Coilover Top Mounts

 

Coilover Top Mounts

The Wilhelm Raceworks coilover top mounts for the MKII (SW20) MR2 provide significant improvements in dynamic camber and allow the suspension to move more freely by mounting both the shock and spring through the spherical bearing. These improvements are discussed further in my suspension analysis.  They also provide more room for wider wheels and tires on the front of the car.

Perfect for those building Koni based coilovers, or as an upgrade to most other coilovers.

Made in the USA!

$210 per pair.

Mount Type
Strut Top Thread
 

Installation Instructions


Standard Spring Perches

Some coilovers do not use a separate upper spring perch, particularly on the rear, instead resting the spring directly on the underside of their strut mount similar to the stock suspension. These require the addition of a new upper perch to be compatible with these strut mounts. See the chart below, or contact me for help choosing the correct perches for your application. Please note that spring perches are special order items and will delay shipment of your top mounts by a few days. Custom sizes not listed below are also available, please contact me to order.

$35 per pair.

Spring Diameter
Center Bore Diameter
 

Roller Bearing Spring Perches

roller bearing perch thumb

Upper spring perch with an integrated, sealed, angular contact roller bearing.  When installed on the front in place of a standard solid spring perch this allows the steering action to be handled by a bearing intended for that rotary motion, just like the stock Toyota upper mounts.  Steering feel is significantly improved, and maintenance is reduced compared to using "Torrington" thrust roller bearings under the springs.  Upgrading an existing setup with these perches will in many cases require the purchase of a pair of shoulder nuts as well.

$90 per pair.

Spring Diameter
Center Bore Diameter
 

Shoulder Nuts

Shoulder Nuts

Beginning September 2017, all top mounts are sold with these shoulder nuts included to replace your coilovers standard top nut.  Custom made from 4130 alloy steel to fit the 3/4" bearings used in my top mounts, these nuts allow for increased thread engagement while allowing for additional room for a spring perch under the top mount.  Sold individually for those wanting to upgrade existing top mount setups.  Available with M12x1.5 and M14x1.5 threads.

$13 each, free domestic shipping.

Thread Size
 

Coilover Fitment

In my experience, M14x1.5 is by far the most common thread found on the top of MR2 struts / coilovers.  A few also use a 12mm thread.  In most cases the ID of the spring perch perch will match the thread size.  The notable exception is on stock replacement struts such as the Koni Sport (Koni Yellow).  These have a slightly larger diameter section below the threads.  The data that I have been able to gather over the years is summarized below.  Blanks or question marks indicate items for which I do not have confirmed data.  Any information that you can provide to help expand or complete this table is greatly appreciated.

Coilover / Damper  

Thread Size Spring ID Perch ID  Notes      
Koni Sport M14x1.5  2.5" 15mm  
Koni Race M14x1.5  2.5" 14mm  
KW V3 M14x1.5 60mm 14mm Requires rear spring perch.
JIC M14 ?   14mm  
H&R M14 ? 60mm 14mm  
Tien Basic M14x1.5      
Tien Flex M14x1.5      
Tien Mono-Flex M14x1.5 2.5" (65mm) 15mm Rear springs 70mm ID.  Reuse existing rear spring perch.
BC Racing M12x1.5 60mm 12mm Requires rear spring perch.
Fortune Auto M12 ? 60mm 12mm Requires rear spring perch.

Technical

The plates are machined from 6061-T6 aluminum and anodized flat black. The spherical bearings are made-in-the-USA FK pieces rated at over 7000lb axial load. Shoulder nuts to adapt the spherical bearing to the thread on the top of your strut shaft are included beginning in September 2017.

The front mounts will move the strut top inward significantly farther than any other on the market, as well as providing increased caster (about 7.2 degrees on my setup). They position the adjuster knob on your strut in line with one of the bolt holes in the chassis, enabling these camber and caster gains without requiring any cutting of the chassis, as shown in the pictures below.

Front Top Mount Installed

Rear Top Mount Installed

These are not "camber plates" in the traditional sense, that is, they are not adjustable. My opinion is that the proper use of adjustable camber plates is to set them to their max camber position, and then use crash bolts to set the desired camber at the hub. The reason for this is that leaning the strut inward provides significant improvement in camber curves, as discussed in my suspension analysis, as well as gaining clearance for wider wheels and tires. Additionally, changing camber plate settings has a large affect on toe, making it a more complex adjustment than it would appear. Better to just set it up once, and set it up right.

The increased caster causes the wheels to gain camber due to steering input giving you more camber when you need it most. The end result of all of this is that you can get the same or better cornering performance while actually running LESS static camber, providing better braking and acceleration grip, as well as better tire wear.

 

A few things to be aware of regarding the use of these mounts:

1. They provide a LOT of camber in front. Depending on your ride height and how much camber you want you may need to substitute a smaller bolt for your upper crash bolt. I have used a 12mm Grade 10.9 bolt from the hardware store, which enabled me to get down to about -2°. Two of the smallest Toyota crash bolts will get you to about -3°.  Other aftermarket lobed camber bolts may be able to achieve similar results to the 12mm bolt I used, although I have not tested to confirm this.

2. The increased caster does effect steering effort. Its not a big deal with power steering, but if you have manual steering it may be more than you want to deal with.  The added caster also may cause tire rubbing on the rear inside edge of the wheel well at full steering lock.  This can usually be resolved by adjusting the strut rod to pull the wheel forward in the wheel well.  Aftermarket adjustable strut rods are required on a 93+ MR2 in order to do this.

3. Because of moving the rear strut top in, the rear strut may contact the frame rails at full droop. This isn't an issue under any normal circumstances, but it does limit droop travel slightly. Just something to be aware of. You may need to lift the hub with a jack and slightly compress the strut during installation.

4. These mounts REQUIRE the use of a separate upper spring perch. Unlike many rear mounts, they are not designed to be use as a combined strut mount and spring perch. If your coilovers do not have a separate upper spring perch in the rear you will need to purchase those as well.

5. Due to the large diameter of stock and stock-style "lowering springs", these mounts will not work with those setups. Sorry, coilovers only.