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Why Bilstein 5100 Series Leveling Shocks Are Better Than Coil Spacers

Front-end leveling kits have become an extremely popular upgrade on many later model trucks and SUVs. Their popularity can be attributed to three common trends in new vehicle designs.

  • Larger Wheel Wells
  • Coilover Front Suspension
  • Factory Rake

Larger Wheel Wells

In recent years, auto manufacturers have begun designing their trucks and SUVs with larger wheel wells and more fender clearance. This has made it easier for vehicle owners that upgrade to a leveling kit to fit (on average) 33″ tires, while in some full-size applications fit 35″ tires. In the past (mostly for vehicles up through the 1990’s), a truck or SUV typically needed a minimum of a 4″ lift just to fit 33″ tires, and depending on the wheel and tire combination, sometimes that wouldn’t be enough and therefore a 6″ lift would be required.

Coilover Front Suspension

Beginning in the mid 1990’s, truck and SUV manufacturers of IFS vehicles did away with their torsion bar suspensions and began making use of coilover front suspensions. These factory coilovers can be easily modified to level the vehicle.

Factory Rake

All later model trucks and SUVs have a noticeable rake whereby the rear sits sometimes as much as 3″ higher than the front. The vehicle engineers designed them this way on purpose so that the vehicle would level out when loaded with cargo or towing, however this look does not appeal to many vehicle owners, especially for those who seldom use their vehicle for hauling cargo or other heavy loads. Front-end coil spacers have commonly been used to correct this aspect of the vehicle’s appearance.

How Do Spacer Kits Work?

Anyone new to the subject might think that spacer kits are all the same. There are in fact three different types of spacer kits most commonly used. They are strut extension kits, spring preload kits, or a combination of both.

Strut Extension Kits

A “strut extension” is simply a spacer that installs between the factory shock mount and the coilover shock’s spring perch. This kit spaces the entire coilover assembly down 1″ to 2″. This type of spacer kit has significant shortcomings, most specifically it reduces the suspension up-travel and over-extends the suspension down-travel.

There are two different designs of factory suspension compression stops. One uses an external bump stop located on the frame or lower control arm. On this type of suspension, when a strut extension spacer is added to the coilover assembly, the shock and/or spring can bottom out before the lower control arm reaches the factory compression bump stop. This can possibly lead to several problems such as major structural damage and/or shock failure. This type is currently found on Toyota and Nissan trucks and SUVs.

The other uses the shock to limit compression travel with bottom out bump stop located on its shaft. When a strut extension spacer is used on a suspension that utilizes the shock as the compression stop, up-travel will actually be reduced from 1″ to 2″ less than was allowed by the stock suspension, depending on spacer size. This type is currently found on Ford, Dodge, and GM trucks and SUVs.

With either design, by adding a spacer kit you do increase ride height, but actually decrease suspension up-travel.

Bilstein 5100 Series Leveling Shocks have been engineered to allow the suspension components to fully travel upward to the factory bump stop as it was originally designed to do.

Bilstein Suspension Up Travel MY4BY
Up-travel is restricted when the shock assebly bottoms out with the Strut Extension spacer installed.
Full stock suspension up-travel is maintained with the Bilstein 5100 Leveling Shock installed.