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Spring rate info - going for stiffer springs experiment

64K views 39 replies 17 participants last post by  tadope 
#1 ·
Lots of talk about coilovers/lowering springs and all the posts normally come down to personal preference. So I thought it would be a good idea to collect some info for those looking to buy a set of coilovers or lowering springs.

I can update this first post when you post info on this thread. Spring rate is not always straight forward, if it's progressive I think we can collect the final rates before the spring closes. Helper springs are normally fully compressed so I think it is useless to collect that data.

SI-units are the easiest so we will use those. I can convert if you have lbs/in or some other values. Kg/cm (N/mm also) seems to be the most common so will use that. Newtons (N) are also used here approximation 10N ~ 1kg is close enough.

Damping is another thing that effects a lot, but I think it is enough just to collect if there are adjustable dampers or not. Damping explains why some coilovers can feel harder even they have softer spring rate, but spring rate is a good starting point in decision making.

If someone has a bench to measure stock springs that would be great too.

Here we go, in alphabetical order for Mk1 TT Quattro:

Make:AP
Model:
Product number: GF10-041
Front spring rate: 70 kg/cm
Rear spring rate: 60 kg/cm
Adjustment: height (F/R)

Make: AST
Model: 4100
Product number: 4622S-0014-M1
Front spring rate: 70 kg/cm
Rear spring rate: 80 kg/cm
Adjustment: height (F/R), Rebound (F/R)

Make: Bilstein
Model: PSS9
Product number: 48-080422 / F4-GM5-8042-H6
Front spring rate: 65 kg/cm
Rear spring rate: 117.5 kg/cm
Adjustment: height (F/R), Rebound (F/R)

Make: GAZ
Model: GHA/GGA
Product number: GHA336/GGA436
Front spring rate: 58 kg/cm
Rear spring rate: 80.4 kg/cm
Adjustment: height (F/R), GGA rebound also (F/R)

Make: H&R
Model: Street
Product number: 29431-1
Front spring rate: 65 kg/cm
Rear spring rate: 108 kg/cm
Adjustment: height (F/R)

Make: H&R
Model: Comfort
Product number: 29431-2
Front spring rate: 65 kg/cm
Rear spring rate: 90 kg/cm
Adjustment: height (F/R)

Make: H&R
Model: Twin-tube
Product number: 35431-1
Front spring rate: 60 kg/cm
Rear spring rate: 114 kg/cm
Adjustment: height (F/R), rebound (F/R)

Make: KW
Model: Variant 3
Product number:
Front spring rate: 81.3 kg/cm
Rear spring rate: progressive, rate unknown
Adjustment: height (F/R), rebound (F/R), compression (F/R)

Make: KW
Model: Clubsport
Product number:
Front spring rate: 101.9 kg/cm
Rear spring rate: progressive, rate unknown
Adjustment: height (F/R), rebound (F/R), compression (F/R)

Make: ST Suspension (KW sub brand)
Model: Coilover kit
Product number: 90830
Front spring rate: 70 kg/cm
Rear spring rate: unknown (marked: 8012 14E11)
Adjustment: height (F/R)

Make: Weitec (KW sub brand)
Model: Hicon GT
Product number: 13210041
Front spring rate: 70 kg/cm
Rear spring rate: progressive spring approx. 110 kg/cm
Adjustment: height (F/R)
 
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#6 ·
I take my time but i get there in the end! 8)

Make: AP
Model:
Product number: GF10-041
Front spring rate: 70/170 N/mm
Rear spring rate: 60/130 N/mm
Adjustment: height (F/R)

Make: Weitec
Model: Hicon GT
Product number: 13210041
Front spring rate: 70 N/mm
Rear spring rate: progressive spring approx. 110 N/mm
Adjustment: height (F/R)

Still working on FK but i'll get to the bottom of it as quick as i can.
 
#8 ·
That's what i thought but the second number is actually the length of the spring off the vehicle! :?
 
