Uploaded July 2021 | Updated September 2026, 3 weeks ago
Howdy friends I'm Mike, I'm an adventurer and a dad and today I'm going to talk about suspension.
While you don't "need" any fancy suspension for overlanding or casual off-roading, the more comfort and control you have when driving rough roads with your family the happier and safer you will be.
To that end, ARB has sent us a new suspension to test for our 2017 Toyota Tacoma TRD Off-Road.
We have here their BP-51 suspension system for Tacoma with springs set up for heavy constant load.
We'll get into more of the install and performance in future videos, but for now here are the important details about this suspension setup.
The shock body and most of the parts are made of 6061 Aluminum including the remote reservoir bodies. This saves weight while maintaining high strength.
The coilovers have adjustable pre-load for fine tuning the ride height as well as X5K grade steel coil springs. The coilovers also have Teflon Lined steel spherical bearings on the bottom mounts.
The shock absorber bodies are also 6061 Aluminum with a 51mm bore diameter.
The shocks also have a plastic shaft guard to keep rocks and junk from impacting the chrome shock shaft. This is replaceable.
What do shocks even do?
Shock absorber is a misnomer. What shocks do is convert the kinetic energy of the springs into heat energy in oil inside the shock which then gets dissipated through the body into the air.
The effect of this primarily is to stop the oscillation of the springs. Without shocks, the springs act like a pendulum and they swing between compression and extension until all the energy is dissipated. That takes too long and is uncomfortable so shock absorbers dissipate that energy faster so you're ready for the next bump.
Shocks also keep the tires on the ground, and the axles off the bump stops. If the tires are off the ground you have no control. No braking, steering or traction. Shocks slow down the compression of the springs so that the axles don't slam into the bump stops, and they also slow down the rebound so they don't bounce you into the air.
On regular shocks, the compression and rebound are set at the factory and are not adjustable. On the BP51s you have an adjustment on each shock to change the rebound and compression for the weight of the vehicle, the terrain you're driving and the speed you want to go.
ByPass?
The BP in the name refers to "By Pass." In a regular shock, there is only one piston that squeezes oil through an aperture to slow down compression and rebound. In a bypass shock, depending on where the piston is in the stroke, there are ways for oil to get around the piston making the shock softer initially and ramping up at the end of the travel.
The BP51s are Internal Bypass, so you won't see any evidence on the outside. If you watch ultra 4 racing or Monster Jam, you'll see big shocks with a bunch of crazy tubes sticking out of them. Those are external bypass shocks.
SPRINGS
As I said, the front springs are X5K grade steel coils rated for heavy constant load.
The rear springs are steel leaf springs also rated for extra load. As I mentioned in a previous video, the springs that come stock on the Tacoma are not suitable for loading. Even though it's a pickup truck.
These springs have 5 main leafs in the pack each with metal shims at the bolt and plastic isolators at the ends.
They stagger down in length for progressivity, meaning they get stronger as they compress.
They have not one but two overload springs at the bottom of the stack. This should help keep our loads from sagging the truck out or bottoming out when loaded.
Remote Reservoir?
The remote reservoir on these shocks is there to handle expansion of the fluid as it gets hot. All shocks need some empty space in the design to accommodate the expansion of the working fluid. Remember, the shocks convert kinetic energy to heat energy. So this is where the energy from the bumps and spring oscillation is going. Heat causes the working fluid to expand.
If it was air in the shocks, the air would mix with the oil and foam up and then the whole thing would stop working. They use nitrogen to prevent foaming, and then separate it from the shock to keep piston travel as high as possible and to aid in cooling the fluid.
All 4 shocks in this suspension setup have remote reservoirs for this purpose.
Adjustment
The other thing these shocks have that regular shocks don't have is damping adjustment. There are a lot of variables with vehicle suspension. The big ones are spring rate, or how stiff the spring is, vehicle mass, and damping. Since vehicle mass and spring rate aren't usually feasible to change for the conditions, these shocks let you adjust the compression and rebound damping for the conditions.
There are two collars on each shock body that let you dial in the damping to suit your needs and conditions.
