KW V3 Swift Spring Conversion

[beta]

I emailed Harold over at HP autowerks asking about their Swift Spring Conversion kit and he mentioned that they haven't done one for Z4M yet, so he'd have to measure, etc.

Anyone interested in something like this? Maybe if there's enough of us I can organize a group buy.

Info on the conversion kit.

Info on Swift springs

[tikamak]

I'm interested in a group buy for swift springs on KW V3 here
Just need the same springs rates (progressive) without the need to revalve your shocks.

[beta]

Swift springs are linear, unfortunately they don't make progressive springs. From the reviews on the e46 forums though they say the ride is actually better with the swifts than with the progressive stock springs. Still trying to wrap my head around that one.

Didn't see anything about needing to re-valve the shocks. AFAIK the shocks are very similar to the ones the clubsport kit uses, so they should just work.

[Beedub]

Originally Posted by beta

Swift springs are linear, unfortunately they don't make progressive springs. From the reviews on the e46 forums though they say the ride is actually better with the swifts than with the progressive stock springs. Still trying to wrap my head around that one.

Didn't see anything about needing to re-valve the shocks. AFAIK the shocks are very similar to the ones the clubsport kit uses, so they should just work.

the shocks are not similar to the clubsport units ;-) drop kw an email.

[beta]

Good idea, I've emailed them (and the german company) to see if they'll clarify. From other car forums though the valving is either identical, or it's slightly higher because they had to shorten the stroke to fit pillowball mounts. I don't think the clubsports for Z4 M have pillowball mounts but I could be wrong.

Hopefully they'll get back to me and we'll have clarification.

[beta]

Here's what I got back:

Our V3s for your application has progressive springs front and rear.

Our clubsports has a 400 LBS/INCH in front and progressive in the rear.

Difference between the 2 are simple. Our clubsports have different internals and oil as well as an option for our top mounts or not.

Both height ranges are front- 0.4-1.5 inch and rear- 0.2-1.4 inch. Also our clubsports DO NOT have our life time warranty like our variants do.

Please let me know if you have any other questions and have a great day.

[tikamak]

What is the recommended swift springs that would work flawlessly with the KW V3 ?
I recon it should be lower than 400, like 350, 260 something like that.

I'm very interested in this as i haven't installed the KW V3 yet, is it possible to have this stream going as soon as possible?

My concerns in order of importance:
1- Reliability
2- Comfort
3- gains in performance

[Beedub]

Originally Posted by beta

Here's what I got back:

Our V3s for your application has progressive springs front and rear.

Our clubsports has a 400 LBS/INCH in front and progressive in the rear.

Difference between the 2 are simple. Our clubsports have different internals and oil as well as an option for our top mounts or not.

Both height ranges are front- 0.4-1.5 inch and rear- 0.2-1.4 inch. Also our clubsports DO NOT have our life time warranty like our variants do.

Please let me know if you have any other questions and have a great day.

thats pretty much what i was told, the clubsport internals are setup very differently to cope with the different demands placed on them, remember the clubsport units are developed @ the nurburgring.... the v3 are a street coilover system and are insanely comfortable, much better than the stock units but are almost ... too comfortable....

the clubsport is very aggressive but imo on the softest setting isnt really to far away from the stock ride..... and i LOVE the new adjustment wheels that kw units come with now.

[beta]

Originally Posted by tikamak

What is the recommended swift springs that would work flawlessly with the KW V3 ?
I recon it should be lower than 400, like 350, 260 something like that.

Here's what Harold said:

Since we have never had a request for a stock like ride, the rate to start is 400F and 500R. 350F and 400R will certainly ride better, but the rear may bottom because of the low rate.

Originally Posted by tikamak

I'm very interested in this as i haven't installed the KW V3 yet, is it possible to have this stream going as soon as possible?

My concerns in order of importance:
1- Reliability
2- Comfort
3- gains in performance

Reliability should be great based on everything I've read about these springs.

Comfort I'm not sure. A linear spring is supposed to be harsher than a progressive spring, however some people have commented that after doing the conversion it feels better because the spring responds quicker (being lighter). This is my biggest concern.

Gains in performance will definitely be there, a linear spring will improve handling and make weight transfers more predictable.

