VikingPower

KW Clubsport Spring Rates

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Hi Guys

Short question About KW clubsport. 

I have on order a KW clubsport 2way for BMW M135i
Becuase of wheel size i will need a shorter spring. 
The OEM 80-170 spring are made of 11mm wire diameter 

The shorter 80-140 spring are made of 10.25mm wire diameter.
the shorter 100-140 are made of 11mm wire diameter. 

Which spring should i choose if i want to keep the suspension to be working with Semi slicks like NS2R and AR1?
Car is undergoing a clubsport conversion, but it is also a daily driver. 


Please help a newbie .. 
Thank you! 

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Hi, would it be an option to delete the helper spring? So in that case you would get much space for the wheels. 

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I dont think its at good idea to remove the helper spring.. It is there to keep tension on the spring it self, when tires are in the air. :-) 

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Hi,
what is the exact reason for the short Springs? Clearance between wheel and spring?
5-10mm Wheel spacers normally do the job pretty well, when combined with much more camber than your were running lately.  -2,5° - -3,1°
And for the the AR1 f.e. you will need that much camber anyway.

I´m pretty sure that the diameter/thickness of the spring wire is not changing the overall diameter of the spring.

Besides, softer springs than standard for the CS do not make to much sense IMHO.
 

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vor 37 Minuten schrieb Krabbenschubser:

Hi,
what is the exact reason for the short springs? Clearance between wheel and spring?
5-10mm wheel spacers normally do the job pretty well, when combined with much more camber than you were running lately. -2.5 ° - -3.1 °
And for the AR1 fe you will need that much camber anyway.

I'm pretty sure that the diameter / thickness of the spring wire is not changing the overall diameter of the spring.

Besides, softer springs than standard for the CS do not make to much sense IMHO.
 

Hi
The exact reason are clearance between wheel and spring yes.
Spacers are illegal in Dänemark, that is the reason to why  i cant run that.
The diamater of the spring do change a bit, but that is not the problem when changing to the shorter spring. but would it be better to use a shorter spring with the same material thickness which is somewhat a harder spring? (100-140)
Or should i choose the spring with the same hardness, but with the shorter spring, but this is thinner than the original spring? (80-140) 

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I think there are more parameters to consider, than just spring rate and wire diameter, when changing to a shorter spring. Maybe you need a different helper spring as well, who knows. I'd make sure to clear the technical backround, instead of guessing which spring could work.

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You won't have a benefit of using a different spring.

They all have the same inner diameter of 60mm. So the shorter one will gain you 0,8mm more space between tire and spring, but i don't think will help you much.

A stiffer spring doesn't help you ether. The space between tire and spring doesn't change. In your case wheels with a different offset might be the only option.

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vor 12 Minuten schrieb Fab#469:

You won't have a benefit of using a different spring.

They all have the same inner diameter of 60mm. So the shorter one will gain you 0,8mm more space between tire and spring, but i don't think will help you much.

A stiffer spring doesn't help you ether. The space between tire and spring doesn't change. In your case wheels with a different offset might be the only option.

sure i will.. a 30mm shorter spring will give clearence almost above the tyre.  
This Photo here of a kw clubsport on a m235i does show a 30mm shorter spring will give the clearance needed.. question is though, what spring? The one with same spring rate (80) and shorter length (140) or the higher spring rate (100) on the shorter length of (140).
OEM are still 80 spring rate and 170 length the 11mm core.

KW CS 18x8.5 et45 +12mm spacer (ET33).jpeg

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So i tried to paint an illustration here.. 
The pink painting area, is where the spring perch will be set, with the same lowering of the car in original picture, but with a shorter spring.  

Spring perch.png

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Okay, i thought the tire protruded further beyond the spring. Im not 100% sure about the free travel of the KW spring. But for H&R Spring it is 80-140 = 87mm travel and 100-140= 83mm travel. H&R don't offer spring with 170 length. The 80-160 has 95mm of travel and the 80-180 has 105mm of travel. Lets assume that a 80-170 spring is in the middle with 102mm travel.

So by changing from 80-170 to 80-140 you loose 15mm of travel in compression, before the spring is fully compressed. You could use 100-140 to stiffen up the suspension but then i would also change the spring on the rear to keep the balance.

