Question about 4L - XLT FX4 locking rear diff

[ericsmr]

I did my 3 month engage 4H today and locked the rear diff too and everything went fine and dandy.

I did 4L for the very first time on a very loose gravel and dirt road and I experienced extremely rough shifting, both up and down from 2-3 3-4 4-3 3-2, my truck essentially jerked me around and I am trying to figure out if this is normal (first time truck owner first time 4L)
I didn’t drive long enough to think there’s any damage but the noticeable tough jerk makes me think something might be wrong and might need to take it to the dealership.

Staying in gear was also fine, just the shifting

Is this normal?

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[ericsmr]

This is a 2025 XLT btw owned for about 4 months

 

[Ron Quixote]

Hmm, that doesn't sound right. You shifted into Neutral before shifting into 4-Lo, right?

If this behavior can be reproduced, I'd take it to the dealer and let them sort it out.

 

[ericsmr]

Hmm, that doesn't sound right. You shifted into Neutral before shifting into 4-Lo, right?

If this behavior can be reproduced, I'd take it to the dealer and let them sort it out.

Yes, I was in neutral before shifting in and out of 4L!

Ok, that’s what I was thinking just wanted to make sure I wasn’t over thinking this. Seems reproducible as I went out and back in to see if it would change

 

[daytoncarter]

My 2025 Ranger FX4 Lariat does shift more abruptly when in 4L. Not jarring, but not smooth either. I think it's expected behavior.

 

[Sharpix]

4L is for LOW SPEED, almost crawling. It halves the speed and multiplies torque force twice (not exactly twice but in a given ratio).
Its NOT for cruising in any way, unless you want to cruise on rough rough uneven rocks where theres not other option but going slowly. in dirt ditches, pulling out somebody or anything in between.

ITS NOT FOR CRUISING. The transmission is actually in a very NOT NORMAL STATE. Its even relatively easy to break the transmission. when in 4L going in pavement when turning.

Please learn from some youtube vids on 4x4s. Your truck will thank you later.

 

[ericsmr]

4L is for LOW SPEED, almost crawling. It halves the speed and multiplies torque force twice (not exactly twice but in a given ratio).
Its NOT for cruising in any way, unless you want to cruise on rough rough uneven rocks where theres not other option but going slowly. in dirt ditches, pulling out somebody or anything in between.

ITS NOT FOR CRUISING. The transmission is actually in a very NOT NORMAL STATE. Its even relatively easy to break the transmission. when in 4L going in pavement when turning.

Please learn from some youtube vids on 4x4s. Your truck will thank you later.

I was going relatively slow, maybe up to 15-18mph but it seems like you’re saying it’s even slower than that if you mentioned rock crawling. So when engaging in 4L for maintenance sake how do you suppose I go about it? If I can’t cruise in it even at low speeds not sure if just engaging for a few mins going 1-3mph and stopping there or just engaging fully stopped for a few mins?

As I mentioned I was in rough gravel and went straight for less than 1/8mile up to 15-18mph and slowed to near 5mph and turned around and went back

 

[hand-filer]

The torque multiplication in 4L will absolutely make the shifts seem more abrupt. Totally normal.

 

[Khamsin]

4L is for LOW SPEED, almost crawling.

To drive this point further, direct from Ford:

Four-wheel drive low provides electronically or mechanically locked four-wheel drive power to both the front and rear wheels for use on low traction surfaces, but does so with additional gearing for increased torque multiplication. This mode is only for off-road conditions such as deep sand, steep slopes, or pulling heavy objects.

The rear locker will automatically disengage on its own above 20 mph for preservation as well.

My personal, completely unsolicited advice to OP: stay at or below 5-8 with lockers on and 4LO engaged, and only on the proper surfaces. Running at 18mph on a gravel/dirt road is wild work.

 

[ericsmr]

To drive this point further, direct from Ford:

Four-wheel drive low provides electronically or mechanically locked four-wheel drive power to both the front and rear wheels for use on low traction surfaces, but does so with additional gearing for increased torque multiplication. This mode is only for off-road conditions such as deep sand, steep slopes, or pulling heavy objects.

