Some ramblings about Shed's Eibach/KW coilovers
As Shed is a V6 TT, despite being a facelift model with the silver headlights, she came from the factory with the original ride height of 370mm from wheel centre to the top-centre of the wheelarch.
When I bought Shed, her rear-left corner was sitting slightly lower than the rest of the car, and on looking through the MOT history, this spring was replaced after snapping. It looked like the replacement spring was probably a pattern part which was facelift height - i.e. 20mm lower than the other three corners, which resulted in some very odd readings when setting the tracking up.
As a result, and after trying H&R's lowering springs on Bilstein's OEM-spec B4 shocks, I decided to invest in a set of coilovers. I wanted a set that weren't too much stiffer than the OEM ride, and I only wanted to drop the car around 30mm to give a 340mm ride height between the wheel centre and wheelarch. I was also keen to find a set of coilovers with stainless steel bodies to try and prolong their life as long as possible - in the end, I settled on a set of Eibach coilovers for the Audi TT Mk1/Golf Mk4 platform.
These coilovers use Eibach springs paired with KW's non-adjustable stainless steel coilovers.
I also ordered a set of neoprene gaitors which velcro over the coilover bodies to keep road salt and dirt off the delicate bits.
Compared to the OEM shocks and springs, the ride is no harsher, and having the ability to precisely set the ride height is a huge help when trying to get the car's geometry set up perfectly.
21st Feb 2018: I've updated this section with more-accurate spring and kerb weights - Alex.
My only complaint is that, because Shed uses the heavier VR6 engine and even heavier DSG gearbox, I think the spring rates at the front are too soft - these coilovers feel like they're designed for the 1.8 turbo 4-pot coupled with the manual gearbox, so the ride on harder-hitting bumps feels like the shock is coming very close to the limit of its travel.
The main coil springs supplied with my Eibach coilovers themselves are marked ERS-H-170-60-0080 which has a rate of 80 N/mm (457 lbs/in) with helper springs of 10 N/mm (57 lbs/in) - you can find these springs here on the Eibach website: Eibach ERS-H-170-60-0080.
My rough back-of-a-napkin calculation is that the two models have a weight difference of about 100 to 150Kg, which means each front corner will probably be seeing roughly an extra 50 to 75Kg weight.
As the front axle sees around 900-ish Kg load on Shed, each front corner is probably dealing with 450-ish Kg, rather than 375-400 Kg of a 1.8 turbo, which is an increase of (again, very roughly) about 20% weight.
So, I started looking at higher-rate springs, but I want to keep a degree of progressiveness.
To do this, I want to replace the 10 N/mm helper springs - which are always fully-compressed on the car, even when the suspension is at full extension, for a spring which will provide a degree of resistance to bumps. The highest-rate helper spring I can find is a KW 50 N/mm (280 lbs/in) jobbie, so I've ordered a pair of those from www.kwsuspensions.co.uk.
I also want to uprate the main springs by the roughly 20% figure I worked out above, so I needed to find some springs to the same spec as these Eibach ERS-H-170-60-0100 springs. Because the Eibach springs had to come from the USA, I looked closer to home for some springs to the right spec, and again the KW Suspensions site came up with a match.
These are the KW springs I've decided on:
Update 21st Feb 2018: the springs have arrived. Now I just need to fit them! Pics to follow shortly... - Alex
Anyway, here's some pics...
To help me convert from imperial spring rates - pounds per inch (lbs/in) - to metric (kilogrammes, Newtons or grammes per centimetre or millimetre), I popped together a simple spreadsheet you can use in your web browser to convert back and forwards.
You can find it here:
Or clicky the pretty picture below...