Rear Spring Question

[GTI_Speed]

So after racing on my ClubSports for about a year, I'm finally ready to try some different things with them. First up, the rear spring collar on it's maximum setting gives a pretty damn low ride height. KW may have designed it this way for weight distribution purposes but the front can probably go up at least another inch and a half before it is at max ride height. To balance this out would I need to find a taller spring or a different collar for the rear. Thought I'd post up here before I go directly to KW.

Thoughts?

 

[the bruce]

On a KW Clubsport coilover all standard 60 mm diameter racing springs will fit
which make things pretty easy.
Look at KW's site if you like them yellow, look at H&R (HRF) or Eibach (ERS) if
you like them black or red.

http://www.kwsuspension.de/pdf/kw_racing_catalog.pdf

http://docs.kwsuspension.de/gaKWCS80842_1257-11.pdf

http://www.hrsprings.com/products/id-race/

http://www.h-r.com/includes/download.php?file=../bin/infos/m_rennsportfedern.pdf

http://performance-suspension.eibac...products_eibach_race_spring_systems__ers__ers

KW use a 70-170* on rear on the Mk.V/VI Clubsport. Spring rate ist 70 N/mm
and (non loaded) length is 170 mm. Other where these might be 70-170-60
or 170-60-50 dependend on manufacturer.

On front KW CS Mk.V is 90-170. Going for a 90 or even 100 N/mm on rear will
be an anternative. I'd go for a shorter one then (100 N/mm and 150 mm length).

 

[bostonaudi]

KW likely supplied a spring a bit too short for rear. Many kits come with 7" linear springs for both front and rear, the rears actually need to be a bit longer in relation to front to have equal range of adjustment front and rear. I run 8" rears, and 7" fronts, using 350f/300r (Hyperco's).

In "real" world of the USA:

f 70-190 = 6.7" 514 lb/in
r 70-170 = 6.7" 400 lb/in

For front, up to about 450 lb you can stay with 7", above that you'll need to go shorter or car will sit high (or shock body will have to allow spinning it down). For rear, 8" up to about 300, then 7" (and shorter) as rate goes higher. The supplied KW lengths should be in ball park, but sounds like slightly longer rear might work a bit better. Hyperco has 2.5" springs in many lengths, a 7" 400 lb might work.

Were you thinking of adjusting the rates, or just the spring length?

 

[GTI_Speed]

Guys thanks for the info!!! Your calculations are spot on because those are what the exact rates are. I never put two and two together and just realized that spring length affects the rate. Durr.

I was thinking about trying some different rates, something like 600 Front and 500 Rear as long as the valving can handle it. Assuming my maths are right, I don't realllly know what I'm doing, this will be close to the same ratio that was originally provided by KW with a little more bias towards the front. Then hopefully with a taller spring I could balance it out to my liking using the ride heights.

 

[Autobahn]

It's not necessary to get new springs, they offer spacers which I'm running in the rear of my KW Clubsports. See the image below, 4th column, 2nd down. I'm using the middle sized spacer and have a lot of adjustment now.

I heard running too hard of a rear spring isn't recommended. I forget the guys name in Australia that now races a Porsche, but he and others have run into issues when the rear end raises off of the ground you can have ABS issues which could cause you too crash. So, choose carefully.

The 400lb springs in the rear seem pretty stiff already and I'm running a heavier R32.

 

[bostonaudi]

It's not necessary to get new springs, they offer spacers which I'm running in the rear of my KW Clubsports. See the image below, 4th column, 2nd down. I'm using the middle sized spacer and have a lot of adjustment now.

I heard running too hard of a rear spring isn't recommended. I forget the guys name in Australia that now races a Porsche, but he and others have run into issues when the rear end raises off of the ground you can have ABS issues which could cause you too crash. So, choose carefully.

The 400lb springs in the rear seem pretty stiff already and I'm running a heavier R32.

A spacer would be way to go.

That's a good point on rates. I've been there with really stiff and didn't feel it was necessary to compromise the car so much. A GTI at 514/400 will be unsettled on wavy or bumpy roads will stick nicely on smooth track. I'm at 350f/300r now and the car handles great, although I'm tempted to bump front to 400 for a little more resistance to bottoming on bad bumps/dips. I run the dampers at full loose on the street so probably making it worse. These little springs don't have a lot of travel so can bottom. If you've never seen or held a 2.5x7" linear spring before, you might think it was for a go cart.

