Anyone drive in 4A and seems to hunt for traction

[FordTechOne]

The operating strategy of the 4WD system changed in 2019.

Due to concerns with IWE (Integrated Wheel End) disengagement on cold starts, Ford revised the TCCM (Transfer Case Control Module) and PCM programming to keep the front hubs engaged until the truck is fully warmed up. This prevents the hubs from partially engaging after a cold start due to lack of sufficient vacuum. There is a software update that is available for earlier models as well with the same strategy.

When 4A is activated, the front differential is engaged with the transfer case, regardless of how little torque it may receive based on conditions. I wouldn't rely solely on the depiction in the Instrument Cluster to determine where the power is actually being routed.

I've had 2 F-150s with the Torque-on-Demand T-case...a 2018 Powerstroke Diesel and my 2019 Raptor. Haven't noticed any difference in the way either drove when in 4A, except the extra traction available.

 

[Hawaiian Time]

I've heard a few people say mention front bias on our trucks and it is just not possible. I know it feels like it sometimes when the rear is slipping hard but it's still a direct connection, not clutched in any way. The rear is directly connected thru the transfer case, not clutched. The front diff connects thru a viscous coupling so it can be varied, but not the rear. The only front bias we get is when the rear tires are on ice.

Front Bias on dry pavement - really. Put rear wheels on dry pavement and front wheels in water crossing street at stop sign. Front wheels spin until back axle locks in with a thunk.

There's a corner on the way home where there's always water running across the street at the Stop Line. Fronts spin everytime for a second then rear locks in.

Sport mode shifts 4A to 2H.

Maybe this exists only on early 2017 Raptors with Torsen Front Diffs.

Somebody else here on FRF wrote about the delay in going from 2A to AWD and the Torque Steer Front Bias on 2017 Raptor 802A's with Torsen Front Diff.

Its good like this, no update needed.

Its not a dream. Ill post video.

Its Quantum Physics!

 

[jabroni619]

I've heard a few people say mention front bias on our trucks and it is just not possible. I know it feels like it sometimes when the rear is slipping hard but it's still a direct connection, not clutched in any way. The rear is directly connected thru the transfer case, not clutched. The front diff connects thru a viscous coupling so it can be varied, but not the rear. The only front bias we get is when the rear tires are on ice.

I wanted to say something similar but didn't want to argue with the folks that think 4A is front biased. It simply isn't.

 

[Loufish]

Front Bias on dry pavement - really. Put rear wheels on dry pavement and front wheels in water crossing street at stop sign. Front wheels spin until back axle locks in with a thunk.

Since there is NO mechanism to lock/unlock the rear drive shaft, the rear diff can't lock in....If I pull on your finger, your hold hand will move with the finger...the to are connected...just like the T/C output shaft is connected to the T/C input shaft...

 

[Hawaiian Time]

Since there is NO mechanism to lock/unlock the rear drive shaft, the rear diff can't lock in....If I pull on your finger, your hold hand will move with the finger...the to are connected...just like the T/C output shaft is connected to the T/C input shaft...

So the power to the rear driveshaft does not go through the transfer case? Indeed it DOES because that's how you get low 4x4 at the rear axle and that's why there is a transfer case differential lock. When that 4x4 lock button is pushed or when you are in 2H there is a direct connection to the rear axle from the transfer case.

The Defense Rests.....

Aloha, HT

 

[jabroni619]

So the power to the rear driveshaft does not go through the transfer case? Indeed it DOES because that's how you get low 4x4 at the rear axle and that's why there is a transfer case differential lock. When that 4x4 lock button is pushed or when you are in 2H there is a direct connection to the rear axle from the transfer case.

The Defense Rests.....

Aloha, HT

you don’t know what you’re taking about. As far as how the rear end gets its power there is no difference between 2H, 4H and 4A. The difference between 4H and 4A is a wet clutch pack that allows for slippage in 4A. That slippage is only applied to the front. The front can get UPTO 50% power. Meaning there’s no front bias. The rear is NEVER disconnected unless you’re in neutral or park.

Also, you can use sport mode in 4A you just need to select sport mode first then rotate the knob. And that lock button you’re referring to? That’s your rear diff lock. It has nothing to do with your transfer case. It makes sure both rear wheels get equal power regardless of traction conditions. You seriously have no clue how your truck works. Maybe try reading the manual or take the RA course to get a clue.

It’s really quite shocking at the level of face palm in your post.

 

[Muchmore]

So the power to the rear driveshaft does not go through the transfer case? Indeed it DOES because that's how you get low 4x4 at the rear axle and that's why there is a transfer case differential lock. When that 4x4 lock button is pushed or when you are in 2H there is a direct connection to the rear axle from the transfer case.

The Defense Rests.....

I would have laughed this off as a newbee comment, but, when you went with "The defense rests" the ignorance is just downright funny

 

[dewalt]

"The defence rests"

pleading insanity by the looks of it

 

[TwizzleStix]

Ok, I have figured out HT’s described scenario that makes him think how he does because he is so wrong, but he doesn’t know what he doesn’t know and is remaining actively ignorant.

If only one front wheel is on slippery surface in any 4wd mode WITH the Torsen diff, and he pokes the gas, the slippery surface front wheel CAN “spin” indeed a small amount while the Torsen diff gearset is driven to full travel before the Torque is applied to the opposite wheel. It is can be up to about a full revolution, depending on the diff type with ZERO rear wheel spin.

When a Torsen/Quaife type differential is allowed to fully run to the stop on either side, it does indeed make a “clunk” sound as the power/torque hits the other wheel. The differential multiplication action results in ONLY the affected front wheel spinning.

It is this normal Torsen function that HT assumes is magically resulting in his truck (and his alone) is “FWD”.

 

[Hawaiian Time]

you don’t know what you’re taking about. As far as how the rear end gets its power there is no difference between 2H, 4H and 4A. The difference between 4H and 4A is a wet clutch pack that allows for slippage in 4A. That slippage is only applied to the front. The front can get UPTO 50% power. Meaning there’s no front bias. The rear is NEVER disconnected unless you’re in neutral or park.

Also, you can use sport mode in 4A you just need to select sport mode first then rotate the knob. And that lock button you’re referring to? That’s your rear diff lock. It has nothing to do with your transfer case. It makes sure both rear wheels get equal power regardless of traction conditions. You seriously have no clue how your truck works. Maybe try reading the manual or take the RA course to get a clue.

It’s really quite shocking at the level of face palm in your post.

Jeez why get personal? I KNOW EXACTLY WHAT IM TALKING ABOUT! ITS MY TRUCK!!!! IM NOT SOME ******** YAHOO!!! To get the rear axle into Low 4WD ALL Raptors go through the center differential gears. A true AWD "Clutch Pack" in the center differential can be biased front or rear or true 100% power to front or rear! Also my truck will shift out of 4A when I choose Sport Mode and go to 2H. It will NOT go back 4A by turning the knob. Give me break! Maybe you should read your manual. The lock button on the 4x4 button is TRANSFER CASE LOCK.

Do you Twizzle Stix own an early 2017 Raptor Screw 802A with Torsen Front Diff? If not then shut your Front Door please. My Raptor's Build Date is January 2017 so the transfer case and / or traction control and / or 4A configuration is obviously different. My truck was an early production new car show truck with Grindstaff for Johnson City, TN. in March 2017.

Until YOU drive my truck don't tell me what my truck does OK? WTF? Don't project your ignorance onto my description of how my truck operates! And don't disrespect people who you disagree with you by calling them names! Its a true sign of low IQ! We are not in 5th grade anymore!!!

HT