Tech Tips

TOP TEN SUSPENSION TIPS

By Rick Mcdowell – Featured Hot4s magazine

So you want to go harder, increase your corner speed and improve acceleration. Believe it or not, but the answers to all of these 'problems' might be found behind your wheels and not under your bonnet.

Yes indeed folks, it's time to talk about spring rates, shock absorbers, strut bars and the numerous other bits and pieces which make up the suspension package on your car. After all, you might have a 400Hp engine, but if you can't lay that power effectively and efficiently onto terra firma, then you ain't going anywhere.

Tip No. 1 - Wheel Alignment
According to Peter, a straight forward wheel alignment will do more for a brand new car than thousands of dollars spent on new shocks, springs etc.

It’s a little known fact that many vehicle manufacturers don’t perform a wheel alignment to each individual car as it leaves the factory. Add to this the fact that many vehicles - especially those from European manufacturers - are right hand biased because in those countries cars drive on the right hand side of the road.


This affects the car’s ability to ‘track’ or basically drive in a straight line and many brand new cars exhibit this characteristic. Curiously, Korean built cars are one of the worst offenders and in addition to a proper wheel alignment, they can benefit from offset bushes made by Superpro and Whiteline to specifically address the problem. Whilst a second hand car will also benefit from a wheel alignment, Peter did add, “An alignment is no good if there's even the slightest movement in any fixed suspension component such as the lower control arms, or if your bushes are knackered, ball joints gone, tie rods worn etc, etc.” 

 

TIP NO.2 - HOW LOW CAN YOU GO ?
Go to any late model car show or cruising venue and there can be no mistaking that the lowest cars are the coolest. Yet significantly lowering your car is something that needs to be done correctly, especially if the vehicle is to be driven daily or competitively. From a safety perspective, cutting springs and removing them altogether are highly dangerous practices.


As Peter explained,“If you go too low, then it can completely throw out your suspension geometry. With cars such as Lancers and WRXs, you can upset driveshaft angles so badly that shaft vibration becomes an issue and the lack of suspension travel can certainly make the car’s steering totally unpredictable.”


Brett Wilkinson then showed us a bump stop which had been totally hammered into a crumbled mess because of suspension that had been lowered excessively. And as Brett succinctly put it, “Bump stops are not shock absorbers...”

So how do you lower your car correctly ?

The basic method is to use short body shocks that are matched to the lowered springs. In fact, in the King Springs catalogue, there are numerous ‘warnings’ to this effect in regards to the King Super Low Sports Replacement Coil Springs. Not only is the use of shorter shock absorbers mentioned several times, but the catalogue states, 'Kings Super Low Sports Replacement Coil Spring range is designed primarily for cosmetic enhancement (show cars etc) They are not recommended for street use and provide limited suspension travel."


Circuit cars, on the other hand, do benefit from lowered suspension, but this is usually done in combination with other suspension measures deliberately aimed at giving the car particular suspension characteristics for the track.

 

TIP NO.3 - SPRING RATE
In addition to ‘slamming’, many enthusiasts are also easily trapped into believing that hard as nails springs are cool because that’s what racing driver’s use. Wrong !


Spring rates need to be correctly chosen for the specific use of the vehicle.

Peter says that increasing your spring rates can increase vehicle stability and reduce body roll, but that there needs to be some compromise with comfort in an everyday driven car. And don’t forget, match your spring rates and spring heights with your shock absorbers !

TIP NO.4 - SHOCK TREATMENT PLEASE
So far we’ve just hinted at shock absorbers, so now let’s be a wee bit specific.

According to Peter and Brett, Koni adjustables are one of the best shockies on the market because they can be ‘tuned’ to provide a wide variety of dampening characteristics. This in turn means that many different springs can be used with them. Correctly matching shocks and springs is something Wilkinson Suspension do a lot, particularly with import cars which tend to arrive in Australia rock hard in the suspension department.


Whether you’re replacing the shocks by themselves or as part of an overall suspension upgrade, remember that shocks and springs always need to be matched to one another.

TIP NO.5 - TYRE CHOICE
Tyres are a feature article all by themselves, yet they are probably ignored too often as regards suspension. The main points to make here are to choose a tyre for your application and to get the inflation pressure correct.

As Peter put it, “If your tyre pressure is too low then you can overheat the tyres and loose traction, regardless of how good your shocks, springs and other suspension components are.”

A good indicator for incorrect tyre pressure, is to measure the pressure before a run or session at the track.