Originally Posted by Beedub

thats pretty much what i was told, the clubsport internals are setup very differently to cope with the different demands placed on them, remember the clubsport units are developed @ the nurburgring.... the v3 are a street coilover system and are insanely comfortable, much better than the stock units but are almost ... too comfortable....

the clubsport is very aggressive but imo on the softest setting isnt really to far away from the stock ride..... and i LOVE the new adjustment wheels that kw units come with now.

I'm going to disagree with you Beedub. I have the V3s and although they are more comfortable than stock, it's not by much. The biggest improvements I've noticed are when going over uneven terrain. Before I'd catch some air, now the tires stay firmly planted. The high speed damping is much better than stock.

Even though the V3s are progressive, the final spring rate is much higher than stock. From this thread (note that he wasn't able to measure the 4" of travel on the rear KWs):

Stock:
Front
1", (preload) 280lb
2, 440lb
3, 620lb
4, 840lb

Rear
1", (preload) 240lb
2, 480lb
3, 720lb
4, 1140lb

KW:
Travel, Load on tester
1", 320lbs
2", 485lbs
3", 720lbs
4", 1140lbs

Rear
1", 220lbs
2", 480lbs
3", 840lbs

Which is roughly:
Stock Front (1-4 inches of travel after preload)
160-220

KW V3 Front (1-4 inches of travel)
165-420

Stock rear (1-4 inches of travel)
240-420

KW Rear (1-3inches of travel)
260-360

The 4th inch of travel on the KW rear would be at least 460, but probably higher.

[beta]

So I think I might actually do the conversion. I need help deciding on spring rates.

Options are:
336
392
448
504
560

Was thinking 400/500, or maybe 400/450. What do you guys think? Mostly street driving.

[Gt4]

Originally Posted by beta

So I think I might actually do the conversion. I need help deciding on spring rates.

Options are:
336
392
448
504
560

Was thinking 400/500, or maybe 400/450. What do you guys think? Mostly street driving.

Buy my KW Clubsport springs that I have for sale.

400 front and progressive rear

[tikamak]

I have built my personal opinion based on research and some calculations:
1- It is not safe to use linear springs on Clubsport in the rear
2- It is not safe to use linear springs on KW V3 in the front and the rear
3- It is not recommended to use progressive springs with KW V3 that have 5% increase in lbs.inches across the travel curve in inches.

So concluding, it is not safe or recommended to use these springs with KW V3. Kw Clubsport is wonderful on the track on the Z4M platform especially when trying to control under-steer.

I can let a professional tracker like TheHack for example chime in on suspension mechanics. Having some body roll is not necessarily a bad thing and i have learned on my KW V3 that this suits the driving style of the Z4M and I bet that's why KW decided to use this design (linear front, keep the rears progressive) in their clubsport.

When my car is understeering in a corner, usually I just apply more gas and lock up the rear 10% in corner when i go in the corner the next time. I see the little body roll as a driving aid to the car that would tell you where the grip is and when is the car ready to let go of the pavement.

[beta]

@tikamak: Can you share why you came to those conclusions? Lots of people have done the swift conversion and all the reviews I've read have been positive. The extra rate shouldn't be a problem, as the final rates of both front and rear are pretty high. However not being an expert I'd really like to understand this better and would really appreciate your info.

@Gtfour: the main reason I'm doing this is to get rid of the progressive rears. They bind under full compression, and talking to KW and other members this is normal for the kit.

[Gt4]

Originally Posted by beta

@Gtfour: the main reason I'm doing this is to get rid of the progressive rears. They bind under full compression, and talking to KW and other members this is normal for the kit.

If interested, I can sell 2x Hyperco springs for the rear: 550-60mm-6''

So you would get 400 front / 550 rear.

I am running 550/650 and I would like to go with 650/750

I am looking for $240 for the 6 springs and 2 top plates.

Let me know if interested

Marc

[beta]

Thanks for the offer Marc. I'm set on swift springs though (pending info from tikamak).

[beta]

This is kind of cool, found a spring rate spreadsheet by vorshlag. They measured the KW V2s for Z4 M.

