Rock sliders are a 4x4 part that should be on everyone’s list. They protect your rocker panels from rocks and stumps, make a handy pivot point when you need to get around or over an obstacle, and give you a convenient spot to step when you’re maneuvering around your 4x4. Whether you’re buying them or building them, here are the factors that make the best 4x4 sliders.
Best slider materials for hard use
- 1020 DOM
- 1020 HREW
HREW and DOM Steel
Most sliders and rocker guards these days are built with HREW or DOM steel tubing. The grade is usually SAE 1020 mild carbon steel and both are stronger and more gouge and dent resistant than aluminum. “HREW” and “DOM” both refer to processes. For instance, in a product spec you’ll see “made from 1020 DOM”, which tells you about the material process (DOM) and the material properties (1020).
HREW (Hot Rolled Electric Resistance Welded) tube is economical steel tubing. It’s used in lots of fabricated 4x4 parts, although you shouldn’t use it for things that your life depends on (like a roll cage). DOM (Drawn Over Mandrel) is stronger and more expensive. Essentially it’s HREW that is cold-worked by being drawn through a die and over a mandrel. This process removes the mill scale (making it smoother), forces the tube to have consistent and precise dimensions, and improves the molecular structure of the steel.
While choosing between HREW and DOM for a roll cage can be a big deal, it’s not as important for sliders. Neither will fall apart on the trail, though DOM tubing may be more resistant to denting from a lot of abuse.
Most sliders are made from steel because it’s strong, widely available, relatively cheap, and makes good sliders. Aluminum sliders are lighter - but that’s probably the only benefit. Aluminum requires different welding processes than steel and more skill to weld (the bottle of C25 you use for MIG welding won’t work for aluminum). Plus, aluminum is more expensive than steel. Aluminum is also softer than steel, so it’ll gouge if you’re sliding your truck over hard obstacles like rocks. Aluminum is weaker than steel, so you generally need to upsize it to have the strength of a dimensionally smaller steel 4x4 part. There are alloys of aluminum that are strong, but they generally still do not have the durability of steel, and definitely not at the same price point. A person determined to have aluminum sliders could skin the sliders with UHMW (as is often done with aluminum skid plates), but that’s a lot of work.
If you don’t expect to do a lot of rock dragging and you’re okay with the added expense, aluminum is fine, but a typical 4x4 that requires a high level of function and durability should stick with steel.
Best material dimensions
- Round tube: 1.5-2" diameter, 0.120" wall
- Square tube: 1.5-2" per side, 1/8"-3/16" wall
- Panels: 3/16" thick
Most manufacturers have settled on certain thicknesses for rock sliders and rocker guards. Round tubing is usually 0.120” thick. Why? 0.120” wall is pretty much an industry standard - it’s relatively inexpensive, light, and easy to bend. Lots of shops got their start in a home garage with a hand operated bender and 1.5” or 2” 0.120” wall round tube bends easily in a manual bender. This seems to do the job for most wheelers.
For square tube, 1/8”-3/16” is the norm, with the occasional truck sporting 1/4” sliders. We tend to prefer thinner materials to save on weight, so we’d stick with 1/8” or 3/16”. Pick one based on your wheeling style - if you’ll spend lots of time on your sliders or you have a heavy 4x4 (like a fullsize pickup), go with the 3/16”.
One last thing to keep in mind with tube size: A 2”x0.120” round tube will be weaker in bending than a 2”x2”x0.120” square tube of the same length. This would seem to indicate that wherever you can use a 2”x0.120” round tube that must resist bending forces, you could use a 2”x2”x0.120” square tube. In practice, many people still go to 3/16” or even 1/4” when using square tube. We wonder if this is for practical reasons or if this is just because of the natural tendency of many of us to overbuild.
Panel or boatside-type sliders that cover rocker panels should be 3/16” thick. This indicates that they’re well-built and they’ll usually be braced along the length with a piece of tubing. If they aren’t braced, they probably won’t last long on a 4x4 and don’t count on a panel less than 3/16” thick standing up to repeated abuse.
Round tube diameter is usually 1.5” to 2”. Square tubing in sliders is usually a minimum of 1.5”x1.5” up to 2”x2”. 2”x3” or 2”x4” rectangular tubing is super strong and creates a wider step. Read below about square tube vs. round tube!
Best slider coating for hard use
- Bare metal finished with cheap spray paint
Several different coatings are available for rock sliders, but if you wheel your truck hard, coatings won’t matter. There is no coating that will stand up to repeated abuse.
Sliders usually come as bare metal, painted, or powdercoated.
Uncoated is the cheapest you can get from the manufacturer. Since you’re going to prep, prime, and coat the sliders you can do whatever you want to them, including painting them pink and stenciling on the outline of a Colt M1911. Your options are:
Paint: Quite a few people will go with the cheapest paint they can find (lots of stores have $1 rattlecan black) and touch up the rockers every so often. This is easy, inexpensive, a piece of cake to maintain, and won’t make you cry like when you chip powdercoat.
