Supra Suspension Guide

[Lupara]

MKIV Supra Suspension Guide

Suspension is a very important part of your vehicle. Whether it be from drag racing, winding circuit, drifting or street.

Firstly, let me start off with saying the #1 rule when buying aftermarket parts for your supra. "You get what you pay for" If you can't afford it, then save. If you can't save LEAVE IT ALONE! Toyota knew what they were doing when the designed the supra suspension. Do your research before jumping into modifying it. Ask questions legitimately and politely on forums (don't bother posting the usual "I want new coil over's so I can lower it, which is best?") or better yet, ask someone with experience in the field of suspension (with motorsports experience if your upgrading for racing).

Secondly, ask your self these questions. Why do I need to change my suspension? Do I regularly do circuit racing or other disciplines? Could the money be better spent somewhere else?

There are a lot of cheap and nasty suspension parts out their. All of these companies talk it up, they will make there products seem like they could turn you into a full racer car driver! Don't believe everything you hear. Do your research before buying.

If you are considering anything but the following for track work, you will regret your purchase.

* Bilstein
* Ohlin's
* Nitron
* KW
* Penske

The above brand dominate the suspension market, not buy promotion and colourful promises, buy buy sheer quality. They are used across the world in motorsports. There are other decent brands out there, don't get me wrong, but none that will really give you major benefits. These companies have specialized in suspension for many years, and they do and they do it well.

Toyota Supra Suspension Setup
Four wheel independent double wishbone, with gas filled coil over shock absorbers and spherical ball-joint-type stabilizer bar.

Lowering & Joints
Lowering can improve handling by lowering the centre of gravity of the vehicle. BUT... It's not as simple as just dropping the ride height. Certain suspension settings have to be changed.

Most lower cars we see on the streets will have shocking suspension, they offer no advantages to the cars roll centre and handling ability, except to increase bump steer, which actually results in poorer handling. As of July 16th 2009 lowering your car under a certain percentage to it's OEM high is now illegal unless engineered.

The Supra uses double wishbone suspension. it has upper and lower control arms. The control arms play a massive role in the handling of the car. The main roles are camber, roll centre, toe and caster. Most of the suspension load is in the lower control arms. Lowering your car without any adjustments will result in more strain on the control arms, bump steer and mis-aligned wheels.

You can lower a supra to a point without modification. Adjustments still need to be made. Camber & geometry settings will need to be adjusted. The wheels should be properly aligned by a professional. They will make all the adjustments suited to your style of driving.

The Toyota control arms will only allow adjustments to a certain degree. Once you have past that point you have two options. Adjustable end rose joints or adjustable control arms.

If you are a real race nut who wants to take his suspension all the way, look at replacing most if not all the connections to adjustable rose joints (or replace all your control arms to fully adjustable r-jointed). This will allow you to have total control to suit your compression and rebound settings by adjusting caster and dynamic changes via the inner control arm joints. Race quality rose joints will be metal on metal joints with no lubrication and will have no play. They also offer a more responsive and high feeling attributes as well as remove bump steer issues.

**Rose jointed ends do not offer dampening like poly brushes, will get pretty rough on some of Australia poorly build roads (95% of our roads ) and wear out a lot quicker**

Adjustable Dampers - Compression & Rebound

Rebound:
The speed rate that your damper forks will pop upwards from a compression state. (EG after hitting a bump on the track)

Compression:
The speed rate the damper forks are compressed. (EG movement allowed in the instance of hitting a bump on the track)

Pre-Load:
The compression rate the spring is under when not subject to any weight (EG Wheel lifts off the ground)

Dampers are quite complex to adjust correctly. I can guarantee easily over 95% or supra owner in Australia will have incorrectly adjusted brand name coil -over's. Unfortunately it's a trend that will continue to hang around.