Tyres do need a certain amount of heat to operate correctly, but if you find your pressure has risen by up to 5psi immediately after a run, the chances are you’re too low in the pressure department. Incorrect tyre pressures can of course also adversely effect tyre wear.



TIP NO.6 - FEEL THE WIDTH - AND MIND THE OFFSET PLEASE
Still on the subject of rubber and in addition to excessive lowering, another cool trend is to fit the fattest wheels and tyres possible, even if the rubber scrapes the guards.


Apart from the fact that rubber ‘outside’ the line of the guards can cop you a defect notice in most states (good pun, eh !), excessively fat wheels and tyres can cause all sorts of suspension dramas.


The key word here is ‘Offset’ - which can be best understood by having a look at the accompanying photographic explanation. Most cars these days can accept slightly larger wheels and tyres, but if you don’t get it right, then wheels and / or tyres start to rub not only on your guards, but also on suspension components.


This can limit the car’s ability to steer correctly and to its intended limits, plus hinder the correct functioning of the vehicle’s suspension systems.

And according to Peter, “Don’t ever run wheels that have an offset for one car on another car with a completely different offset - that’s just asking for trouble.”


So remember, just as you’re about to lay down $7,000 for those exotic 19” rims direct from Japan, make sure they meet the factory offset requirements for your vehicle.

 

TIP NO.7 - FRONTAL ASSAULT
Front wheel drive cars have their own idiosyncrasies, not the least of which is that they tend to understeer. The big fix here, is to install a castor kit and to increase the thickness of the rear sway bar.


For the latter, Whiteline provide a varied array of products, which work to stiffen the rear axle and reduce the weight transfer which helps to ‘force’ the front of the car into the corner.


It’s not often realised either, that in terms of basic suspension and steering, AWD cars such as Lancers and WRXs are effectively front wheel drive.

Yet bigger is not always better with sway bars.


Whilst front wheel drive cars tend to have an understeer characteristic, rear wheel drives have the opposite, or oversteer, tendency.

Brett says that an upgraded front bar in this case would help reduce oversteer, but too big and you’ll be understeering. 

TIP NO.8 - WREXALMANIA
Peter and Brett singled out the WRX for its own special mention, due largely to the car’s overwhelming popularity on the performance and club scene.

“An anti-lift kit is a major player in helping to cure the WRXs basic understeering habit,” explained Brett.


These kits will change the front control arm geometry, thus allowing more positive castor to be dialed in, which leads in turn to improved traction and less understeer.”


Brett also added that this will help acceleration on cornering and, of course, an upgraded rear sway bar can play a key role too.

The above mentioned wheel offset is a rather critical aspect to WRX handling too.



TIP NO.9 - IMPORTS LIKE IT HARD
Another vehicle - or vehicle group - singled out for special attention is imports.

Said Brett, “Jap Imports such as 180sxs, Silvias, Skylines and 300zxs are coming into the country with rock hard ‘Drift’ suspension.

The main problem here is that the bump valving in the shock absorbers is too harsh and so breaking traction is easily achieved.”

Whilst this may be great to watch and fun to do, for everyday driving it’s so good.

“We have experimented by trying to match up lighter spring rates to these cars, but it generally doesn’t help enough and a full suspension overhaul is really the only way to go.”


Brett also added that the excessive lowering of some imports is another problem area. “We see these cars here all the time with their rear cambers way into the negatives - we have to insert an offset bush into the upper trailing arms to bring the camber back within spec’.” 

 

TIP NO.10 - I LOVE ACCESSORIES, BUT POLY’S A BIT HARSH
Whilst most people are happy to enhance their suspension with just upgraded shocks and springs, others prefer the Full Monty approach.

Sway bars, poly bushes, rose jointed tie rods, camber and castor kits, offset bushes ... but are all of these items really necessary ?

For sports and racing applications the answer is yes, but for the street and show scene, a little thought might be more appropriate before going mental on the suspension front. The subject of polyurethane bushes is a tricky one though. As Peter explained, “Poly bushes do remove much of the flex from suspension systems and they are definitely longer wearing than factory bushes - but they can introduce harshness and vibration into a car.”

Peter further explained that NVH (Noise Vibration Harshness) is the big subject for car manufacturers these days and that the increasing use of hydraulic engine mounts and larger bushes is testimony to how seriously the auto’ manufacturers regard NVH.


Poly bushes do absolutely nothing for NVH, but Peter admits that most enthusiasts will put up with the harshness for the improved handling.