Differential question

[mschiap]

Experiencing the first rains since I purchased the truck, my (2010 "SSV" with 4WD) is having a hard time getting up my slippery dirt road in the rain. I recently almost got stuck in 4 Low.
I am running the stock tire size 265/70R17 Goodyear Wrangler All terrain Adventure (cop tires.)

My understanding is I should turn off the traction control when stuck, since it is applying the brakes, which makes it more difficult to get unstuck. I also believe both differentials (front and rear) are "open" and rely on the traction control / stability control system to prevent wheelspin in less drastic situations.

My primary questions are
1. Are both differentials in fact "open"?
2. If yes, is there a junkyard swap part (from pickup or other trim level Expedition) that has a limited slip differential?
3. I am looking at purchasing a TrueTrac limited slip unit (Torsen-like )for my truck's rear differential. Anybody have experience with this part?

FWIW, my diffs are 3.73:1 ratio.

Finally, my other truck has no prob getting up the road, but it has 37x12.5 inch tires with 4wd and Torsen differentials front and rear.

 

[JExpedition07]

How steep is the road? I’d be leaning toward your 4WD not engaging even if it does go into low range it may not be sending power forward.

 

[mschiap]

Im pretty sure the 4WD is engaging, since I have engaged it before (4H) on dry gravel and I could feel it in the steering.
This was my first use of 4L, in desperation.

One section of road (dirt road on private property, not mine) is approx 100 yds long steep uphill. That's where I almost got stuck.

 

[Plati]

I'm far from an expert on 4WD … but my guess would be that the tires are the limiting factor here (assuming 4WD is functional without some major fail). Tires like that can fill up fast and become slicks. Can't they?

You can determine if you have LSD by looking at the axle code on the sticker plate on driver door threshold, and looking it up in Ford brochures. You might have that already?

 

[mschiap]

Thanks, I did not know there was a factory LSD possibility. My door label is painted over, but maybe I can get the info from the VIN, via dealer.
Once I found the code (after scratching-off the paint on the door label, it might be "16")
and using this:

https://www.blueovaltrucks.com/tech...y-your-ford-truck-axle-from-the-door-sticker/

I think I have a 3.73 (3.73 confirmed with VIN on this site:
https://www.ford-trucks.com/forums/vindecoder.php?
)
with no LSD

Better "Mud Tires"would help, but I was trying to keep this truck more "highway friendly" since I use it for towing long distances.

 

[762mm]

Put the rear wheels off the ground by placing axle stands under the rear frame.

Spin one of the rear wheels by hand. If the wheel on the other side spins in the opposite direction, you have an open differential; if both wheels spin in the same direction, you have an LSD. Easy test.

You can also take your VIN to a Ford dealer's service dept and they can tell you, although testing it yourself is still recommended in case the truck was already "upgraded" by previous owners.

My 2014 SSV has an open differential, I think they all do when they are stock. Although worse for climbing rough terrain, I prefer it to an LSD for longevity. Many members here with LSDs have had problems with the clutch packs in them, so I'll live without one. Problem-free simplicity is what I'm for with my trucks, lol.

 

[JExpedition07]

The reason I ask is I’ve had my truck with stock tires and 4WD with open diffs in some pretty serious mud/ loose stuff and it’s never gotten stuck. A dirt road should be no challenge for the ControlTrac 4WD system imo. In 2007 for the 3rd generation Ford removed the LSD option and in place used a 4 wheel braking bias off-road mode for 4H and 4L modes that acts like front and rear limited slips. This new system outperformed the previous rear limited slip option. I would jack up the truck and verify 4WD is working first since just because the front is locking in doesn’t mean power is being sent there....at least that’d be my first attack. If it is a limited slip may be in order for sure.

I *believe* I recall reading you cannot simply add a limited slip to the 2006-2012 Expeditions with Fords included off-road software as it and the limited slip will fight. 2006 was the only year they were available side by side and you could only option one or the other.

 

[max78]

I think you should have a door sticker that will tell you the ratio and if you have a limited slip or not.

