Quote:
Originally Posted by gmx
I agree with you to an extent. Frequency primarily depends on what rubber you're using. I presume you're on slicks and nothing less? Oversteer is very vague. I recall you had oversteer in entry/braking, the rest was good?
FCM relies on the big bar soft spring theory. Nothing really wrong with it neither new with it actually.
I have noticed since the E36 generation with "professional" race cars the driver applies such input and the the front end of the car visibly oscillates and even skips along the surface. I see this a lot on American race-prepped E36s but I do not know anything about the condition of rubber, track, ie. surface type etc. The tyre, roll-centre, surface type are key variables regardless of suspension, specifically front/rear spring rate coupling. I've assumed they don't know wtf they're doing and have slammed the front for more static camber while ruining or not correcting the roll-centre. Who knows. Or maybe crap tyres, brash inputs etc - a lot can cause that.
Anyway, I NEVER see such things on raeder motorsport (Manthey Racing), schirmer cars lapping the ring. You can see this slight behavior in my own car at 0:38 in the first video.
I agree with cwlo , much of the stuff is tuned for understeer. These brands have a reputation to uphold. And to add, most of them copy eachother without doing any engineering. More than we think imo.
@tsk94 To get your frequencies, you have unsprung weight for the M3 noted down, right? Would you mind sharing them, specifically the front/rear knuckle and rest of the factory arms.
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Yeah, the oversteer was primarily entry-mid corner. All of that has been sorted since now I'm experimenting with tire setups and tweaking damper settings now that the alignment and ride heights have been sorted. I'm running R-comps and scrub slicks.
Yes I have all of the unsprung weights. With that being said I'm not running any factory arms, all have been replaced with spherical arms. These vary a decent amount depending on my wheel and tire setup but ~110 for the front corners, ~100 for the rear (total). I have the individual weights from when we built the car and I added them up, but that's buried somewhere in a pile of paperwork..
I'm not saying that FCM's approach cannot work, I hope I didn't come across that way. But, from my experience, the vast majority of well-setup track and race cars are running higher front freq. And beyond that, you could make a 'flat-ride' approach setup understeer biased with things like alignment and ride heights.
Also to add onto the soft spring, big bar theory thought. I agree this is nothing new. TC Kline implies basically the same principle, the difference being he doesn't try to maintain a higher rear freq compared to the fronts.
I will agree that a lot of the street or semi-trackable stuff is very likely understeer biased. This thread pertains to track spring rates so that theory doesn't hold as much.