In this post
My MX5 NC already has some chassis bracing both on the front struts (see the images in my previous posts)and on the chasis rails underneath the car (see below), in this post new upgraded bracing goes it to try an improve already excellent handling.
The why of it
From the start the aim has been to create a grand touring track day car and in my post on the new BC Racing Coilovers, I mentioned that the car had acquired a kick when changing gear under load and whilst this was not a track day problem it was a put off when driving on the street.
The forums suggest that this can be chasis kick caused by the relative softness of the previous suspension no longer soaking up the chasis twist from the rotation of driveline.
It may also be a contributing factor that I Polybushed the rear suspension and the diff bushes where replaced with even harder poly bushes.
Sites like Flying Miata suggest that it is difficult to overdo chasis rigidity and forums have suggested improved feel in the driving experience.
For all these reasons and because they are hidden underneath the car I pushed the go button the IL Motorsport X-Brace and Rear Suspension Lower Brace as a first step in bolstering chassis rigidity.
Why IL Motorsport?
Only because I liked the look of the parts (they’re red) and in comparison to others they seemed pretty good value. I didn’t buy the full kit because I’d heard that the OEM front suspension tower brace is pretty good anyway and doesn’t really need replacing and the OE front bar (before the X brace) could be upgraded later as it is still pretty substantial.
Instalation
So you need to have confidence that the suspension won’t collapse when you start loosening bolts, and you’ll need to take a moment to search google for the installation instructions which didn’t arrive in the box and then a further moment to get your head around the instructions before you start any of this.
I lacked the confidence to pull the bolts without chocking the subframe but it was either overkill or additional body stabilisation for the whole operation.
I found that you need to pull the bolts out first, then instal from the back forward as the suspension brace sits under the cross brace. The hex bolts supplied replace the originals from the cross brace (I wasted 10 mins trying to work out why the wouldn’t bite on the suspension bars).
The instructions also give torque settings for all the bolts, but these are pretty low. I triple checked them all with a torque wrench.
Impressions
They are both light and strong, the OEM x-brace could be flexed with my hands but the new one could not. Once I worked out what went where and how, it all went on pretty easily.
As the rear module sits on top of the existing subframe rails it does hang down below the chassis and lower suspension arms rails a little (~1 – 1.5cm), the X brace less so as it is a replacement for the original. So if you have clearance issues you’ll need to work around these when driving over an obstacle or like me when pulling off the drive.
It does not seem to foul the BBR exhaust that I can see, but it gets a thorough shake-down test next week at Thruxton.
How the mod affects handling is something I’ll find out next week when I’m back on track.