My expedition for example is 3.73 with limited slip rear.

As for no traction, my guess would be completely different vehicles with vastly different tires. Smaller tires fill with mud much quicker making them useless.

 

[JExpedition07]

I’m not sure of the other code off the top of my head, but my 2007 Expedition EL Eddie Bauer 4WD has axle code 16 this is 3.73 open diff. The only other option was 3.31 open diff (available on standard wheelbase models).

 

[WEDGE]

Put the rear wheels off the ground by placing axle stands under the rear frame.

Spin one of the rear wheels by hand. If the wheel on the other side spins in the opposite direction, you have an open differential; if both wheels spin in the same direction, you have an LSD. Easy test.

You can also take your VIN to a Ford dealer's service dept and they can tell you, although testing it yourself is still recommended in case the truck was already "upgraded" by previous owners.

My 2014 SSV has an open differential, I think they all do when they are stock. Although worse for climbing rough terrain, I prefer it to an LSD for longevity. Many members here with LSDs have had problems with the clutch packs in them, so I'll live without one. Problem-free simplicity is what I'm for with my trucks, lol.

The OP could give me his vin number, or even just the last 8 digits and I can tell you if it's an open diff or not. (I work @ ford)

 

[mschiap]

The OP could give me his vin number, or even just the last 8 digits and I can tell you if it's an open diff or not. (I work @ ford)

Thanks much, I sent you a message with my VIN.

 

[Derp]

IMO tires make a big difference on greasy mud or ice, particularly when you add grade. I'm assuming the road is smooth and all 4 tires are staying on the ground?

 

[mschiap]

It's a smooth dirt road, with a litte gravel on top. But a fairly steep uphill section. Rear tires with deeper tread are probably the easiest improvement.

If there is no LSD in the rear, I think I am going to install Eaton TrueTrac 915A550 as it will help keep power going to rear wheels off-road without being intrusive on dry pavement. Also, as this is a Torsen style LSD unit, there are no clutch packs to wear out, as user 762mm cautioned.

 

[Derp]

Id be interested how it goes with the TrueTrac. I have open diffs too and might look to do something about it down the road.

 

[mschiap]

Thanks to user WEDGE, confirmed my differentials are "open."

I'm planning to add a Torsen in the rear, as this type of LSD is unobtrusive a (no lockup causing problems on pavement in dry or the rain, and no maintenance.) Torsen style LSD comes from factory in my Hummer H1, Mazda Miata and RX7, and I have found them to be a good compromise.

I'll post once I get the LSD installed.

Id be interested how it goes with the TrueTrac. I have open diffs too and might look to do something about it down the road.

 

[Dr0idattack]

Back to an earlier comment, the stock tires aren’t the best for towing. So if this appears to be a tire issue, you might explore going to an LT tire with better traction.

 

[Congage]

Up here in Wyoming. 7 -8 months of winter. 1300 ft driveway. 2 -10 % grades. 1 tire choice. BF Goodrich KO2.
I run them on 2xF250 and 2xF150 plus my 2017 Expedition El. Never a problem of any kind.

 

[otterpat]

You can go to your dealer and ask for an oasis report it will tell you everything

 

[Derp]

Up here in Wyoming. 7 -8 months of winter. 1300 ft driveway. 2 -10 % grades. 1 tire choice. BF Goodrich KO2.
I run them on 2xF250 and 2xF150 plus my 2017 Expedition El. Never a problem of any kind.

IMO pretty bad tire in mud or deep snow. Works pretty well in on road snowy conditions though. Fantastic in dry on/off road conditions.

 

[Congage]

Many choices for many conditions. My son took 1st place with his old Bronco running Ko2's mud bogging. Only 2 ft mud class with 33's on. I pull thru 12-18 inch snow in f250 on ranch every winter and stuck it twice that I remember. Most importantly is they handle all our gravel and rock roads. No flats ever. In our choice of lifestyle these have proven better than expected. Now with slippery dirt road with grade and no 2 to 8 inch ruts to claw up I say good luck.