RCBasher.com - HPI Wheely King Mods

Wheely [sic] (hwee-lee) -noun: A stunt in which the front wheels of a vehicle are raised so that the vehicle is balanced momentarily on its rear wheels
King (king) -noun: a person or thing preeminent in its group or class

HPI Wheely King Modifications

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Locking the Diffs

4WD is great, but in the stock configuration it's only 4WD if all four tires are on the ground. If one of your front tires is off the ground, all the power going to the front end will go to the tire in the air and the other tire will do nothing. Worst case, and not uncommon, is when one front tire is in the air and one rear tire is barely making contact with the surface. Squeeze the trigger and one front and one rear tire spin, and the truck goes nowhere.

The solution? Lock the diffs! Doing so eliminates any differential action which isn't very good for cornering, but we're talking about low-speed crawling and the like, not driving a road course. With locked diffs and full-time 4WD like the Wheely King has, all four tires spin at the same speed all the time. No exceptions. One rear tire in the air and a front tire on ice? No problem, the one or two tires making good contact with the ground will get the truck moving.

How to lock the diffs? Some people put Silly Putty in the diff case to stop the gears from rotating, but I've not had much success with that method. You can also fill the diffs with thick diff lube which will allow some differential action but keep it under control. That's great for racing vehicles to prevent "diffing out," but not really necessary on a crawler, and they can be messy because eventually they always seem to leak. We want a method that truly locks the diff.

The most common methods are are using a dedicated diff-locking device and filling the diff assembly with Liquid Steel, JB Weld, or some other sort of epoxy. These methods prevent the internal gears from rotating, essentially turning the diff into a "spool" or solid mass, forcing both front and both rear wheels to rotate at the same speed under all conditions.

Fixed Diff Lockers

Dedicated diff lockers are usually metal inserts that take the place of the internal gears inside a differential to lock it. They're available for many different vehicles, including our Wheely Kings. The main advantage is these lockers is that they're removeable in case you change your mind, and they don't damage your diff gears or cup.

Here's a set of lockers from ST Racing Concepts, sold in pairs for around $15. They have a few colors available in case you want the inside of your diff cups to be colorful.

Here's a locker from Axial Racing which is designed for their AX10 crawler, but it's a direct bolt-in for the Wheely King. They're under $10 each and sold individually. And they're a pretty green. Basically the same as the STRC pieces.

Click here for a write-up on installing fixed diff lockers.

Epoxy Lockers

A slightly cheaper (but much more labor-intensive) method is using a two-part epoxy material such as JB Weld or Liquid Steel. Just remove and clean the insides of your diff, reassemble, mix up a little more epoxy than you think you'll need, fill the diff, screw the ring gear back on, and make sure the epoxy isn't oozing out of the driveshaft holes. You'll need to be able to insert the driveshafts into the diff after this project is complete, but you don't want the driveshafts to be locked in place, either, so you need to keep the driveshaft area clean of epoxy. It's not difficult, but it's something that should be done. If you do epoxy the driveshafts in place it's not a huge problem as long as they're inserted the proper amount. It's just that it'll be difficult or impossible to remove them later if you so desire for some reason. This epoxy method is quite permanent! If you want to unlock it you'll need to buy an entire new diff assembly. Full write-up for epoxy lockers coming...

Difficulty: Getting to the diffs is where the work is; once you're there, both methods are easy
Pros: REAL 4WD for go-anywhere traction, locker insert is removeable
Cons: Locking the front diff will decrease your steering ability; the epoxy method is permanent
Cost: $5 - $15
Additional Tip: Buying the removeable inserts will allow you to test the steering with and without the locked front diff; if you don't like it locked, you can remove it. Tough to do with an epoxy-filled diff!

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