Hi, I am trying to troubleshoot an issue I am having. I am not sure if understeer is the best term but basically when crusing on the highway and going over some undulating roads, the car feels like its floating and wanting to push on the outside of the turn - so if I am going right, it wants to drift to the. Sort of like its on its but its not. I had new rear tires put on, a 4 wheel alignment done and had the suspension looked at but did not find anything. The tires were over-inflated (42 fr, 46 rr) and adjusted them to 37,39 which did make a difference but I still have this drifting type sensation.
Re: Diagnosing understeer/floating at highway speeds
The M5 can get floaty at high speeds (120mph+), but I think you might have some luck changing your tire pressure around. To reduce the amount of understeer, try 41psi front, 39psi rear. I have found this to be a great pressure to help keep the vehicle fairly neutral in turns and have the ability to power the rear around when needed. Hope this helps.
Re: Diagnosing understeer/floating at highway speeds
Thanks, I'll give those settings a try. The floating is happening even at relatively low speeds for the M5 (70 - 80 mph). It also seems to be tramlining more than I remember it being, so maybe the fronts are getting worn down
Re: Diagnosing understeer/floating at highway speeds
Floating at 70-80? Something is definitely wrong. My experience has been that the faster I go, the more planted it feels, at least up to 150 (haven't had an opportunity to exceed that yet).
How is the wear pattern on your tires? Even? Cupping? Inside-out?
Re: Diagnosing understeer/floating at highway speeds
Quote:
Originally Posted by Osodog
Thanks, I'll give those settings a try. The floating is happening even at relatively low speeds for the M5 (70 - 80 mph). It also seems to be tramlining more than I remember it being, so maybe the fronts are getting worn down
The M5 needs a suspension upgrade, to either stiffer struts/springs or a coilover suspension. I also noticed exactly what you are describing, at around the 60-70mph level, so I doubt anything is wrong with your M5. If you are used to driving sports cars, you will be much more sensitive to this "bouncy" feeling.
Re: Diagnosing understeer/floating at highway speeds
I know this will sound a bit nuts, but on tire pressures, I have found the best setup is 38 front/ 34 rear. I was really wearing out the middles of the rears and with this setup the steering takes on better weighting and the rears are wearing more evenly. I have purchased a pyrometer to help me see if if I have it right, but so far I havent had the time to go drive the car hard and take readings.
If you have any worries at all, I suggest you have the dealer inspect it and get someone who is familiar with M5s to take your car for a quick test drive with you in the passenger seat. Then you'll know if its a normal car and you are just extra sensitive or if you really have a problem.
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All the best,
Jerry 00 Z8 Jet Black/Red Sport / some others
Re: Diagnosing understeer/floating at highway speeds
Quote:
Originally Posted by PhilSeastrand
Floating at 70-80? Something is definitely wrong. My experience has been that the faster I go, the more planted it feels, at least up to 150 (haven't had an opportunity to exceed that yet).
How is the wear pattern on your tires? Even? Cupping? Inside-out?
I have to agree with the above statement. The one time I was at 145 the car just sucked down on the road. Very stable and confident.
Re: Diagnosing understeer/floating at highway speeds
The car had some decent toe-in (the right slightly more than the left), the outer edges of the front tires were getting worn. I will probably replace the fronts soon, hopefully that will help.
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