In our continuing buildup of a "grocery getter" 1997 Ford Explorer into a competent trail rig, we are seeking more traction. In the first part of the upgrade, we added a Superlift 4" lift to get us up and over the obstacles, but found out that we'd get stuck when we lifted a tire. The obvious next upgrade is some sort of traction assistance.

We have choices when it comes to adding traction to a stock SUV.

• Limited Slip (factory or aftermarket)
• Automatic Lockers
• Selectable Lockers

Anyone who does any wheeling will tell you that limited slip is "limited" in terms of how much it will help you off-road. I can validate that, my Explorer would lift a tire and spin when crossing over deep ditches at an angle. Luckily for me, support for the Ford 8.8 is plentiful for both automatic and selectable lockers.  This truck is a daily driver, with both my wife and myself driving it weekly, and I wanted something simple, reliable, and always there. While selectable lockers have their place, the added complexity of wiring made it a second choice, with automatic lockers rising to the top of the list.

There are a few downsides to automatic lockers:

• Always-on means that you will get a little more squirrelly in icy/slippery road conditions, correctable with alert driving
• Automatic lockers tend to be noisy around turns, as their mechanisms for locking click or bang when engaging/disengaging to allow differentiation.

Given all the above facts and tidbits, I decided on the Richmond Gear Powertrax. The Powertrax has a unique design that limits the noise, and gives it a much more streetable personality than some more intense lockers. In addition, Powertrax is one of the few models out there that has a specific application for a Ford 8.8 with Limited Slip. Most lockers only support the non-L/S carrier, necessitating a carrier swap which increases the cost and complexity of the upgrade. Remember, we're building a daily driver that can also hit the trails, not a hard core rock crawler, so we need to be concerned with budget.

Finally, the Richmond Powertrax has a reputation for ease of installation. I'm not a daily wrench monkey, and I figured that if I can do it, so can thousands of other Explorer owners.

Installation

The Powertrax comes in a handsome box with a clear and legible installation guide and user manual:

Note: I found the user manual to be VERY detailed, and absolutely valuable in this process. Keep it handy, and follow it closely. There are details in the installation manual that aren't found in this review!

I was having some problems with my existing axle (pinion gear whine), so I sourced a used axle in really good shape, cleaned it up, hit'er with the rattlecan and threw it on a stand for upgrading before putting it under the vehicle. Here we see it draining, the oil was very clean and the magnetic drain plug had almost nothing on it. This was a well maintained rear end from a fleet vehicle with highway miles.

First order of business is to remove the pinion shaft: First, remove the retaining pin. It will be torqued on pretty tight, so you'll have to prevent the carrier from turning by using a dowel or other tool to wedge the carrier in place. This is a 5/16" head on the retaining pin, so we're not talking about having to use a breaker bar here!

The pinion shaft will be firmly caught inside the carrier, best bet is to turn the carrier until this side shown above (the side with the retainer pin) is facing away, and then lightly tap the pinion shaft out an inch or so, enough to turn it back around and grab it, but not enough to pound it into the back of your differential housing and really get stuck!  Then simply push the axles in in order to expose and remove the C-Clips. Note: If you drop a C-Clip with your axle up on a stand like this, it will fall down and get lost in the back of the diff case, necessitating you rescue it immediately!. If you are doing this with the axle on it's side, such as under a vehicle, that's a near impossibility.

With the C-Clips removed, slide your axles out about 8" per the instruction manual, and remove the clutch spring. The clutch spring is in there pretty tough, in my case we tapped it out part way (into the housing), then turned the carrier 180 degrees and pulled it out.

The next step of the instruction manual tells you to remove the spider gears and their thrust washers. But how! Well, if you think about it, the spider gears are held in place by the pinion shaft, and with that gone, just turn one axle (re-insert it first!), and the spider gears will walk out by themselves. In my case, the thrust washers were stuck to the spider gears, so no small parts to fall back into the diff case. Then, with those out, just pull out the side gears, clutches and thrust washers

Old limited slip internals out, new parts ready for installation! A little bit of locker terminology: The top two pieces on the left are the couplers. They are the outermost portion of the locker, splined to couple with the axles. They have teeth that engage with the drivers, which are shown just below the couplers. The drivers install in the center between the couplers. They are driven by the pinion shaft. To allow differentiation, the teeth between the coupler and the driver will disengage, yet stay engaged when necessary for locking.  In the center of each driver is the spacer.

After verifying that the gaps in the coupler are aligned with the synchro ring (see Powertrax install guide for details), you grease up the driver teeth and the spacers, and use grease to hold in 4 saddle springs per driver:

Now you install the couplers into the carrier, ring-side first, then install the C-Clip on that side.

Next, install the coupler on the passenger (non-ring) side.

Then install a C-Clip on the RING SIDE ONLY! After C-Clip installation, you want to make sure that the widest gap in the coupler teeth (the "paddle opening") is facing UP. It will align with the paddle on the spacer which you've previously inserted into the driver.

Next, insert the non-slotted driver over the ring-side couple. Align the paddle with the gap in the coupler.  Note that this photo shows the lugs in the driver facing up, when following the manual they will be at the bottom.  Why is that necessary? In order to drop the passenger-side driver in, you must drop it in lug-first, see the second and third picture below:

Note!!: We got stuck by leaving in one thin thrust washer on the ring-side. We all looked at it and said "nope, it's clear", but there was one thin washer left on the carrier surface, stuck there by gear oil. We couldn't get the locker installed with it there, that's how fine a tolerance Richmond uses, and that's a GOOD THING. After struggling with the installation of the locker drivers between the couplers, we pulled them out, found the extra thrust washer, pulled it and everything went together. 

