I will give some info facts and stats, and different types of lowering etc.
The main reason why we lower cars is it looks a lot better, standerd suspention is usully always to soft as it made for a wide range of markets, and its always to high in my opinion.
Lowering a car should improve handling if done correctly, it lowers the cars centre of gravity closer to its roll and pitch centres, which help it to stick to the road in the corners and under braking, with stiffer springs and shocks reduces body roll and increases the tyre contact on the road, a handling improvment is only achieved to a point, if the cheap route is used its not always what you will get, i.e just springs, or extreme lowering.
it can be very hard to guess the amount of drop you can achieve its best to do as much measurements as possible to avoid burning / bumping rubber or scraping, most cars take up to 40mm drop with no problems at all its over 60 where the problems start but can be solved by arch rolling spacers etc.
as you are proberly aware most french cars( citreon peugeot etc) have a rear torsion bar setup on the rear, which uses very strong steel bars the steal bars are spindled at each end, and they link the trailing arm to the opposite end of the axle cross member and the behind it, very confusing i know. These steal bars twist as the suspention moves up and down throughout all of its travel and its the cars resistence to the twisting which make the springing of suspention another steal bar passes through the centre of the rear axle crossmember and like the trainling arm both of them, this is the anti-roll bar ,which is stiffer than the other two, but still function on same concept of others.
to reset the height is a very involved task, not difficult or dangerous but very fiddily, on older cars may be very diffcult as cars could have rusted parts , the positive of torsion bars is you only pay for labour of doing no new springs to buy
to adjust it involves removing torsion bars, setting both rear trailing arms to desired height, reinserting bars and ensuring the split lines are put back correctly, not easy its best get it done profesionally.
Lowered cars, will always give a more firm ride and cope less well with bumps and imperfections in the road, buying the best you can afford will couter this.
I recommened bilstein and eibach, there the best quality and very good especially with vw group cars.
These are the setups you can have
UPRATED SPRINGS ON ORIGINAL DAMPERS:
PROS: This is very cheap you will get lowered look, and can mildly improve handerling
NEGS: handerling can be destroyed, as there designed for matched dampers so lenth of dampers is greater on normal dampers dif rates etc characteristics, can give bouncy poorly absorbed bumps etc
always buy progressively wound springs for smoother ride and cope with big bumps and extreme cornering, only use drop between 20-40 mm on standerd dampers or handerling wil be rubbish any lower, personaly i think its a false economy to buy just springs
THERE is hydrolic suspention but dont know much about it apart from better ride and adjustability and its sky high prices to buy
UPRATED SPRINGS AND DAMPERS KITS:
FOR: You get a massive handling improvement, due to it being well developed, some shocks even have adjustable damping to adjust to your preferance, The ride will be more controlled and a lot less bouncy than not modded suspention or just uprated springs,
NEGS: there is always a compromise in life and its no different here due to the incresaed damping spring rates the ride may be quite harsh, as it is well developed and controls handling well, id recommend this option on a budjet but want good handling, coilover are always best but should be for the price
A FULL KIT IS A GENUNIE UPGRADE, WITH A WELL SORTED CONVERSION YOU WILL GET REQUIRED DROP AND STILL RETAIN PREDICTABLE HANDLING CHARACTERISTICS, DEFINATLY A MUST IF YOU LIKE TO PUSH HARD ON THE ROAD, WITH A MATCHED SET OF SPRINGS DAMPERS IS ASSURED TO IMPROVE HANDLING AND RIDE QUALITY SHOULD BE SMOOTH YET TAUT, BUT HARD ALSO.
PROS: ride height can be changed usully between 20-80 mm more expensive ones even moredamping can be set to prevent bump scrub and can be set up for amazing handling, or slammed for shows
NEGS: the are very expensive up to £2000 most start at 400-600 but last few years there plenty of chepaer ones that are reasonable quality but usually not as good ride. Most coilovers are hard to set up too mainly timeconsuming and tricky, ride is seriously hard too on coilovers.
COILOVER ARE THE BEST,A ND THE CHOICE IF YOUR NOT PREPARED TO COMPREMISE, IT COSTS A LOT BUT YOUR GET WHAT YOU PAY FOR, IT OFFER ONE FEATURE OTHERs DONT TRUE ADJUSTABLE RIDE HEIGHT AND DAMPING ADJUSTMENT, CAN MAKE FINE TWEAKS, EASY SCOPE TO FIT BIG RIMS, THEY ARE BASICLY AND IMPROVED SPRING AND DAMPER KIT WITH HUGE ADJUSTABILITY.
SUSPENTION/FACTS INFO/ TERMS/JARGEN ETC
CIRCLIP= ITS IS A FLAT STEEL STEEL SPLIT WASHER, IT FITS INTO THE GROOVEON THE BODY OF DAMPER, ON WHICH THE SPRING CUPS SIT.
BUMP SCRUB= THIS OCCURS WHEN THERE IS TO MUCH COMPRESION FROM THE SUSPENTION, GOING OVER A BUMP, THE WHEEL IS FORCED UP AS SUSPENTION COMPRESSES, SCRUBBING THE WHEEL ARCH
DAMPING /SHOCKS=DAMPER ABSORB SKINETIC ENERGY OF SPRING STOPPING FURTHER THE REACTION OF THE SPRING, DAMPERS STOP THE CAR BOUNCING ALONG THE ROAD HENCE WHY IT DOES IF THE DAMPERS ARE SHOT
PROGRESSIVELY WOUND = ON THESE SPRINGS HAV EBEEN WOUND CLOSER AT ONE END THIS OFFER A RACE CAR FEEL PERFORMANCE WITHOU AFFECTS STANDERED RIDE HEIGHT MUCH
SPRING RATE= IS THE POTENTIAL RESISTANCE AGAINST COMPRESION OF THE SPRING, MEASURED IN POUNDS A LOW SPRING RATE MEANS IT HAS A LOWER POUNDAGE AND IS SOFTER
TO avoid problems with car after wards after any setups of suspention , i advise full geometery setup and check, and cambers tracking etc un les you want cronic tyre wear on edges or inners and stodgy handling. Your geomety wil be changed affected more of a problem the lower you go, so get it checked straight after its lowered
IVE PROB MADE A FEW SPELLING GRAMMAR MISTAKEs will amend soon , cheers for reading would very much appreciate a vote if its been of use
all the best britman