I need to replace a bearing(s) and was looking through the Amsoil catalog to get some gear lube. I noticed they have different types based on what kind of rear end you have. I knew that already. But I am curious and seen many ask about the type of rear end they have in their 7.3; did Ford actually offer anything BUT a posi unit in there trucks? Did they really offer an open rear end for trucks like these? I see no benefit and I also did not think there were many options as far as differentials go for these trucks besides gear ratios.

 

You could get either an open or a limited slip diff in these trucks.

 

Guess I just can't see the reasoning behind it. There really is no benefit of having an open rear end. Maybe it's just a way for Ford to hit you with upgrades.

Since I don't post here often I guess it's only fair to offer some input. I searched all over this forum for a solution to a problem I am having with my truck. I am having the symptoms that I've seen some people talk about; a groaning howling type noise that sounded like it was coming from the drivers side front starting at about 40 MPH. Until I sat in the passenger seat and realized it was coming from the drivetrain. Possible solutions from everybody was front wheel bearings, U-joints, carrier bearing, etc. All these sound like possible solutions so I checked all these. Without actually taking off the driveshaft, I did not see anything out of the ordinary. So I went down to the shop and put it on the lift and jacked up the back end to get it up to about 50 MPH and sure enough it was coming from the rear end; I could hear the noise inside the rear end with a slight vibration. I checked the rear U-joint and it's in perfect condition. Checked the fluid and sure enough it's full of metal. Not 100% sure if it's a bearing and if so, which one. But it is definitely coming from inside the housing. I'll pull it apart tomorrow to see exactly what it is. So if anybody comes across such a noise and is trying to diagnose the problem, check the fluid first. It's a quick check and might save you some time and aggravation.

 

My F-250 is an open rear. I didn't order it that way, I bought the truck used, but I prefer an open rear unless it will be used in off-road situations. I use it almost strictly for street use.
We went through the same symptoms with my son's 8.8 locking rear end with howling, clanking and fresh oil full of metal bits.
First off, the spiders and axle gears became chewed up - something common with 8.8s. We replaced them, cleaned out the housing and put in fresh oil and friction modifier (and did not have to remove the carrier.)
Less than 5K miles later, it turned dark and was full of fine metal shavings suspended in the oil.
Turns out the clutch packs were just shot. Replacing them solved the problem, and restored normal locking capability. We were able to replace them in situ easily enough, without removing the carrier. Worked well, too.
I would look first at the spider and side gears, then at the clutch packs.
I do not know how the clutch packs are replaced on the 10.5 though, although I wish I could help out there.

 

I don't see the benefit of having a limited slip in a truck that stays on the road like mine does. The limited slip costs more, has more maintenance, and can cause handling problems on slippery roads that I don't need. I haven't had a limited slip in a long time because I prefer an open diff.

 

Thanks for the info. I'll post when I find out more.

 

Personal preference I guess. I wasn't knocking open diffs. I've never owned anything that had one. Always been a LS. I know when the posi wore out in the 8.8 in my Mustang I couldn't stand driving it.

 

This why I went with the Detroit Truetrac: "TrueTrac differentials are unique in that they increase traction but do not affect steering or wear out
prematurely; these problems are common with limited-slip differentials that use clutch plates and springs.
TrueTrac performs like a conventional differential, until there is a loss of traction. Only then will the power
transfer occur - when it is needed."
Also,"The TrueTrac differential is designed to operate in those lubricants recommended by the vehicle/axle
manufacturer for conventional differentials."
These are quotes from the Truetrac owner's manual. I just put mine in last week and love it.

 

How much did that run you if you don't mind me asking?

I took my diff out earlier today and it was the diff bearing (ring gear side). It wasn't completely shot, but enough to cause a noticeable vibration and noise. Would have gotten worse had I waited. Everything else looks perfect and the unit itself is still strong. Just can't see why a bearing would go after 125K miles. Oh well, things break. Easy fix, just time consuming.

 

NEW FORD 10.25 TRUETRAC 10.5 POSI PN: 915A550 F250 F350:eBay Motors (item 270466001486 end time Jan-03-10 14:53:12 PST) Comes with the diff carrier bearings, races, shims, and a gasket. He can sell you just the bearings if you want to go that route.

 

Agreed.
The easiest way to end up in the ditch is to try and drive a posi rear end in the ice.
With an open diff you have the "inconvenience" of one wheel spinning vs the "inconvenience" of having to call the tow truck because, despite your best efforts, the rear end just swung around on that glare ice and dropped the RR wheel into the ditch.