Cup Racer EE Brackets & Roll Centre Correction - The Numbers...

[R20BTG]

One thing that I’ve heard mentioned on this forum is the lack of ‘numbers’ surrounding the performance difference between OEM front end setup and the ‘cup racer’ front end setup. The 'cup racer' setup consists of correcting roll centre and bump steer characteristics by:

- Raising the front subframe
- Lowering the connecting point of the front suspension arm

I'm not going to repeat other articles about roll centre correction

Roll Centre and Roll Moment – How To Adjust And Tune Suspension Secrets

Roll Centre and Roll Moment - The roll centre positions of your front and rear suspension geometry are key features affecting the lateral...

suspensionsecrets.co.uk

Roll Centre Correction - The Pinderwagen

The Roll Centre of a vehicle has a large impact on handling but it`s something not many people fully understand. A “roll center” (RC) is a theoretical point around which the chassis rolls when cornering and is determined by the design of the suspension. - That`s all well and good but it…

pinderwagen.com

Tech Explained: Roll Centre

www.racecar-engineering.com

This is achieved in the Clio by:

- New 'EE' brackets (named after the diagram used in the 2008 Clio Cup chassis handbook). What we refer to as the 'EE' support is named because it connects Point E (wishbone ball joint) to Point E' (lower swivel hub rotation point).
- The motorsport 'EE' support has both a lower and offset connection point compared to the road car version which widens track, increases caster and camber
- Longer driveshafts are needed due to wider track from moving the bottom of the swivel hub outwards
- Adjustable anti-rotation links are needed to match the new wishbone position.


The 'cup racer' setup also corrects bump steer.

Bump steer - Wikipedia

en.wikipedia.org

Bump Steer Explained: What It Is, Causes & How to Eliminate It! | Low Offset

If you’ve lowered your car & haven’t corrected for bump steer, you should. This guide will help you to understanding what bump steer is & learn how to fix it.

low-offset.com

Bump Steer – Suspension Secrets

Bump steer is a change in the steering angle of the wheel when the wheel is in bump or droop without turning of the steering wheel

suspensionsecrets.co.uk

This is achieved by:

- Raising the steering rack by adding a spacer beneath
- Lowering the connection point of the TRE to the swivel hub by adding a spacer above.
- The TRE need extending to deal with the wider track

It used to be that you could get this kit by using Renault parts but these are getting scarce. Pure Motorsport (PMS) have developed their own version:

Clio 3 RS Cup Racer EE Bracket kit

Clio 3 RS Cup Racer EE Bracket kit

www.pure-motorsport.co.uk

You'll have seen from my project thread that I've had all this done.

First of all, the subjective, non-numerical butt-dyno feedback. It makes a noticeable difference for the better. Front end turn in grip is increased, understeer is virtually eliminated, body roll and weight transfer feel significantly reduced. The car feels much more eager to turn into a corner and keep the desired line. That said, this is all subjective and I would say that given that it probably cost me two grand all in. I’m not gonna say it’s shit.

However, I also have the benefit of having recorded extensive data via 10Hz GPS two years in a row and I have two data sets that can compare.

Disclaimer(s):

• I’m not a professional racing driver, I’m a bloke who likes to drive on track days.
• I don’t claim to be able to extract 100% of the car’s performance over the course of a lap. I suspect the car is capable of much faster lap times than I am.
• I’m not good enough to say that I’m consistently at the limit on a corner-by-corner basis.
• I’m driving my own car, so there is going to be an element of self-preservation when it comes to my commitment.
• Because of the nature of the Nurburgring, over such a long lap, it is inevitable that I will come across traffic, or have to move over for faster cars, meaning that I might not be on the perfect line for each corner. Therefore the data should be looked at as a trend rather than irrefutable corner-by-corner statistics.

