Coil over alternatives?

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srichards
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Coil over alternatives?

Post by srichards » Sat Jun 04, 2022 10:06 am

Taking the car out the other day made me realise how much I detest coil overs. Every road that's not billiard table smooth is like banging down an endless flight of stairs on your arse. The KWs are slightly better than the ancient Bilsteins that were on before but it's not that great.

So possibilities are: a set of springs and dampers that are entirely separate designed for a more comfortable ride and possibly stiffer anti roll bars to compensate ie the Rover method. Is there a stock alternative spring and damper that was used instead of the DRC system? Stiffer anti roll bar recommendations? Is it better to have soft spring and firm damper or the other way around? The suspension needs to be more forgiving without going full space hopper/pogo stick.

Or air suspension. https://airride.co.uk/air/shop/air-susp ... rformance/

If the soft ride of Jonny Smith's Cedric can be done with air then it should be possible to get something a little firmer but not uncomfortable.

My other car even on 21 inch wheels with skinny tyres is nowhere near as bad as either the Bilsteins or KW suspension I've had on the RS in the time I've had it. It's even known for its apparent poor ride quality but it's still far more forgiving over rough roads.

It's an endless can of worms that I've not solved yet.

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Re: Coil over alternatives?

Post by Shoppinit » Sat Jun 04, 2022 10:23 am

Which Bilsteins did you have? I find mine very comfortable on the PSS9* - very similar ride comfort as my friend's RS4 b7 on DRC sports when it was newish. The PSS are well known bone rattlers.

For a damped system, you need a particular spring rate and damping force which is determined by the sprung mass and the frequency you want to damp. Small oscillations (such as those on a very smooth surface) require a different spring rate / damper combo to big oscillations (crap surface, bumps, etc.). It's the eternal problem in speccing a damper and spring rate to cover as wide a range of oscillations you're likely to get during driving conditions.

Lots of clever ideas have been tried to try to get around this limit. From magnetic dampers (to alter the damping rate) to the infamous DRC junk. Don't forget that the initial press reviews of the C5 RS6 were somewhat critical of the hard ride, even with factory suspension.

I don't know much (anything, really) about air suspension. I assumed it was a sacrifice of handling in favour of aesthetics.

*except big bumps / dips. I hate those. But I drive on a lot of less than optimal surfaces in mine. Probably I should have been a scooby fanboi because I love single track country lanes with grass growing down the middle.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
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Re: Coil over alternatives?

Post by srichards » Sat Jun 04, 2022 10:48 am

Not sure which model. The Billsteins were on the car when I got it.

It explains why the Billies were better over bigger bumps but more tiresome over smaller imperfections. The KW are better on smaller rougher bits of road but slam your arse into the scenery for bigger imperfections. They do have some clever bump stops that are supposed to control the rebound but I've not noticed them actually doing that job well at all.

The air suspension can be used for the daft lowering but I'm assuming you can set the ride quality of the car as well. Adaptive air is used in a lot of big fat cars and it seems to do it all.

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Re: Coil over alternatives?

Post by Shoppinit » Sat Jun 04, 2022 11:00 am

The C7 RS6 has air suspension as an option, but I don't think it's anything like these slamming kits.

This is what I hate about suspension questions: how do you compare? If you are lucky then you can have a back to back comparison on the same car (or model) with different setups, but unless you know a lot of local owners then it's tricky. Otherwise you have to take an expensive punt and hope for the best.

You can get others' opinions but they have the same problem as you: Limited experience of other setups.

Maybe you could find someone on PSS9 (or other) who will take you for a ride. What region are you in?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Coil over alternatives?

Post by srichards » Sat Jun 04, 2022 11:41 am

It's very difficult. Also suspension behaves differently with age as well so once it's had a few years of use it's different to when it's new. I've fiddled about on previous cars and made them worse. Stock suspension seems to be better most of the time.

What we need is the YouTube guy that does tyre reviews to do comparative suspension set up reviews.

