Suspension misconceptions - Preload and height adjustment

[JamesBryan]

Been reading a bit more about alignment and suspension setups recently.

One thing i came across was some posts from guys who setup race cars, like LMP2 and such like. They had a few interesting things to say which i couldn't quite get my head around until they linked to this video.



Pretty much blows some of the myths out of the water and it's good to know for someone like me who has BC's which can be adjusted via the lower collar as demonstrated in the video.

What do you think @NorthloopCup i know you're a bit of a wizard with chassis setup.

 

[PhillipM]

Some of that is b****cks really, the rebound and rebound damping curve required *will* change depending on the spring preload. because you change the forces especially near full rebound travel. Changing the handling and chassis behavior too.
Usual case of a little bit of knowledge being a dangerous thing. What they're also not showing there if you look is although the spring length ends up the same when loaded, the damper position is very different for different preloads. So you use your lower adjustment as well as your preload to get the ride height you want with the bump and rebound travel you want. And altering how much compression/rebound travel you have respectively does change a car behavior.
Not always an issue on a car that's built from the ground up to use full compression possible, definately an issue when fitting aftermarket kits (which are generally just combinations of universal internals in a case to fit) to road cars.
The other thing is those long bumpstops are a lot more progressive than their short, soft ones, they're designed to be run on, not just a stop. Showing a race car doesn't prove anything because usually the long stops are for long travel road cars - there's a reason you see those fitted to almost every road car OEM system going. I can quite easily fully compress those kind of stops on the racers that they try to show being too hard - because if you're hitting the bumpstops hard, you've got a lot more force than just the single load of the car they're showing there (obviously, otherwise you wouldn't be hitting the bumpstop, you'd be at normal ride height) - I've split a few of them doing it, you tune the bump stop to the the use case.

It's a rather wishy-washy PR piece tbfh. I get that they're just trying to show people that you shouldn't wind the spring perches up and down and expect the car to suddenly be stiffer or softer, but it could have been done better.

 

[JamesBryan]

I think you're right in terms of adjusting both to get the ideal setup.

 

[NorthloopCup]

How long is the video? I struggle to get time to watch anything nowadays!

 

[David172]

How long is the video? I struggle to get time to watch anything nowadays!

7 mins

 

[NorthloopCup]

7 mins

Ah ok. That’ll be about 2hrs to watch in snippets then lol

 

[bashracing]

My Mate Paul was world swearing champion 1996 he was also a chassis set up engineer at Mclaren F1,
I'll see what he say about it, but his standard answer for stuff like is
"who the f**king f**k are these f**king clowns, more knowledge in the s**t i've just pushed out, etc etc"
regardless of if its right or wrong.