The data sources are:

Sample 1
Nurburgring Nordschleife
1st July 2022
Bridge to Gantry (BTG) 08m 44s
OEM EE brackets
OEM driveshafts
OEM steering rack and height
Solid subframe with +5mm height (Josh Wheeler solid mounts)
MRF ZTR Tyres (new) 28psi hot
Gaz Gold set at 20F 18R
PMS rear beam strengthening kit
3.1 degrees of camber
Slight toe out on the front
Polybushed front suspension arms.
Dry track, sunny conditions, approx. 16:00

Sample 2
Nurburgring Nordschleife
29th June 2023
Bridge to Gantry (BTG) 08m 34s
PMS EE brackets
PMS extended driveshafts
PMS extended track rod ends
PMS steering rack spacers (approx 9mm)
Solid mounted subframe with +5mm height
Total of 16mm roll centre correction
MRF ZTR (same set as 2022), scrubbed, 28psi hot
Gaz Gold set at 20F 18R
PMS rear beam strengthening kit 3.1 degrees of camber
Parallel toe
Solid PMS bushed front arms.
Dry track, sunny conditions, approx. 18:00.

The two data samples are relatively close in terms of time of year and time of day. Interestingly, Sample 1 was a flying lap start on a TD so my starting speed at Bilstein Bridge at 111.3mph, whereas Sample 2 (the faster lap) was taken from a TF session meaning it was a standing start from the barriers, at 78.1mph.

I picked these corners as ‘landmarks’ throughout the course of a lap. If anyone wants to do a deeper dive into the data then I’ll happy make them available in .CSV format.

Hatzenbach
Apex Speed 2022 - 77.1mph
Apex Speed 2023 - 76.1mph
Overall Result - 2023 apex speed 1mph slower

Flugplatz (1st Apex)
Apex Speed 2022 - 100.7mph
Apex Speed 2023 - 101.0mph
Overall Result - 2023 apex speed 0.4mph faster

Flugplatz (2nd Apex)
Apex Speed 2022 - 100.6mph
Apex Speed 2023 - 103.7mph
Overall Result - 2023 apex speed 3.1mph faster. In 2023 I was taking Flugplatz flat in 5th whereas in 2022 I recall having a security lift. This additional speed is then carried all along the next fast section leading to Schwedenkreuz.

Schwedenkreuz (arrival speed)
Top Speed 2022 - 122.0mph
Top Speed 2023 - 124.3mph
Overall Result - 2023 arrival speed 2.3mph faster, probably due to the gains found at the previous corner by taking Flugplatz flat out and not lifting.

Schwedenkreuz (apex speed)
Apex Speed 2022 - 107.4mph
Apex Speed 2023 - 89.6mph
Overall result - 2023 apex speed 17.8mph slower. I suspect this shows that I was either catching slower traffic over the crest or being caught myself and having to move out of the way. Despite my slower apex speed over the crest on this lap, this was the faster overall lap.

Foxhole Compression
Apex Speed 2022 - 115.2mph
Apex Speed 2023 - 126.4mph
Overall Result - 2023 apex speed at the compression 11.2mph faster, clearly I found my big boy pants in 2023 and I was taking the Foxhole flat in 5th.

Miss Hit Miss (Apex Speed)
Apex Speed 2022 - 77.4mph
Apex Speed 2023 - 83.8mph

Miss Hit Miss (Exit Speed)
Exit Speed 2022 - 95.7mph
Exit Speed 2023 - 100.9mph
Overall Result - big improvements in 2023 through this section, minimum apex speed 6.4mph faster which translates to a peak exit speed 5.2mph faster.

Ex-Mühle (Entry)
Entry Speed 2022 - 78.7mph
Entry Speed 2023 - 82.2mph

Ex-Mühle (Exit)
Exit Speed 2022 - 56.6mph
Exit Speed 2023 - 64.9mph
Overall Result - again decent gains through here in 2023, entry speed 3.5mph faster leading to exit speeds 8.3mph faster. This is important as it leads to the Lauda Links. I’m told that I could be even faster through this section as I have a dab of the brakes just before corner entry but I’m told it can be taken flat in a Clio. Perhaps one to practise next year.

Lauda Links
Peak Apex Speed 2022 - 86.8mph
Peak Apex Speed 2023 - 103.5mph
Overall Result - I don’t think this tells the full story on the 2022 lap, I suspect again I was either behind traffic or moving over for others.

Mutkurve
Peak Apex Speed 2022 - 90.3mph
Peak Apex Speed 2023 - 100.2mph
Overall Result - almost 10mph quicker in 2023, this is one of the corners that I wanted to work on. By taking a wider entry using the rumble strips on the right on entry and letting the car run wide right on exit I was able to take this flat, which is a bit scary as it’s a 5th gear blind left hander. Mutkurve is translated as ‘courage curve’ for good reason.

