2002 Mountaineer 3.55 Open to 3.73 LSD Swap Questions

[fastcougar]

So my 3.55 Open rear end is so damn loud that I suspect it's going to fail any day now. I've wanted limited slip for some time now for better winter traction in the snow and general wet/slippery conditions. So I figured why not replace the front & rear diffs with the 3.73 LSD units and cure both problems at the same time. My question is does anything else have to be done besides the differentials/carriers? What about the transfer case? I wouldn't think so, but I've never looked into a swap from purely open to LSD before. BTW, I suspect a carrier bearing or the pinion bearing is shot in the rear, but no way to know without doing half the work of a swap, so why not right?!?! Any advice on what to avoid or specifically do is greatly appreciated.

 

[drdoom]

I believe the existing transfer case should work fine. A programming correction to account for the ratio change would be a good thing though.

 

[TechGuru]

Ya, will need computer reprogrammed for the speedometer to be correct. Unfortunantly ForScan can not do this, will need a Ford NGS to do it. While they have that connected for that have them enable Neutral towing!

http://ddwt.us/ourarticles-how_to_make_a_ford_explorer_dinghy_ready.htm

 

[fastcougar]

Thanks for the feedback guys, I greatly appreciate it! I'm having a bear of a time finding a front carrier group on eBay with LSD ... did they only have LSD in the rear? If that's the case, I may as well just stick with the 3.55 and rebuild the rear end and drop in an LSD aftermarket solution as the 3.73 doesn't offer much over the 3.55 other than being offered in LSD from the factory (rear only apparently if my search results are true).

 

[drdoom]

Yes just the rear. Torsens are available for both if you want to trick it out.

 

[fastcougar]

So that the job is a quick and easy turnaround, I went ahead and ordered a salvaged 3.55 rearend on eBay along with a case gasket so I can split it open and give it a thorough inspection upon arrival. I also plan on getting a set of new seals (pinion & output/carrier), pinion nut and yoke sleeve to ensure there are no leaks going back together. While I'm in there, I might drop in a Torsen, haven't decided on that yet. This way, if I feel adventurous moving forward, I can rebuild the "old" rear-end as a spare or sell it on here as a project starter for someone else and the turn-around time will be a few hours under the truck on a nice Saturday afternoon. Cheers and thanks for the help gentlemen!

 

[fastcougar]

So the salvaged 3.55 and Spartan are on their way ... I should have them next week ... time for a build thread & video (I have a YouTube channel completely unrelated to cars/trucks/mechanics that I sometimes vlog on).

 

[drdoom]

I look forward to your update. I am looking for a parts truck now mostly for the differentials so I can build up a set with 4.56s or 4.11s to swap in with some 33s.

 

[ProjectAviator]

I too will look forward to up dates. I have 3.55s in my 05 and want to put on 265/70-17s on it. so at least 4.11s.

Tim

 

[fastcougar]

Long story short, got the salvaged unit pulled apart, inspected and installed the Spartan locker without much fuss. Dropped the stock unit and noticed something was different ... the salvaged unit didn't have the speed sensor so I swapped it over and then though how the hell is it reading the ring gear? So I took the stock unit now on my garage floor and opened it up and BAM! Ring gear has a speed sensor toothed gear attached to it and I did all that work for nothing! FML!

So I sent the yard the details and they have agreed to a return, so I now have to climb back under the truck and drop the unit again, but I have the process down now and the rust is broken on everything so the drop should only take 30-45 minutes. I then need to uninstall the locker and replace with the stock spiders and send it back. What a PITA!

I now have a new 3.55 Ford Racing Ring & Pinion on the way along with a Master rebuild kit ... time to get down and dirty and educate myself on the job while I wait for parts to arrive. I also had to order some specialty tools such a bearing splitters and side carrier bearing pullers, but I always welcome new tools. Don't worry, I'll be memorizing this thread before I begin anything! http://www.pirate4x4.com/articles/tech/billavista/Gear_Setup

 

[fastcougar]

Started a new thread here: http://www.explorerforum.com/forums/showthread.php?t=445242

 

[leov5]

Fastcougar, my '02 with AWD and 4.6 came with the 3.73 posi rear and the 3.73 front. Why the difference between our models. I do know that I have an early '02.

 

[fastcougar]

Pretty sure it was a package option and the previous owner didn't opt for the LSD.