The rear locker will automatically disengage on its own above 20 mph for preservation as well.

My personal, completely unsolicited advice to OP: stay at or below 5-8 with lockers on and 4LO engaged, and only on the proper surfaces. Running at 18mph on a gravel/dirt road is wild work.

Thank you!

 

[superj]

I would think that putting it in 4h would be fine for making sure everything is lubed and working.

 

[MasterCylinder]

I did my 3 month engage 4H today and locked the rear diff too and everything went fine and dandy.

I did 4L for the very first time on a very loose gravel and dirt road and I experienced extremely rough shifting, both up and down from 2-3 3-4 4-3 3-2, my truck essentially jerked me around and I am trying to figure out if this is normal (first time truck owner first time 4L)
I didn’t drive long enough to think there’s any damage but the noticeable tough jerk makes me think something might be wrong and might need to take it to the dealership.

Staying in gear was also fine, just the shifting

Is this normal?

When going into 4L you just multiplied your gear ratio by 2-2-1/2 times. If you have 3.73 you just went to 7.50-9.375 ratio. 4L should be kept below 5-10 mph and is not really designed for normal type of driving situation, up-shift/downshift scenario, you should be selecting the gear you want to be in and holding it, it will/should shift more abruptly and faster. That ratio is a strain on all the components especially in shifting mode. but if worried let dealer check it out. I wouldn't be mentioning how high a gear you were shifting in and out of myself!

 

[Hurricane_Whisperer]

I did my 3 month engage 4H today and locked the rear diff too and everything went fine and dandy.

I did 4L for the very first time on a very loose gravel and dirt road and I experienced extremely rough shifting, both up and down from 2-3 3-4 4-3 3-2, my truck essentially jerked me around and I am trying to figure out if this is normal (first time truck owner first time 4L)
I didn’t drive long enough to think there’s any damage but the noticeable tough jerk makes me think something might be wrong and might need to take it to the dealership.

Staying in gear was also fine, just the shifting

Is this normal?

I have never driven an automatic transmission in 4wd low.

I have driven a manual transmission in 4wd low.

In lower gears especially, you had to be very easy just stepping on the gas.

Really, anything below 3rd was extreme.

I suspect at least part of the roughness is due to a lack of calibrating your foot to proper 4wd low throttle application.

I know it was a shock to my foot calibration first time I drove 4wd low.

Feather touch or balloon touch on the throttle.

It was actually difficult to be smooth in a 2004, 4wd Diesel pickup or even a 1986 Bronco 2 in lower gears. The slightest touch rev’d the engine a couple hundred rpm’s

Lower gears were for crawling over logs or rocks. 3rd and 4th were for steep ups and downs where precision speed control was desired.

It definitely took practice on the throttle in those old manual vehicles.

Maybe the newer vehicles have drive by wire circuits that lessen fuel pedal sensitivity in 4wd low. If they did, that would probably be a good idea, because that first 1/4 inch was a bang.

 

[daytoncarter]

Maybe the newer vehicles have drive by wire circuits that lessen fuel pedal sensitivity in 4wd low. If they did, that would probably be a good idea, because that first 1/4 inch was a bang.

I think the Ranger does, and if you use slippery or rock crawl mode, it should be damping the throttle further.

 

[Tri5Ford]

I did my 3 month engage 4H today and locked the rear diff too and everything went fine and dandy.

I did 4L for the very first time on a very loose gravel and dirt road and I experienced extremely rough shifting, both up and down from 2-3 3-4 4-3 3-2, my truck essentially jerked me around and I am trying to figure out if this is normal (first time truck owner first time 4L)
I didn’t drive long enough to think there’s any damage but the noticeable tough jerk makes me think something might be wrong and might need to take it to the dealership.

Staying in gear was also fine, just the shifting

Is this normal?

As your RPMs are higher, your shifting will be more abrupt.

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