[Airtruksrus]

I've been having some time to think about getting the 8.8 rear end from the explorer with discs prepped for swapping out with the 7.5 currently installed in the V8 Ranger. The spring perches still have to be purchased from summit for around $9 for the set. The big question I'm faced with, would a posi trac differential from a 91 mustang 8.8 fit into the 2000 explorer 8.8, don't know if the bolt pattern is the same for the 2 different gears (2.45 to a 3.55). When I picked up the explorer rear, the differential felt really sloppy, alot of play in the axles and worried about it breaking if i try to use it as is. The one on the mustang rear is alot tighter and alot of life left in it. Hope someone has a little bit of info on this before taking everything apart.

Reading the thread about Nick's problem with the 7.5 and 302's and wonder how much life is left in mine.

 

[Demon-FX4]

what about finding a fx4 level II 8.8 ?

 

[rngrdanny22]

I'm not 100% sure, but I dont think it will work. I believe the Mustang 8.8" has 28 spline shafts whereas the Explorer 8.8" has 31 spline shafts.

what about finding a fx4 level II 8.8 ?

Those dont have discs.

 

[Demon-FX4]

true but they are great axles right? and plum told me it was easy to put the explorer discs on this axle soo i'm just saying yea kno lol

 

[Airtruksrus]

I was thinking about the differential itself, unbolting the gear attached to it and changing it for the one in the explorer housing. Didn't know if the gear has the same bolt pattern, as for the shaft, it wouldn't change unless you're referring to the input to the differential from the axles.

Really want to make this explorer rear work since it's a much more reinforced assembly than the mustang rear

 

[Airtruksrus]

Here's a pic of the explorer rear,

and the mustang rear.

Theres some compatibility issues with the different driveshaft attachments, it's slightly larger as well as a wider wheel base than the 7.5.

 

[rngrdanny22]

The explorer axle is about 1.5" wider if I remember correctly.

Also, you will probably need to grab the driveshaft flange that came with the Explorer axle (probably pick one up in a junkyard pretty cheap).

 

[alwaysFlOoReD]

I've not done any rear gears but I would think an 8.8" ring gear is the same across all platforms. Swapping the ring gear from one carrier to another should be possible but I think you would have to swap the pinion gear too. That would mean setting backlash etc. Plum or maybe sloue will have good insight on this.
Richard

 

[Airtruksrus]

Thanks, i should be able to do some additional research as well. I'm sure more questions will come up since i've never torn one apart yet.

 

[Demon-FX4]

are both those ur axles or ones u want?

 

[Airtruksrus]

Haven't checked on this one in a while, and both rears are sitting on a wheel dolly cart in the garage getting ready to be torn down to check the condition of both and compatibility with the differentials. Most likely the explorer rear will be a bit larger than the other, get to find out soon. Ordering the spring perches from summit in the next week or two.

 

[badinten]

have some imput for you first off the expo is a lil wider however the splines are different between the two and will not interchange sorry bro

 

[plumcrazy]

They will interchange. The only thing that makes an Expo 31 spline is the spider gears. The carrier from a 28 spline (Ranger/Mustang) is the same as the carrier from a 31 spline Expo. All 8.8's have the same pattern for gears (there is no carrier break). Swapping gears isnt a simple as just unbolting the old ones and bolting up the new ones. You need to make sure the backlash is set correctly and tooth contact is even and in spec (smear some connect grease on the teeth and rotate by hand adjust shims and pinion depth until pattern is perfect).

-PlumCrazy

 

[Demon-FX4]

plum knows all lol

 

[Airtruksrus]

They will interchange. The only thing that makes an Expo 31 spline is the spider gears. The carrier from a 28 spline (Ranger/Mustang) is the same as the carrier from a 31 spline Expo. All 8.8's have the same pattern for gears (there is no carrier break). Swapping gears isnt a simple as just unbolting the old ones and bolting up the new ones. You need to make sure the backlash is set correctly and tooth contact is even and in spec (smear some connect grease on the teeth and rotate by hand adjust shims and pinion depth until pattern is perfect).

-PlumCrazy

Should have checked on this sooner, but it sounds like it should change over just fine since i'm almost there, just have to finish the teardown of the explorer rear. It'll be great to find that the housings are the same and the gear just has to be changed out. The only problem i'm coming across is the tension spring in the center, how to remove it without screwing it up. Looks like an "S" pattern.

 

[Airtruksrus]

Got both the differentials opened up and took measurements, looks like the spider gears will fit with no differences except the splines, the only thing that does look different is the spacing for the 3.55 ring gear which concerns me as to whether I can use the differential housing from the Mustang or not. Maybe taking out the spring tensioner to reduce the slop between the gears for the one on the Explorer.

Mustang diff...

Explorer diff - looks like a less built up assembly.

 

[Airtruksrus]

Just came across the reason that the spider gears are not compatible. The Mustang differential is a "trac loc" and uses a gear that is longer internally to accomodate for the clutch and locks that slide into the insert on both sides of the differential housing, where the explorer differential spider has none of the clutches. This results in a smaller gear for the 3.55 with the 31 spline insert. I would need to go the junkyard possibly for parts of the axle. It was wierd to find the Mustang had a longer shaft on each side versus the explorer rear drive axles. Probably end up using the original explorer diff and add a couple carbon clutches with the spring/spacer

 

[rngrdanny22]

That sucks it wont be a easy swap over, but I'm sure you will get it done! You do awesome work man, keep it up!

 

[alwaysFlOoReD]

You can add an extra shim/spacer behind the side/spider gear, this makes it act like a limited slip. As you can see, the spiders aren't as big as in the trac-loc so are weaker. This set up should last 10,000 miles.Depending on how much traction you get, and horsepower, you could blow up the spiders. I did this with a 9" in a Torino with a stock 429 and had no problems BUT had no traction; so no shock loads to the rear end. Re-read your post and it sounds like this is what your going to try ?
Richard

 

[Airtruksrus]

I was wanting to use some of the trak lok shims as a way to eliminate the slop in the Explorer differential. Will go ahead and use the original differential from the Explorer rear anyway since the axles are 31 spline and just a bit beefier. Looking to get the weld on leaf spring perches here fairly soon, need to place it on order with a new Zoom Performance clutch.

After the traffic nightmare going down to Olympia and burning the clutch for almost 4 hours, it started making one of those metal to metal grinding sounds every time it takes off in first. Hope the 3.55 gearing on the Expo rear might lighten the load and extend the life of the new clutch. I'll get some pics of the welded add ons as soon as it gets in to the auto hobby on the navy base. The drive shaft has a slight possibility it might have to be resized again, but most likely it will just be the rear u joint changed out that uses the larger mount for the rear.