The are three main types of dampers (coil over's). 1-way, 2-way and 3-way.
1-way dampers allow the adjustment of compression and rebound together. A very basic adjustable setup, manly used but beginners, usually costing around $2000 for a set.
2-way adjustable dampers allow you to individually tune rebound and compression. This allows a high level of accuracy in how your car will react to cornering, braking, accelerating and bumps. Used mainly by professional race teams. Usually has a separate mountable canister which is equipped with nitrogen gas. Need to be regularly serviced to keep in good condition. Will set you back around $6000.
3-way dampers are identical to 2-way except have a speed bump control vales, which allows an even finer and more advanced tune. Expect to pay around $8000.

Adjustments of compression and rebound will not only control the affect of hitting a bump or a ditch, but also over steer and under steer.
[ Over steer - rear wheels loose traction. Under steer - front wheels loose traction ]
Front and rear dampers need to be tuned correctly for the best results. Because of brake force and weight distribution, more often than not your front and rear will have different compression settings.

Making adjustments that are too stiff will result in over or under steer, harsh ride quality and wheel hop. Too soft will result in a very bouncy ride and very unresponsive cornering. Too slow of a rebound rate will leave your tyre out of road contact and could lead to a complete loss of traction as well as underpowered and unstable corner exists.

The easiest way to tune your suspension would be to take it to the track , do a lap or two, adjust and try again till you perfect you setup. Professionals will use measuring devices that ready the load on each damper and allow the to graph it on a PC. Fluid forks and level sensors are used. This allows for a much more accurate tune.

Continued next post

[Lupara]

Springs
Springs (coils) rates will affect your suspension settings as well. For circuit racing a fairly stiff coil is used to help reduce body roll.

If your springs are too stiff it will result in a harsh drive and excessive wheel spin. Too hard on the front will cause over steering on corner exists. too hard on rears will cause over steer and loss of traction on high torque loads. Too soft and it will result in bad body roll, sluggish turn in response and the always hilarious to watch... squatting under acceleration.

Springs are rated in the amount of weight needed to compress it. Either in metric or the imperial system. Basically the higher the weight rate of the spring, the stiffer it will be. For example: We have a 350 kg spring. This means if we add a load of 350 kg to the spring, the spring will compress 1mm. Obviously a softer spring will require less weight to compress the spring to a mm.

Sway Bars
Sway bars are mainly responsible for body role. They are linked directly to your suspension system. It is the bar that connect directly to the left and right arms. Because of the link the opposite wheel will usually react to the effects of the other, for example; hitting a bump.

The RZ series has stronger sway bars compared to the SZ series. There are few types of aftermarket sway bars. TRD, TITAN, CUSCO and WhiteLine being the main ones. The most popular choice being TRD and Titan. TRD sway bars are 27% stiffer than RZ sway bars, however offer no weight saving. The Titan weight only 6.8 kg for both bars and are adjustable in stiffness.

Have sway bars that are too stiff will cause over or under steer and wheels will have violent reactions to bumps. Too soft at the front will result in body roll, steering becomes unresponsive and sluggish. Having a stock rear sway bar or similar stiffness is actually good for winding circuits, helps to put power down on corner exists as lateral load transfer would usually cause the rears to skate on a stiffer setup.

Strut Bars
Strut bars are metal or composite based bars, that bolt onto the chassis to stiffen it. Bolted on top of the shock towers together in the front and rear of the vehicle. In violent cornering your chassis will flex a few mm. This alters the alignment of the car. Strut bars will help to reduce movement.

Ask yourself again.. Do I take my car drifting or circuit racing to really need these? If you don't attend these disciplines, you have just added unnecessary weight to your car that you will never use. Increasing fuel consumption, increasing your braking distance, decreasing your power to weight ratio and burning your money for ZERO benefit.

Wheels & Tyres
While wheels are not a direct suspension part they play a big role. All your upgraded or stock suspension won't improve handling if you have bad wheels. When I refer to bad wheels I mean... Heavy, incorrect offsets, spacers, poor build, incorrect widths or damaged. Never put spacers to try and fit a wheel, they are illegal for road use and a death wish for racing.

Wheels weight is a huge factor in not only suspension, but un-sprung weight, power and braking. The lighter the wheel the lower the rotating mass and inertia. This allows you to brake quicker, accelerate faster and have a more accurate and precise turn in. Losing rotating un-sprung weight is the best weight to loose!

