I have a '92 F350 with a limited slip sterling single rear end. I want to swap in a sterling dually rear from a '97. I know the dually axle has an open diff. Will the limited slip diff from the '92 fit in the '97 axle?

Does anyone know the difference in wheel mount surface to wheel mount surface between the two axles?

 

I dont believe limited slip can be simply swapped in, but I would recommend reading this thread first, I would personally say to add an auto locker if you add any at all.

https://www.ford-trucks.com/forums/1...erentials.html

 

I would think the '92 diff would fit into the '97 axle, but you will need to set up the gears (or pay someone else to do it). That's about half the cost of a diff swap, so I certainly wouldn't go to that much effort or expense to put a worn out limited slip in. Actually I wouldn't ever put any clutch-type limited slip in any axle ever. But even people who like clutch-type limited slips wouldn't put a worn one in.

You can rebuild your old limited slip and make it as bad (in my opinion) as new. Or you could get something new.

If it were me, I'd go with a Truetrac assuming that a dually axle means you'll be hauling or towing with it. I like automatic lockers, but not for hauling and really not for towing. A selectable locker (like an OX or ARB) would be another good choice in my opinion, but getting a little more expensive.

 

Diff would swap in and would just need a back lash check.

 

X2...agree 100%

But it would be silly to not rebuild the clutches. Great opportunity to tighten the lockup like many do with the 8.8" axles.

 

Yes, as the above posters said, swap right in, just check backlash. One question though, the dually rear is from a pickup right, not a cab and chassis because that won't fit in a pickup.

 

You can MAYBE get by with just checking backlash if you use the gears that came in the "new" axle, transferring that ring gear to your limited slip carrier and not touching the pinion.

In order to get gear mesh set up correctly you need to get the pinion positioned correctly (front-to-back) and the ring gear positioned correctly (side-to-side). If you have the pinion located wrong, you will not get the correct contact if you only check backlash. If you don't move the pinion, then positioning the ring gear correctly from side-to-side SHOULD give you both a good contact pattern and good backlash. So adjusting it to get the backlash correct SHOULD therefore give you the right contact pattern. Personally I'd check the pattern before you take the gears out, and then again after you get the backlash set up to be sure it's OK.

If you move the gears from your current axle over to the new one you will be repositioning the pinion gear so then you will need to do a full gear setup. And don't keep the pinion from the new axle and use the ring gear from your old one. Even if they are the same ratio, ring and pinion are a matched set that you can't mix up.

 

X2^ In a perfect world it would be fine, but manufacturing tolerances can wreak havoc...

 

Bob, pinion depth is established by the housing,pinion gear and bearings. If he installed his original ring gear on the new diff, the only thing affected is the backlash, pinion depth would not change.

You can never "transfer gears" to another housing without checking pinion depth/pattern.

Maybe I'm misunderstanding your post. Are suggesting mixing ring/pinion combos?

 

I'm saying the same thing you are. Only "difference" is that from what I understand, his "original" ring gear is the one currently on his limited slip diff that he's moving into his "new" axle. So he needs to use the ring and pinion from the "new" axle, and not use the gears from his "original" axle.

So to be clear, you're getting a dually axle with an open diff. If you hope to have a simple gear set up you MUST use the ring and pinion that came in that dually axle, even if you are swapping a limited slip carrier in from another axle.

 

Thanks everyone. I would not mix a pinion and ring gear set, both trucks have the same 4.10 ratio. After thinking about it, it would be smarter to just bite the bullet and get a locker and have it set up right.

 

I don't know if the truetrac is any better for a Sterling than an 8.8, but in my opinion those things are trash.

Back when I used to drag race a lot I used to mess around in the shop parking lot looking at traction patches at adjust tire pressure. I had a truetrac in a GM 10 bolt (maybe that was the real problem, haha) and after a couple burnouts it would only spin on the one side. Lame.

I had a friend that used to autocross a fullsize Ford station wagon, and he had the same issues.

I've never heard anyone say that about a Detroit Locker; and I've known folks to drive home with a broken axle with a DL. Plus, since your truck is a stick, parking lot/ tight maneuvering won't be as big of a deal.

 

A Truetrac is not a locker. If you're comparing it to a Detroit it'll either come out way better or way worse, depending on if you should have a locker or a Truetrac in the application.

Truetracs don't positively lock, which is great in most street driving situations, but not so great in rocks, mud or at the strip.

Truetracs don't have friction clutches to wear out, but I don't know what would happen to one if you continually slipped it. I wouldn't think it would "loosen up", but I still wouldn't think it would be happy about it.

 

Understood. A Truetrac is a traction enhancement device, though, and in my experience not a very good one as it pertains to drag racing, which is probably the most ideal environment for a differential to operate in. No turns, no drive wheels coming off the ground (hopefully ), inclines, etc. Have you had positive experiences with the Truetrac?

 

I don't have any personal experience with Truetracs. From what I've heard (and from understanding how they work) they are great for general street use and probably better than clutch-type limited slips for light off-roading (mud, snow, etc) and much better than clutch type limited slips regarding wear in that type of usage.

However I will respectfully disagree with you about drag racing being the ideal environment for a limited slip differential. Yes you're going straight. But although you aren't literally lifting a drive tire off the ground like you do rockcrawling, you are significantly unweighting the right tire (and weighing down the left). So if you are spinning one or both tires you are making the diff work hard.

Again, with no friction surfaces to wear it's not completely clear to me why "roasting" a Truetrac would result in it losing it's torque bias. But I would never choose a Truetrac for that usage.

For what it's worth, my friends who are into that seem to use Auburns (clutch-type limited slips) or spools.