# Spring rate info - going for stiffer springs experiment



## nate42

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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## nate42

KW's have so far the hardest springs that probably was not a suprise to anyone who has driven a car with KW coilovers 

Here is spring rate explained


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## TTSPORT666

Nate i tip my hat to you sir [smiley=toff.gif] .... exellent idea this thread. Would be fantastic to have information one page for reference and comparison! 

Damien.


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## nate42

Sent a PM to AwesomeJohn as he is selling quite many brands of springs and coilovers, I hope he can fill in the data for Weitec, AP, FK.


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## jamman

I'm sure he will help but he is off for a week so don't expect a quick reply


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## AwesomeJohn

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.


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## nate42

Excelent, thanks John!

Those AP's have progressive springs also? I'm quessing that first number is the starting rate and the last one just before the spring closes.


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## AwesomeJohn

That's what i thought but the second number is actually the length of the spring off the vehicle! :?


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## Matt B

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


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## glslang

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


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## nate42

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
Click to expand...

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.


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## nate42

glslang said:


> 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
Click to expand...

What version you have V1/V2/V3? They might come with different springs. Car weight, ARB's and damper settings also effect alot, good you like them


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## nate42

Old and bad quality pics of AST 4100


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## AwesomeJohn

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
Click to expand...

Propper job, seriously expensive but just about as good as you can get! [smiley=thumbsup.gif]


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## nate42

Added Bilstein PSS9


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## alexisgt

What about Bilstein PSS B14?
Do you have specs?

I'm thinking of buying it for my 8N Quattro.
Any suggestions?


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## nate42

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!


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## AwesomeJohn

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!
Click to expand...

I can't seem to find the info but the PSS9 was mentioned a bit earlier in the post,


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## nate42

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.


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## nate42

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.


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## warrenstuart

Nice topic, bookmarked now for future use.


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## nate42

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.


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## nate42

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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## Basscube

Nice orange rusty discs :lol:


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## nate42

Basscube said:


> Nice orange rusty discs :lol:


Everything has to match the springs, that's why the whole car is rusty :lol: 
300mm S4 discs BTW and not that rusty anymore after track abuse :wink:


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## Jay89

Anybody running eibach springs? Looking for a set of 25mm ones and these seem to be best available?


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## TT_CS

Fantastic, informative post

Thank you for putting this together

Did you (or anyone else) manage to find out what is the rate of standard springs as fitted to a 225 Coupe facelift?

Just trying to get some idea of how much stiffer these are over the standard fitment

Cheers


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## A8VCG

Thought i'd relight this badboy.

Make: Koni
Model: 1150 5057
Product number: fronts 2230 1350 / rear 1533 04 7120
Front spring rate: 230lb (progressive) - 42KG/CM
Rear spring rate: 533lb (Linear) - 95KG/CM
Adjustment: height (F/R), Rebound (F/R)
Verdict: Unsuitable for Quattro 3.2 variant









http://forums.vwvortex.com/showthread.p ... ring-rates


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## mike_tt 2018

i hope i'm not ruining this thread - if it's not the kind of response you want on here, i apologise.
i'm just after some information on what suspension setup i should go for.

i'm a complete novice with suspension setups, so any advice would be greatly appreciate. i'm on a budget so the top end is out of my reach unfortunately. top wack i'm willing to push £700, as i have to factor in labour cost to.

i'm looking for a setup that will give me good, fast road use mainly, and decent enough to do the odd track day.

i've been told the following are decent setups, but would love to hear your guys input on it, as it seems you know far more about this than i do.

https://www.apcoilovers.com/ap_coilover ... .php?id=58

https://www.cbauto.co.uk/gaz-gha-coilover-gha336-2

thanks for any help/advice.


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## desertstorm

I would go for the GAZ coilovers. I have GAZ gold coilovers on my TT , Bit outside your price range but the quality of GAZ stuff is good. They can be rebuilt as well if required and spares are easy to come by. 
If you can specify the spring rates you want something like 550Lb/in on the front and 850Lb/in on the rear . The ride quality even with the higher spring rates is still good.


