Ohlins R&T Spring/Sway Choice

[OldRanger]

The purpose in adjustable end links is to eliminated preload.

Got it. Thanks Obioban and eacmen .

As I understand:
The adjustable end links are ONLY intended for eliminating preload on the bar and nothing else. There are no dependencies between corner balancing and the sway bar - as long as it is a bar that has adjustable end links and it is properly installed without preload.

To do this properly, the shop will set ride height and corner balance concurrently. Then, using a sway bar that has adjustable end links they will adjust the links accordingly so there is no preload.

Do not confuse adjustable end links (side to side preload) with adjustable sway bars (stiffness)

(#tomanyconcussions)

Oh, and Ground Control gets a nod as a good front sway option

[Obioban]

Got it. Thanks Obioban and eacmen .

As I understand:
The adjustable end links are ONLY intended for eliminating preload on the bar and nothing else. There are no dependencies between corner balancing and the sway bar - as long as it is a bar that has adjustable end links and it is properly installed without preload.

To do this properly, the shop will set ride height and corner balance concurrently. Then, using a sway bar that has adjustable end links they will adjust the links accordingly so there is no preload.

Do not confuse adjustable end links (side to side preload) with adjustable sway bars (stiffness)

(#tomanyconcussions)

Oh, and Ground Control gets a nod as a good front sway option

Technically, adjustable end links also allow you to get the sway bar to be parallel to the ground (where it optimally functions). That's why you need two.

But, yes, the different mount holes in the sway are to select stiffness, so you can fine tune your front roll couple (oversteer/understeer).

[9kracing]

I'm very curious who came up with this "flat ride" thing, and what testing was used to come to those conclusions.

What problem is flat ride trying to solve?

I removed my Dinan suspension setup for Ohlins R&T with stock spring rates, and the car rides 100 times better. I don't understand how lowering my front spring rate would be an improvement.

Swaybars are used to dial in and out oversteer. Having too low of a spring rate in the front, where ALL of the weight of the engine is, would cause nothing but problems from everything I know about suspensions.

If anything I'm tempted to raise my front spring rate. I will occasionally scrape on undulating roads.

[cobra]

I'm very curious who came up with this "flat ride" thing, and what testing was used to come to those conclusions.

What problem is flat ride trying to solve?

I removed my Dinan suspension setup for Ohlins R&T with stock spring rates, and the car rides 100 times better. I don't understand how lowering my front spring rate would be an improvement.

Swaybars are used to dial in and out oversteer. Having too low of a spring rate in the front, where ALL of the weight of the engine is, would cause nothing but problems from everything I know about suspensions.

If anything I'm tempted to raise my front spring rate. I will occasionally scrape on undulating roads.

I researched the origins - it dates way back, pretty interesting stuff: https://www.millikenresearch.com/Mau...WFMilliken.pdf



I am currently running Ohlins spring rates (400/630) with stock sways and I like it a lot. Not what I'd consider super compliant, but the chassis balance and response is amazing.

If you're scraping you might need to raise your car.

[Obioban]

I'm very curious who came up with this "flat ride" thing, and what testing was used to come to those conclusions.

What problem is flat ride trying to solve?

I removed my Dinan suspension setup for Ohlins R&T with stock spring rates, and the car rides 100 times better. I don't understand how lowering my front spring rate would be an improvement.

Swaybars are used to dial in and out oversteer. Having too low of a spring rate in the front, where ALL of the weight of the engine is, would cause nothing but problems from everything I know about suspensions.

If anything I'm tempted to raise my front spring rate. I will occasionally scrape on undulating roads.

Every single oe car manufacturer, from Rolls Royce to GT3RS.

[mrgizmo04]

Because of geometry/angles/vectors (and some of those cos[theta] things), and why I "think" swaybar mounts get ripped out - is when the swaybar link is not perpendicular to the bar (or at least the line between the bushing and the endlink attachment hole).

Any angle from perpendicular is a deflection and force multiplier that sends (unwanted) force through the bushing/mount (in the fore/aft direction) vs simply rotating the bar within the bushing. So getting adjustable swaybar links is important not just for corner balancing and dialing out preload side to side, but also as you play around with different holes/stiffness settings on the bar, from soft to medium to hard holes, you introduce geometry changes with how the endlink angle changes and therefore unwanted forces multiplied and experienced at the bushing/mount.