But as already mentioned, KW support you on this.

bearbeitet von Fab#469
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vor 13 Minuten schrieb Fab#469:

Okay, i thought the tire protruded further beyond the spring. Im not 100% sure about the free travel of the KW spring. But for H&R Spring it is 80-140 = 87mm travel and 100-140= 83mm travel. H&R don't offer spring with 170 length. The 80-160 has 95mm of travel and the 80-180 has 105mm of travel. Lets assume that a 80-170 spring is in the middle with 102mm travel.

So by changing from 80-170 to 80-140 you loose 15mm of travel in compression, before the spring is fully compressed. You could use 100-140 to stiffen up the suspension but then i would also change the spring on the rear to keep the balance.

Aah okay that makes sense then :-) 
I am not totally sure on upgrading the rear spring, why? because of this: 
My car F21 M135i: 80-170 Front spring rates and Rear spring rates 120-200.
F22 M235i : Front 90-170 spring rate and rear spring rate 120-200..

So even the f22 have a higher spring rate in frontend with the same rear spring.. maybe i should buy the 90-140 spring instead of the 100-140 spring? 
An m235i and a M135i are basically the same car.. :-) 

I like this forum, thanks to all who is anticipating.
Edit: I wrote an email to KW yesterday, so i am just waiting for their confirmation, but maybe someone in here have the knowledge i look for :-) 

bearbeitet von VikingPower

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I don't think spacers are a solution, because the front spring is just way too long and in the way to fit any proper tires. If you keep the stock spring with your M135, you won't fit any more tire than 235 realistically.

Changing the spring for a shorter and harder one is absolutely common and in my opinion more than recommended. I think KW says if you go for a spring that's 30mm shorter you should up the spring rate by 20n/mm, so for example 110-140. The stock spring is also too soft, so you should go for a harder one anyway! You lose spring travel and you have to compensate that by going for a higher spring rate.

I had a M240i with 120-140 springs up front and 140-200 in the back and it drove perfect and way better than stock - a friend of mine also still drives that on his M140i. I also changed the spring to fit 255 tires up front. KW themselves say, they only fit springs that long to give much room for height adjustment.

No need to change the helper spring too. I can guarantee you the following to work with your M135, keeping the stock helper springs: 120n/mm - 140mm long springs front and 140n/mm - 200mm springs rear.

bearbeitet von xerik

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vor 22 Minuten schrieb xerik:

I don't think spacers are a solution, because the front spring is just way too long and in the way to fit any proper tires. If you keep the stock spring with your M135, you won't fit any more tire than 235 realistically.

Changing the spring for a shorter and harder one is absolutely common and in my opinion more than recommended. I think KW says if you go for a spring that's 30mm shorter you should up the spring rate by 20n/mm, so for example 110-140. The stock spring is also too soft, so you should go for a harder one anyway! You lose spring travel and you have to compensate that by going for a higher spring rate.

I had a M240i with 120-140 springs up front and 140-200 in the back and it drove perfect and way better than stock - a friend of mine also still drives that on his M140i. I also changed the spring to fit 255 tires up front. KW themselves say, they only fit springs that long to give much room for height adjustment.

No need to change the helper spring too. I can guarantee you the following to work with your M135, keeping the stock helper springs: 120n/mm - 140mm long springs front and 140n/mm - 200mm springs rear.

Hi Erik

Much thank you for your review off this. That is exactly why im choosing the shorter springs, to fit 255 tires up there in the front end. 
with your details in mind and the KW recommendation, i will choose the 100-140 spring.. for now i will keep the stock rear springs and see how it performs.
I guess with the stiffer springs in front i also dont need to upgrade the swaybar because the car will handle more flat. 
I have an apointment with Manthey Racing 2/7-21 with alignment and corner weight setup ( i will do a basic alignment for the travel). Should i have adjustable endlinks for the car?
Hopefully i can try and adjust the suspension on TF same Friday, and then on Sunday 4/7 enjoy the car and learn the track better.. I only have 2 laps on NOS.

Everyone who wants to have a chat is welcome, but i cant speak German, sorry.. :-) 
 
 

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