Lowered suspension information

[Res]

suspension mods are one of the most common mods done. both for performance in handling and for looks

why we lower our cars
the lower the chassis is to the ground the lower the centre of gravity the car has
the lower the centre of gravity the better for handling

ways of modifying suspension
now there is right way and a wrong way to modify suspension

wrong way = cut springs (this is illegal)
right way = replace springs with lowering units on stock shocks or aftermarket shocks, or buy a coilover package

Lowering springs
these are the cheapest most cost effective way to lower your car, they generally come in different lowering increments designated by their name
so here is an example from the smallest drop on the left to the most lowered units
(ie: lows springs ---> superlows ---> ultralows(?)) lol dont actually know if ultra lows exist but u get the point

important info for lowered springs on standard shocks: the stock shocks were made for ur stock springs and putting lowered springs in them can reduce their lifespan
generallythe lower units u put on them the faster they will get worse
how to kno if ur shocks are dying: they will become 'squishy' and will bounce a bit longer after u hit a bump, the worse that gets the more dead they are, and these can potentially be a hazard

how can i stop my shocks from dying?
bottom line is u cant all shocks wear over time, but lowering springs increase the wear
however suspension companies make shocks specifically for lowered cars, get some of these and they will last and wear way slower than ur stock shocks

Coilovers
coilovers are your all in 1 shock and spring package and are considered the ultimate in shock and spring combination, they generally have added features that make them better than buying shocks and springs separate
your basic overview of what majority of coilovers offer:
* around 5->30 levels of dampening adjustment (some may even adjust bound and rebound separatly)
* adjustment in camber
* adjustment of height without having to change shocks or springs
* different spring rates that can be swapped in
* generally made of stronger shiny-er material for show quality

so the coilover is the best choice for handling performance and adjustable suspension
most people would consider coilovers very expencive but if u buy some loweing springs and some lowered shocks you have almost spent enuf to buy a set of coilovers

if anyone has info on spring rates or anything else to do with this plz feel free to add on

 

[tryg]

very nice! I don't want to hijack only add..

There are two types of springs, linear and progressive, each have their own uses and characteristics.

Linear
Well linear spring theoretically keep the same spring rate regardless of stroke.
If you have a 6kg/mm linear spring, if you compress it 10mm it should only take an additional 6kg to compress another mm. Therefore, if you compress a linear 6kg/mm spring with 60kgs of force, it will compress 10mm.

Linear Spring Characteristics
The benefit of a linear spring is consistency, meaning the weights transferring from side to side should be very smooth and consistent. After getting use to the car dynamics, drivers can anticipate weight transfers and body roll more accurately. While exiting a corner, a linear spring will return the body in a smooth manner because both sides are compressing and rebounding at the same rate, which keeps one mm of expansion to one mm of compression throughout the traction of the springs.

This reduces the demand for excessive counter steering, which can result in fish tailing. For winding roads driving, this has great benefit and allows for more confident use of weight transferring because the driver won’t experience unpredictable weight shifts.

Progressive
Progressive springs are springs that gradually increase spring rate as the spring compresses. So, if the spring starts out with a 6kg/mm spring rate after 50mm of compression it may then measure 17.75kg/mm.

Using the above example a 6kg/mm linear spring will take 300kg to compress 50mm while it will take 594kg to compress the progressive spring.

Progressive Characteristics
Say you are cornering with these progressive springs, you have compressed your outside spring by 50mm (a little over 2”). While you are exiting the corner the centrifugal channeled inertia (the force that causes body roll during cornering), reduces, allowing the body roll to stabilize. You now have an outside spring that has stored 17.75kg/mm of force. As the centrifugal inertia reduces, it throws the outer side of the chassis up with 17.75 kilograms per/mm of force, roughly 950lbs/ inch of force.

Since suspensions are designed to keep the vehicle level that force throwing the outside of the chassis up will be partially transferred to the opposite side. But the outside spring has not compressed during cornering so it will absorb the transferred energy at 6kg/mm of compression so for the first mm the outside releases, will translate to almost 3mm of compression on the inside. As the outside spring releases the excess energy and the inner springs absorb it, the ratios gets closer to 1:1, it may even change back and forth.

