Explorer ST/Timberline Part Swap

[I Bleed Ford Blue]

The part number for the ST/Aviator entire carrier is L1MZ-4000-D (to the best of my recollection), whereas it’s M1MZ-4000-TB for the Timberline.

The complete ST assy lists for ~$800 new, the timberline unit is $2500. The aviator unit that unbroken listed comes up with nothing.

I'm still curious to know what's inside the unit he scored. Is it a torsen or just a ford trac-loc LS differential, or even an open diff?

 

[jrgoffin]

It’s not going to be a Torsen. It will be the same Aviator/ST diff. There are a lot of them on eBay for just a few hundred dollars. Just because the housing is the same, doesn’t mean the internals are.
This will help:

 

[UNBROKEN]

Well…they got back to me and said they in fact did make a mistake. The Aviator is open. Oh well….wouldda been sweet.

 

[PlatinumST]

IIRC, Platinum ST did this and posted about having some type of problem with axle fitment- before he ditched the whole thing and sold his truck. Any idea about whether that is a problem?

I think the issue I had was that the dealer ordered the wrong axles. Since they're a high volume shop, they slapped everything back together again and said they couldn't/wouldn't do it again.

I was really hoping this question would have been solved by now given all the brilliant minds in this group

Now I'm also wondering if the new, 1000 HP DSS axles are compatible with the Torsen LSD...

 

[jrgoffin]

As far as I can tell, the same ‘non-coated’ axles have matching part numbers between the Timberline, ST, and Aviator:

L1MZ-4K138-C and L1MZ-4K139-C

Then again, Ford has known to be wrong before. If common sense came in to play, I’d like to assume all the inner and outer splines are the same, but there’s only one way to find out, and there can be no limit to oddities auto manufacturers throw in to their model differences.

I did contemplate buying a used ST axle off eBay and then just coughing up the $2K for the diff (spare shaft for test fit of the inner stubs), but haven’t gotten around to it. A buddy of mine works at the Sterling Axle Plant, so I’ll pick his brain soon enough.

 

[UNBROKEN]

The Aviator diff and ST axles went into my car yesterday with no issues.

 

[jrgoffin]

The Aviator and ST diff’s are the same. No brainer.

 

[Franz01234]

After a long time of the torsen sitting on my shelf I finally got around to attempt the swap. I got myself a used diff so I did not have to remove the diff from the car to try to swap the internals.
When the rear cover is removed it looks like this.



The gear is welded to the carrier.



Side by side comparison of the two internals.

 

[Franz01234]

The number of the splines for the halfshafts is the same.
After pressing on the new bearings and fitting the carrier into the housing with the correct shim thickness and preload the differential looks like this.



My Explorer has a gear ratio of 3.31 as seen on the tags below.

Sticker on the bottom of the diff.


Sticker on top of the diff.

 

[Franz01234]

I have not yet installed the differential in the car so I am not yet 100% certain it works but I am fairly confident it will fit.

For others I dont think this swap is a good idea though since it would be easier to get a Timberline diff once they become available on the used market.

 

[UNBROKEN]

I have not yet installed the differential in the car so I am not yet 100% certain it works but I am fairly confident it will fit.

For others I dont think this swap is a good idea though since it would be easier to get a Timberline diff once they become available on the used market.

There’s a guy in my FB group with one installed now. He got a wrong axle from Ford so he’s waiting to swap that out but other than that it dropped right in.

 

[jrgoffin]

For others I dont think this swap is a good idea though since it would be easier to get a Timberline diff once they become available on the used market.

That’s what I’ve been saying all along. Not worth the effort to pull the gears when the carrier will most likely be plug-and-play.

 

[I Bleed Ford Blue]

Unless he also changed out the pinion gear, he's probably gonna have premature wear on the ring and pinion. The pinion now has a wear pattern worn in from the old ring gear so they are now mated for life. If you put a new ring gear with a used pinion you will most likely get premature wear.

 

[locoliberty]

Picked up a timberline diff a bit ago and going to be swapping it in a couple days. Any tips for the diff R&R?

- do exhaust sections need to be removed or can i get around it? (thermal 2.5" installed)
-mitchell1 says to remove a bunch of underbody covers and the driveshaft, I assume I can get away with not doing that
-instructions also say to full remove the knuckles, can I just partially disconnect and tilt them to pop the halfshafts out?

 

[locoliberty]

Well fun update, did the swap in its many hours of glory but now have fluid puking out of the vent hose and the fix actually looks like a warranty concern on timberlines only with ford.


TSB 205-02
SSM 51098