Rear Differentials

[koda2000]

'01 Sport Trac, RWD, 4:10 LSD

After examining the box of parts I brought him this morning, my mechanic friend tells me that he now believes my diff noise is not being caused by my spider gears (although they are worn). He also thinks my axles should probably be replaced and that repairing my diff will be too expensive by the time I put all new parts in it, plus the labor to set it up.

So I'm looking for a good used complete rear diff. My question is, is the complete rear diff from a Ranger the same as what's in the Sport Trac? I think that would be cheaper and easier to find than one from an ST. Maybe even an Explorer rear diff would work as long as I delete the 5th shock. I'm not married to the gear ration or LSD. Lastly, will I be able to swap my drum brakes over to a disc brake axle? if that's what I find.

Any help is appreciated.

 

[skpyle]

Hello Koda2000, I am going to go out on a limb and say two issues will be key:

1) hub to hub width of the ST rear axle assembly vs that of a Ranger or such.
2) location of spring saddles on axle tubes. What is distance between rear leaf springs of ST rear axle assembly vs that of Ranger or such?

Is the ST rear axle assembly that different from a second generation Explorer, other than the brakes?

Good Luck!

Seth K Pyle

 

[2TimingTom]

Ranger axles are 29 spline while Explorer axles are 31 spline. More splines are better.

STs have drums? 2nd gen Explorers all have rear disc. Swap should be plug and play.

5th shock- haven't had one in years.

 

[boominXplorer]

It's sport trac only. Rangers use 28 spline axles and all explorers are 31. I would swap in a rear disc axle from a 95-01 as it would upgrade it to discs and they are way easier to find.

 

[koda2000]

I found a good used one from a company that specializes in complete used rear ends. They have one from an '01 ST, 4:10 ratio complete with drum brakes, so that would be a perfect match. $795 delivered, inspected good with a 30 day warranty. I have no idea if that's a good deal. I was hoping to find something around $500. I've got some other feelers out. One is a parts vehicle '01 ST and the other's an '03 ST (which means disc brakes). The issue with converting to rear disc brakes is the master cylinder, proportioning valve and maybe ABS unit would need to be changed.

Update:
The salvage yard (2 hours away) wants $300 for the '03 ST disc brake axle assembly. Good price, but It's a long drive and I don't know about swapping over the drum brake system.

 

[2TimingTom]

The issue with converting to rear disc brakes is the master cylinder, proportioning valve and maybe ABS unit would need to be changed.

Not necessarily.

But I don't know for sure. But guessing that the 1st gen STs are largely based on 2nd gen Explorers and both were in production at the same time, having all this equipment the same would make a great deal of sense from a supply chain management point of view.

Rockauto's compatibility search would be helpful here.

And an axle straight up from a junkyard should be under $200. But then you're starting with an unknown unit.

 

[96EXXLTinCO]

5th shock- haven't had one in years.

I was gonna ask about that 5th shock Tom..........added to the eviction list......

 

[koda2000]

I was gonna ask about that 5th shock Tom..........added to the eviction list......

Not sure what the 5th shock is for, but I figure Ford must have put it on there for a reason so I've kept it on my 4-door Ex's/Monty's. Must help to control rear end somehow. I've read posts where people have said they feel an increase in stability when corning after replacing a missing or worn out 5th shock. I don't see any point in removing it. It's referred to as an axle damper.

 

[96EXXLTinCO]

Not sure what the 5th shock is for, but I figure Ford must have put it on there for a reason so I've kept it on my 4-door Ex's/Monty's. Must help to control rear end somehow. I've read posts where people have said they feel an increase in stability when corning after replacing a missing or worn out 5th shock. I don't see any point in removing it. It's referred to as an axle damper.

Well I know one thing its NOT for and that's axle articulation. As soon as I crawl under there to make some sway bar disconnects I'll pull it out and see what happens.

 

[koda2000]

I just finished removing my rear diff. Now I just need a replacement for a price I can live with.

http://s1303.photobucket.com/user/kodabear2000/media/115_0065_zpscv3gtpml.jpg.html?o=1

http://s1303.photobucket.com/user/kodabear2000/media/115_0066_zpsmnva5xct.jpg.html?o=2

 

[manimal]

Why would your Sport Trac have drums? Explorers have had rear discs since 95.

 

[swshawaii]

Why would your Sport Trac have drums? Explorers have had rear discs since 95.

01-02 Sport Tracs came with drum brakes in the rear. In 03+ the Sport Tracs have rear disc brakes.
http://www.explorerforum.com/forums/showpost.php?p=2145972&postcount=1

 

[swshawaii]

Koda- Here's a rear disc brake conversion posted by Cayman in 2006. No mention of changing
the master cylinder, proportioning valve, or ABS components if you use a 2003 or newer ST axle.

http://www.mysporttrac.com/mysporttrac/projects/RearBrakeConversion/RearBrakeConversion.htm

 

[swshawaii]

Another from RPS.

http://www.rangerpowersports.com/fo...plorer-rear-disc-brake-conversion-merged.html

 

[sr139fox]

If you decide to keep the truck. This would be a good time to add a locker to the differential. Dave p.

 

[koda2000]

Koda- Here's a rear disc brake conversion posted by Cayman in 2006. No mention of changing
the master cylinder, proportioning valve, or ABS components if you use a 2003 or newer ST axle.

http://www.mysporttrac.com/mysporttrac/projects/RearBrakeConversion/RearBrakeConversion.htm

While it may be possible to make the line connections w/o modification, the rear discs will not perform correctly with a disc/drum master cylinder. I know, from my hot rod building days, that when you do a disc brake conversion (front or rear) you need a master cylinder and some sort of proportioning valve that is disc brake specific. This is necessary because disc brakes require much more fluid and pressure to work compared to drum brakes. Without a 4-wheel disc master cylinder the rear discs will still engage to some extent and, as the front brakes do most of the work when stopping, it may not be noticeable that the rears are barley working.

 

[manimal]

01-02 Sport Tracs came with drum brakes in the rear. In 03+ the Sport Tracs have rear disc brakes.
http://www.explorerforum.com/forums/showpost.php?p=2145972&postcount=1

Huh, weird. Had no idea.

 

[koda2000]

Update:
Used rear ST diff arriving tomorrow (according to shipper). Here's hoping it's the right one and in better shape than my old one. Fingers crossed.