How low can you go? A fair question when you want to improve the stance (and perhaps performance) of your car, which happens to be an MG ZT 260.
My own car (see ‘Project Cars’ on this website) was bought a few years ago with 96K miles on the clock and (thankfully) a brand-new set of struts and dampers in the boot. The first job was to fit a tow bar given that it was going to have to earn its keep. Having gone to the trouble of removing trim for access to wiring, it made sense to fit the rear dampers. The fronts followed as they are a much easier swap. The old struts and dampers looked cosmetically poor, but no leaks. I was rather disappointed to feel no difference in body control when driving – a testament to the quality of the original parts.
So how low can you go? This depends on the vehicle. In the early days of ZT 260 and 385, the initial prototype cars had been handed over to us for assessment. We submitted them to our standard ‘EU test’, used throughout the days of MG Rover product development. It consisted of a drive to the Nürburgring (for a few laps on public days as we couldn’t afford to join the industry pool) making use of the many and varied road conditions available, including derestricted autobahn in Germany and poorly surfaced minor roads in Belgium.
One such road through Belgium, approaching the border with Germany, is of stone ‘pave’ construction with large undulations. At the 90 km/hour speed limit, the ZT 190 reference car was firm and abrupt but gave no cause for concern. Our ZT 260 by comparison was using more suspension travel and felt more ‘grown up’………… until the cabin started to fill with oil smoke. The sump had hit the road and damaged the drain plug. The ensuing oil leak burned on the exhaust and came into the car via the gear lever surround (the gaiter did not exist yet). We managed to fashion a repair and continue the test trip. It revealed the ZT 260 to be somewhat underwhelming in its dynamics, feeling rather heavy and cumbersome.
Back at base, we changed several tuning parts to improve handling balance, body control and agility. The sump pan was also modified, and a mushroom head plug used to mitigate the risk of an occasional scrape.
So how low can you go? To get all facts to hand (specifically the available suspension travel), I decided to strip down one of my old 96k mile struts. As an ‘upside down’ monotube, the bump stop (or spring aid) is contained within the unit. Unfortunately, the debris that I removed (see picture) would not have been acting as the designer intended! The spring aid (in good condition) provides a progressive rise in rate towards full travel and provides the final stop. Beware: sump to ground proximity alert. [As an aside, we have brought together a ZT 260 strut and damper refurbishment kit which includes new spring aids, dust covers, seals and labels – contact us for details.]
Lowering the car will improve stance, but also bring it closer to the spring aid contact point. By increasing the spring rate, the progression can be improved and for a given input, the dynamic ground clearance will be helped. Here at VHS Ltd, the dynamic performance is what matters. But it must also look right. Style and substance. We have decided to produce a spring kit for ZT 260 which will lower the car by 15mm and offer greater agility via careful selection of front and rear spring rate increases.
How low can you go? Yes, it could go lower. But I prefer to drive……