Sent from my SM-S911U1 using Tapatalk

[9kracing]

Every single oe car manufacturer, from Rolls Royce to GT3RS.

What I meant is who came up with the recommended spring rates for our cars RE flat ride.

You only need your rear spring rate 10-20% higher than your fronts, and Ohlins are higher than that. So why is Ohlins not considered flat ride.

[oceansize]

What I meant is who came up with the recommended spring rates for our cars RE flat ride.

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/5660-fcm-e46-m3-ride-harmonizer-suspension-spreadsheet-aka-flatride

[cobra]

What I meant is who came up with the recommended spring rates for our cars RE flat ride.

You only need your rear spring rate 10-20% higher than your fronts, and Ohlins are higher than that. So why is Ohlins not considered flat ride.

You don't want spring rate 10-20% higher you want wheel rate 10-20% higher. Because the rear springs are inboard there's more leverage on them, the effective spring rate at the wheel is quite a bit softer.

therefore with ohlins 400/630 rates it's actually stiffer at the front than the rear

[Tbonem3]

You only need your rear spring rate 10-20% higher than your fronts

Where'd you get that from?

Stock is 143lb/in front to 345-685 (progressive) so rear is a good 200%+ greater, not 10-20%

You have to remember that the location of the rear spring diminishes its net rate (something like 60% of original rate) nevermind that you want the rear stiffer in order to "catch up" to the front which is the core tenet of "flat ride" I believe - bounce ratios.

[9kracing]

Sorry what I meant was your rear spring rate hz, not overall spring rate. IE 1.8 front, 2.0 rear

Everything I can find posted on the web traces back to this guy Shaikh, who owns Fat Cat Motorsports. Everything, on every single forum. BMW, Porsche, Miata. Every single one.

I'm not saying he doesn't know what he's talking about, because I've watched his videos, and he seems pretty knowledgeable.

But there's a ton of factors that go into your suspension besides spring rate, I'm not sold on generic "flat ride" spring rates for every E46 M3.

[Obioban]

What I meant is who came up with the recommended spring rates for our cars RE flat ride.

You only need your rear spring rate 10-20% higher than your fronts, and Ohlins are higher than that. So why is Ohlins not considered flat ride.

You need frequencies that are higher in the rear than the front for flat ride-- not spring rates.

If you want to figure out your own flat ride spring rates, you can do so here:
https://www.fatcatmotorsports.com/FC..._M3_Online.htm

[Obioban]

Sorry what I meant was your rear spring rate hz, not overall spring rate. IE 1.8 front, 2.0 rear

Everything I can find posted on the web traces back to this guy Shaikh, who owns Fat Cat Motorsports. Everything, on every single forum. BMW, Porsche, Miata. Every single one.

I'm not saying he doesn't know what he's talking about, because I've watched his videos, and he seems pretty knowledgeable.

But there's a ton of factors that go into your suspension besides spring rate, I'm not sold on generic "flat ride" spring rates for every E46 M3.

Flat ride was THE biggest suspension upgrade I've ever done, when I moved my Ohlins to flat ride. I've since moved all my cars to it. IMO there's a reason the OE's all use it-- I find it makes the car more predicable, faster, easier, and better riding at overall frequencies.

But you do need to change you mindset to make it work-- with softer front springs, you need to be higher (also beneficial for geometery) and have a beefier front sway.

Good to do, since it's very much dependent on corner weights, etc.

I'm not sure if the term "Flat ride" is fat cats specific, but agreed that term doesn't come up much-- but I think that's why all search results come back to Fat Cats.

But, as a concept-- seems to be almost universally adopted by those who know most (the OEs).

[freshprince2421]

Soooo... is there a consensus on an optimal spring/sway bar combo to achieve flat ride w Ohlins R&T?

Cliff notes appreciated

[gaiakai]

Soooo... is there a consensus on an optimal spring/sway bar combo to achieve flat ride w Ohlins R&T?

Cliff notes appreciated

Obioban mentioned it earlier in this thread but 350 front 700 rear (or 6kg/338lbs & 13kg/728lb) will give you flat ride. And then a CSL front sway bar with stock rear will get you to around 69% FRC. I don't understand FRC enough to ELI5, but that spring and sway combo is what I'll be running when I order ohlins for myself.