KW V2 Front 10" length
1" 160
2" 324
3" 500
4" 694
spring rates: 160-164-176-194

KW V2 Rear 7" length
1" 227
2" 499
3" 917
Spring rates: 227-272-418 (after 3" starts to bind so rate shoots up)

So it would seem one could run as low as 224/336

Options are then: 224/336, 280/392, 336/448, 392/504. Part of me thinks I should go as low as possible to match the valving of the V3s. I was thinking of replacing the whole suspension with ASTs, but their 4(X)50s are taking forever.

[tikamak]

I read the technical specifications sheet of the KW V3 and how is the valve constructed to have damping and rebound characteristics based on how the springs load curve is drawn.
Based on this, I have made the conclusion that it is not recommended or healthy to change the curve in which the spring will accept load and rebounds.

You might argue that the highest load rate of the KW V3 spring is higher than the linear spring of swift's that you are choosing but that will bring you 2 problems:
1- this means that when the car is heavily loaded (bump or pothole(on compression phase)) the linear springs will bottom out since they are not providing the necessary rate at this compressed state.
2- this means that you will be needed to increase the compression and rebound of the shocks to avoid case 1, If you do that you will have a bad gripping mechanism on the street since the shocks are designed in the following way: the dampers will play the fishing game (loose when you need them to be loose and stiff when things get exciting (hard compression and rebound)) and this is designed to give you the highest tyre contact possible without compromising grip or comfort.

If you need track professional tracking coilovers, the KW V3 is not very suitable as they do have this valving pattern, you will need to go with clubsport.

If you need track only suspension, then you need moton or ohlins or such coilovers.

If i were you, i'd switch my KW V3 with clubsports or just learn to drive on the KW V3 with max results.

[tikamak]

Sorry for the double post.

Personally, I'd learn to drive with the KW V3 as i think that these are brilliant coilovers, far more evolved than anything i have seen before.

If you ever get the chance to take a hydraulics course in engineering school, you'd know exactly why i think these are brilliant, they are simply astonishing coilovers.

Just do a little test and try to go over a relatively big speed bump without slowing down on them, the way they absorb this road imperfection is simply genius: The shocks decide not to dampen when you're going on the bump (compression phase) then between this point and the point when you reach the tip of the bump and the compression phase is reversed, the shocks will progressively dampen and slow down the car's movement upwards and do the same behavior on rebound phase.
This happens without going into full compression or full rebound (which makes this behavior viable on the track).

As an analogy, imagine you are running on this road and trying not to move your head vertically, just observe how your legs behave and absorb the imperfection of the bump without your head feeling anything.

This makes the KW V3 give you outstanding tyre contact patch across most compression and rebound phases. personally i've been able to go up to 290 KM/H on very bumpy roads without ever feeling the car is going out of hand, Just because of a good alignment and correct bump, rebound settings.

Body roll at the track is your friend to maximize driving skills. If you drive a stiff car, it will be harder for you to learn how to approach a corner and feel the car under you and how it behaves on the apex and how to control understeer and sometimes oversteer.

[beta]

Thanks tikamak, both posts have very good info.

To be honest I'm happy with the performance of the V3s. The high speed damping that you talk about is really apparent. There's a rough patch of road where I used to feel the tires get airborne on the stock setup. With the V3s the tires stay in contact with the road the whole time. My only issue is how the rear springs bind.

I emailed ohlins see if they'll do a road & track coilover for the Z4 M, they have one for the e90 and apparently e92. If they come out with one I'll sell my V3s on here and I'm sure someone will be happy to have them.

[tikamak]

How do you feel that ?? Did you contact KW ?? I didn't see anything wrong with the spring coils yesterday when I was lowering the rear.
Could it be that your setup has a glitch int it ??

[beta]

Yes, contacted KW (both KW US and Germany) and made a thread about it. I also got PMs from a few members that told me they had the same issue, one of them solved it with cable wrap.

Both contacts at KW said it was normal for progressive springs.

I really hope Ohlins comes through for us. It's only about $800 more than the KWs. I think my only other option for an upgrade is moton or mcs, but I'm not about to spend 7 grand on suspension.

[Beedub]

if i was you guys id be happy with the v3 but dial up the settings on the rebound maybe?? i find the clubsports rock hard on the road.... its not something id want to ride around in everyday, infact im glad to get out the car at the end of driving it all day!! lol, its very in keeping with that ive done to the car and how i use the car... but imo on an everyday car its way to hard, at the recommended KW settings i can feel my eye lashes vibrating when i driving along... lol