A GUIDE TO BUMP STOPS FOR OFF-ROAD SUSPENSIONS

As you research the web looking for bump stops for your off-road vehicle, it might be helpful to take a look at bump stops in general before you decide which product is right for you.

This short guide describes in some detail what a bump stop is, what it does, and outlines for you the reasons for using off-road bump stops. Additionally, Timbren will explain the different kinds of bump stops that are available on the market today, along with a few unbiased recommendations.

What is a Bump Stop?

Whether you call them bump stops, jounce bumpers or axle snubbers, it all means the same thing. Timbrens talking about a small-but-ever-important component that works together with your suspension and, in some cases, is part of the suspension on your car.

In the case of trucks and SUVs, most bump stops are mounted to the frame just above the lower control arm of an independent front suspension or somewhere between the frame and the axle tube on the rear. Bump stops can also be found inside the shock absorber or on the shock shaft.

Depending on the design, a bump stop could be made of various materials. Factory bump stops are usually made of rubber or microcellular foam. Many aftermarket bump-stop manufacturers choose polyurethane for its durability and its capability to be used for injection-molded products.

Some bump stops are designed for trucks that go off-road. Two of the best are Hydraulic bump stops and Timbren Active Off-Road Bumpstops. Hydraulic bump stops use fluid, typically lightweight shock oil, to absorb suspension energy. Active Off-Road Bumpstops are made of natural rubber, designed to absorb the harsh jounce when the suspension bottoms out.

What is the purpose of a Bump Stop?

Protection

The main purpose of a bump stop is to serve as a cushion when the suspension finally bottoms out. That way, there’s always a bit of protection to prevent metal from hitting metal or, in some cases, prevent the frame from traveling too far. In either case, bump stops help avoid damage to the suspension or the chassis, as well as preserving the integrity of the shock absorbers.

Ride quality

The most common type of bump stop used on production vehicles is made from rubber. These are simple to employ and low in cost. A common aftermarket step-up from rubber stops is urethane. But neither style of bump stop offers great ride quality. A better alternative to factory bump stops is Timbren’s Active Off-Road Bumpstops which provide a soft, comfortable bounce when the vehicle bottoms out.

Control

If you’re planning to leave the pavement and cut to the off-road trail, you’re quickly going to find that factory bump stops are woefully inadequate for the task. Not only is the ride quality poor, but the loss of vehicle control can be rather dangerous. The best way to regain control of your off-road vehicle requires the use of bump stops designed specifically for rough terrain.

How do Bump Stops Work?

A modern suspension system has hundreds of different parts working together. There are, however, seven main sections to every suspension system:

  1. Springs;

  2. Wheels/Tires;

  3. Shock absorbers;

  4. Rods/Linkages;

  5. Joints/Bearings;

  6. Steering System;

  7. Frame.

One of the tiniest components of the entire suspension system is the bump stop. If you understand the purpose of a bump stop, then you know how they work. Factory bump stops limit the travel of the springs and protect the axle and frame to a certain extent by preventing the metal frame from smashing down on the metal axle (as in a straight-axle setup).

Various types of bump stops

There are basically three types of bump stops:

  1. Factory bump stops
  2. Shock-absorber bump stops
  3. Off-road bump stops

All 3 types minimize the damage caused when the suspension bottoms out.

Off-road bump stops take it one step further by helping to maintain better ride quality on rough terrain, as well as giving the driver more control over the vehicle. Nitrogen bump stops and Active Off-Road Bumpstops are both designed to absorb the constant stress of bottoming out by allowing a better cushion between frame and axle.

How do You Install a Bump Stop?

There’s no real trick to installing a bump stop if it’s the kind that replaces the one from the factory. Most OEM bump stops are bolted on to the frame, so the after-market replacement required will be similar to the original. Just remove the old and bolt on the new right in the same spot.

Active Off-Road Bumpstops fit several off-road vehicles on both front and rear. Most of them are bolt-on kits, i.e., they bolt on using the existing holes in the frame. If the factory bump stop is removed by prying it out of a cup, you replace it by simply pressing the Active Off-Road Bumpstop assembly up into the same cup.

Installing Hydraulic Bumpstops will require a much higher skill set than that of the average person along with special tools for cutting, welding, grinding and painting metal. Each kit includes metal brackets designed to make the installation a little easier.

So, how do you install a bump stop? The easiest way possible! Having said that, the particular set of bump stops that meet your needs may cost more than the average, not to mention the price.

What Size Bump Stop Do I Need?

Of the many types of bump stops on the market today, the only style that gives you any choice in size are the hydraulic kind (sometimes called air-bumps). Hydraulic bump stops usually come in 2.0”- and 2.5”-cylinder sizes, including 2" 3" and 4" stroke lengths, adjusted using internal spacers. The cylinder diameter is decided by the weight of the vehicle and how it is used. The stroke length is determined by your suspension travel and where the bump stops are mounted.

2.0 Bump Stops work best for solid axle vehicles 5,000 lbs. or under used for extreme off-roading like rock crawling. For vehicles with relatively low ride heights, Timbren recommends 2” or 3" stroke bump stops if you are tight for space. For vehicles with ride heights above 6-7", Timbren suggests the full 4" bump stops.

2.5 Bump Stops can absorb significantly more energy than the 2.0 size, so they are better suited for solid axle vehicles over 5,000 lbs. or in highly leveraged a-arm/trailing arm applications. Mud trucks and desert racers with large amounts of suspension travel should run 4" travel bump stops, while vehicles with a-arms or low ride heights should use 2" or 3" travel bump stops.

What Bump Stops are Used Off-road?

There are basically 3 types of off-road bump stops:

  1. Active Off-Road Bumpstops (Timbren):
    Active Off-Road Bumpstops (Timbren Industries) are made of natural rubber and come in many shapes and sizes. Depending on what you drive, there is a custom kit that will fit your off-road vehicle. If you can remove a bump stop, you can install Active Off-Road Bumpstops on your chariot.

  2. Wheeler Superbumps:
    Wheeler Superbumps resemble factory bump stops but are much taller and provide better ride quality.

  1. TeraFlex Speedbump bump stops:
    TeraFlex Speedbumps use the same principle of a factory bump stop but look and act much like a hydraulic bump stop. Installation requires some customization.

  2. Hydraulic bump stops (Bilstein or King):
    If price is no object, hydraulic bump stops are the way to go. They’re filled with shock oil and nitrogen and are adjustable allowing you to fine-tune them to your particular needs. You’re going to need a custom shop that specializes in made-to-measure installation because these bump stops work best in conjunction with your existing shocks. Two of the most popular brands are Bilstein and King.