The calculation is made by inertia. For example: your old rim weights 20kg, you upgrade to some 10kg wheels. You have saved 40kg off you static weight. However you have lost around 200kg in weight inertia wise, so braking, tuning accelerating will feel A LOT LIGHTER!

Tyre pressure is very important for your suspension. Play around with your pressures and see what works best. The supra's recommended pressure is 36psi cold. Remember that your pressure will increase as your tyre heats up.

Too much pressure will result in a harsh drive, over or under steer, wheel hop and a high wear in the middle of the tyres. Too little pressure will result in a high wear rate on the inside and outside of the tyres, bad steering response and reduced traction due to the lack of a contact patch.

Other Useful Info & Guides
MAZMAN's re-built bilsteins
http://www.supraforums.com.au/forum/showthread.php?p=671485#post671485

http://en.wikipedia.org/wiki/Bump_steer
http://en.wikipedia.org/wiki/Over_steer
http://en.wikipedia.org/wiki/Understeer

Summary
You can see just how complex an sensitive every adjustment is in your supra suspension system. I have only scraped on the basics in an easy to understand format. There is still a lot more to your suspension. I hope people can now understand why others may criticize them for buying some "brand name" coil over's and trying to self install them on a very sensitive and complex suspension system.

The Toyota bilsteins are more than sufficient for street driving and the occasional track day. They are a well built damper, which provides comfortable and sporty advantages. If you feel you need to get more out of them, they can be modified. Stiffer springs, height adjustment and C/R can be added. There is no need to buy useless coil over's. If you want to upgrade for regular racing use, do it right and go with a reputable company. When buying some of the more expensive systems, the company will actually come out, install them and help tune them. Ohlin's does this with most the 2-way setups.

I hope people gathered some knowledge and benefited from this write up. Should help out and solve a lot of regularly asked questions from our newer and inexperienced members.

If any of you other know-it-all's have something to add send me a PM

IMPORTANT NOTE:
When ever; removing, installing, fixing or adjusting any suspension components, you should have your wheels re-aligned by a professional. Usually costs $30 - $50.


Disclaimer
I am not a professional. I am in no way responsible for any problems you may have. Use the information I have provided as a guide. Always seek professional advise when making any modifications.

[2JZZ12]

Adjustable Dampers - Compression & Rebound

Rebound:
The speed rate that your damper forks will pop upwards from a compression state. (EG after hitting a bump on the track)

Compression:
The speed rate the damper forks are compressed. (EG movement allowed in the instance of hitting a bump on the track)



Continued next post

just a bit of a clarification on your explanations...

mathematically, a damper exerts a force as a function of velocity. this force is always in the opposite direction to the velocity.

therefore, the velocity (or speed) that the strut moves is somewhat controlled.


i would interpret "speed rate" as acceleration which isnt quite accurate.


the rest of the article is pretty good

[Kez]

Springs
Springs (coils) rates will affect your suspension settings as well. For circuit racing a fairly stiff coil is used to help reduce body roll.

If your springs are too stiff it will result in a harsh drive and excessive wheel spin. Too hard on the front will cause over steering on corner exists. too hard on rears will cause over steer and loss of traction on high torque loads. Too soft and it will result in bad body roll, sluggish turn in response and the always hilarious to watch... squatting under acceleration.

Springs are rated in the amount of weight needed to compress it. Either in metric or the imperial system. Basically the higher the weight rate of the spring, the stiffer it will be. For example: We have a 350 kg spring. This means if we add a load of 350 kg to the spring, the spring will compress 1mm. Obviously a softer spring will require less weight to compress the spring to a mm.

Sway Bars
Sway bars are mainly responsible for body role. They are linked directly to your suspension system. It is the bar that connect directly to the left and right arms. Because of the link the opposite wheel will usually react to the effects of the other, for example; hitting a bump.

