Nürburgring Compliance: KW Automotive’s five-way damper

Setting up a car for the rigours of the Nürburgring 24 hours is one of motor racing’s great challenges. Suspension company, KW Automotive, worked hard to develop a five-way damper to give teams such as Porsche and BMW set-up options previously unavailable on their GT3 cars. Although the 24-hour race was shortened by rain and fog this year, car set-up was crucial for the sprint to the flag and performed well enough on Olaf Manthey’s 25th anniversary at the ’Ring for him to take the victory.

‘We just launched a new specification for the Manthey car, and that will be a future GT3 damper, which will also be on the BMW M4 GT3,’ confirmed Thomas Rechenberg, head of motorsport at KW Automotive. ‘We have built from a single adjustment to a five-way adjustment and developed it on the seven-post rig with the Manthey car. The damper has a cartridge system, so basically, we are benchmarking against Öhlins and Multimatic, looking at what they are doing now, seeing how we can put strength into our modern system.’

The damper is an update to the company’s four-way damper that was introduced in 2017 and campaigned successfully at the ’Ring in the VLN series (now called the NLS). From the extensions seen over brows of hills to the compressions in dips, plus aggressive kerbs and changes in track surface, the Nürburgring is a uniquely demanding circuit, and suspension development is key to good lap times and traffic management. ‘What we learned from our four-way damper is to have a really short valve opening time, and so the opening time is extremely short with our new product,’ says Rechenberg.

‘On the Nürburgring, you need to have a short valve opening because if it is too long, you have two choices – no grip because your valve is too often closed, or your car bottoming out because it is always open.’ All ways ahead While the five-way damper is the gold standard in the range, KW continues to offer two, three and four-way dampers for competitors in the 24-hour race. ‘The two-way damper is pretty easy, solid damping technology with no reservoir, so is affordable to small teams in the RCN or GLP, but for the NLS and the Nürburgring 24 hours, we are always providing the five or three-way adjustable dampers,’ says Rechenberg.

Development has been ongoing on the seven-post rig with Porsche and BMW in preparation for the season, and KW found it was going softer on spring settings than expected. That gives the flexibility to run offline, a pivotal point to racing in a multi-class formula where cars regularly overtake traffic. It also gives the teams better options in adverse weather conditions. ‘If you are driving a single lap in super pole and you are on the line, then everyone is quick,’ says Rechenberg. ‘As soon as you leave the line to overtake, though, other cars were completely lost.’ Managing the kerbs is always a key to surviving the 24 hours, as often cars will have to run over them to avoid contact with other cars, while the nature of the track can heavily punish minor mistakes.

‘You build a car that is basically half rally because sometimes you have to cut through the grass,’ notes Rechenberg. ‘We thought that maybe we also needed to fit hydraulic bump stops into the road course damper because we think it is necessary.’ Softly-softly Setting the cars up at the ride height required for the Nürburgring is also a challenge for the GT3 teams, with a minimum ride height of 70mm specified, far higher than other circuits. In this case, it is preferable to have a softer spring that will sit the car down under load. For example, at full speed on the Dottinger Hohe, which will then help to reduce drag. ‘For us, it is a very difficult story,’ admits Rechenberg.

ADAC TOTAL 24h Nürburgring 2021 – Foto: Gruppe C Photography

‘Our development advantage, what we might be working with, can be taken away when you get a smaller restrictor, or more weight, because of our top speed. On the other hand, we always have to work with a homologated car, and if you stop developing, you are not competitive anymore. ‘These soft springs give the option to drive dynamically lower, which gives you better downforce, less drag and therefore more top speed. You enter the NLS 1 or NLS 2, and they see that the Porsche has gained top speed, and they wonder where that is coming from. You then receive more weight and a smaller restrictor [from the BoP engineers], but you have to work like this.’

Having such changes in set-up creates a huge problem for the engineers managing the Balance of Performance, too, as their job is to look at the physics and try to come up with a fair system, but they can only go so far into the data for each car. ‘The BoP is now a bit blind,’ says Rechenberg. ‘If they are working on tyre wear, and you give the car a set-up that allows it to work offline without compromising tyre wear, how is that going to be judged by Balance of Performance? You can have a good lap but also be quick over a stint.

‘Then you have other manufacturers who can do one quick lap in the race and then see their pace dramatically fall off. That is making the whole process harder to handle.’ One of the keys to understanding suspension set-up is, of course, to have data from multiple cars, and for the Nürburgring 24 hours this year, KW supplied 61 cars, around 50 per cent of the grid. Not all of them were in SP9, and not all of them featured the latest damper technology, but all were equally as important to the company. ‘GT4 is probably a more important category for us,’ admits Rechenberg. ‘We will do the next [BMW] M4 GT4, and we have done all the AMG GT cars, apart from the Toyota and the Porsche, so we don’t want to lose ground there, either.’

Development is allowed in the SP9 class at the Nürburgring and, with BMW’s M4 testing at Spa mid-June, more data has been gathered to help with the set-up sheets available to Porsche and BMW customers under the new homologation. Under current rules, dampers are homologated into GT3 by the manufacturers with no option to change mid-cycle, which means race data is harder to come by other than open test days or open technical regulations. Prototypes ahead; however, the company has also its sights set on slightly different targets. Having secured the GT3 win at the Nürburgring and partnered with BMW, KW is also looking at the new Hypercar and LMDh rules to supply one of the chassis manufacturers and OEMs that are interested.

It won’t be Porsche or Audi as the VAG companies have signed with Multimatic and so will use its suspension technology, but Rechenberg is confident KW will be on the grid in Prototypes at Le Mans. ‘We are in good contact with one of the chassis manufacturers and one of the manufacturers,’ he says. ‘I think the possibility to end up in one of the projects is quite high, and it is still open from the rule side whether or not the damper will be a manufacturer part or a chassis design part. The Americans are favouring the cost side that the dampers are part of the chassis design, but the ACO wants to give manufacturers a little bit of freedom, but that is something that is not yet decided.’ What is likely is that GT3 will be at Le Mans in 2024 at the latest, and that puts KW Automotive on the grid at the world’s most famous endurance race with cars that will be capable of securing class wins. The development work that continues to be done on the Nürburgring will certainly put KW in good stead for that eventuality.

END

The post Nürburgring Compliance: KW Automotive’s five-way damper appeared first on Racecar Engineering.