2007 Level II Front & Rear Diff Fluid Change, is the FRONT diff a Tru Lok - Posi? or Open?

[MaicoDoug]

Hi fellow ranger warriors-

I'm on my way up to the jeep trails in Colorado and I thought this would be a decent chance to finally service the differential fluids. I was going to use the Ford OEM recommended. I'll be "representing" the Ranger way!

The rear is no question; Motorcraft 75w-140 synthetic oil, it's the front that has me puzzled. Now we all know that 99% of all 4wd vehicles have an open diff at the front, but of all those the FX-4/ with the Level II option may or may not. Would be interesting to finally know, as the tag is possibly not accessible to attempt to discover the "L" between the numbers "4 & 10" like the rear has. I'll attempt to get up in there with a light, but it's tight. Here is a pic of the label of the front diff, the top right corner is clipped, sorry it says "STD". Thanks in advance for your interest & expert advice, & comments.

 

[19Walt93]

I've never seen a Ranger with front limited slip- and I worked at a dealer form 1975 until 2017. Older trucks with manual locking hubs sometimes had from limited slip and they handled twitchy if the hubs were locked, even in 2wd. By the way, no Ford ever had "posi". Positraction was Chevy's name for their weak kneed, breakage prone limited slip rear ends.

 

[sgtsandman]

None of the Rangers that came with the Dana 25 SLA came with anything other than an open differential from the factory. There are lockers and LSDs that are available for them though. So, it is possible there is one in there.

The only way to know for sure is the drop the diff and pull the cover. You have to do that anyway since there is not enough room to properly pull the cover for cleaning and resealing.

 

[MaicoDoug]

Thank you thank you thank you.

LSD, limited slip differential works for me. It does take quite a bit of concentration to keep from zigzagging, especially since the front end was rebuilt & a 4 wheel alignment checked, toe was dead on, just camber adjusted. That was a reason why I wondered. With 16mpg factory those live axles are most likely why, but in the dirt everything is nice.

Walt, "Tru Lok" I believe, sorry for the posi reference. Thanks

Sandman, the truck is 100% stock except for the beefed up front shock tower & coilovers.

Need to climb up in there & have a decent look at the tag. The oil pan gasket leaks & needs some star lock washers on those 10mm bolts. So I already plan on having a date with a bar of lava soap. But now it's time to pull some more recommended maintenance.

Hope to post some 4 wheel'in picks of the truck out there in the rockies where it belongs.
-Doug

 

[MaicoDoug]

The fluid change went well, 75w-140 in the rear and 75w-90 in the front. Crazy tight and rocky, what a blast in this thing! However...I have a concern, up on the Imogene pass trail between Telluride & Ouray, Colorado I noticed the inside front tire trying to jump ahead wanting to spin with the outside as if the front axle had locked each wheel together. Pushing through each turn making the turning radius wider than it should. Was in 4WD low, in 1st gear going slow in very tight, wet trail conditions.

Would my issue be because I just noticed that the label says "Limited Slip Friction Modifier Included"?
Whoops... I did add the Motorcraft friction modifier in the rear. Would of used all Motorcraft fluid front & rear but the parts dept was a bottle short for each diff. So I went with the Mobil 1. I'll post about the trip in the off-road section. Thx again guys, she perfomed crazy awesome on the M/T Degans 31s at 20psi with very little difficulty on a trail rated 4 / 5 for difficulty. At 12,000 feet above the tree line.

 

[Curious Hound]

Pushing through each turn making the turning radius wider than it should.

Probably due to rear limited slip. Both wheels trying to spin same speed tries to push the truck straight ahead.

you DO want friction modifier for the rear due to the LS components. Front open diff doesn’t care if it has friction modifier or not. It won’t hurt anything.

 

[Uncle Gump]

The Torsen diff in the rear doesn't require the friction modifier.

In my experience... even an open front diff will scrape and scrub a little on tight turns when in 4wd.... even rocking the steering wheel a bit. Don't think the friction modifier hurt anything in the front but you didn't need it.

 

[bobbywalter]

i usually run a cheaper conventional. often enough i have to change fluids from water crossings or sitting in holes for extended periods extracting others.

but i also have higher capacity axles....even conventional isnt cheap compared to factory ranger pigs if you change it 3 times in a month. over 2 1/2 gallons between front and rear.


the bronco isnt too bad...the 44 and 9 hold less then 2 gallons.

i do use synthectic in the rear when running heavy hiway....like back when i was driving from northern michigan to southern florida every other week.


just mentioning it...as you may end up in some water. that place out there is off the hook. especially black bear.

 

[MaicoDoug]

All went well, with some water crossings, since then (6 weeks ago) I have noticed some half teaspoon amounts of gear oil from the rear on the ground. It may over full and weeping out. Need to line up the drip to the rear end exactly. The cover sealing came out perfect using the Permatex gear oil formula and total degrease and bead style application. Now I need to find where that weep hole is. The input yoke & bushing-seal may need attention as the prior owner had indicated, but I never had any issue although the snout has always had some discoloration from oil, nothing fresh however. The 5 times it has left an oil spot since the oil change, typically after a 10 mile drive, now nothing....& still full. Need to get under there and take a pic & wipe real well, then watch.

But along with that, and thank you all for the help, I wanted to inquire about where that darn weep hole was?

Having the tires underneath the fenders was the only way to pass on the trail. It drives better in the stock configuration that way too. The M/T Deegan 32x12.5x15 no complaint off road air'ed down to @20psi and the highway was no issue, noisy but hey. It was especially tight on the trail. Mainly side by sides up past 12,000 Ft.

 

[rubydist]

My experience is also that the Torsen really likes to lock and does not like to differential when under load, so on those trails with lots of loose rock its sometimes challenging to get the vehicle to turn.

 

[MaicoDoug]

If the slight sliding forward in the tightest turns is the only issue, I'm so glad. She did about the best all day long I could expect. It probably was the rear LSD. With the camper shell & our stuff in the bed, had Apx. 500 pounds payload.

If the leak keeps up, I may recheck the fluid level, and then look into the new yoke, input bushing & seal replacement process. 4 link one of these days. Never touched a rear end in my life.