traction-lok application question

Hey guys, quick question(s). My 4x4 (2001) has an open 3.31 differential. I've been looking on craigslist etc. for parted out expeditions with H7 and H9 (all limited slip codes) 9.75" rearends. To keep my costs down, I'm going to keep my 3.31 in the front and just swap any guts to my existing rear gear set.

Have any of you done this swap yourselves or had it done? I'm assuming any 9.75 differential with a traction loc / traction lok / limited slip would be a direct bolt in, but I'm not sure. Are all of them 34 splines? And do you guys know if entire axle housings from F150 pickups of certain years would be a direct bolt in? And finally, do I need to find a 1st gen 4x4 to get a 9.75 rear OR will a 2wd expi rear work? (thinking those are 8.8" diffs). Thanks!

f150s wont bolt on. they had leafs we have coils. also if you are going to get different ring gear patterns then never put it into 4wd. even in the dirt. its too different of a ratio. also i would stick with the 9.75 axle. the 8.8 will bolt up if you find one, but if you have a heavy foot the 5.4 will break it. also the 2wds are the same as the 4wds. as long as it is the 9.75.

If you are looking at swapping just the internals, while they do "bolt" right in, there is a big thing you need to keep in mind. The bearings and whatnot need to be spaced properly else you are going to trash that hear set in a heartbeat. We are talking down to the thousandths of an inch here. So, even pulling the shims and all out of 1 truck and putting it in yours may not be the same. Also keep in mind that in mid 2000, the internal machining of the rears changed. So, that can add to confusion when looking at gear sets that will work.

For the heartache of trying to make things work, for what the precision tools cost, you will be money ahead in just getting complete differentials and bolting them into place.

Thanks, guys. This is exactly the response I was looking for. Much appreciated!

Thermo, looks like it makes the most sense to find an entire 1st Gen rearend with the correct ratio/trac lok and do the swap. Only downside is not knowing the condition of the gears, axles, clutches, etc. I'm finding these for $150-250 (range), and that's doable to me. I could probably sell mine for half that to recoop some money. Good info about the internals switch in mid 2000. Let me ask you this. A buddy of mine has a NIB trac lok unit (9.75) from "Ford" that he bought at the parts house that I can get for about $250. I'd assume it's 34 spline but am waiting for confirmation about that and the part number on the unit. Think this is wise way to go? Cost would be much greater but the known aspect of "what I've got today works" is something to consider, even though I'm trying to keep my costs down.

Panda, I didn't think about the coils/leafs. Good point, man. Definitely not going to mix the front/rear ratios...but I'm finding pretty reasonable H9 3.55 and H6 3.73rears (common!) whereas the H7 3.31 is pretty scarce. Definitely agree with you on staying away from the 8.8. And good to know about the 2wd/4wd... I'll just make sure to have the guy on the phone describe the diff cover to make sure we're looking at the right thing!

I personally would just swap open diff carrier case to traction lock unit keeping existing ring and pinion gear. The most difficult part of a ring and pinion swap is setting pinion depth and that is already done for you if you keep existing gear set. Reusing existing carrier case shims just as they came out should keep backlash (gap between the ring and pinion gear) the same but it should be checked because of manufacturing tolerances. If it is off you would have to adjust the shims appropriately moving carrier case left or right. You also need to add friction modifier to the new fluid you put in.

But then I have some experience setting up ford 8.8 ring and pinion gearsets before and have the necessary tools. You would need one of these or equal to check backlash..
KD Tools Dial Indicator Set with on/off Stand - Tools - Mechanics & Auto Tools - Automotive Specialty Tools

You can also use gear paint to check wear pattern but this is more critical for pinion depth as opposed to backlash and pinion depth should be correct.

If backlash is set improperly it can make for a noisy gearset and or premature gear failure!!! I would suggest that you read and re-read up on how to set up a ring and pinion and decide if you feel comfortable before attempting. It can be itimidating.

Thanks, Toms. While I've been jacking around with Ford muscle for 30 years, I'm no expert on setting up third members and have none of the tools to do so. I'd look to an expert for that (or a buddy I trust). So your thoughts are much appreciated.

Great points about the pinion depth being set and reusing carrier case shims to keep backlash close and about patterning the gears. Intimidating it is.

So my thoughts are:
1) Buy the trac loc unit and have it installed / help install it to my original gearset and axle setup.
2) Keep looking for an entire 3.31 trac lock rearend from an expedition and swap them out. Fun little project right there...

71Rcode, you can install that locker into any 9.75 axle. The differential insides are the same with the exception of a little bit of machining (which requires a different amount of spacers). To the best of my knowledge, all 9.75 axles use 34 spline axle shafts. So, you should be good to go.

But, like Panda states, when you start messing with the gears and whatnot, you need to know how to put things back together or you can make things really ugly in no time flat. If it says something, I passed on putting in my own gears. Not that I couldn't, but I knew that a little bit off means a whole bunch and I didn't want to save myself $200 in the end and chance ruining $800 in gears while in the middle of moving from Hawaii to Virginia.

Thanks, Thermo. More good information from you guys that I can use! The last differential I swapped parts around in nearly fell out of the 9" carrier under my '71 M-code Mach 1 back in the late '80s. Had no idea about backlash etc. Point taken about finding a pro and paying the $ to have it set up.

This is the NIB (from a friend) unit that was offered to me for $250...I'd save about $150 off the retail price. G2 Axle and Gear Part 45-2012 - Ford 9.75in. Limited Slip By G2

It's a G2 (gear to gear) 45-2012 (G/245-2012)

My friend told me it looks like a ford trac-lok that had the ford part number ground off. Crazy. I'm assuming these are just like OEM and not any beefier. Thanks for any further thoughts, guys.

Just wanted to report back on a few things I've found. Wanted to share this with anyone out there considering this swap, too.

If you have all of this done "retail", expect to pay right under $1,000. This includes $420 for a G2 trac lock carrier, your gear lube and friction additive, $230-350 for a reputable shop to do the swap out and set up the lash, etc., and $200-250 for the "install kit" that shops will require, which includes a new pinion crush sleeve, shims, new carrier bearings and races. Yikes.

I'm thinking that all the kit components aren't necessary.. and if you're a DIYer with the balls to do the swap, you should try to reuse your carrier bearings from your working unit.

AI'm still thinking about doing just this...picking up this used traction-lock carrier from my friend for $250 and installing it with the help of another friend, only replacing the pinion crush sleeve and reshimming as needed, and swapping over the carrier bearings.

Let me know if anyone has done this == and if you can get the old carrier bearings off without ruining them.

71RCode, I have regeared my truck. Now, I did not do the regearing myself, but I was involved in it quite heavily as the shop was giving me a play by play with what they were running into. This is my thoughts on whether to get a basic kit or to get the full install kit. When I was looking, there was like a $100 difference between a basic kit and the full blown install kit and the only difference being was the 2 bearings. If you are going through the hassle of putting new gears and whatnot into it and you have the bearings out anyways, why not put new bearings in so you know the axle is 100%? By the time you redo the carrier bearings, you will have pretty much rebuilt the axle and now you will have a brand new axle that will outlast the truck.

yes, you are correct in that you do not have to buy new bearings. But, for what you are spending, why have that question in your mind. I managed to get out the door for around $1600 having both front and rear done. I got the gears and install kits for $800 and the shop did the install for $800.