Golf GTI MKV Suspension upgraded in 3 stages.
A little on dynamics of each set-up.
Stock GTI suspension:
Sachs dampers/24mm front & 22mm (hollow) rear bar/stock springs:
Ride at lower speeds felt choppy and ride at higher speeds a little bouncy - due to softer damping. Ride in mid-range OK. Ride on rougher B-grade roads somewhat punishing. Avoid pot holes, if possible to give more comfort to kidneys and preserve tooth fillings. Found that I tended to slow vehicle on rougher B-grade roads to maintain some comfort cruising. Hard driving resulted in continued stabs at the wheels through sweeping corners to fight the understeer of stock set-up. Visibly see outside front tyre walls worked hard as outside front camber change occures through hard cornering. Journalist have noticed this also. Driving hard & fast sometimes tiresome due to need to fight understeer. A positive of the stock set is that it is forgiving, and fun to balance the vehicle via the throttle mid corner (ie: lit off oversteer to a degree).
Koni FSD dampers ($1,350):
Koni FSD are a brand new product in Australia. They are standard fittment on Lamborgini Gallardo. They have an internal valve with makes them firm on smooth roads for performance driving, and soft when striking bumps/pot holes on rough roads. Best of both worlds in one damper without need for expensive and heavy electronic or air suspension systems. Had reservations about whether Koni FSD would be firm enough for my spirited driving or firmer than stock items. They are definitely firmer. After installing the Koni FSD dampers, vehicle lifted in the rear about 5-10mm (9mm left rear - 5mm right rear - front unchanged). Generally most shocks with settle to within 5mm of vehicles original ride height.
Koni FSD made GTI feel like it sat lower to the ground. Koni FSD improved the understeer of the stock set-up. Less continued stabs at the steering wheel to fight the inherent understeer biased Golf chassis. Hard driving reveals that Koni FSD depress about 1 inch then hold the vehicle up. Like some one wedging a chock into the springs. My confidence to throw the GTI around dramatically improved. Koni FSD definitely firmer than stock items (about 15% stiffer). Striking bumps/pot holes mid corner did not unsettle the car. Driving over patchwork/pot holes/bumps on one side of the roadway would only activate the softerning valve on that side, keeping the car straight, rather than bouncing it offline. Noticeable improvement in inner front wheel spin with need for traction control 50% reduced.
The softening valve in the Koni-FSD feels like it does not open up until about 45-50kph; not until you encounter a significant bump/pot hole. As speeds rise and vehicle impacts with pot holes/broken sections of tarmac, the valve opens up to give you that silky smooth trade mark Koni ride, like being on standard Koni Reds I imagine (softening aobut 10-15% softer than stock dampers - but not as soft as comfortline Golf). Bilstein dampers (originally under consideration) are 25% stiffer and in my opinion, would be too firm for stock GTI springs.
The reason, apparently for the rear end lift with Koni FSD is that the rears are higher pressure relative to the front dampers - pushing the vehicle forwards to give maxium front end grip. With stock items, and 3-4 persons on board, weight would transfer rearwards, causing front wheels to spin easily.
The softening valve generally doesn't open hitting minor undulations in roadway - only bigger bumps. I am very impressed with Koni FSD's and consider them to be well worth the price.
Negatives of Koni FSD dampers - they are valved a little too firm for stock GTI springs. Can feel some of the minor undulations on freeway, that were not noticeable with stock Sachs units. The lift at the rear, which did settle a few mm after a while. Koni brochure states that FSD's will work with stock springs, but not ideally, as I found out. Enter stage 2.
Stage 2:
Eibach ProKit Springs ($605.00)
Eibach are a repsectable German Brand. I considered either Eibach ProKit or H&R OEM Sports Springs, but went with Eibach. Why? (1) Eibach appear to have some sort of product & reasearch agreement with KONI; (2) They appeared to lower the GTI about 5mm more than H&R according to website (3) Eibach springs are usually a tad softer then H&R (H&R are German also and R32 had them as stock items from factory).
The Ride with Koni FSD and Eibach ProKit was suprising better than stock or stock with FSD's. More sway, pitch and swat reduced with Eibach springs. They are progressive springs, meaning that they are softer for first part of travel, before becoming progressively harder and they compress. Found with stock items that 4 adults in car softened up suspension. Eibach settle down into there harder spring rate with more load on board.