#10 ·
nate42 said:
KW's have so far the hardest springs that probably was not a suprise to anyone who has driven a car with KW coilovers :)
I find them quite comfy :)
 
#11 ·
Matt B said:
nate42 said:
Make: KW
Model: Clubsport
Product number:
Front spring rate: 101.9 kg/cm
Rear spring rate: progressive, rate unknown
Adjustment: height (F/R), rebound (F/R), compression (F/R)
My ride :)
I bet that is one nice coilover setup for serious driving :evil: Do you have any pics of your coilovers? I think would be great addition to this thread.
 
#14 ·
Matt B said:
nate42 said:
Make: KW
Model: Clubsport
Product number:
Front spring rate: 101.9 kg/cm
Rear spring rate: progressive, rate unknown
Adjustment: height (F/R), rebound (F/R), compression (F/R)
My ride :)
Propper job, seriously expensive but just about as good as you can get! [smiley=thumbsup.gif]
 
#18 ·
Make: Bilstein
Model: PSS9
Product number: 48-080422 / F4-GM5-8042-H6
Front spring rate: 65 kg/cm
Rear spring rate: 117.5 kg/cm
Adjustment: height (F/R), Rebound (F/R)

nate42 said:
alexisgt said:
What about Bilstein PSS B14?
Do you have specs?

I'm thinking of buying it for my 8N Quattro.
Any suggestions?
Don't have the info sorry, you can ask from your retailer or send an email straight to Bilstein. Post here if you find out!
I can't seem to find the info but the PSS9 was mentioned a bit earlier in the post,
 
#19 ·
Originally started this thread as I was looking for confirmation for my feeling that the tail on my TT was a bit soft when pushed hard. Data collected here shows that 80kg/cm is not much in the rear.

I want linear springs, as predictability in track use is more important for me than smoothness in daily driving.

Ended up ordering H&R springs, have their ARB kit already and was pleased with that. They have huge selection of coilover springs and for the rear I orderd the springs they use in their Street kit.

On the rear I'm going from 80kg/cm to 108kg/cm, so 35% stiffer (29431HA1) and in front from 70kg/cm to 80kg/cm, so 14% stiffer (HRF 160-60-080).

I hope I don't have to revalve the dampers, will see. That will also move the balance to more to oversteery direction. Balance was quite right to begin with, but rear ARB is adjusted stiffer than front.

I'll post pics when parts arrive and first track day is 14.6, so then I'll know if this was worth the effort.
 
#20 ·
Springs arrived and we all love pics :lol: :lol:

Springs

New front spring next to old one

Just for laughs next to OEM springs that I found while cleaning

Looking at my current spring plates on the earlier post you can see that I probably have to remove the lower spring plate. I hope the top one fits so that I don't have to buy H&R part. Here is the pic of H&R kit I found. It doesn't come with lower spring plate for the rear.
 
#22 ·
Rears are on. Painted to orange to match the front springs. Will change the fronts later as I have some bushes to change in there too, also need a bolt gun to get the fronts open.


Compared to old spring the most noticiable difference is the diameter, these new ones are much smaller -> stiffer. Top plate fitted perfectly 8) At once something goes as planned :lol: :lol: Bottom end of the spring (upwards in the picture below) is different. H&R spring keeps it self in place around the stud as AST uses outer edge grooves on the bottom plate. In general it is easy job to change the rear springs.

Comparing to old springs. IN THIS PICTURE SPRINGS ARE UPSIDE DOWN ON PURPOSE!

Feels stiffer that is all I can say at this point. I'll report more after trackday.
 
#23 ·
Just did 1000km mixed roads and trackday on top of that. Rear felt very good on the track and road. On track I had dampers as hard as possible, on the road I tried max soft and halfway. Looks like the dampers can handle these springs OK. MOT damper test was also OK, with this combo.

Fronts are so close to previous springs that I'm sure there wont be any issues. Very happy with results, this went as planned 8)
 
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