Flat Ride, Bounce Frequencies and Tires: A Question

[r4dr]

See this and timmo 's comment makes a lot of sense to me. This whole thing is very confusing. I know you either believe in flat ride or you don't, but saying that your standard chosen spring rates are better than a setup that according to math is a near perfect frequency ratio just because tires aren't included is just weird.

I'll pm you about the shop, I don't really want to call out a shop publicly, as there are plenty of different opinions on the forum.

Read your PM and responded, funny that it's exactly who I guessed.

I would say their comment was not technically incorrect in its basis, but everything from then on was plain misleading.

Does the tire have an effect? Yes. Is it something that we can measure and control for? Maybe in a vacuum. But the effect is a drop in the ocean. If your car is going to snap oversteer because your slicks with stiff sidewalls cycle out and you're running street tires for the day...

[Str8f4c3]

You can dial in/out understeer/oversteer with tire pressures at the track, but that's like the last 0.5% of adjustment. Think about all the different tires people run. If the tire as a spring really had a meaningful impact such as to cause "snap oversteer" don't you think we would see a lot more cars spinning out?

Someone should tell OEMs like Porsche, because to my knowledge all their setups have flat ride and god forbid that new GT3 RS spins out uncontrollably because the flat ride only works when the tires are exactly what the door card says...

Who is this shop? I really want to know.

See this and timmo 's comment makes a lot of sense to me. This whole thing is very confusing. I know you either believe in flat ride or you don't, but saying that your standard chosen spring rates are better than a setup that according to math is a near perfect frequency ratio just because tires aren't included is just weird.

I'll pm you about the shop, I don't really want to call out a shop publicly, as there are plenty of different opinions on the forum.

[r4dr]

You can dial in/out understeer/oversteer with tire pressures at the track, but that's like the last 0.5% of adjustment. Think about all the different tires people run. If the tire as a spring really had a meaningful impact such as to cause "snap oversteer" don't you think we would see a lot more cars spinning out?

Someone should tell OEMs like Porsche, because to my knowledge all their setups have flat ride and god forbid that new GT3 RS spins out uncontrollably because the flat ride only works when the tires are exactly what the door card says...

Who is this shop? I really want to know.

[timmo]

It's hard to say without tire data. My intuition would tell me sure, perhaps if you aren't running a square setup the delta in stiffness could have an effect on ride, the tires themselves will have a different cornering stiffness. But that factor alone being sensitive enough to cause snap oversteer is doubtful

[Str8f4c3]

I guess I take back my statement that the person knows what they are talking about. Also, who suggested the word “snap” before oversteer. Analytically, that would suggest a rapid response in the suspension, like excessive bump damping or running out of travel.

He did say "snap oversteer" which kinda surprised me, I've never heard that term associated with our cars. The whole thing kinda seemed a little odd as a comment and that's why I wanted to ask some of the Wizards here.

[T.J.]

He didn't use the terms compression and rebound, those are my terms, they just sound better than "squish" and "un-squish" that was going through my head at the time🤣

I guess I take back my statement that the person knows what they are talking about. Also, who suggested the word “snap” before oversteer. Analytically, that would suggest a rapid response in the suspension, like excessive bump damping or running out of travel.

[Str8f4c3]

More likely the person was talking about dampers when using terms like compression and rebound. I would say the person knows what they are talking about. Just think, all else being equal, wouldn’t greater rebound damping up front help both axles return to their neutral position at the same time?

He didn't use the terms compression and rebound, those are my terms, they just sound better than "squish" and "un-squish" that was going through my head at the time🤣

[T.J.]

So I spoke with someone at a well known suspension company today, and they said that the current theories on flat ride and bounce frequencies don't factor in the any compression/rebound (As I understood it) that come from tires, and it therefore throws the bias rearwards makes the cars prone to snap oversteer. Can someone comment on this? I had a near-flat-ride ratio on my last suspension setup, and was quite impressed with the ride of the car, but would like to know if this guy's comment holds any water. My car is aggressive street-only for reference. Thanks!

More likely the person was talking about dampers when using terms like compression and rebound. I would say the person knows what they are talking about. Just think, all else being equal, wouldn’t greater rebound damping up front help both axles return to their neutral position at the same time?

[Str8f4c3]

Correct, they don't factor in tires, we also confirmed this with Shaikh on the old forum. Tires would be pretty complex to factor in accurately because there is so much variation between manufacturers. Sidewalls have different flex, for comfort (think PS4S) vs aggressive driving and response (think rs4). Plus even running the same tire from the same manufacturer in different sizes would have an impact (like running a 245 vs a 265 on x9 rim).

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That's good to know, thanks! So realistically, flat ride as a theory isn't compromised as a result of not factoring tires?

[mrgizmo04]

Correct, they don't factor in tires, we also confirmed this with Shaikh on the old forum. Tires would be pretty complex to factor in accurately because there is so much variation between manufacturers. Sidewalls have different flex, for comfort (think PS4S) vs aggressive driving and response (think rs4). Plus even running the same tire from the same manufacturer in different sizes would have an impact (like running a 245 vs a 265 on x9 rim).

Sent from my SM-G950U using Tapatalk

[Str8f4c3]

So I spoke with someone at a well known suspension company today, and they said that the current theories on flat ride and bounce frequencies don't factor in the any compression/rebound (As I understood it) that come from tires, and it therefore throws the bias rearwards makes the cars prone to snap oversteer. Can someone comment on this? I had a near-flat-ride ratio on my last suspension setup, and was quite impressed with the ride of the car, but would like to know if this guy's comment holds any water. My car is aggressive street-only for reference. Thanks!