The next level up would be using a hard bedliner coating (like Herculiner) or POR15. Again, you have a wide selection of colors and you can apply these coatings yourself. These coatings will not stand up to prolonged rock drags or tight rock slider pivots. This means that, like the spraycan method, you’ll still have to do touchup if you’re rockcrawling. If you do more casual backcountry exploring or you spend a lot of time in the mud, either of these coatings will be fine and will hold up much better over the long term than spraypaint.
Powdercoating is the next level of swank. While it is a beautiful, hard coating, it will chip if kissed by enough rocks. Most normal people don’t have the equipment to do powdercoating and most fab shops farm this out anyway. It’s only worth the extra expense if you won’t be seriously scraping your sliders - again better for 4x4 campers and mudders. Powdercoated sliders cost significantly more than bare metal. If you decide to get your bare metal sliders powdercoated, it will be expensive.
Evaluate your coating options before buying and make sure the rock slider coating you get matches your use! If you plan to do lots of trails and will be rubbing your rockers all over the place, buy some bare metal sliders and some spray paint.
Weld-on or Bolt-on
Welding vs. Bolting
- Weld or bolt to the frame for hard wheeling
- Bolt to the body for light protection, though it may hurt resale
- Weld to the body for custom strength
Rock sliders need to be mounted securely to your 4x4. When you’re fourwheeling, you’ll probably need them to support the weight of your vehicle and you may need to use them as a winch point if you flip. Since sliders stick out from your truck a little bit, they give you a convenient spot to attach a winch line and you have the added leverage from the slider being so far away from the center line of the truck. But should you weld-on or bolt-on? This is a big factor for most people, since, if you don’t have a welder, you’ll have to either pay someone to do the job or use bolt-ons. But it isn’t just as simple as whether you have a welder or not.
With bolt-ons, you’ll need to drill your frame or body. Once you’ve drilled your body/frame, there’s no going back!!! If you drill holes in your rocker panels you’re introducing a point for water entry which will cause rust. You can prep and paint the hole edges, but you need to pay attention so that the paint adheres properly. You might consider pulling off the rockers once every 1-2 years to make sure you’re not collecting dirt between the rocker and slider and to touch up the holes that you drilled in the body.
By drilling the body you may also affect the resale value and future mod potential of your rig. If you decide to switch out your rocker guards in the future - well, you might end up with some unsightly holes in your rocker panels. If your rocker guards are on long enough (years) you might have paint fade on the rest of your body, but not under the rocker guards. Prospective buyers of your truck might not be as fond of your rockers as you are, but your truck will have holes in the body if they pull the guards off.
Drilling the frame is not as as bad as drilling the body as long as you aren’t making the frame into swiss cheese. However, the same issues with rust still apply. You’ll need to prep and paint the holes and make sure that the paint is holding up over time. Water can seep in to the holes you make and between the slider bracket and the frame. Your frame channel will need to be able to drain and dry out after getting wet. This is easy for a c-channel frame, but a full tube or boxed frame will hold in moisture without regularly being blown out or having clear drain holes.
In terms of strength, bolt-on sliders are just as strong as weld-on sliders as long as the hardware is properly sized and graded for your truck (not a problem with any reputable manufacturer).
Weld-on Rocker Protection
Welding to the Body
When we talk about weld-on rocker protection, we’re almost always talking about welding on to the frame. Welding to the body is almost always custom. Usually it’s because the rockers have been chopped or trimmed due to rust. Welded-to-the-body protection cannot be directly welded or bolted to the frame on non-unibody vehicles. On a traditional ladder-style frame the frame and body are isolated from each other - if you welded a slider to your body, then welded a straight stringer from the rocker to the frame, you’d lose the isolation. Some people that do things like this incorporate rubber or poly bushings between the body and frame.
Welding to the frame
Like we said above, welding and bolting to the frame are functionally equivalent. Before you weld the sliders on, you need to prep the frame. To use the sliders as actual sliders, where you’ll be sliding off ledges and rocks or pivoting your 4x4 around obstacles, they need to be solidly welded to the frame. The steel of most 4x4 frames isn’t more than 1/8” to 3/16” thick. If you weld a slider stringer to 1/8” or 3/16” material, you’ll run the risk of creating stress cracks around your welds, especially if the slider frequently supports the full weight of your truck. You can solve this issue by welding frame plates to the frame, then welding and possibly gusseting the slider stringer to the plate. This effectively makes your frame thicker and spreads the load out.
If you just want rock sliders for looks and the occasional hard use, you’ll probably have different requirements from someone that expects to constantly be hard on their sliders. Important design considerations include:
A rock slider needs to provide exactly the amount of rocker protection that you need. For most people this means that they’ll be the full length of the rocker. This shouldn’t be too hard for you to figure out when you’re buying as you’ll hopefully know if you have an extended body 4x4, like an extra cab truck. Since different manufactures make different sliders, make sure to check out side shots of the sliders you plan to buy so that you know they provide the coverage that you want.
