So I have a 1988 F-250 with axle code 35, meaning I have the sterling 10.25 axle with 4.10 gears and an open carrier. I have confirmed this by looking at the carrier and bull gear. My friend is parting out a 1997 F-350 with axle code C9, meaning it has the sterling 10.25 with 3.55 ratio and a limited slip carrier. I have confirmed the axle ratio and the fact that it is limited slip. I know there was a change around 1992 with these differentials, but I think it was just the pinion shaft and bearing that changed. So now to my question, I'd like to upgrade my axle to a limited slip one and was wondering if I could swap carriers without too much trouble. I also need to keep my gear ratio, since I have 4X4. I plan on rebuilding my differential this winter anyways (new seals and bearings).

Thanks in advance.

 

What all do you use your truck for?
Personally, to avoid having to swap ring gears, get new bearings, new clutches for the limited slip unit, possibly have to reshim the carrier for the right backlash...etc. I would just get a lunchbox locker and stick it in the open carrier, and be done in a couple hours

 

I'm pretty sure you could put the '97 limited slip carrier in your '88 axle, moving your 4.10 ring gear to the new carrier. Can you do it without too much trouble? And is it worth it? I can't answer either one for you.

You will need to set up your gears, no matter what. That's not rocket science, but it's not typical shade tree stuff either. I've done it once and it was a PAIN! I could imagine doing it again, but I wouldn't say it's "without too much trouble."

The other thing is that I'm no fan of factory limited slips. In my experience they are the worst of both worlds, all of the traction limitations of an open diff when you need traction, most of the stability limitations of a locker when you need stability. I know many disagree with me on that, but I wouldn't go to any effort to add a factory limited slip.

If I was going to the effort or expense to add a traction adding diff I'd spend a little on the diff and get something worth adding. Either a TrueTrac (if you just want a limited slip), an automatic locker like a Detroit (if you want the ultimate in traction and are willing to put up with definitely noticeable handling quirks) or a selectable locker like an ARB (if you want traction but don't want to deal with the handling issues).

(edit to add: sticking a lunchbox locker in the existing carrier as Mudsport96 suggests is another good option in my opinion.)

 

I do some towing and driving in slippery conditions, I just want a bit more traction so I don't have to get out and lock my hubs as often. What is a lunchbox locker? I've never heard of those. I also want to learn how to do a gear set up and do all of that stuff, so it's not a big deal if it's a lot of work. I would also have to set them up on my axle again if I was doing the pinion bearing if I understand that correctly.

Did some googling,
A lunchbox diff sounds like it would be awful for my driving style and conditions, as I drive on very curvy roads on my way to work and like to gas it around corners and have a bit of fun sometimes. If the diff were to lock and unlock around corners like it seems they do that would be hard on tires and axles. Not to mention take the fun out of tooling around on curvy roads.

 

at 24 years old, i am pretty sure that 97 rear diff is now an open diff too. the clutches in the ford limited slip diff leave a lot of room for improvement.

 

Lunchbox lockers get a bad rap because every ******* who dailys a mercedes swaps one into their short wheelbase weekend jeep and then complains that it adds clunikness to a vehicle that already had poorer manners than they were used to.

You won't even notice it there in a long wheelbase truck. Increased tire wear is negligible if any.

If you want predicable sliding when you mash the gas mid corner a lunchbox is far better than an open.

The factory limited slip is little better than an open.

 

I guess that makes sense, but I don't want any sliding. I'd rather it behave like an open, but with a little more traction in the winter months for starting from stops and whatnot. And as for what tjc transport said, it's 24 years old at this point, but I suppose that proves his point even more 😂 I think I'll go with the factory limited slip, swap around some parts and sell the axle that doesn't end up under my truck and maybe break even on the whole deal.

 

Lunchbox lockers are automatic lockers that you can install in an open diff carrier without having to setup gears (assuming you aren't taking everything else apart).

Automatic lockers are kind of a love-it-or-hate it thing. Some people drive them on the street and think they are the worst thing anyone could ever do to a truck. Others value the performance enough that they are willing to put up with the quirks. I fall into that second camp, but the first camp does exist, and they aren't wrong, they just value things differently than I do.