Hohe Acht (Left Hander)
Apex Speed 2022 - 74.7mph
Apex Speed 2023 - 75.0mph

Hohe Acht (Right Hander)
Apex Speed 2022 - 74.7mph
Apex Speed 2023 - 76.1mph
Overall Result - only marginally quicker in 2023

Wipperman
Apex Speed 2022 - 82.6mph
Apex Speed 2023 - 82.3mph
Overall Result - near as damn it the same

Pflanzgarten Jump
Jump Speed 2022 - 87.1mph
Jump Speed 2023 - 103.5mph
Overall Result - found my big boy pants again and took this flat in 4th in 2023 whereas I’ve never done that before and either had a dab of the brakes before the hump, or just a security lift. I can’t really put this down to the car, this was just having a bit more confidence that the car would deal with it.

Pflanzgarten 2 (drop away)
Peak Speed 2022 - 100.5mph
Peak Speed 2023 - 104.5mph
Overall Result - 4mph quicker in 2023, could be that I’m arriving quicker because I’m carrying more speed through the preceding corner.

Galgenkopf 1
Apex Speed 2022 - 77.2mph
Apex Speed 2023 - 85.8mph
Overall Result - 8.6mph quicker in 2023, I was lifting in 4th whereas beforehand I was braking a little to scrub some speed off.

All this translates to a lap that was 10 seconds faster overall. Whether this is to do with the new front end of the car I don’t know, but looking at this I’d say that I am a little faster here and there in general. The largest gains seem to come from the fast stuff where I have more confidence to either turn a lift into a flat out section, or turn a previous dab of the brakes into just a lift.

Of course, I’m drawing conclusions from data that may or may not be true, so feel free to debate and discuss.

I've been asked whether it is worth it. Overall it's an expensive upgrade and chances are you'll need to replace things (I replaced track rod ends, a swivel hub ball joint and a damaged ABS sensor). You'll also need the geometry redoing. It has made a difference, so if you have the money it definitely changes the behaviour of the car for the better, but value is determined by your own situation.

 

[RSRowe]

Busy day in the office?

 

[burrellbloke]

Good information Ian.

It is really helpful that someone who has made the upgrade has given some feedback. There are cars out there with a "cup racer front end" but not people I have the chance to speak to or ask questions.

The science seems to make sense that if your car is more like a cup racer it will be able to perform more like a race car than a road car.

Ethan priced this up a few weeks ago and with the parts from Pure it was about £1,950 including some solid bearings for the wishbones. I am fairly confident that provided the car doesn't blow up or suffer some horrible damage in an accident that we will go for this set up next year. That is after stiffening up the rear beam and swapping out the bushes for bearings on the beam.

I am hoping that after acquiring the parts they can be installed on the drive and then taken somewhere to sort out the geometry.

Did you manage to get the car set up so that your wheels did not destroy your arches and wing (not your arch liners)?

 

[R20BTG]

Busy day in the office?

Coming from the guy who spent the morning rendering videos [emoji1787]

 

[LiamP]

Great write up, in my rather limited testing I would agree with everything here, interestingly the percentage improvement in times was about equivalent. It’s just a shame it costs so much, I do wonder if similar improvements could be possible with a tubular subframe / RC correction.

Overall the car just felt like it had so much more to give, limitation became the driver.

 

[Jack Maxwell]

Nice write up. Be good if PMS could make an EE bracket that doesn't add so much castor and cause the bumper to rub and need trimmed. That's the main thing that is holding me back getting the kit.

I did see you can pull some caster back with the adjustable anti rotation link. Is there enough room to pull back enough to stop the rubbing?

 

[R20BTG]

It rubs under compression, it’s shaved away the inside of the outer wheel arch plus a bit of the rear of the bumper. I have been discussing a fix to this with [mention]jambo [/mention] but haven’t got there yet. Will report back.

 

[Marsch]

I saw the pic with how far to the front the wheel was moved after your mod but mine did exactly the same after I got my KW Clubsport installed. In my case it rather was the height and width (20mm spacers) combo and not the castor (mine didn't change much) that caused this. It may still help adjusting it but I'd say you presumably also have to go higher and/or smaller in the front to avoid this in the future.

Just my 2 layman cents.