This is excessive body roll requiring more attention and finesse to effectively control. While negotiating chicanes (or in lay speak - quick changing twisties) it can make steering extremely complex and demanding compared to what linear spring would produce.

 

[tryg]

I would also suggest that a MacPherson strut assembly (that most small Japanese cars employ as a suspension system) with it's spring seated over, would weight considerably more than a good quality steel coilover assembly. Additionally, very good examples of coilovers employ cryodized or forged aluminium as a production medium and therefore accentuate unsprung weight savings, over and above both traditional OEM assemblies and good steel coilovers.

So, in essence, coilovers are more expensive, but give you a tunable, rapidly adjustable system that is equally at home on the road (dependent on settings) as it is on the track.

My 2c

 

[Skippy]

So... when I'm looking at getting new lowering springs I should look at getting linear ones?

 

[Res]

So... when I'm looking at getting new lowering springs I should look at getting coilovers?

fixed
tbh if ur not on a budget or can save $900 ur better off doing it right the first time

 

[tryg]

hehe, I don't know exactly what you are doing with your car.. hard to say without at least you telling me something!!

Why choose progressive (I did)?

Linear springs can have some poor characteristics, should you work them hard; firstly, bottoming out the spring (if you choose a pliant ride, but occasionally venture into race-mode!!). If you chose a heavy rated spring, you would have the race-mode covered, but would suffer side-effects due to the stiff springs (such as the shocks would struggle to control the fierce rebound made by these heavier springs).

Progressive give you the soft ride, for day to day, but also have built in measures to stop the bottoming out and potential spring entrapment, that can befuzzle linear springs.

Remembering the principle, 'the less coils in a spring, the higher the spring rate' as the spring compresses under load the gathered coils come into contact and become inactive thus increasing the spring rate.

De-Rate
Progressive Rate Springs in most cases are designed around the De-rate principle, i.e.; the critical part of the suspension travel from ride height back to full suspension drop. The aim is to allow the spring rate to decrease smoothly back to original spring rate or as close as possible.

Example:
Original Spring Rate 120lb/"
Heavy Duty Linear Spring Rate 160lb/"
Progressive Spring Rate 130lb/" to 200lb/"

Result:
The above progressive rate spring would have similar or more improved ride quality than the heavy duty spring with a substantially higher spring rate being achieved at ride height.

Does that make sense?

 

[Res]

pretty sure i got prograssive springs in the front
i asume the identifying factors are that linear springs are the same coil each rotation, whereas progressive start signtly wound rotations to less?
i dunno just my guess

prograssive

linear

 

[Skippy]

Sorry should've given more detail. I am probs gonna do a couple of track days here and there, as well as flang it round corners etc on the street. Budget is a semi-issue, due to I am saving for an evo 8, but at the same time want to make my ch a nice little streeter. The hole linear vs progessive make sense now.

Also coilovers might be just outta my budget range, maybe if I went 2nd hand.

 

[tryg]

I hope this helps all. Progressive is the 'jack-of-all-trades', whereas linear are better for one application (and excel at this.. if chosen properly).

Is one better than the other?

Put 10 engineers in a room and there would still be a bitter division after 12-hours of debate, I assume.

If you know exactly what you are doing, then go with linear. If you want the best of both 'real' worlds, then progressive is my choice.

 

[BI65ND]

Not sure where this is cut and pasted from, but the lower the centre of gravity the better the handling is not entirely correct. There is what you would refer to as a sweet spot. If u go too low it can be detrimental to the cars handling.

Also coilovers are not the best solution all the time. I have had coilovers in my last 2 cars because I like the adjustability in height. But quite often a good shock and spring combo will lead to better handling than coilovers, eg good koni shocks and a quality eibach, bilstein, etc spring will have much better handling and ride than coilovers give. If I couldve found an appropriate height spring I wouldve gone that route with some koni shocks.

