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:
- Dobinsons kit for 5th Gen: Check Today’s Price
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
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.
Measurement 1: Spacers (TRD, Dobinsons, and two washers)
Measurement 2: Longer Screw
CV Angles Before
CV Angles After
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.
Questions and Comments, leave them below!