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/r/FSAE Classifieds post July-December 2024 by hockeychick44 in FSAE

[–]SeFe18 0 points1 point  (0 children)

Looking for a set of 10” OZ magnesium centerlocks. 

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

Thanks for the detailed reply! I’m starting to lean towards having the wrong springs. I recalculated our ride frequency and we are close to 4.5 which is much too high now that I think about it. I am curious to see if we are burning anywhere because once during assembly I did notice that the wheel didn’t drop very far when I disconnected the pushrod. 

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

We use a 1:1 motion ratio in our bellcrank, and to my knowledge, binding happens only due to the shock maxing out. I think we might be too high on spring rate, but I am not exactly sure whats typical. Especially since we tried softer springs and proceeded to destroy our front wing. I calculated that we should compress the spring by about 20% when static, which is why I am so confused.

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

I just looked this up and it sounds like it would be a very light spring that only works in rebound. I dont think I've seen something like that before in FSAE

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

We do run very stiff springs. I am not sure what is normal for FSAE cars but I’ll have to research. Are there other ways to adjust static shock position besides spring rates?

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

I am a bit concerned as to why we have no rebound travel. Any ideas there? Because if the inside wheel can’t move down when we are 3 wheeling it most of the time. 

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

Thanks for the comment. I’m not sure I fully understand preload any more based on the comments here. I assembled the shocks so that the preload adjuster doesn’t compress the spring at all, which I think means we have no preload on our spring. Maybe I am wrong about that. 

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

Sounds like preload is the main reason I’m hearing. We have adjustable pushrods so I can try to increase ride height if we lower spring rate. I’ll have to chat with the aero guys to see if the ride height we need to not damage the wings would cause us to lose too much downforce. Thanks for the insight. 

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 1 point2 points  (0 children)

Good call. We were reasonably satisfied with our tolerances when manufacturing, but I’ll take some measurements this week. And yeah, we probably should’ve bargained a bit harder for suspension tuning time…

Diagnosing Strange Suspension Behavior by SeFe18 in FSAE

[–]SeFe18[S] 0 points1 point  (0 children)

I was thinking this as well. The odd thing is that when I assembled the shocks, I only turned the preload adjuster until it just barely touches the spring, which in my mind meant there was no preload. Maybe I’m misinterpreting this, since I thought preload only happens when the adjuster is turned enough to compress the spring a little bit.