 

[daigo]

I heard running too hard of a rear spring isn't recommended. I forget the guys name in Australia that now races a Porsche, but he and others have run into issues when the rear end raises off of the ground you can have ABS issues which could cause you too crash. So, choose carefully.

This is an interesting information. I'd like to read that post.

Currently I am running with high rate springs as below... and had problem with ESP intervention while mid-high speed cornering. ESP grabs brake without my intention, it is so dangerous while on turn and really annoying.

I don't really know why this phoenomena occurs, and I have no idea of how solving the issue, so I made a guess of three wheelling, decided to change my rear spring to take longer stroke for stretching the rear suspension.

I think ESP intervention calmed a little, but still has. Now I disconnected ESP module, but this is not what I've wanted to do...

Front: 784lb/inch (6inch)
Rear : 670lb/inch (7.9inch) => now 670lb/inch (6.9inch) + 447lb/inch (3.15inch)

Maybe I should try more softer.
Picture shows both rear springs (L:before/ R:after)

 

[GTI_Speed]

Daigo, any ill effects from removing the ESP module? Does your dash light up like a Christmas tree? Haha.

Boston, here is some in car from my local track. This video should give a good representation of the stability at speed, I would not consider it a smooth course by any means but it also is not Sebring. The bumpiest part is def the backstretch, also the fastest, and the car is very planted even though it looks like its jumping all over the place. My rebound/bump are set at the default KW tells you to use. It would get hairiest coming out of the kink and into the braking zone for the final turn but I would just get a little a twitch.

Last 5 minutes are the best, when I finally get some open track.

 

[GTI_Speed]

Techno, does the spacer have any ill effects as far as suspension travel goes? Is a full spring a more optimal solution?

 

[daigo]

Daigo, any ill effects from removing the ESP module? Does your dash light up like a Christmas tree? Haha.

Yea, dash are bright with many lights lol.
ABS works fine, but I wonder EBD are working...

 

[the bruce]

Daigo, your 2006 GTI has the ESP sited under the seat, right? I run a 2008 GTI.
Sadly my all ESP parts are integrated in the ESP/ABS module in the engine bay
like it is in the Mk.VI GTI.

Speed, I'd prefer swapping the rear springs. There's so large choice of springs
in 60 mm diameter suitable to the KW adjusters.

 

[bostonaudi]

Daigo, any ill effects from removing the ESP module? Does your dash light up like a Christmas tree? Haha.

Boston, here is some in car from my local track. This video should give a good representation of the stability at speed, I would not consider it a smooth course by any means but it also is not Sebring. The bumpiest part is def the backstretch, also the fastest, and the car is very planted even though it looks like its jumping all over the place. My rebound/bump are set at the default KW tells you to use. It would get hairiest coming out of the kink and into the braking zone for the final turn but I would just get a little a twitch.

Last 5 minutes are the best, when I finally get some open track.

Looks like in that last 5 you are really moving and car is holding speed really well. High rates work nice on a high speed track, but you can see car is fairly reactive to bumps. If you don't mind the ride, and its working for you, let it rip.

My car started buzzing and rattling apart so I backed springs off a bit. The fuel line came loose by the firewall too, which made a really nasty noise. Surprisingly, we have pretty crappy roads in SC, so car was always bouncing around over bumps. Not too bad with 350/300.

 

[Autobahn]

I found the info, it was Al Walker, he has some more detailed threads about the issue, but this should provide enough info.

http://forums.vwvortex.com/showthread.php?5013645-Two-R32-s-in-the-2010-11-Australian-Targa-Championship&p=67411426&viewfull=1#post67411426

OP: no issues with that spacer at all, KW recommended them. I actually got them with the kit form the previous owner. I personally wouldn't change springs, KW designed proper spring rates and they've been tested on their 7-post suspension dyno.

Just as Boston mentioned, he's been down that road with a real heavy spring rate. Clubsports work so well because of the absorbers and finely matched springs working in harmony together.

I think the previous owner got some different shock adjustments from HPA which really dialed things in.