diffs is that the traction control can kick in to distribute the torque.
BUT (and this is a big BUT) this is not as efficient or driver friendly.
The traction control will very quickly (immediately?) cut the engine back to regain traction. And its firing your brakes to slow individual wheels.

If you are a grandma driving to the store (no offense to Grandmas) this is no big deal probably. But if you are a more performance-level driver who doesn't mind a little wheel slip on hard acceleration this is very frustrating. As soon as you gun it a wheel breaks loose and then the power is gone.

Hence the need to more frequently pop it into 4WD. I find myself turning on the 4WD to pull out into traffic if the road is busy and its raining. Otherwise its too hard to get out quick. Especially if the bed is empty.

Long story short - on my next truck I will try hard to get a limited slip diff.

 

and to elaborate on the limited slip - the traction control is still needed and could be beneficial in snow and or ice. After all, its "limited slip" and not a locked rear differential.

The advantage of the limited slip is that the traction control kicks on more rarely so you get better driving in dry/wet conditions.

The systems will never really "compete". The traction control is slightly "redundant" to the limited slip, but not exactly.
No matter what your rear diff, the traction control will not kick in till it detects one wheel spin loose.
The goal of the limited slip is to get more torque to the ground without spinning a wheel.

 

Traction control will hold the brake on which ever corner is spinning as well as reduce throttle, and may even upshift

 

Traction control, ELD? Yea, this new stuff makes me want to keep my current truck even more. Looking at the Ford website for gearing options. Can only get a 3.73 limited slip with the V6's, seriously? For that kind of money, I should be able to have the differential I want. I don't trust electronics very much in vehicles. The fewer the better, IMO.

 

No more limited slip in the 2015's - open or e-locker only.

 

I got an E locker in my '14 which can be engaged regardless of 2H, 4WD hi or 4 low. I had a L/S in my previous '06 FX4 and opted for the E locker on the new one with all the snow/ice driving I do during big snowmobile trips in the winter.