As arse_sidewards said, they are less noticeable in a longer wheelbase truck. Automatic trannies damp out the bad stuff too. But I had one in an F-150 SCSB with an automatic, and anyone who couldn't notice it in that vehicle isn't very observant. I definitely didn't mind it, but it was very clear it was there when starting around a right turn (where it will light up the right rear tire pretty easily). You could also feel a slight amount of torque steer when getting on and off the throttle, but that would be easier to miss in the longer truck. Getting on the throttle too hard on snow in a corner would kick the back end out pretty easily (but predictably). (And no, I'm not saying arse_sidewards isn't very observant. But I do think he's minimizing the handling issues a bit more than some people would.)

 

Thanks for the even handed response Nothing Special, I'll still go with my plan of going to factory limited slip. But I think others will value your fairly written response. I'll post back when I get this project done in a few months and say what I have to say after going through the trouble. Maybe it will deter people going down my path, or maybe it won't, we'll see!
Thanks again all of you for your input.

 

If you want very smooth on road(dirt or paved) manners with added traction then you want a Detroit truetrac diff, it is an all mechanical true posi. Detroit Trutrac Differential, Helical Gear Limited Slip Differential - Vehicle - Eaton

The big problem with the Ford Traclok is it provides virtually no added traction in the stock configuration, it has to be shimmed tighter before it even starts to do anythng and then it's a very fine line between allowing some slip between tires and completely locking, so while it is usually smooth acting(no noise or clunking) it will make a truck into a but of a tail wagging beast when setup so it actually doing something. I don't have any problem with that.. I loved being able to make the backend step out on command with a stab of the gas, but it caught me off guard a few times and I actually looped the truck around 180 deg in the middle of traffic once. Opps. The key to driving safely with a traction diff in the rear end of a pickup it to always coast around corners.. especially in the wet or in snow, otherwise you have to expect it to slide.

 

I'll second the truetrac. It's always my first option, if I don't want a locker.

 

I have a TrueTrac in the rear of my current truck, and while I do love it, I don't love it as much as I'd hoped.

A TrueTrac doesn't do anything if one tire gets no traction. As long as both tires get a little traction it's great. But put a tire in the air and it's an open diff. OK, I never pick a tire in my F-250 crew cab, but I do stop at a stop sign at the top of a hill three blocks from my house a lot. In the winter the right rear is usually on ice there, with the left rear usually on bare pavement. With the TrueTrac it BARELY gets moving, while an automatic locker makes it seem like there's no ice.

In every other situation I've found the TrueTrac to be great. It's completely invisible except that you (almost always) don't spin a tire when you expect to and if you get a little too happy in a corner on snow you'll step out quicker than an open diff.

So for me, open diff in snow is OK because although the traction isn't good, it's best for stability. And I have 4WD when I need traction anyway.

An automatic locker is probably my favorite in snow. Traction is best, the only stability issue is if you get on the gas too hard, and that's predictable and preventable. But I get how the handling quirks aren't for everyone. And I've got to admit, I don't love towing with them (which is why I have the TrueTrac).

A TrueTrac is probably a close second for me on snow. Traction is as good as a locker most of the time, but terrible occasionally. Stability is much like a locker, no issues unless you get on the gas too much. And it's more forgiving than an automatic locker then too. And a big plus is you never notice it in a bad way (unless you get on the gas too hard in a corner, see above).

A factory limited slip is in distant last place for me. In my experience in snow driving there's no happy medium between too loose and too tight. Before I put the TrueTrac in my F-250 it had a factory TracLok. With about 200K miles it was toasted and didn't do much pulling away from that stop sign either. But coasting around a corner it would still cause the tires to scrub and kick the rear end out.

 

Reviving my old thread when I finally got around to tearing into the project. I took apart the parts axle and got the carrier, looks fine and will work for my purposes. Took apart my axle and found some pitting on the ring gear, concerning enough to make me want to buy a new gear set. Now I can only seem to find the long pinion versions of these gear sets. These are advertised for 93' and newer. Are these going to be compatible with my older housing? Will I need a different bearing? Any info will be helpful. Here's the photo of the ring gear for your viewing displeasure.