I have found one youtuber that is testing the PSS10 and is using an iPhone app to test vibration. I'd think this is the sort of thing to do. Go over known regular local roads and film it each time with old set up and new set up then it's possible to see what the difference is.

https://www.youtube.com/watch?v=xvrSGJfZs40

The basic problem is usually the stock suspension is the best of all but with the Audi the DRC was crap to begin with and for some reason the after market uses that as the low bar rather than trying to make the car what it could have been with a better suspension.

Ohlins don't make RS6 kits either. Had those on a previous car and they were very nice.

I'm in the Midlands so not too far from anywhere.

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Re: Coil over alternatives?

Post by Shoppinit » Sat Jun 04, 2022 12:24 pm

Good video. Confirms what I've found that even with 9 settings on the PSS9, there's only really scope for adjusting between 2 and 4. Anything higher than that and the car is underdamped and, in my experience, dangerous.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Coil over alternatives?

Post by srichards » Sat Jun 04, 2022 4:25 pm

I think I might try the separates route first unless Sachs or Ohlins do something decent.

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Re: Coil over alternatives?

Post by srichards » Thu Jun 09, 2022 12:32 pm

Has anyone checked ride quality with the same coil overs with both 18 inch and 19 inch wheels? Are the 18s much better or is it just the same? Wheels are looking a bit shabby and tyres need changing so I'm wondering whether dropping a wheel size might be something to investigate as well. I changed from 21 to 19 on the other car and I can't say it was a radical difference at all. It just means not wincing as much every time you go over a pothole as the 21 inch wheels were made out of kitkat biscuit.

The 255/40 on an 18 would be a 4 inch sidewall. Half an inch bigger than the 35 profile.

The 225/45 is also a 4 inch sidewall and with a reasonable choice of tyres. The 255 is lacking in the 18s.

Would 225s look a bit skinny? Would 255 aggravate the old nobbly issue?

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Re: Coil over alternatives?

Post by Shoppinit » Thu Jun 09, 2022 12:34 pm

Probably it's more to do with the weight of the wheel rather than the diameter. Unsprung mass is much more difficult to dealwith and only the tyres are helping with the damping there.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Coil over alternatives?

Post by Shoppinit » Thu Jun 09, 2022 2:38 pm

FWIW I don't think the RS6 looks very good on 18's.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Coil over alternatives?

Post by Mɐʇʇ » Thu Jun 09, 2022 4:44 pm

I’m still happy with my koni setup and hotchkis arbs. I’ve had that in, what, 6 or 7 years now.
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Re: Coil over alternatives?

Post by srichards » Thu Jun 09, 2022 5:02 pm

Mɐʇʇ wrote:
Thu Jun 09, 2022 4:44 pm
I’m still happy with my koni setup and hotchkis arbs. I’ve had that in, what, 6 or 7 years now.
I'd be interested to know more about that. Have you got links to all the parts of it?

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Re: Coil over alternatives?

Post by srichards » Thu Jun 23, 2022 1:22 pm

Had the height adjusted of the current coil overs to be as high as it can without squishing the springs. It's a bit better. It's still too firm at times but some of the smaller bumps it just floats over rather than etching them onto your arse.

KW do a street comfort version of the KW1s but not for the RS.

Will leave it like this until next year I think. Then decide whether to go air.

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Re: Coil over alternatives?

Post by V!per » Thu Jun 23, 2022 7:41 pm

srichards wrote:
Thu Jun 09, 2022 5:02 pm
Mɐʇʇ wrote:
Thu Jun 09, 2022 4:44 pm
I’m still happy with my koni setup and hotchkis arbs. I’ve had that in, what, 6 or 7 years now.
I'd be interested to know more about that. Have you got links to all the parts of it?
I think It's standard RS6 Springs with Audi S6 KONI Shock Absorbers:
Part Number: 151 14113
Part Number: 151 09552
And Hotchkis Sway Bars - Not easy to get:
https://www.hotchkis.net/product/2003-2 ... uspension/

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Re: Coil over alternatives?

Post by Mɐʇʇ » Thu Jun 23, 2022 8:43 pm

Sorry, I missed this post.

This was my bible for it, inc part numbers : https://www.rs6.com/showthread.php/2394 ... low-Sports

For the roll bars, I bought them from summit in the US : https://www.summitracing.com/parts/HSS-22827
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