Suspension - Struts, Springs, Coilovers, Camber Plates, and Sway Bars
Struts
KYB
KYB were the original equipment manufacturer of struts for Geo Storm and Isuzu sister cars. KYB are also the
highest quality OEM replacement struts on the market for these vehicles.
Gabriel and Monroe are junk, typically lasting less than six months before they loose their charge and cease
dampening suspension movement.
KYBs will last 3+ years with the original springs, but be warned not to use them with lowering springs, because
this will significantly reduce their life, usually by half or more.
GAB
GAB made adjustable dampening struts for the Isuzu sisters of the Geo Storm (with the Lotus/Irmscher style sway
bar end mounts instead of the shackle style used on the Storm). These were identical in dimensions to the stock
struts, but provided a knob to increase or decrease dampening within the strut. These were also the only struts
durable enough to live a long life with lowering springs.
Custom Struts Using Racing Dampers
On the face of it, this looks like a very promising and cost effective solution. Water cooled Volkswagens
originally came with rebuild-able strut assemblies and replaceable damper cartridges. These same vehicles became
popular for racing, and more durable cartridges with adjustable compression and rebound became available. It
wasn’t long before these damper cartridges were being used on other vehicles. Installation involves cutting the
original struts, gutting the housing, inserting the damper cartridges, and securing the damper in place with a
threaded end cap. The result is a custom racing strut. These became very popular for use in racing classes
that prohibit full coilovers, such as SCCA Solo Stock classes and SCCA Club Racing Showroom Stock classes,
as well as any class that follows the Group-N limited modification rule set. Popular names include "Cut-A-Strut"
and "Group-N Strut".
However, the Geo Storm strut bodies are 1 ¾ inch in outside diameter, and the shaft within is about 1 9/16 inch
in inside diameter. The replaceable VW damper cartridges are 1 7/8 inch in outside diameter. The original strut
bodies are too small for the damper cartridges to fit inside.
Custom made bodies could be made, but the cost would quickly move upwards of $4,000 for a set, which is
not-so-coincidentally just about the same price range as a set of decent coilovers. The main differences being
that coilovers have adjustable spring perches and lower spindle mounts, and custom made struts do not. Unless
the car is being built for a racing class that prohibits full coilovers, the better choice is to use that
same money on full coilovers and benefit from the added adjustability that full coilovers provide.
TrueChoice
TrueChoice is repeatedly cited as a custom suspension company willing and able to make anything, though costs are
never mentioned. A little research shows that they are not overly friendly and somewhat less than reliable:
http://www.bimmerfest.com/forums/archive/index.php/t-97858.html
At best, the Australian owner seems unwilling to discuss reducing their $50+ per hour labor rate and is quickly
angered by customers who argue about their prices. At worst, the company is running a bait-and-switch scheme to
jack up fees for rather simple and easy tasks. Draw your own conclusions. But rest assured, at $50 per hour
labor rate plus materials, a set of custom struts or coilovers from Truechioce will quickly pass the $4000 mark.
Cutting Springs - A Bad Idea
Theory
The theory concerning cutting springs is fairly simple. The work being done by the spring is spread across
all of the coils, evenly. Each coil compresses a little bit to make the overall spring rate of the group.
Take the front spring of the Geo Storm, for example, which measures 144 lb/inch in spring rate (140 lb/inch
for Base model). Cut the spring in half, and the spring rate of the half spring is doubled, because there
is only half as many coils to carry the load. So cutting a spring increases the spring rate.
Practice
The problem is that the increase in spring rate is small, compared to the change in spring length and ride height
of the vehicle. Cut the spring in half, and that spring rate might be 288 lb, but there isn't enough spring
length to hold the car up. The tires will be resting against the insides of the wheel wells.
What's the real reason for lowering a car? Ignore all the BS about lowering the center of gravity. Estimate the
center of gravity at about 16 inches above the ground, lower the vehicle two inches, and the center of gravity is
14 inches above the ground. The change in handling is not going to be noticeable to 99% of the population.
