Tony Posted January 1, 2008 Report Share Posted January 1, 2008 I have a curious question.... When the coils are set it's probable the lower platforms are not uniform over the axle.... My question is this..... Unsprung there are no issues but sprung and dynamically i assume there would be.... I wonder to what extent and how to address this Quote Link to comment Share on other sites More sharing options...
Sam@TDi Posted January 2, 2008 Report Share Posted January 2, 2008 Ok I think to start with you need to be a bit more specific about the method used to "set the coils" .... are you setting the ride heights level on a car with uneven weight distribution?... or are you setting up a perfectly balanced car with poor quality coil springs that just happened to have all come out of the box with differing spring strengths?... or have you deliberately manipulated the ride heights to influence weight distribution at the contact patches? Quote Link to comment Share on other sites More sharing options...
Tony Posted January 2, 2008 Author Report Share Posted January 2, 2008 The car was a Lotus Elise and we needed to set the body height so the markers on the undertray-to-ground were uniform on each corner. Once done it was evident that the coil platforms were set at different lengths in particular over the front...... To my knowledge the Elise has a very good CG so i ponder to why there is such a disparity. My question is.... If one coil is more compressed/relaxed will this change the rate and the dynamics.... FYI the cambers front/rear are even. Quote Link to comment Share on other sites More sharing options...
Sam@TDi Posted January 2, 2008 Report Share Posted January 2, 2008 Cool ok your right the Lotus Elise is very evenly balanced but still not perfect. So I'd guess the differences in the positions of the lower spring platform come from poor tolerances in the original spring strengths and the slight imbalances of the chassis. Yes this will effect the way the sprung and the un-sprung masses interact with one another and therefore it will effect the dynamic movement and subsequent weight transfer. Personally I don't like adjusting ride heights by adjusting springs pre-load (which is exactly what you were doing) I prefer to adjust it by mechanical means and leave the pre-load on my springs even all the way around the car unless otherwise called for by the set-up. All Penske, and most high end Ohlins and Tein coilover suspension units have separate adjustment for ride height independently of spring pre-load. And for a competition car, serious road/track application I would always suggest double checking that all of your coils are of the correct strength before you fit them and it's not a bad idea to monitor them throughout the season. Quote Link to comment Share on other sites More sharing options...
Tony Posted January 2, 2008 Author Report Share Posted January 2, 2008 I'm worried now...... The car is one of four i'm setting for the track..... According to the data the chassis is true and i fail to see how the coils could be out of manufacturing tolerances to need such compensation. The pre-load disparity is a real issue for the track.... Would it be wise if i experiment with the damper ratios Quote Link to comment Share on other sites More sharing options...
Sam@TDi Posted January 2, 2008 Report Share Posted January 2, 2008 Well your barking up the right tree as the softer coils will need slightly more compression damping and slightly less rebound damping. But I wouldn't suggest you start just tweaking randomly hoping to pick up a difference because the feed back you'll get from most drivers won't be anywhere near reliable enough to use for this type of work. The only way to know for sure would be to remove the springs and have the spring rates accurately measured. Or perhaps just suggest to the customer that they purchase a better suspension kit, one with reliable coil springs and a mechanical ride height adjustment. Although to be frank I doubt your drivers will really notice anything particularly negative about the current suspension set-up. Unless their lap times are regularly consistent down to within couple of tenth's then I wouldn't worry to much about this level of accuracy. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.