Square and round tube
Square tube resists bending forces better than round tube. Round tube resists torsional forces better than square tube. In the context of sliders, this probably doesn’t matter too much since most sliders made by smaller manufacturers are built with tested and proven material sizes. But if you’re ever wondering why round tube is so much more common as a fab material than square tube, given it’s strength advantages in bending, it’s for two reasons:
- Square tubing does not easily bend into pretty shapes with relatively inexpensive equipment. It’s extremely easy to find a bender that can bend round tube into tight radius bends that is cheap.
- It looks better. This is a matter of taste and opinion but most people would probably agree that exposed round tube fits the look and contours of their rig better than square tube.
There are rock sliders that mix square and round tube, which makes a good combo strength and good looks. These will often use a slider directly under the rocker panel with an additional round tube that runs a few inches off the square tube along the length of the rocker panel.
Practically, if you plan to use your slider as a step square tube is superior - you won’t slide off like you will on round tube sometimes. You may find yourself using your slider as a step more than you think. If you ever need to hi-lift your rig from the slider, square tube is again much easier to deal with. Round tube will require a chain, strap, or other adapter to hold the jack in place. On the other hand, the angularity of a square tube can also make it easier to hang up on the trail.
The most common and effective design for rockers is to have a main tube running directly under the rocker panel with a second tube outside it running parallel to the body. The main tube is supported by stringers to the frame and the secondary tube is welded to the main tube. The main tube provides the primary protection and sliding surface. The secondary tube provides some extended protection laterally - it keeps a little bit more distance between rocks and trees and your rigs body. If it’s correctly braced, it will stiffen the main tube, which means that additional weight resting on your rock slider is less likely to bend it.
Most sliders have enough stickout to give you a convenient place to step. This sounds pretty mundane, but practically speaking, having a rocker-panel-length step is really convenient. It makes it easier to install/remove hard and soft tops, clean off your windshield, lift and secure things to your roofrack (like canoes), and get into your 4x4. If you ever get stuck in a mud pit, you’ll also be able to shimmy along the side of your rig to your bed or your winch and possible stay out of the worst of the muck. If the tube of your rock slider is wet or muddy, it will be ridiculously slippery. Some manufacturers have added diamondplate or expanded metal to give you better traction. You can also use spray-on rubber coatings or friction tape on the upper side of your slider to keep yourself from falling into the mud pit you’re stuck in.
Often when you’re turning, your rear wheel will track too far to the inside for comfort. You might be making a sharp left turn and have a tall boulder 6” from the side of your slider. As you’re making the turn, your truck moves closer and closer to the boulder - from the shape of the boulder, you’re a little worried about it making contact with sheetmetal. But there’s nothing you can do! A kickout solves this problem. A kickout is a bump at the end of the slider that helps to push your truck laterally away from whatever obstacle you’re close to. As you move forward, the slider slides along the obstacle and is pushed away from the obstacle by the kickout. By putting distance between your rig and an obstacle before the wheel, it also protects the sheetmetal over your wheelwell back to the rear fender. A kickout doesn’t have coverage over your wheelwell or rear fender, it just pushes you away from stuff that’ll dent your body.
Integration with Other Parts
Some manufacturers build “systems” where several protective parts integrate cleanly with each other. Depending on your 4x4, available rock sliders and rocker guards might mate up with front fender protection, rear fender protection, internal roll cages, and external roll cages. The pieces of these systems can be bought separately, but if you’re buying sliders (or any other part) do a little planning. If you’re dead set on one manufacture’s rear fenders, make sure they’ll work with the sliders you’re buying. Right now, no manufacturer makes sliders that purposely integrate with another manufactures parts.
Interference with Other Parts
If your rig has a mostly stock underbelly, you won’t have any problems with this. When you buy sliders for your truck, it’s meant to fit your truck. But once you start throwing different parts together you’ll start losing space on your frame to mount things. This is a tougher issue than part integration since there are so many vehicles and so many modifications, so you can’t really know if future you will have trouble mounting a new part because your slider is in the way.
Most rock sliders have at least three attachment points to the frame. This can interfere with link mounts, spring hangers, crossmembers, and skid plates. What really makes this complicated is that sliders and bumpers are often an early stage modification for most wheelers - you’ll start off building your truck with a lift, bigger tires, sliders, and bumpers. As you keep wheeling, you think, “I wish my suspension would do X a little better,” or “I need double low in my t-case.” This might lead you to longer leaf springs or link suspensions to get more flex, or a doubler t-case setup to get the gearing. Both will take up real estate on your frame.
You can’t really do too much about this except try to plan or get slider mounting point measurements before you buy. However, if you get to the stage where you’re talking about linking your front or rear or you’re making extensive drivetrain mods you’ll probably have a welder or be thinking about getting one. If that’s the case, no problem! All that stuff under your 4x4 is made of metal - you can cut it, grind it, and weld it however you want.