Especially if the
roll center is not corrected. The fact of the matter is that 99% of the handling improvement is due to
the use of a stiffer spring, and not the change in ride height. So the reason to change the ride height
is because using a stiffer spring reduces suspension travel, and does not require as much ride height to
absorb the bumps that the car travels over in the road.
Back to cutting the springs, people usually want to reduce the ride height by 2 inches. And the corresponding
spring rate increase for such a ride height reduction is from 144 lb/inch to around 190 lb/inch. That would
require cutting 1/3 of the spring off, and would reduce the ride height by 3-4 inches. While cutting the
spring enough to reduce the ride height by the desired 2 inches, would only increase the spring rate to 155-160
lb/inch, which is not enough to keep the strut damper from bottoming out at that reduced ride height.
When a strut damper bottoms out, the piston within the damper slams against the end of the cartridge, damaging
the strut, and causing the car to spin which usually ends in a wreck.
This ignores the fact that the relationship and ratio between the front and rear spring rates is what
determines if the handling of the vehicle and if it tends to oversteer, understeer, or handle neutral.
Cutting springs for the desired appearance of how the tires fill the wheel wells, ignores the resulting
spring rate and handling characteristics that result.
Remember, this is about "tuning". The primary concern is how the vehicle functions, not how cool it looks.
Making the car handle correctly means concentrating on the spring rate as the primary concern. Ride height
and reducing wheel well gap are secondary, tertiary, or even lower in the list.
The minimum correct way to lower the vehicle is with quality mass produced lowering springs or
real
coilovers. And if absolute control over ride height is the minimum requirement, then
real
coilovers are the only real answer.
Lowering Springs
Lowering springs are a quick and inexpensive way to change the handling character of a car by switching the springs
out for stiffer, shorter springs. The original struts are retained. And this is the Achilles heal of lowering
springs for Geo Storm, because none of the available struts are durable enough to handle the additional stress of
a lowering spring.
The valving within the damper must be matched to the spring. A typical manufactured lowering
spring is going to be 30% stiffer than the spring the strut is designed to work with. Handling is going to be
muddy, mushy, and unresponsive, and ride will be rough with suspension movement poorly controlled. The strut
is going to be overworked in its attempt to dampen the movements of a much stiffer spring, which will be
absorbing less movement and transmitting more movement to the chassis. This added stress will degrade the
strut very quickly.
All of the available OEM replacement struts for the Geo Storm are gas charged. Manufacturers like gas charged
struts because they provide good ride quality. The gas pressure within the strut resists the compression
movement of the suspension. The strut and gas charge was designed for the at-rest position of the piston
within the damper at mid stroke, which is where it is with at the stock ride height. Lowering the car on the
stock struts compresses the strut and increases the pressure within the strut. For handling, this places a
pre-load on the suspension that is difficult to calculate and deal with in tuning the suspension. But more
important than this is that the increased pressure will raise the temperature within the strut housing.
Basic physics: increase pressure = increased temperature. The increased temperature will quickly overheat
the struts and rapidly decrease the life of the seals or simply melt the seals, resulting in a blown strut.
Finally, reducing the ride height will move the damper piston closer to the end of the strut housing, increasing
the likelihood (inevitability) that the strut piston will strike the end of the damper housing when the car
encounters a large bump or long duration cornering maneuver. This will cause damage to the damper piston,
and quickly render it inoperable.
Even the KYB struts will last only a year or two with lowering springs, due to the stiffer
spring and lower ride height.
Manufactured Lowering Springs
Eibach, Intrax, and Suspension Techniques made lowering springs for the Geo Storm. The springs seemed decent
quality, but offered only one option for ride height and stiffness. When used with stock or OEM replacement
struts (the only struts available), these slightly-stiffer-than-stock springs will accelerate wear, and owners
can expect to replace struts every 1-2 years.