The drivers come in slotted and non-slotted form. The slot allows for insertion of the C-Clip at the end of the process. After the hassle with the washer noted above, I rushed everything together and had the slotted driver on the wrong side. The following pictures illustrate that. When I got to the point where I had to insert the C-Clip, I said "Doh!" in my best Homer Simpson impression. Luckily, after you've gotten this far, it really is just 5 minutes to take it all out, swap the drivers, double check your paddle/gap alignment, and put it back together.

Here I am pointing out the spring slots in the drivers, you can see the slot just in the upper (ring-side) driver. It should be on the other side! Doh!

The springs are doubled up, a light weight inner spring to keep the system under mild compression, and a heavier duty outer spring to handle the loads. Put the inner spring inside the outer spring, and insert into the slot. Don't let it loose to fall into the diff case!  When installed, turn 180 degrees and repeat.

Check the clearances with the "check block" supplied with the locker. It should slip between the drivers when inserted along it's narrow edge, but block if inserted across it's width.

You're in the home stretch!  Insert the C-Clip through the slot (note, the above pictures have the slot on the WRONG SIDE. Follow the manual, it is very clear!). After inserting the C-Clip, you will want to feel through the pinion shaft opening to make sure that all 8 saddle springs are still in their slots in the driver. I had one fall out on me, we retrieved it with a magnet, and reinserted it with more grease to make sure it stayed put.

Insert the pinion shaft, and fix it in place with the pinion shaft retaining bolt.

The manual describes a function test to make sure it's all working. Make sure to run through the steps before sealing everything up.  Once you have passed the function test, clean up your old RTV on the diff cover and differential case, apply new RTV and seal her up!

Road Test and Driving Impressions

Powertrax is really one of the more quiet, streetable lockers out there. There is no ratcheting sound noticeable around turns, although if you apply power in a tight turn you will feel it engage. Occasionally (usually during power-on/off maneuvers while turning, such as parking lot driving) you will hear it "clunk" into engagement. Like all automatic lockers, power-on while turning at an intersection is going to lead to a little bit of tire slip or chirp.  If you are a young guy, the police might think you are trying to show off, so keep the throttle down and you'll be fine.

On the highway, the average driver won't even know it's back there. I drove the vehicle up to Tahoe a week after installation, and it was working perfectly. If you are a very astute driver, one who understands what trailing throttle oversteer is and who knows how to subtly steer a car with the throttle on an offramp, you WILL notice that there is a locker back there. If you are driving, for example, on a freeway speed turn, application of moderate throttle will tend to "push" the truck to the outside, due to the fact that both rear tires are pushing at a constant speed, forcing the truck in a more "straight" line of travel. Back off the throttle quickly, and the locker disconnects and the nose will edge in. These tendencies are subtle, most people will notice that something is "different" but nothing is going to surprise anyone.

I haven't had the truck out to the trails yet, but quick tests on ice, snow, and mud around Tahoe showed me how much more traction was possible with a locker. One complaint of lockers is that on hard pack snow or ice, the rear end can come around because both rear tires will "light up". With the automatic 4WD on the Explorer, as soon as this condition exists, torque is transferred to the front axle, resulting in immediate traction at 3 of the 4 tires. Despite my disdain for automatic 4WD, this setup is very cool for driving on the road in slippery conditions.  

I have nothing but the highest recommendation for the Richmond Powertrax. If you want to find a dealer, download manuals, or just find out more info about the Powertrax by Richmond, check out their website at http://www.powertrax.com/

The Differential Cover

During the planning for this review, we contacted Blue Torch to see what applications they had for diff covers, and found out about their Kryptonite line of differential protection. We didn't have it in time to include in the installation that day, but I got it shortly thereafter.

I say "protection" instead of covers, because that's what this product is. It's protection against the rocks. The Kryptonite diff covers for the Ford 8.8" rear end is fabbed from 1/4" steel plate with a 3/8" steel ring for the base. Considering that the truck we're putting it on is a dual purpose, daily driver and sometimes trail rig, this is overkill protection! If it's good enough for a rock crawler, it's good enough for my SUV.  It IS worth it, though. Think about the money you drop into your ring and pinion, or your locker. How would you like to destroy those parts by dropping your diff onto a ledge? Or peeling the stock sheet metal cover off and dropping gear oil all over the trail, leaving you stranded?  At under $140, this is cheap insurance.

Serious Protection

The BTF Kryptonite cover is beautiful to behold, especially if you are a gearhead! BTF laser cuts the plate steel, then folds and welds it into shape.  Each diff cover comes unpainted, and includes new 12-point bolts and washers for installation. In the pictures below, from left to right, we see the inside, the welding detail, and the overall exterior. The unit is shipped with a thin coat of oil on it for rust protection, which picks up a bit of lint in shipment, but that's no big deal.

After cleaning the cover with brake cleaner, I hit it with some 80 grit sandpaper in order rough up the surface for paint adhesion. I then painted it with a gray hammertone paint, which contrasted nicely with the black hammertone that I used on the axle. After letting that cure for a few days, on it went.

You'll notice the shine of the unpainted differential housing where the BTF Kryptonite cover isn't covering metal. I'll shape that up with some rattlecan later, but it's nice to know that I don't have a 3/8" steel lip down there to catch on rocks!

Looking for a cover for your application? See the Blue Torch Fabworks' web site, they have just about everything.

Vendor Contact Info

Blue Torch Fabworks, Inc.
P.O. Box 8367
Dothan, AL  36304
Sales: 866-RCK-CRWL
Tech: 334-673-2755
email: info@bluetorchfab.com