Suspension Lift/Upgrade Types – Toyota IFS Coil Spring Suspensions

Spring spacers are an entry level component to achieve additional lift height, without addressing load carrying capacity of the suspension. Spacer lifts are not recommended for applications where additional lift is required due to the addition of heavier aftermarket components on the vehicle.

They are typically manufactured from aluminum, steel or urethane.  There are two types of spacers, Pre-load spacers and Top-Out spacers.

Pre-load spacer installs between the coil spring and strut top plate.  Installation requires the shock/spring (coil-over) assembly to be removed from the vehicle.  Using a wall mounted strut compressor the factory assembly is disassembled and factory spring is further compressed allowing room for the spacer to be installed.  The additional pre-load on the factory spring achieves a greater ride height.

There are a few concerns with this type of product.  First is it relies on the factory suspension components (OE springs and shocks) which can be worn, damaged or is insufficient load carrying capacity for the application.   Additionally, many original equipment shocks are borderline in controlling the factory springs.  With the extra preload applied by the spacer the suspension lacks the ability to perform proper handling, control and ride quality.

Based on the factory bump stop locations, the spacers allow the factory coil spring to be over compressed and possibly put into coil bind. The available space for the coil spring between the coil seat and top plate is reduced by the spacer thickness. This results in the iner coil winding spacing to be less. Due to this reduced space, when the suspension cycles, the coil can be compressed until the coil windings touch. This process is called Coil bind . This can rapidly degrade the spring causing loss of height and possible failure.

 

Top out spacers install between the spring bucket (frame) and the top plate of the factory assembled spring/shock (Coil-over).  This effectively lengthens the shocks (coil-over) assembly and increases the distance between the lower control arm and the frame, thus raising the vehicle.

With most if not all Toyota IFS coil suspensions the shock length limits the down travel of the suspension to protect other components such as ball joints, steering rod ends and CV joints/axles.  Adding a Top out spacer extends the down travel or “droop” of the suspension.  If extreme, it can severely reduce the life or cause catastrophic failure to these components.

Top out and pre-load spacer

Some companies utilize Top out spacers and Pre-load spacers together in the same kit to minimize the negative effects.  In most cases the installation of spring spacers require modification to the factory spring top plate (or top out plate) making it costly to reverse the installation.

With many Toyota IFS vehicles the factory suspension has room for improvement  By upgrading the suspension you can achieve better vehicle control, additional load carrying capacity, additional wheel travel and improved ride quality all while increasing ground clearance for better on and off road ability.

Companies such as Old Man Emu (OME) offer tuned springs and shocks that are vehicle and application specific.   By offering both components it helps ensure the upgraded spring rate can be properly matched with accurate shock valving.   This match is less likely when using products from two separate sources.

Factory Strut Top

When used properly, these components can offer additional wheel travel while maintaining proper shock compressed lengths utilizing the factory bump stops ensuring proper shock life.  As the coil springs have a “set” rate and height, it is important to choose the proper part number for the application at the time of installation.  If the weight or application is changed substantially at a later date the springs may need to be replaced to match the new load.  Installing “heavy” springs with the anticipation of additional weight is discouraged as this will net excessive lift height.   This will not allow for a proper wheel alignment and decrease the down travel having a negative effect on ride quality and handling.

Rebuildable shocks or Coil-overs are a necessity in racing and competition.   This is because each shock can be tuned and adjusted individually to achieve the desired control and reaction.  Changes can be made in the valving (shim stack), oil type (viscosity/weight) and gas pressure (nitrogen). The only constant is shock length and diameter.  In the Toyota IFS application this all holds true.  Referred to as Coil-overs, there are many manufactures offering Toyota specific applications.  Comparing apples to apples can be very difficult.  Common variables are shock body diameter (commonly 2” or 2.5”),  reservoir type (internal, external or non (emulsion)), material type (cast or billet components such as shock body, piston and top cap/housing) and types of finishes/coatings (important in winter conditions).

Most coil-overs offer a threaded shock body allowing the pre-load on the spring to be adjusted.  This allows for adjustments in vehicle height or compensation for additional weight added after the initial installation.  In most cases the coil-over must be removed from the vehicle and the pre-load adjusted using a spring compressor.  In the case of a coil over, preloading the spring is not a negative since the coil spring is longer and  designed for the application thus  coil bind is normally not a factor.

As with anything rebuildable, serviceable and designed for competition, this type of component requires additional maintenance.  A rebuildable shock commonly uses spherical bearings at either end instead of bushings.  At a minimum they require cleaning and depending on conditions, will require replacement much sooner than traditional bushings.  The same is true for the shock seals which can be damaged due to contaminates and abrasive material.  Due to the mounting direction of many coil-overs the shock shaft is exposed to road debris causing it to be pitted or damaged requiring additional service.

It is important to understand each type of product including its pro’s and con’s before making a decision.  Here at Slee Off Road our most used product is the OME spring and shock option as it is a cost effective upgrade and replacement of many the factory components without adding additional maintenance. It is a rare instance if ever that we would recommend a spacer kit as they have more negatives than positives.   In some cases where budget is the largest concern a replacement coil spring can be substituted for a spacer kit.  A tuned 2.5” reservoir coil-over will offer the best performance with some compromise with additional maintenance.  As with all of the products Slee offers, we are here to discuss your options and requirements.