The manufacturer’s decision making about the specs of their product were determined based on providing looks,
comfort, and low speed handling feel, rather than optimum handling on the race track. Depending on the intended
use, manufactured lowering springs may be just as undesirable as the OEM springs.
Custom Springs - A Bad Idea
CSS
Isuzuperformance
set up Coil Springs Specialties (CSS) to make custom lowering springs for Geo Storm and Isuzu
cars in the 1990’s, when the company was still run by Dave Pflum. The springs would be custom made to order in
whatever ride height and spring stiffness that the customer desired.
Dave Pflum retired, and turned the company over to his son. Immediately following the changeover, problems emerged
with the springs delivered by CSS. Ride height and record keeping became big problems. CSS repeatedly lost their
own spring blueprints and nearly every order required resending the sample OEM springs to be re-measured, basically
starting from scratch. But the biggest problem revealed itself after racers commented that they needed abnormally
large sway bars when using the CSS springs on the track. The springs were checked on a spring dyno, and the
claimed spring rates did not match the measured spring rates. One set specced at 350 lb/in measured an actual
spring rate of 127 lb/in! This last issue was the clincher, and Isuzuperformance ceased offering custom lowering
springs, completely converting over to coilovers for the dependability of mass produced coilover springs and
adjustability of threaded body dampers.
The single most important consideration when purchasing a spring for an automobile suspension is that the spring
rate be accurate and correct. When tuning the suspension of a vehicle, correcting oversteer and understeer,
and making decisions to change the spring rates of the springs, or change sway bar sizes or damper settings
is dependent upon knowing the accurate and correct spring rating of the suspension spring. Coil Spring
Specialties can not make springs that are accurate and correct to the spring rate ordered, and are therefore
unsuitable for use when tuning the suspension of an automobile.
Coilover Springs
Coilover springs are standardized springs meant for use on race cars. Coilover springs are made to standardized
inside diameter (ID) sizes, usually 3 inch, 2 1/2 inch, 2 1/4 inch, 2 inch, 70 mm, and 60 mm ID, and in
standardized lengths of 6 inch, 7 inch, 8 inch, and 10 inch length. In addition to this, coilover springs
are offered in a wide range of stiffnesses, typically ranging from 100 lb/in up to 1000 lb/in, usually in 25 lb/in
increments.
Coilover springs are significantly smaller in diameter than the springs used on the McPherson struts of normal
road cars such as the Geo Storm. McPherson strut springs are larger in diameter, and the upper and lower spring
perch of a McPherson strut are correspondingly larger to match the size of those springs. Directly below, under
Fake Coilovers, the use of slip-on threaded sleeves with McPherson struts is discussed, and why this is a bad
idea due to lack of the damper's ability to handle the stiffer coilover spring.
Coilover springs are designed for use with
Real Coilovers, which are purpose built threaded body dampers with special upper and lower spring perches
specifically designed to use standardized coilover springs.
The real advantage of coilover springs is that they are available in standardized stiffnesses or spring rates,
making it quick and easy to tune oversteer and understeer handling by changing the springs. Because the springs
are standardized in size (ID or inside diameter), and are an off-the-shelf item from the spring manufacturers
and race supply vendors, obtaining springs is easy and less expensive than
McPherson strut lowering springs or
custom made springs. And because coilover springs are available in a large range of stiffnesses (spring
rates), it is easy to fine tune the handling of the vehicle to match the specific use (autocross, road racing,
drag racing, spirited road use) and to match the driving style of the driver (right-foot-braking requiring
oversteer tendency, left-foot-braking requiring understeer tendency).
For any and all performance and motorsport use, coilover springs are the best choice.
Coilover springs are available from reputable companies like Eibach and Hyperco, from many racing
suppliers such as Pegasus, Speedway, HRP, and Hoerr.
