Diff Drop Kits: Do You Really Need Them?

If you’re the lucky owner of a 4×4, and you’re looking to give it a lift to improve its off-road capabilities, you’ve probably heard of diff drop kits.

On 4x4s with solid axle suspension, the axles and CVs will remain in line with the diff center when the vehicle is lifted, and only the castor angles will need some tweaking.

However, lifting a 4×4 with independent front suspension is a different story, as it can potentially upset the suspension and driveline geometry.

In this article, we’ll take a closer look at diff drop kits, what they do, and when you need to install a differential drop kit.

What Is a Diff Drop Kit

As the name implies, a diff drop kit will lower your 4×4’s differential

On 4×4 vehicles with independent front suspension, raising the suspension will also raise the diff and the ground clearance, which changes the driveline geometry.

Stretched CV axle

When that happens, the CV shafts will be at a downward angle, and when you drive, this angle may be altered even more (especially if you have one wheel hanging in the air), which causes strain on the CVs, which will weaken and potentially get destroyed.

Another potential issue is the stub axle, as this also faces increased strain. That can cause the diff carrier bearings and seals to fail.

Finally, the CV boots will be stretched more and there’s more tension on them, they may also rub and wear through.

Torn CV axle boot

Installing a diff drop kit is a simple solution to all these problems, as it will bring the CV angles closer to the factory specs and back into alignment. 

It’s certainly a better option than changing CVs during an off-road adventure or having to call a rescue truck.

When Do You Need a Differential Drop Kit?

As we’ve already mentioned, you only need a diff drop kit if you own a lifted 4×4 that’s equipped with an independent front suspension; a lifted Tacoma, for instance.

Also, it’s not necessarily needed if you’re only going for a slight lift, as the geometry won’t be all out of whack with a mild setup. 

You may wonder, “do I need a diff drop for a 3-inch lift.” As a rule of thumb, we’d highly recommend that you install one of the available kits if you’re lifting your vehicle 2″ or more.

Lifted Toyota Prado

At that point, you’re putting a lot of extra stress on the CVs due to the altered geometry, and chances are they will fail at some point.

If you’re going for a lift that’s less than 2″, you can still fit a diff drop kit. Any lift will change the geometry, and if you’d rather be safe than sorry, it’s a good investment. 

Which type of diff drop kit you should get depends on your specific build, but we’ve outlined some options below.

Different Types of Diff Drop Kits

So we’ve covered when you need a differential drop kit, but what are your options when it comes to these kits?

There are different types of diff drop kits available, and you must choose the right one for your build. Also, not every style is available for every vehicle.

Something you should keep in mind, no matter which kit you install, is that while your diff will still be higher than standard, it will sit lower than you might be used to if you’re driving a vehicle that’s already been lifted. 

For that reason, it may be a good idea to install some type of under-body armor to protect it.

Spacer Diff Drop Kit

Supreme suspension spacer diff drop

First up, we have the basic spacer kits, also referred to as puck kits. It doesn’t get much simpler than this – as the name implies, they’re just a set of steel spacers.

Some kits have a set of spacers that go on the front diff mounts and one set that drop the diff cross member further down.

Some kits include front and rear spacers that drop the whole diff by a certain amount.

If you’re on a budget, or not lifting the vehicle by much, they can be a good option – certainly better than nothing.

Welded Arm Kit

Differential drop kit

One step up from the spacer-style diff drop kits, we find the welded arm, also known as cradle-style, diff drop kits. 

Early kits were often of questionable quality and were known to break. These days, with better materials and technology, quality has improved, but you should still steer clear of the cheapest kits out there.

Seeing as these kits replace the diff mounts and cross members, the diff and CVs can be dropped further than with a spacer kit, but they also cost a bit more. 

Billet Cradle Diff Drop Kit

Billet cradle diff drop kit

The billet cradle diff drop kit is certainly the strongest and most durable option. It’s also the most expensive.

These are made from one big piece of billet steel, which is then machined to suit specific vehicle models. 

Billet cradle diff drop kits are essentially a new set of brackets that attach the diff to the chassis, and they also replace the stock arms.

Billet cradle diff drop kit installed

While the strength and quality is great, there are a few issues with these kits, however. 

Since they’re not that much stronger than a quality welded arm diff drop kit, those are a cheaper and more readily available option.

Also, due to the associated costs, manufacturing process, and the weight of the kit, there aren’t as many manufacturers that make billet diff drop kits either, so finding one that fits your vehicle can be problematic.

Concluding Summary

Toyota prado wheel articulation

If you’re planning to lift your 4×4 fitted with independent front suspension, a diff drop kit will certainly help sort out the driveline geometry.

Whichever type of kit you go for, it will be an improvement, but you need to make sure it’s made by a reputable company and avoid the cheapest kits.

It can also be beneficial to install some under-body armor to protect the diff from getting smashed on rocks while you’re off-roading.

Do you have a lifted 4×4? Let us know what your thoughts are on diff drop kits in the comments below.

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