Dobinsons Differential Drop (Diff Drop) Install on 5th Gen 4Runner

Icon Stage 2 3.5″ + 1″ Ekstrom Shims = 4.5″ lift and Toyo Open County 285/75R17s (33.8″).

Dobinsons Diff Drop Install on 5th Generation Toyota 4Runner with TRD Pro Skid Plate

I probably waited too long to install this on the 4Runner.

We have had quite a few questions come in asking if we have had a differential drop installed. I have had the Dobinsons diff drop kit sitting around in the box of mods to-do list for almost a year now.

Jimmy Jet at Snail Trail 4×4 and I finally got around to it.

The kit we bought: 

What is a differential drop?

First, a differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed. In this case, the output is your CV (Constant-velocity joints) axles.

A diff drop is typically a kit that comes with two 1″ spacers that fit in between both differential mounts and the cross member. A 1″ spacer typically amounts to .5″ of the actual differential drop.

Diff drops are needed to literally drop the differential and differential mounts in order to bring the CV axles closer to factory angle.

Hence the terms “I have bad CV angles” or “You should check those CV angles”.

Do I need a diff drop?

Bad CV angles occur when you lift your 4Runner. When you lift your truck, your tires lower and pull further in, the angle of your CVs get steeper thus making it harder for the axle to turn your wheel. Once your wheel has a hard time rotating, it will eventually put stress on the CV boots (the rubber portions covering the inner CV joints and outer CV joints).

Once any one of the four boots has enough stress, it will break open causing dirt, dust, and debris to enter. Once this happens, the CV joint will eventually get damaged. To avoid all this from happening, you may want to buy a diff drop kit.

You may need a differential drop if you are pushing 2.5″+ lift or higher.

Many leveling kits, like the ProComp 3″,  come with a diff drop spacer.

With any Icon, KING, Fabtech, FOX, Radlfo, OME, etc. lift kit of 3″ and higher you should consider dropping your differential to help level out or lessen your CV angles.

When did I notice a need for a diff drop?

When my truck was off the ground one day in the shop, my tire/wheel was having trouble freely spinning.

Until then, I never saw a need for it. Once I saw that, well you get the point. Granted this was at full droop but the 4Runner was at 4.5″ of lift in the front and was likely ready for a differential drop of some type.

Diff Drop Installation on 5th Gen 4Runner with TRD Pro Skid

The install was done on our 2014 4Runner with a TRD Pro skid plate which did make things interesting.

The Dobinsons kit ships considering you have factory skid plates. If you are running aftermarket skid plates like the TRD Pro, RCI or any others, prepare for adjustments.

The kit comes with the two diff mount spacers and 8 additional spacers for the skids. The first four mounted up to our first factory skid pan just fine.

The second four spacers did require some longer bolts that required a special trip to Ace hardware.

This install assumes you know how to safely jack up your truck using a floor jack and jack stands.

Step 1: Remove Skid Plates

Step 2: Locate the front Differential Mounts

Step 3: Loosen Bolts on Diff Drop Mounts

Step 4: Before/After Diff Drop Hardware

Step 5: Installing the Diff Drop

Installing the Diff Drop 5th Gen 4Runner

Step 6: Reinstall Skid Plates

Step 7: Reinstall the TRD Pro Skid Plate

You can see the factory TRD spacer on the bottom. That spacer was down by where the Maglite is shining. We had to move that spacer up and then add the Dobinsons spacer on top. Also, you can see two washers on top of the Dobinsons spacer. To get an exact fitment, we needed just shy of another 1/4″.

The hardware on the TRD skid plate did not match up with the Dobinsons diff drop kit.

On the TRD skid plate, you already have two spacers towards the rear. With the Dobinsons diff drop kit, you will add 4 more spacers, so you will be stacking one pair of spacers.

We drove to Ace Hardware, bought longer bolts but reversed the setup.

Stacking two Dobinsons spacers on the rear spacers did not work. We had to move the TRD rear spacers to the front of the skid plate and then stack two Dobinsons spacers on top. Then we used the remaining two Dobinsons spacers towards the rear. Then we drilled out the ID (Inside Diameter), to accommodate new bolts.

Correct measurements

Measurement 1: Spacers (TRD, Dobinsons, and two washers)

Measurement 2: Longer Screw

CV Angles Before

Diff Drop Before 5th Gen 4Runner

CV Angles After

Diff Drop After 5th Gen 4Runner

Diff Drop Measurements Before

Diff Drop Measurements After

The last image was a bad angle. That’s my bad.

The 1″ differential drop did give us 1/2″ of drop. It doesn’t look like much but hopefully, it helps you sleep at night. Any improvement in CV angles we can get, we will take it.

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11 months ago

It’s worth hearing what an engineer has to say about diff drops in this video – Not really needed, even with 3″ lift. If anything, just get better CV boots that can handle the increased angle and replace the CVs when needed, which won’t happen for a long time. Dropping the diff just reduces your ground clearance and causes issues fitting skid plates.

3 years ago

The CV angles look the same and the boot rib rub looks identical. Prob not really worth it.

3 years ago

Did you remove the lower radiator brackets to install the skid plate?

after installing my lift and diff drop, I noticed the lower brackets interfere with my sway bar (non-KDSS). I had to remove them. I’m concerned the radiator will not be properly supported without them.

4 years ago

Would a 2″ lift be good in term of longevity of cv boot with the diff drop?

William Lane
William Lane
4 years ago

I have a 4″ lift could a larger diff drop help?

5 years ago

Any Issue with your CV boots? I’ve read a few threads on T4R that say lifting over 3″ will shorten the lifespan of the CV boots.

Aaron J Villegas
Aaron J Villegas
5 years ago

4.5″ of total lift! Sweet, kdss holding up well with that much lift? Any lean?

Awesome truck!

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