 

[DR1FT]

 

[cesario]

actually that is a valid point drift
should add onto the spring section, "why not to cut and drop your car yourself "

 

[Geophray]

Coilovers are also illegal on a road car (in SA anyway).

 

[Res]

i did add it a bit, just not the why

ways of modifying suspension
now there is right way and a wrong way to modify suspension

wrong way = cut springs (this is illegal)
right way = replace springs with lowering units on stock shocks or aftermarket shocks, or buy a coilover package

 

[tryg]

Not sure where this is cut and pasted from

You can blame me and my dad for a lot, if there are inconsistencies.. but he is a mechanical engineer and former-formula ford racer... I a betting he knows a bit, at least a lot more than me. The math and principles are sound, and are reverberated throughout the motoring community. Each DO have their own properties and pros/cons.. end of chat.

Also coilovers are not the best solution all the time. I have had coilovers in my last 2 cars because I like the adjustability in height. But quite often a good shock and spring combo will lead to better handling than coilovers, eg good koni shocks and a quality eibach, bilstein, etc spring will have much better handling and ride than coilovers give. If I couldve found an appropriate height spring I wouldve gone that route with some koni shocks.

Once again, these threads should try to be as non-biased as possible, I just present ACTUAL facts (if that was levelled at me, unsure). YOU might think shocks/springs are a better combo (as do I), but that wont be everyone's thoughts.. so lets just present what we find, of the one's we have used or can substantiate.

Koni, Eibach and Bilstein all make coilovers too.. oh what a dilemma.

 

[tryg]

Coilovers are also illegal on a road car (in SA anyway).

I think you will find there are a few sets that have achieved ADR compliance for use in every state. The reasons coilovers 'might' be illegal (anywhere except on the track) is that they have not yet complied to Australian testing to meet ADR.

Pedders sell BC Coilovers, from the literature I have read, they have been tested and found to comply with ADR (being that ADR is the supreme statute within our country), if that is correct, they can be used anywhere here...

 

[DR1FT]

i got some papers that came with my ksports and they said in bold multiple times

"TRACK USE ONLY"

 

[tryg]

Although, there are so many reports on ADR and coilovers it is hard to be sure... I think TEIN might have also been trying for ADR recently..

Good point to note, look for ADR compliance on any products you intend to put on your car, from a mechanical standpoint...

If it does not meet ADR, then you basically are opening yourself up to denied insurance claims, defects or registration denial!

 

[BI65ND]

Not sure where this is cut and pasted from

You can blame me and my dad for a lot, if there are inconsistencies.. but he is a mechanical engineer and former-formula ford racer... I a betting he knows a bit, at least a lot more than me. The math and principles are sound, and are reverberated throughout the motoring community. Each DO have their own properties and pros/cons.. end of chat.

Also coilovers are not the best solution all the time. I have had coilovers in my last 2 cars because I like the adjustability in height. But quite often a good shock and spring combo will lead to better handling than coilovers, eg good koni shocks and a quality eibach, bilstein, etc spring will have much better handling and ride than coilovers give. If I couldve found an appropriate height spring I wouldve gone that route with some koni shocks.

Once again, these threads should try to be as non-biased as possible, I just present ACTUAL facts (if that was levelled at me, unsure). YOU might think shocks/springs are a better combo (as do I), but that wont be everyone's thoughts.. so lets just present what we find, of the one's we have used or can substantiate.

Koni, Eibach and Bilstein all make coilovers too.. oh what a dilemma.

Sorry, wasn't trying to doubt the credibility of the info cos its very in depth, just wanted to point out a couple of extra pieces.

With coilovers, I keep seeing comments everywhere when someone asks about lowering their car the immediate response is don't waste money on springs, as if coilovers is the only good option. I'm not saying coilovers are bad, but they're not the be all and end all

 

[tryg]

Agreed, and noting the enduring requirements for the coilovers to pass ADR, is it really worth risking a fine, a defect or worse....a denied insurance claim.

I believe you have shed some good light here and it should serve as a warning to all, DO AT YOUR OWN RISK or GET GOOD ADVICE AND THEN PROVE ITS RIGHT!!