This sounds uneducated, but what exactly does 4A do over 4HI or 4LO? Is it more than just automatically engaging 4HI when a wheel slips?

 

4A is AWD vs 4HI being 4WD. In 4A all wheels are engaged but the fronts are clutched so the truck behaves as would any AWD system with the principal noticeable difference being no driveline binding on hard surfaces. It's perfectly OK to leave 4A on all you want (small mileage hit) while 4HI is for low traction surfaces only. It's truly the best of both worlds.

EDIT: Biggest reason to have 4WD vs AWD is the positive front rear lock when in situations where the front and rear have radically differing traction. 4WD will turn fronts and rears the same but AWD will allow front/rear slippage. This is not good when you need full power to both ends. With 4A as a standard mode in low traction, you only switch to 4HI or LO when you absolutely want everything locked together, such as off road, deep snow, or mud.

 

I am somewhat surprised, that looks like quite the easy (ie straightforward) mod with no BS

 

Your reasoning was exactly mine too for converting to 4A. Not accidentally smoking the tires on spirited launch is a nice side effect too.

Actually there are other parts that actuate when shifting from 2H to 4H the front hubs must lock also. I was really more concerned with those constantly switching on and off, more than the transfer case.

Mike

 

It really wasn't bad to be honest....Even if you hire the heavy lifting (Transfer Case) and do the electronics yourself. Basic plug and play and a simple Forscan change.

Mike

 

For continuous off-road use will the 4A and 4H transfer cases hold up the same or is one or the other more light duty?

 

Havent had a 4A truck, but my last car was symmetrical AWD (subaru STi) and it's one of those things that you dont "miss" until you have it.
pay attention and a "manual" 4x4 is perfectly fine. But after driving something that is more adaptive its noticeably better unless you're completely off road. Would I pay $5k+ more on a truck for it? no and I live somewhere with winter for 7 or more months a year. Just my 2 cents

 

The Raptor has 4A...Do I need to say anything more?

Mike

 

Some of the guys on the Raptor forum found out that if the 4A clutches in the transfer case start to overheat you'll get a message on the dash and it will automatically go into 4hi. It shouldn't happen with normal driving but can happen with overly spirited driving in slippery conditions.

 

Subaru works much different. The Subaru always uses power 50/50 to front and rear at all times. The F150 only if slippage is detected. For an all wheel drive 4A it's not the best system. Not saying it's bad because you still have 4H if needed.