The RZ series has stronger sway bars compared to the SZ series. There are few types of aftermarket sway bars. TRD, TITAN, CUSCO and WhiteLine being the main ones. The most popular choice being TRD and Titan. TRD sway bars are 27% stiffer than RZ sway bars, however offer no weight saving. The Titan weight only 6.8 kg for both bars and are adjustable in stiffness.

Have sway bars that are too stiff will cause over or under steer and wheels will have violent reactions to bumps. Too soft at the front will result in body roll, steering becomes unresponsive and sluggish. Having a stock rear sway bar or similar stiffness is actually good for winding circuits, helps to put power down on corner exists as lateral load transfer would usually cause the rears to skate on a stiffer setup.

Strut Bars
Strut bars are metal or composite based bars, that bolt onto the chassis to stiffen it. Bolted on top of the shock towers together in the front and rear of the vehicle. In violent cornering your chassis will flex a few mm. This alters the alignment of the car. Strut bars will help to reduce movement.

Ask yourself again.. Do I take my car drifting or circuit racing to really need these? If you don't attend these disciplines, you have just added unnecessary weight to your car that you will never use. Increasing fuel consumption, increasing your braking distance, decreasing your power to weight ratio and burning your money for ZERO benefit.

Wheels & Tyres
While wheels are not a direct suspension part they play a big role. All your upgraded or stock suspension won't improve handling if you have bad wheels. When I refer to bad wheels I mean... Heavy, incorrect offsets, spacers, poor build, incorrect widths or damaged. Never put spacers to try and fit a wheel, they are illegal for road use and a death wish for racing.

Wheels weight is a huge factor in not only suspension, but un-sprung weight, power and braking. The lighter the wheel the lower the rotating mass and inertia. This allows you to brake quicker, accelerate faster and have a more accurate and precise turn in. Losing rotating un-sprung weight is the best weight to loose!

The calculation is made by inertia. For example: your old rim weights 20kg, you upgrade to some 10kg wheels. You have saved 40kg off you static weight. However you have lost around 200kg in weight inertia wise, so braking, tuning accelerating will feel A LOT LIGHTER!

Tyre pressure is very important for your suspension. Play around with your pressures and see what works best. The supra's recommended pressure is 36psi cold. Remember that your pressure will increase as your tyre heats up.

Too much pressure will result in a harsh drive, over or under steer, wheel hop and a high wear in the middle of the tyres. Too little pressure will result in a high wear rate on the inside and outside of the tyres, bad steering response and reduced traction due to the lack of a contact patch.

Other Useful Info & Guides
MAZMAN's re-built bilsteins
http://www.supraforums.com.au/forum/showthread.php?p=671485#post671485

http://en.wikipedia.org/wiki/Bump_steer
http://en.wikipedia.org/wiki/Over_steer
http://en.wikipedia.org/wiki/Understeer

Summary
You can see just how complex an sensitive every adjustment is in your supra suspension system. I have only scraped on the basics in an easy to understand format. There is still a lot more to your suspension. I hope people can now understand why others may criticize them for buying some "brand name" coil over's and trying to self install them on a very sensitive and complex suspension system.

The Toyota bilsteins are more than sufficient for street driving and the occasional track day. They are a well built damper, which provides comfortable and sporty advantages. If you feel you need to get more out of them, they can be modified. Stiffer springs, height adjustment and C/R can be added. There is no need to buy useless coil over's. If you want to upgrade for regular racing use, do it right and go with a reputable company. When buying some of the more expensive systems, the company will actually come out, install them and help tune them. Ohlin's does this with most the 2-way setups.

I hope people gathered some knowledge and benefited from this write up. Should help out and solve a lot of regularly asked questions from our newer and inexperienced members.

If any of you other know-it-all's have something to add send me a PM

IMPORTANT NOTE:
When ever; removing, installing, fixing or adjusting any suspension components, you should have your wheels re-aligned by a professional. Usually costs $30 - $50.


Disclaimer
I am not a professional. I am in no way responsible for any problems you may have. Use the information I have provided as a guide. Always seek professional advise when making any modifications.

Someone can fix this up properly later if that want, just thought I'd add it now.