Fake Coilovers or “Slip-On Coilvoers” / Threaded Sleeves on Stock Struts – A Bad Idea
These are a threaded sleeve, slipped over the top of a stock strut assembly, in order to provide an adjustable
spring perch for a 2 ½ inch ID (or similar size) spring. They seem to have been originally developed for
archaic, restrictive club racing rules (SCCA Production and/or Touring) which allowed the use of any spring,
but required the use of the original strut or damper. The rule was an attempt to limit the cost of racing by
prohibiting the use of adjustable dampers or more expensive real coilovers.
During the 90’s they became a popular, cheap method for extreme lowering of compact cars. And their limitations
became immediately evident.
- Stock struts are not strong or durable enough to work with stiff springs, and they blow quickly under the
added stress. The original Geo Storm struts (KYB and all other OEM replacement struts) were designed to work
with springs rated at 92-144 pounds per inch. When someone starts talking about putting 350-400 pound springs
on the stock struts, they are delusional.
- Long, stock struts are designed to be at mid stroke at the tall, stock ride height. Lowering the ride height
compresses the strut, moving the damper piston close to the end of the housing. The range of motion is severely
limited to the point that if the car rolls over a large bump, the suspension moves so far up that the damper
piston bottoms out, or slams against the end of the damper cylinder. This results in an abrupt jarring stop to
the suspension arm movement, damage to the damper, and usually loss of control of the vehicle when it spins.
- All of the available OEM replacement struts for the Geo Storm are gas charged. The strut and gas charge was
designed for the at-rest position of the piston within the damper at mid stroke, which is where it is with at the
stock ride height. Lowering the car on the stock struts compresses the strut and increases the pressure within
the strut. For handling, this places a pre-load on the suspension that is difficult to calculate and deal with
in tuning the suspension. But more important than this is that the increased pressure will raise the temperature
within the strut housing. Basic physics: increase pressure = increased temperature. The increased temperature
will quickly overheat the struts and rapidly decrease the life of the seals or simply melt the seals, resulting
in a blown strut.
- Stiffer springs have a shorter free length (the amount they expand when not under load). When the suspension
droops, the shorter springs fall out of the assembly, only to jam crossways as the car comes back to rest on the
suspension. When finding the cheapest suspension solution, helper springs are never on the menu.
- The threaded sleeve sets do not include an upper spring perch, and when installed, the upper end of the
spring is allowed to move around loosely in the upper spring perch., changing the ride height as the vehicle
rolls down the road.
- Decent quality 2 ½ inch ID springs sell for around $150 per pair ($75 each)(Eibach and Hyperco from Pegasus,
Speedway, HRP, and Hoerr). Threaded sleeve and spring sets sell for $30-45 for a set of four. The quality
and accuracy of the springs included in these threaded sleeve sets is suspect at best.
Robie the Robot
RTR are/were the most prolific source of slip-on-coilover kits for Geo Storms, and Mr. Blair is the strongest
advocate of this product. Perhaps because he is/was selling the same no-name springs and no-name threaded
sleeves (likely Chinese made) for $210, that are available on Ebay for $40 per set. Or perhaps because he is
repackaging the Megan Racing (not a respected brand) Honda Civic slip on coilover set PN Model Number :
MR-CO-HC88 (recognized as a low quality product), which has a manufacturer’s suggested retail of $169.95, and
can be found for as low as $119.00 (according to Google
Shopping). More recently, slip-on-coilovers purchased from Mr. Blair have been delviered in
DNA Motorsports packaging. The suggested retail of these is $59.99, but they can be found for
as low as $29.99 (according to Google Shopping.
Mr. Blair makes somewhere between $91 and $180 per set, even if he is buying them at the retail
price.
Remember that Mr. Blair’s entire racing experience is a single event entry, driving a SOHC Storm, in Stock class,
at a Rocky Mountain Solo Series event, on July 30, 2000, finishing 130th our of 140 entries. And also that
Mr. Blair will be happy to sell his slip-on-coilover-sleeve customers as many KYB struts as the threaded sleeves
will blow. Certainly this is a “cosmetic upgrade”, sold by someone with little or no racing experience, to a
market segment of people who will never see a race track or participate in an organized racing event, and who do
not know what a properly tuned suspension feels like.
