2007 Explorer 8.8 IRS gear pattern

[explorerguy97]

This is my first time rebuilding a differential and I wanted to get some opinions on the contact patterns im seeing with my current setup. Ive got a seemingly great contact pattern on both the drive and coast side (as far as even engagement goes), my only concern is that the coast side seems to be a bit towards the toe of the tooth. Ive played around with pinion depth (set it up a few times within a 0.008" pinion shim range so far) and the coast side hasn't moved drastically. Most sources online suggest that the pinion shims are too thick if the coast side is further towards the toe than the drive side. My concern if I keep chasing a better coast side is im eventually going to negatively affect the drive side.

My question is: should I just proceed with final assembly as is (is what i have good enough?), or should I keep making adjustments to the pinion shims and try to get the coast side contact further towards the center of the tooth? I don't want to sacrifice the drive side for a better coast side but I also dont want to be doing this again anytime soon

The carrier is out of the case in the photos because i was playing around with backlash, but the pattern in the photos is from a pattern I ran with a 0.009" backlash Thanks in advance

 

[donalds]

I'm sure someone will have more of an opinion but in my opinion
I would run that

 

[amj441]

Thats a great contact patch on both drive and coast side. well done. make sure your bearing preloads are correct and Id run that!

 

[explorerguy97]

Thanks guys!

 

[Fbird]

Provided the back lash is per manufacturer (they differ per 2 cut vs 5 cut) and the pattern was run with load...yeah thats good!
With all that work WHILE it's out...I would go ahead and add a posi carrier! You can get one from a 2002-2006 Sport Trac for about $150. Thats what i did to mine.

Adding a Locker to the rear diff

Looking at adding a powertrax locker to the rear useless open diff in my 06 2wd 4.0L. I have NOT dealt with lockers before as I'm more of a street rod guy not a mudder. Any daily driver issues with them? I know the work very well but still on the fence of a LSD carrier swap vs Locker drop in.

www.explorerforum.com

 

[explorerguy97]

Provided the back lash is per manufacturer (they differ per 2 cut vs 5 cut) and the pattern was run with load...yeah thats good!
With all that work WHILE it's out...I would go ahead and add a posi carrier! You can get one from a 2002-2006 Sport Trac for about $150. Thats what i did to mine.

Adding a Locker to the rear diff

Looking at adding a powertrax locker to the rear useless open diff in my 06 2wd 4.0L. I have NOT dealt with lockers before as I'm more of a street rod guy not a mudder. Any daily driver issues with them? I know the work very well but still on the fence of a LSD carrier swap vs Locker drop in.

www.explorerforum.com

Thanks! And yes pattern was ran with a load in both directions. I thought the same thing about the carrier and actually purchased a brand new ford performance LSD carrier that I went back together with. Seems like it was a great buy for the price!

I actually completed final assembly yesterday afternoon with the specs and pattern i posted photos of before, only thing left to do now is throw it back under my explorer and procede with the break-in procedure.

Factory gear ratio was 3.55, and i occasionally tow a trailer with it, so i would have preferred to go back in with 3.73s but i didnt want to have to re-gear or replace the front differential also or worry about spedometer recalibration, so i just stuck with 3.55. My explorer is a v8 so it doesnt do that bad with towing to start with.

When i started the rebuild I stripped the case down to a totally bare case, and took it to a local machine shop where they cleaned it all up and looked it all over for me. I was also sure to replace everything and use all genuine ford or OEM parts for everything (seals, shims, gear set, carrier assembly, bearings & races etc). I want to not have to worry about the rear differential again for a long time and wanted to make sure it was set up properly. Thanks for the help!

 

[Fbird]

nice! Don't forget the posi lube additive I even stole the "tag" off the other diff...just because.

 

[amj441]

nice! Don't forget the posi lube additive I even stole the "tag" off the other diff...just because.

Absolutely good reminder, make sure its the motor craft additive, super stinky, but the only thing that works correctly.

 

[donalds]

Google Search

Motorcraft xl3

 

[explorerguy97]

Thanks for the heads up.

Question for you guys on that subject: I noticed the valvoline 75w-140 gear oil ive already purchased has limited slip friction modifier already added. Is that an issue?

I got online and it looks like most 75w-140 oils already have limited slip modifier added (mobil 1, valvoline, Lucas, etc.) I found a motorcraft 75w-140 for $30 a quart on Amazon that doesn't appear to have the additive already in it but that's almost twice as expensive as most other oils.

Wondering if I should just bite the bullet on the motorcraft oil + the little LSD additive or keep looking for an oil that doesn't have LSD additive. Was in advance auto this afternoon and was very disappointed in their gear oil selection, all off-brand stuff

 

[donalds]

Use the oil you bought and add friction modifier anyway
that's my opinion that's how I do it

 

[Fbird]

^^^^ yes add the modifier. They ALL say "includes...WERTYUhjhggtf" yeah i call B.S. Thats like GL5 gear lube vs OLD OLD OLD GL4 gear lube. GL5 is NOT for use with BRASS syncho's.