KW Clubsports & linear springs

[EMP07]

Looking to up the spring rates on my clubsports. Called KW and they indicated that i should NOT be swapping out the rear progressive for linear. Lots to do with the nature of the suspension set-up and not being a "coil-over".

Looking for member guidance and feedback on this.

Thoughts?

[F360C]

Did KW mention any reasons behind why they think it is bad to run a linear spring on a none coilover rear?

I am interested to know the reasons why because I would like to switch over to a full coilover rear in the future

I believe The Platte Forme guys in Cali run that red line time attack m coupe with KW club sports but have substituted all the springs for Hypercoil spring

[seank]

I would assume that it would have to do with the rebound and compression nature they designed in the strut. Different struts have a range which they work well. IE ground control and tc kline are good from 400-800 lb spring and its resisiance on a graph is linear.

It would seem that it would be difficult to go from a strut designed for a progressive spring to a linear, due to the resistance not being correct. At least if ride quality is important.

You should be able to install a larger sway bar, which is progressive by nature. That might work for what you need. What are you attempting to do?

[EMP07]

seank - i'm simply trying to stiffen up the ride for the track (I plan on 2-3) and for the spirited drives up and down santa cruz hills

They specifically define the rear suspension to be progressive based on a non-coil over design. I simply did not understand this and wondered if other did as there seem to be linear rates people are running with AST and TCK etc?

My target is 500 frt and 600 rr. The clubsports are surprisingly soft.

[seank]

F1soul-

It sounds like you may be wanting the struts to do more than they are capable. It has to do with that particular model: the clubsports. From my understanding, they were designed to be a very street friendly design. I have not owned them. Just going off of what I have read on this forum.

That type of spring rate is usually used on a coilover that is atleast single adjustable.

Hopefully someone who has experience with this particular model with linear springs will chime in regarding the effects.

[crfine88]

I agree that the clubsport run a little "soft"
I have been looking into swift springs and like the idea of a true coilover in the rear. Most companies are running linear springs in the rear (GC, TKK, etc) and they work. I think KW may be concerned about running linear springs that are too short and could have the potential of working themselves out of position.

Companies like GC, TCK, H&R and Vorshlag use different rear height adjuster, so maybe they have the safety aspect of using linear spring in the rear figured out. The other issue is noise. The progressive spring is more forgiving in the chatter department because even when the suspension is fully extended, the progressive spring maintains contact with the body of the car.

her is a pic of a true KW rear coilover on a Z4. Can't find a part number for it, but there it is

[The HACK]

I would be surprised if they did that coil-over installation right. BMW didn't put in nearly enough reinforcement to allow coil-over springs to be attached to the shock tower. The ONLY way you can run a coil-over rear on the Z4 chassis without it literally punching a hole through the back side is if you weld your cage directly to the rear shock tower and reinforce the f**k out of it, so the force from the springs are spread out onto the cage structure.

[modernbeat]

Yep, and I wonder what they are doing with that car. That's a quickchange rearend under there.

[beta]

I'm also interested in this topic. I previously posted a thread on Swift spring conversion for V3s. My reason is I'd like to tighten up the rear a bit, but also prevent the coils from rubbing and groaning under full compression.

If the springs are going to be chatty as crfine mentions, then it might not be a good solution.

I've thought about just changing the rear shocks as well, but there doesn't seem to be anything that isn't either very loud or very expensive like mcs. I don't know about the clubsports, but the V3s have reservoirs that make replacing the rear brake pads a bit of a chore (you can disconnect from the top mount if you have one, but it would be nice to not have to).

[inTgr8r]

Originally Posted by The HACK

I would be surprised if they did that coil-over installation right. BMW didn't put in nearly enough reinforcement to allow coil-over springs to be attached to the shock tower. The ONLY way you can run a coil-over rear on the Z4 chassis without it literally punching a hole through the back side is if you weld your cage directly to the rear shock tower and reinforce the f**k out of it, so the force from the springs are spread out onto the cage structure.

Bingo!
I've seen this attempted on other makes without proper reinforcement.
The results were not pretty.

[onelove]

Originally Posted by modernbeat

Yep, and I wonder what they are doing with that car. That's a quickchange rearend under there.

It's Mike Essa's competition FormulaD Drift car.

http://www.motoiq.com/magazine_artic...t-monster.aspx

Some build details, the entire car is caged and seam/stitch welded.

[The HACK]

Originally Posted by onelove

It's Mike Essa's competition FormulaD Drift car.

Would have been my first guess based on that double caliper setup on the rear.

[EMP07]

I found a set of KW 600lb 60mm rear springs at 5.5".

I'm going to test fit them at the same time I swap out the fronts for 500lbs.

I'll post updates.

[crfine88]

Originally Posted by F1soul

I found a set of KW 600lb 60mm rear springs at 5.5".

I'm going to test fit them at the same time I swap out the fronts for 500lbs.

I'll post updates.

Very interested in you findings.

If you run into coil chatter or noise from the rear springs, check out these articulating spring perches from rogue. I am thinking about trying these out.

http://www.rogueengineering.com/rogu...SH/RE-ASP.html

[seank]

Originally Posted by crfine88

Very interested in you findings.

If you run into coil chatter or noise from the rear springs, check out these articulating spring perches from rogue. I am thinking about trying these out.

http://www.rogueengineering.com/rogu...SH/RE-ASP.html

Now that is cool and worth every penny. Good find.

[inTgr8r]

^WHS... very cool idea!

[EMP07]

Very cool indeed. Must give RE some credit.

I would assume spring length and rate play a role, to what extent I don't know.

[pal]

One thought on why the clubsport rear springs are progressive is to allow for more grip over uneven track surfaces. A softer intial rate will let the suspension soak up the undulations better while keeping the tires planted.

[inTgr8r]

^sounds plausible.

[seank]

Slightly off topic, unless you have wheel chatter:


http://www.rogueengineering.com/rogu...SH/RE-ASP.html

BTW. Ground Control has this same part for cheaper. I will be installing it tomorrow, as well as many other suspension parts. I will let you know how it goes.

[flipm3]

Originally Posted by seank

Slightly off topic, unless you have wheel chatter:


http://www.rogueengineering.com/rogu...SH/RE-ASP.html

BTW. Ground Control has this same part for cheaper. I will be installing it tomorrow, as well as many other suspension parts. I will let you know how it goes.

Nice! Not only cheaper, but Ground Control was the first to develop this articulating perch. GC released this MANY years ago ahead of RE.

[EMP07]

Originally Posted by flipm3

Nice! Not only cheaper, but Ground Control was the first to develop this articulating perch. GC released this MANY years ago ahead of RE.

Yes, GC did develop this years ago and it is cheaper. but on it's own it is flawed. A reinforcement plate was added after this type of failure was discovered on the e46.



Thus they created a reinforcement plate.



RE actually brings these to together and is made of better materials. In my opinion the RE are much higher quality. Kudos to GC for acknowledge the need for a "weight jack" or articulating perch.