It is clear that slip-on coilovers, or threaded sleeves, are a half-assed approach to suspension tuning, the use
of which results in poor handling and inevitable damage to the struts.
Real Coilovers
Tuning the suspension involves making adjustments wherever adjustments are possible. Vehicle manufacturers
typically make suspension components that are not adjustable, or have limited adjustability, in order to keep
those who do not know what they are doing, from hurting themselves.
Real coilovers provide true race car handling through infinite adjustability.
- Real coilovers provide maximum adjustability of choice of spring rate, damper compression and rebound, ride
height, damper position, etc.
- Spring rate is easily adjusted by changing out the springs for another set of commonly available springs
usually available in 25 pound/inch increments from reputable companies like Eibach and Hyperco, from many racing
suppliers such as Pegasus, Speedway, HRP, and Hoerr.
- Compression and rebound are adjustable via knobs on the dampers.
- Ride height adjustable via threaded lower spindle bracket.
- Damper position adjustable via threaded spring perch.
It is most desirable to have the lower spindle mounting bracket threaded, so that the ride height can be changed
without changing the damper piston position. And it is more desirable that compression and rebound be separately
adjustable (double adjustable).
For the Geo Storm, if the spring rate is to be 275 lb/in or greater, plan on using helper springs and spring
separators, to keep the springs lined up in the perches when the suspension droops.
TrueChoice
TrueChoice is repeatedly cited as a custom suspension company willing and able to make anything, though costs are
never mentioned. A little research shows that they are not overly friendly and somewhat less than reliable:
http://www.bimmerfest.com/forums/archive/index.php/t-97858.html
At best, the Australian owner seems unwilling to discuss reducing their $50+ per hour labor rate and is quickly
angered by customers who argue about their prices. At worst, the company is running a bait-and-switch scheme to
jack up fees for rather simple and easy tasks. Draw your own conclusions. But rest assured, at $50 per hour
labor rate plus materials, a set of custom struts or coilovers from Truechioce will quickly pass the $4000 mark.
Isuzuperformance
Isuzuperformance pioneered double adjustable coilovers for Geo Storm nearly 20 years ago, with its Steel
coilvoers. These featured external reservoirs, but the lower spindle bracket was not threaded or adjustable.
Isuzuperformance followed this with their Aluminum Series coilovers, dispensing with the external reservoir,
reducing weight, and adding the threaded lower spindle bracket for complete adjustability.
Camber Plates
Camber plates are typically used with coilovers, and make up the upper spring mount assembly of the coilover.
Camber plates provide for adjustment to the camber, and are essential for fine tuning the suspension.
Increasing negative camber of a vehicle with a strut type suspension allows the tire to be set at an angle to an
ideal point for maximum cornering grip. This is usually a compromise, because increased negative camber reduces
the straight line tire contact patch of the tire and reduces acceleration and braking ability.
Camber plates also allow for dual use of the vehicle on the track and on the street. The suspension can be set
aggressively for high speed cornering with sticky race tires at the track, and then easily and quickly changed
back to milder settings for use on the street with street tires. But remember that the toe setting will change
when the coilover (strut) assemblies are leaned over, and the tie rod ends on the steering rack will need to be
adjusted whenever the camber plates are adjusted.
A Teflon coated heim joint bearing should be used where the strut rod attaches to the camber plate. Anything
less would degrade quickly and require frequent replacement. These cost upwards of $40 each. Keep this in mind
when comparing prices, $25 Chinese made pair of camber plates probably don’t have anything approaching a decent
quality bearing.
Better camber plates will have the upper spring perch resting against a ball-and-socket on the underside of the
cambler plate, instead of rigidly attached to the shaft of the damper. This places the weight of the vehicle
directly on the camber plate assembly, instead of on the damper shaft. This is a feature of camber plates made
by both Ground Control and Isuzuperformance.