Happy Trials
Howdy friends I'm Mike, I'm an adventurer and a dad and today I'm going to talk about suspension.
While you don't "need" any fancy suspension for overlanding or casual off-roading, the more comfort and control you have when driving rough roads with your family the happier and safer you will be.
To that end, ARB has sent us a new suspension to test for our 2017 Toyota Tacoma TRD Off-Road.
We have here their BP-51 suspension system for Tacoma with springs set up for heavy constant load.
We'll get into more of the install and performance in future videos, but for now here are the important details about this suspension setup.
The shock body and most of the parts are made of 6061 Aluminum including the remote reservoir bodies. This saves weight while maintaining high strength.
The coilovers have adjustable pre-load for fine tuning the ride height as well as X5K grade steel coil springs. The coilovers also have Teflon Lined steel spherical bearings on the bottom mounts.
The shock absorber bodies are also 6061 Aluminum with a 51mm bore diameter.
The shocks also have a plastic shaft guard to keep rocks and junk from impacting the chrome shock shaft. This is replaceable.
What do shocks even do?
Shock absorber is a misnomer. What shocks do is convert the kinetic energy of the springs into heat energy in oil inside the shock which then gets dissipated through the body into the air.
The effect of this primarily is to stop the oscillation of the springs. Without shocks, the springs act like a pendulum and they swing between compression and extension until all the energy is dissipated. That takes too long and is uncomfortable so shock absorbers dissipate that energy faster so you're ready for the next bump.
Shocks also keep the tires on the ground, and the axles off the bump stops. If the tires are off the ground you have no control. No braking, steering or traction. Shocks slow down the compression of the springs so that the axles don't slam into the bump stops, and they also slow down the rebound so they don't bounce you into the air.
On regular shocks, the compression and rebound are set at the factory and are not adjustable. On the BP51s you have an adjustment on each shock to change the rebound and compression for the weight of the vehicle, the terrain you're driving and the speed you want to go.
ByPass?
The BP in the name refers to "By Pass." In a regular shock, there is only one piston that squeezes oil through an aperture to slow down compression and rebound. In a bypass shock, depending on where the piston is in the stroke, there are ways for oil to get around the piston making the shock softer initially and ramping up at the end of the travel.
The BP51s are Internal Bypass, so you won't see any evidence on the outside. If you watch ultra 4 racing or Monster Jam, you'll see big shocks with a bunch of crazy tubes sticking out of them. Those are external bypass shocks.
SPRINGS
As I said, the front springs are X5K grade steel coils rated for heavy constant load.
The rear springs are steel leaf springs also rated for extra load. As I mentioned in a previous video, the springs that come stock on the Tacoma are not suitable for loading. Even though it's a pickup truck.
These springs have 5 main leafs in the pack each with metal shims at the bolt and plastic isolators at the ends.
They stagger down in length for progressivity, meaning they get stronger as they compress.
They have not one but two overload springs at the bottom of the stack. This should help keep our loads from sagging the truck out or bottoming out when loaded.
Remote Reservoir?
The remote reservoir on these shocks is there to handle expansion of the fluid as it gets hot. All shocks need some empty space in the design to accommodate the expansion of the working fluid. Remember, the shocks convert kinetic energy to heat energy. So this is where the energy from the bumps and spring oscillation is going. Heat causes the working fluid to expand.
If it was air in the shocks, the air would mix with the oil and foam up and then the whole thing would stop working. They use nitrogen to prevent foaming, and then separate it from the shock to keep piston travel as high as possible and to aid in cooling the fluid.
All 4 shocks in this suspension setup have remote reservoirs for this purpose.
Adjustment
The other thing these shocks have that regular shocks don't have is damping adjustment. There are a lot of variables with vehicle suspension. The big ones are spring rate, or how stiff the spring is, vehicle mass, and damping. Since vehicle mass and spring rate aren't usually feasible to change for the conditions, these shocks let you adjust the compression and rebound damping for the conditions.
There are two collars on each shock body that let you dial in the damping to suit your needs and conditions.
Happy Trials
