F83 spring rate

[travismelo3]

Hi, does anyone know what the stock F83 M4 base spring rates are? I’m trying to find the best springs to get and there aren’t many F83 options, so I want to see what F82 springs would work on my car. Thanks!

[M3SQRD]

I haven’t seen F83 stock or lowering spring rates listed for the F83. Most HAS, except for H&R VTF, do not offer a dedicated F83 spring rate. The F83 H&R VTF kit just lists the progressive spring rates as being 10-20% stiffer than stock. I’d bet the F83 spring rates aren’t too much higher than F82 spring rates. For example, the spring rates used on a full interior F82 and a partially stripped interior F82, which is ~200-400 lbf lighter (without going to extreme measures), will typically still run the same spring rates unless front and rear aero is added. The extra ~100 lbf extra per corner is a small percentage of the total 3900 lbf weight the four corners are already carrying. Stock F83 springs are probably in the 10-15% stiffer range.

[TouringM3]

This is a great question, especially given that the F83 is minimum 500lbs heavier.
I'm particularly interested as my F81 feels like it is suffering a bit from too-soft rear spring rates.

(F81 fully hydrated without driver is 3,980 lbs)

[M3SQRD]

Originally Posted by TouringM3

This is a great question, especially given that the F83 is minimum 500lbs heavier.
I'm particularly interested as my F81 feels like it is suffering a bit from too-soft rear spring rates.

(F81 fully hydrated without driver is 3,980 lbs)

It depends on the weight distribution. If the 500 lbm is divided equally between all four corners you increase the spring rates by ~20% to maintain the same frequency or, if all 500 is carried by the rear, you’d increase the rear spring rate by ~44% to maintain the same frequency. This neglects any change in balance, actual corner weight vs estimated corner weights, sway bar tuning, etc. So the F83 rates will likely be ~20-45% stiffer than

[FaRKle!]

Originally Posted by travismelo3

Hi, does anyone know what the stock F83 M4 base spring rates are? I’m trying to find the best springs to get and there aren’t many F83 options, so I want to see what F82 springs would work on my car. Thanks!

F83 front spring rates are roughly the same as F80/82, but the rear spring rates are around 25-30% stiffer.

Most aftermarket kits don't properly handle the F83's rear weight increase.

[N44RP]

Just fyi KW HAS has an F83 kit
Just ordered, they don’t specify what’s different between the f83 and f82 kits. Maybe worth a call

[FaRKle!]

Originally Posted by N44RP

Just fyi KW HAS has an F83 kit
Just ordered, they don’t specify what’s different between the f83 and f82 kits. Maybe worth a call

If you look for the TUV documents on their UK or DE site it'll show you the spring differences.

[M3SQRD]

Originally Posted by FaRKle!

F83 front spring rates are roughly the same as F80/82, but the rear spring rates are around 25-30% stiffer.

Most aftermarket kits don't properly handle the F83's rear weight increase.

I edited my post because the 7 and 15% didn’t seem right. Well I took the square root instead of squaring the number The corrected numbers are ~20% and ~45% for the F83 so your 20-25% stiffer range is a good realistic spring rate increase over the F82.