Isuzuperformance
The Isuzuperformance camber plate is additionally designed to allow the bearing carrier in the mounting plate to
be turned around backwards, expanding the range of camber adjustment of nearly 6 ½ degrees.
Sway Bars
Sway bars are really nothing more than a lever arm that ties the spring on one side of the car to the spring on
the other side of the car, forcing them to work together. These are extensively used by vehicle manufacturers to
provide more effective spring rate for cornering (when the sway bar is working), while keeping the actual spring
rate soft enough to provide a comfortable ride over a rough surface in a straight line (when the sway bar is
inactive).
Sway bars are commonly misunderstood as a tool to reduce body roll, usually leading to the use of really large
diameter sway bars. This strategy becomes a serious problem once the vehicle is driven at its limit, and the true
nature of sway bars is revealed.
Sway bars are a tool for reducing grip on one end of the car, while forcing the other end of the car to grip
more. For rear wheel drive cars, adding a more front sway bar will reduce oversteer, by reducing grip at the
front, and forcing the rear suspension to work more. Conversely, for a front wheel drive car, adding more rear
sway bar will reduce understeer, by reducing grip at the rear, and forcing the front suspension to work harder.
So the true nature of sway bars is that they are used to adjust the balance of oversteer and understeer. This
is handy when the step between available spring rates is too wide for the ideal spring rate, or when fine tuning
oversteer and understeer conditions.
There are several different sizes of front and rear sway bars used on the Geo Storm and its sister cars, the Isuzu
Impulse and Stylus. These can provide a range of choices for fine tuning. But be aware that the Lotus Tuned
suspension uses balljoint style end links, while the Storm uses shackle style end links. Attaching one style bar
to the opposite style strut mounting bracket usually involves changing over to use the Lotus Tuned balljoint end
links, which is an improvement anyway.
The Base models Storm uses a smaller diameter front sway bar, and no rear sway bar. The DOHC Storm GSi is
equipped with the "F41" or "Sport Suspension" which includes a larger front sway bar, and a rear sway bar.
The Base model can be converted to use the DOHC Storm GSi sway bars by swapping the front sway bar, and swapping
the rear cross member, rear sway bar, and rear struts. The rear cross member and rear struts have the mounting
brackets for the sway bar.
The Isuzu sister cars (Impulse, Stylus, and Asuna Sunfire) use additional different diameters of front
and rear sway bars, but have a different end link. While the Storm and Non-Lotus Tuned Suspension cars
use a shackle style end link (two rubber bushings, one in the end of the bar and the other in the suspension
mounted bracket, connected by a metal side plate on each side, bolted through the center of each bushing),
the Lotus Tuned Suspension cars use balljoints. The balljoint is more desirable, because there is no flex
in the connection and it transfers all of the suspension movement to the bar. The Storm can be converted
over to use the balljoint end links by cutting the original sway bar ends off and welding on flat mounting
plates with a bolt hole, and doing the same to the suspension mounting brackets. This is described below in
the section covering
Lotus Suspension Conversion.
Isuzuperformance
Isuzuperformance developed and offered oversized sway bars for the rear, and helper front sway bars. The
manufacturer closed long ago, but Isuzuperformance has a few left in stock.
Isuzuperformance also developed a modular Nascar style sway bars for both front and rear of the Geo Storm
and Isuzu sister cars. These provide fine tuning in bar thickness increments of 1/16th inch.
Isuzuperformance also offers OEM reproduction weld-on rear sway bar mounting brackets to convert the Base
model Storm rear cross member over to match the DOHC Storm GSi rear cross member.
Careful planning and proper spring choice will reduce the need for sway bars, usually to the smallest sizes for
very fine adjustment in balance.
For autocrossing front wheel drive cars, it is most often desirable to have no front sway
bar at all, to maximize front end grip. A little more sway bar might be added if understeer persists.