GTI lowered 20mm at front and 12-14mm. German springs are designed to lower car front to rear equally, provided that you have 4 adults on board, full tank of full, and some luggage, other German springs will almost always (except race springs) be higher at rear and lower at front.
Springs would be about 15% stiffer than stock item at their hardest (difficult to measure due to their progressive nature). They are an ideal fit for Koni FSD (although I reserve my judgement until I try a GTI with H&R OEM Sports springs).
Lower centre of gravity helped handling on the limit. Due to the progressive nature of the springs, I felt that it took the first entry part of the corner for the Eibach ProKit to settle onto their harder spring rate. Once at apex, the springs would go hard, and you launch out of the corner. Its almost like the Golf GTI had a split personality from corner entry/apex/exit. Car was still forgiveable at limit and still throttle adjustable mid corner. Unintended emergency stops hard on the brakes reveal bugger all pitch. Car stayed firm with minimal dive. Impressive. Still some body sway/roll in hard driving conditions though.
Negatives of Eibach ProKit (or any progressive rate springs) - The coils at the bottom of the spring are spaced widely and the top coils have minimal spacing which acts basically as a filler so the springs do not pop out at full extension. Due to this type of design, I have been told that you receive spring slapping, where the top of the larger (bottom end) spaced coil impacts with the top (narrow filler) coil, causing a metallic crashing sound on pot holes. A loss of some refinement as opposed to stock linear springs. I have my springs sleeved - which involves putting some type of plastic/rubber around coil so when the metal impacts, it hits the rubber, reducing the metallic crashing noise. GTI still wore the front outside edges of the front tyres due to mid-corner camber change. Stock anti roll bars felt that they did not work as effectively as did did with stock springs. I felt Golf GTI could be further improved with addition of stiffer bars. Enter stage 3.
Stage 3:
H&R Anti Roll Bars (26mm/22mm) ($890.00).
H&R is a top quality German Company. Everything H&R is imported from Germany. H&R make a bigger set of bars (28mm/24mm). Both sets are sold in pairs and you cannot mix and match. They are 2 x adjustable (hard/soft). The hardest setting on the smaller bar is softer than the softest setting on the bigger bars. H&R bars come with no need to oil Telfon bushes that should be quieter in operation. I considered Eibach Bars (26mm/23mm - $1045) with polyurethene bushes that may squeak and may require oiling to reduce noise. So I went for the smaller H&R bars. They are on their softer setting (soft/hard). Whiteline only make a rear bar ($220-$250) which will aid the reduction in understeer & turn-in, but may make the steering crispness of GTI a bit more doughy. The front bar is 2mm thicker than stock. The rear is same size, but solid rather then hollow.
The bars reduced the split personally of the GTI from corner entry to exit. They feel like they have added weight to the bottom of the vehicle, keeping it planted more firmly down. On smooth roadways, I feel as if they could be put on their harder setting. On rougher roads like broken concrete or rough B-grade roads, the softer setting is enough. In tight twisting driving, mountainous roads or hill climbs, I would probably put the rear bar on hard and front on soft to improve turn and further reduce understeer.
GTI has lost some of it's fun throttle adjustability in mid corner. It is now a sharper instrument, moving closer to what you would expect from a race prepared car. On limit, vehicle is less forgiving. Understeer further reduced and front tyres wear more evenly due to less mid-corner camber change. Handling limits have dramatically improved and hard/fast driving has become an ease. Point, and there she goes. Before, you have some time delay weighting for weight to transfer (ie: body sway). Single wheel bumps have become more noticeable, only marginally. Ride in town is firmer. ARB's have not made ride rougher, just reacts more quickly to undulations/pot holes.
Advantage of Eibach ProKit Springs & H&R bars is that they are both black in colour & look stock.
If I had one choice as to which of these items (only one) I could have out of the three - Koni FSD dampers would be my first choice.
Websites for reference articles:
www.tirerack.com excellent tests result for Koni FSD)
www.eastcoastsuspensions.com.au
www.koni-fsd.com
www.eibach.com
www.h&r.com or
www.h-r.com
Cheers
White James
Sydney, Australia
