[52172]

What is everyone running with their coilovers? I'm ordering a set on Black Friday and was gonna go with the default setting since fortune auto guys personally drive bmw's and I believe have the rates pretty well thought out and engineered. They are 9k front and 12k rear. I have heard from a few guys going a little softer up front and stiffer out back might be better? Ohlins has softer front and stiffer rear springs than the default. Was thinking maybe 8k front and 14k rear? Anyone have any experience with different rates? Thanks

[andino]

It depends what your goals are. Stock is probably fine but the ride will be more choppy but many perceive that as sporty. Bilstein for example uses a rates that are pretty close together and it feels sporty but the performance is actually pretty rough and choppy. Unless you're on smooth roads or traveling at high speeds, it's quite rough.

Another consideration to take into account is the damping range that fortunes dampers are set up for.

[Watsey]

My Ohlins R&T are running 9/16 but you know that from my previous replies

Definitely pretty firm around town but the car loosens up as the speed increases.

[FaRKle!]

Spring rates are used to determine ride frequency (which is calculated from the spring rate and weight). So arbitrary spring rates without understanding the load is missing the main point. If someone/company says to use "x" spring rate without considering the weight (or if they recommend the same spring over various weights like for 4cyl and 6cyl models), then they haven't thought things through or done much engineering.

[johnung]

Originally Posted by FaRKle!

Spring rates are used to determine ride frequency (which is calculated from the spring rate and weight). So arbitrary spring rates without understanding the load is missing the main point. If someone/company says to use "x" spring rate without considering the weight (or if they recommend the same spring over various weights like for 4cyl and 6cyl models), then they haven't thought things through or done much engineering.

Since this discussion is on coilovers and spring rates I'm curious if you guys have an opinion of Bilstein B16? A friend who lives in a harsh winter environment is interested in B16's and likes the feature to be able to easily raise the car high for winter driving and lower for sportier driving in summer. Car is an F30 4-cyl sedan RWD with upgrade mods such as BM3, MSport brakes, 18" summer sporty tires & studded winter tires. Any comments on B16's?

[FaRKle!]

Originally Posted by johnung

Since this discussion is on coilovers and spring rates I'm curious if you guys have an opinion of Bilstein B16? A friend who lives in a harsh winter environment is interested in B16's and likes the feature to be able to easily raise the car high for winter driving and lower for sportier driving in summer. Car is an F30 4-cyl sedan RWD with upgrade mods such as BM3, MSport brakes, 18" summer sporty tires & studded winter tires. Any comments on B16's?

I have a high opinion of Bilstein construction, but a low opinion of their performance for the F2x/F3x/F8x platforms.

Front rates are too high IMO, rears are too low, damping is typically overdamped (though I guess with B16 you can adjust that to an extent), and gas pressures are too high (making the dampers more harsh). You can probably correct the spring rates on the B16, but by that time, how much money have you spent? It'd probably make financial sense then to go with a bespoke or semi-custom setup.

How much is he thinking of raising and lowering? That affects camber and toe too, so is he planning on getting alignments twice a year?

[52172]

Originally Posted by andino

It depends what your goals are. Stock is probably fine but the ride will be more choppy but many perceive that as sporty. Bilstein for example uses a rates that are pretty close together and it feels sporty but the performance is actually pretty rough and choppy. Unless you're on smooth roads or traveling at high speeds, it's quite rough.

Another consideration to take into account is the damping range that fortunes dampers are set up for.

My goal basically is just an excellent handling street car that will see the track here and there. I will run a ltd slip and am running 19" wheels with 275/30/19 and 245/35/19's. I need to ask Fortune if they adjust the dampers if I pick different spring rates hopefully they do and if not would be a reason to stay near stock specs.

[52172]

Originally Posted by Watsey

My Ohlins R&T are running 9/16 but you know that from my previous replies

Definitely pretty firm around town but the car loosens up as the speed increases.

If you had to do it again would you choose the same rates?

[52172]

Originally Posted by johnung

Since this discussion is on coilovers and spring rates I'm curious if you guys have an opinion of Bilstein B16? A friend who lives in a harsh winter environment is interested in B16's and likes the feature to be able to easily raise the car high for winter driving and lower for sportier driving in summer. Car is an F30 4-cyl sedan RWD with upgrade mods such as BM3, MSport brakes, 18" summer sporty tires & studded winter tires. Any comments on B16's?

No thread stealing 😎🖐🏼

[52172]

I'm leaning toward 8k front and 14k rear unless I hear some valid reasons otherwise..

[Watsey]

Yes, probably (say 80% likelihood) but I'd keep the following in mind :

I'd try and keep the effective spring rates equal F/R. The rear springs are inboard (they are not attached directly to the wheel hub, unlike the fronts) and are (say) half way between the hub and the chassis. This means that the rear spring rate is effectively halved.

F/R spring rates may need to be chosen according to the actual wright distribution of the car, the weight of the engine, and the desired handling characteristics. My car has a 48/52% weight distribution and the 30d power unit is quite heavy - I found the Ohlins R&T standard front spring rate (7X) resulted in a ride which was too soft, so I increased the springs to 9X. The F/R spring rates are now much more in line with my preferences.

If you're increasing the spring rates you may need to be careful with your selection for anti-roll (sway) bars. Stuff springs + stiff ARBs can compromise grip through bumpy corners. I have H&R bars F (28mm) & R (20), which were installed prior to having the R&T, and I may need to downgrade the torsional resistance by fitting slightly thinner bars. If the metallurgy was the same I'd be aiming for 25/17.

[52172]

I have no plans for aftermarket swaybars. Do you think 8k ft and 14k rear would be good?

[Watsey]

Considered purely in isolation, they could be a nice choice : a step up from OEM, but not so stiff to be jarring.

I think it's unlikely that the dampers would need to be re-valved. Ohlins were happy for me to supply front springs with my chosen rate, with no damper adjustment and no loss of warranty.

[FaRKle!]

Originally Posted by 52172

I have no plans for aftermarket swaybars. Do you think 8k ft and 14k rear would be good?

What level of research are you willing to do to figure out what "optimum" means with respect to your goals? It really looks to me like the numbers you're picking are kind of arbitrary.

[52172]

Originally Posted by FaRKle!

What level of research are you willing to do to figure out what "optimum" means with respect to your goals? It really looks to me like the numbers you're picking are kind of arbitrary.

I've been researching for a year now and am pulling the trigger on 8k front 14k rear. It will be great for what I'm gonna use the car for. Very spirited street with some track in the mix.

[52172]

Originally Posted by Watsey

Considered purely in isolation, they could be a nice choice : a step up from OEM, but not so stiff to be jarring.

I think it's unlikely that the dampers would need to be re-valved. Ohlins were happy for me to supply front springs with my chosen rate, with no damper adjustment and no loss of warranty.

Fortune said the dampers will be matched to the spring rates. I'm gonna run Megan Racing camber and toe bars to dial in the alignment and run the coilovers on their highest setting which is 1" lower than stock. Wonder how much neg camber I should run in the front with the new camber plates? Neg 1.5deg seems about the sweet spot.

[Watsey]

Originally Posted by 52172

Fortune said the dampers will be matched to the spring rates. I'm gonna run Megan Racing camber and toe bars to dial in the alignment and run the coilovers on their highest setting which is 1" lower than stock. Wonder how much neg camber I should run in the front with the new camber plates? Neg 1.5deg seems about the sweet spot.

My car is running -1.75deg. It's a huge improvement over stock and a good balance between street and track. Inner shoulder tyre wear is acceptable; wheels & tyres don't look too tucked-in (403M wheels + 12mm spacers all round help with that as well).