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## mike_tt 2018

desertstorm said:


> I would go for the GAZ coilovers. I have GAZ gold coilovers on my TT , Bit outside your price range but the quality of GAZ stuff is good. They can be rebuilt as well if required and spares are easy to come by.
> If you can specify the spring rates you want something like 550Lb/in on the front and 850Lb/in on the rear . The ride quality even with the higher spring rates is still good.


thank you for your input.

did you fit your setup yourself or take it to a garage? i've been warned off taking it to a local garage as the setup needs to be done correct to get the best out of it.

also, i was advised to install an adjustable rear bar:
https://www.cbauto.co.uk/adjustable-con ... ms-tiebars

this sorts out any negative camber when taking the car lower than..30mm i believe it was.

was this something you had to install with your gaz coilovers?


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## infidel.uk

I have the H&R monotube and the rear springs are actually not that firm, anyone willing to suggest something stiffer, or is that not advised ?

I suspect this is probably because i have a boot full of audio equipment.


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## wheeliegood

desertstorm said:


> I would go for the GAZ coilovers. I have GAZ gold coilovers on my TT , Bit outside your price range but the quality of GAZ stuff is good. They can be rebuilt as well if required and spares are easy to come by.
> If you can specify the spring rates you want something like 550Lb/in on the front and 850Lb/in on the rear . The ride quality even with the higher spring rates is still good.


Those rates sound high for road use? but do you know what the actual front & rear motion ratio's are ? to calculate the wheel rate..

R


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## desertstorm

Front motion ratio is 0.97 rear motion ratio is 0.63 .
There is a really good thread here on TT suspension by Max Clesca.
https://forums.vwvortex.com/showthread. ... suspension


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## wheeliegood

desertstorm said:


> Front motion ratio is 0.97 rear motion ratio is 0.63 .
> There is a really good thread here on TT suspension by Max Clesca.
> https://forums.vwvortex.com/showthread. ... suspension


Ok, thanks so that's a very even front / rear set up and I thought the rear trailing arm design looked a low ratio
Front .97 of 550 = 533 and the rear .63 of 850 = 535 on a what 1450kg car?

I've got a classic Transaxle 2.7 Porsche that is a Full time Race car, weighs 1030kg and has 450lbs front & 800lbs rear with ratios front .90 (405lbs) and rear .55 (440lbs) .

The front was on 550, but we had too much understeer...

R


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## desertstorm

My car is pretty well stripped and is a road legal track car. Comes in around 1280Kg with half a tank of fuel. With decent shocks the ride quality is still quite good.


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## wheeliegood

desertstorm said:


> My car is pretty well stripped and is a road legal track car. Comes in around 1280Kg with half a tank of fuel. With decent shocks the ride quality is still quite good.


Ok that looks familar, lots of time and money directed at a car project !"

I lost 250kg from my Pork, what did yours start at before you added lightness?

Do you have a Laptime from Donnington (Normal circuit, not the Melbourne loop)?

R


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## tadope

In my search for a good track street coilover. I got some feedback from st

225 2001 tt quattro

ood morning and thank you for that information. The spring rates for the specific ST XA kit for your vehicle are as follows:

Front 400lbs per square inch

Rear 632lbs per square inch

ST XA Kit number 18210041

You can go the maximum spring rate of 150lbs per square inch over what we already equip with this kit. Let me know if you have any other questions that I may be able to assist you


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## desertstorm

Hard to get a good track / street suspension setup. It's not only the spring rates that define how well the suspension is going to perform the dampers are just as important. Having a high spring rate will help to stop roll and keep the car more stable in corners, If the damping cannot cope with the controlling the springs or is too overdamped then the ride quality can be quite poor. My springs are a pretty hard but the ride quality is not that bad on the road because of the adjustable dampers.
I believe that the ST XA dampers are made by KW and have adjustable damping so should be good quality. I would go with the 150 Lb extra rating on the springs and soften the dampers for road use and you should hopefully get the best of both.


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## tadope

Thanks good advice. I agree, I think the xa kit is very good. 
It is just a "tiny" bit out of my budget.
I found ceika coilovers. they use gaz shocks and custom build the set for you to whatever spec you want.
shipped to my door it would be around 1100. I think that's the best deal for a full blown perfectly sorted track setup.

Temporarily though i'm just going to put some random ebay coil springs on there, and possibly some bilsteins. idk, but better to test it with cheap stuff then dump all that money on a car i'm not used to yet.


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