Adjustable End Links (For Sway Bars)
When setting up a suspension, especially when setting corner weights, it is important that the sway bars be
unloaded when the car is at rest, sitting on a flat surface. If there is a load on the bars when the car
is flat, the bar is said to be "pre-loaded", meaning that the bar is twisted and applying force to the
left and right sides of the suspension, when it is not supposed to be. If the bar is pre-loaded, the car
will handle differently when turning right than when turning left, due to the bar pushing up on one side
and pulling down on the other side. This can be due to a twist in the bar, variances in the center mounts
of the bar, variances in the position of the end link mounting brackets in the suspension, or variances in
the lengths of the end links from one side to the other.
Instead of fighting in vane to get the sway bar and mounting arrangement perfectly symmetrically, the easiest
solution is to use adjustable end links. This is also the best argument for converting to the Lotus Tuned
Suspension sway bars as described in the above section on
Sway Bars, and as detailed in the section below on
Lotus Suspension Conversion. The Lotus Tuned Suspension uses balljoint
style end links, which are two little balljoints permanently welded to a little tube. This arrangement
is not adjustable, but can be easily changed to make it adjustable.
The common racing solution is to use spherical rod ends, which are heim joints or rose bearings set in
an housing with a male or female thread. Short end links can be made by using a male and a female rod end,
threading them together, and securing them with a jamb nut. Longer end links can be made with two male
threaded rod ends threaded into a short section of threaded tubing and secured with jamb nuts. These
are then attached to the sway bar and suspension brackets by inserting a bolt through the heim joint and
through the sway bar or bracket.
The adjustability of these eng links is achieved by changing the length of the assembly threading the pieces
in or out. This will allow for the sway bar to be adjusted so that it is not in tension when the vehicle
is sitting flat, and it will also allow for the bar to be adjusted parallel to the ground when at rest,
where it is at its centered, most effective point.
Lotus Suspension Conversion
The Isuzu sister cars, and the Japanese market Gemini Coupes, were available with the Lotus Tuned suspension,
while the Geo Storm was available with "standard" suspension, and the technical name for the Storm GSi
suspension was option code "F41" or "Sport Suspension".
The Lotus Tuned Suspension was highly touted in the advertising, claiming that Lotus tested hundreds of damper
and sway bar combinations to tune the suspension for race-car-like handling. The actual changes were to soften
the front springs for softer ride, stiffen the rear springs to reduce understeer, increase sway bar diameter to
restore effective spring rate for cornering, and increase the damper rates to reduce suspension travel over
bumps. The cars equipped with the Lotus Suspension do score higher in handling tests than the standard
suspension cars, and in the Best Motoring video test comparing the Lotus and Irmscher suspension packages, the
Gemini with Lotus Tuned Suspension was a fraction of a second quicker on the road circuit, than the Irmscher
car.
Converting a Storm over to the Lotus Suspension is an understandable desire, and would involve swapping the
following:
- Front and Rear Struts
- Front and Rear Upper Strut Mounts
- Front and Rear Strut Bump Stops
- Front and Rear Springs
- Front and Rear Sway Bars and Sway Bar Center Bushings
- Front and Rear Sway Bar End Links (Ball Joint Style)
- Front Lower Control Arms (Due to Alternate Style Sway Bar End Link Bracket)
It is a popular belief that the Lotus Suspension uses different bushings, but the bushing part numbers are all
the same.
While the Lotus Suspension does score higher than the standard suspension in handling tests, the car reviews
also criticized the suspension for failing to insulate the passengers from even the smallest bump in the road,
and seemingly amplifying every seam in the pavement to the vehicle occupants.
Motorsport enthusiasts additionally criticize the Lotus Tuned suspension for its excessive body roll due to
the soft spring rates. It is seen as a good starting point for tuning, but nowhere near the true potential
of these cars. The cost and effort of converting the suspension over to the original Lotus Tuned parts, would
be more effectively spent building a race suspension with
real coilovers.

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