2002 rear end issue

[Icesurpher]

I find myself dealing with an axle that is out of true at the flange. Due to this I began the effort of getting a new axle or whole rear end depending on what the yards have at what price. So like most I start with the door sticker to identify what axle I need. The door is tagged D4 (3.73 LS 8.8). Being thorough I crawled under the truck to get a look at the tag. Now this is where the crazy starts. The tag is stamped S661A and there is also a sticker near the right spring ubolt with the same number. Since the tag did not match the door I went on line to Ford to see what the tag number corresponded with. Ford tables show this number to be from an 82 - 85 Ford Areostar. On top of that it also shows this to be a 7.5 rear differential with 4.10 gear ratio. So since the truck is 4 wheel drive we all know the front and back have to match regardless of the 8.8 or 7.5 aspect of the difference. SO...what I really want to know is what is the easiest way to figure out which gear ratio is correct. Can some of you tell me what RPM your ST turns at 60mph with a 4.10 gear and some give same info running the 3.73. Running stock size tires would be necessary also for apples to apples comparison. I know I can pull the cover and count the teeth but of I can be relatively sure (as in a big gap between the information) I can pick up a whole rear end and get on this thing quickly. I kind of need the truck to be able to haul the rear end and tbh I hate the idea of pulling the cover, counting the teeth, putting it back together just to pull it out a day later. Also out of curiosity, does anyone know if a differential from an Areostar could have even been used in the truck. Thanks in advance.

 

[HELMUT RONER]

In a nutshell....

Sport Tracs have 8.8s The ratio should be stamped on the pinion gear (viewable with cover removed).

Did the truck slide sideways into something to cause the axle to become that way? It just one side, right?

I'm about to swap my right rear axle because a stud is spinning in the axle flange and the seal has been leaking for I don't know how long. I got a new rear axle shaft from Rockauto.com for $78 shipped.

 

[koda2000]

The diff ratio has nothing to do with the axle shafts. I believe the 2002 still used a solid rear axle assembly with drum brakes. I replaced my worn out 2001 ST RWD rear axle assembly with a complete unit out of a 2001 Explorer 4 door ('95-'01 8.8's are all the same) and other than switching over the disk brake parts for the drum brake parts the axles were identical. When replacing the complete assembly, the ratio only matters if you have a 4x4, otherwise you could substitute a 3:73 for a 4:10 or vise versa or even an open for a LSD. If you check the RockAuto on-line catalog, you'll see that the axle shafts have the same part number.

If someone did install a rear diff from an Aerostar I'd just replace it with one out of an Explorer and go by the door sticker the ratio, as I doubt anyone changed the front diff to match the rear. Were Aerostars even available in 4WD/AWD? I would not be surprised if the Aerostar also used weaker rear axles (28 spline) like the Ranger uses.

I new axle shaft will run you around $100. A used complete assembly probably around $300.

Below is a picture of the Explorer 8.8 4:10 I installed in my ST. The ST and Explorer rear diff assemblies both have the bracket for the 4 door 5th shock cast into the center section. I don't believe an Aerostar 7.5 would have this.

Below is the ST 8.8 I pulled out.

Below is a pic of an Areostar 7.5 rear axle from eBay (through '97). It looks like a completely different animal.

http://www.ebay.com/itm/REAR-AXLE-A...ash=item4d0c0f3110:g:rxIAAOSwpdpVedml&vxp=mtr

 

[Mustang Guy]

My 2002 XLT 4.0 SOHC is an 8.8 independent axle and not a solid axle. I believe independent rear axles were standard on Explorers and solids were only on Rangers.

 

[koda2000]

My 2002 XLT 4.0 SOHC is an 8.8 independent axle and not a solid axle. I believe independent rear axles were standard on Explorers and solids were only on Rangers.

Sport Tracs didn't even have rear disk brakes until 2003 and I'm 99% sure the '02 ST's still had a solid rear axle. I'm not sure what year the ST's switched over to the independent rear suspension, maybe in '03.

 

[429CJ-3X2]

The 2002 Explorers were a whole different vehicle from the Sport Tracs and the 2 dr Explorer Sports.

 

[Icesurpher]

Thanks

Thanks for the replies. Once I was certain that the rear end was in fact an 8.8 I moved on with the assumption that the gear was as indicated on the door tag. Best I can tell the Ford chart that listed the axle number on the tag as a 7.5 from an Areostar was just simply incorrect. I got an axle shaft from the local salvage yard for $50 and 2 hours later had it all swapped out.

 

[koda2000]

Thanks for the replies. Once I was certain that the rear end was in fact an 8.8 I moved on with the assumption that the gear was as indicated on the door tag. Best I can tell the Ford chart that listed the axle number on the tag as a 7.5 from an Areostar was just simply incorrect. I got an axle shaft from the local salvage yard for $50 and 2 hours later had it all swapped out.

Wow! You got a great deal from that salvage yard for $50. Most charge around $300 for a used 3rd member where I live. $250 is a bargain.