[HP Autosport]

AST SUSPENSION 5100 SERIES COILOVERS: 2021+ BMW M3/M4 (G80/G82)

Achieve optimum handling and stance with the 5100 Series Coilovers for the 2021+ BMW M3 (G80) and M4 (G82) from AST Suspension. Available for both xDrive-equipped models and those without, the kit features an inverted front shock and converts the rear suspension to a true coilover configuration. Top mounts are included, and the front pair allows for camber adjustment. The shock bodies are threaded for height and preload adjustments, and an easily accessible rebound adjustment knob is located at the base of the shock.

AST Suspension specializes in producing suspension components for vehicles serving regular street use and competition purposes such as race, rally, autocross, and more. The company has continuously evolved since its establishment in 2000 and has always taken pride in its work. By combining in-house design and production with technical know-how, industry experience, and road-and-track testing, AST Suspension consistently produces exceptional suspension components at a competitive price.

*1-Way Adjustable, the 12 positions give clear feedback with each adjustment, each offering a different driving experience.
*Inverted strut design to cope with (heavy) side load and braking loads.
*Improved handling and consistent performance due to Monotube technology
*Ride Height adjustable
*Gas Pressurized (i: gas and oil are divided by a floating piston)
*Included front and rear top mounts
*True coilover rear (spring over damper)
*10K front and 8K rear springs
*Adjustable sway bar links included
*Separate kits available for xDrive and non-xDrive models

Application: 2021+ BMW M3 (G80), M4 (G82), 2023+ BMW M2 (G87)

Part Number:

ACC-B2112SD, AST 2021+ BMW M3 G80 / M4 G82 5100 Comp Series Coilovers



ACC-B2115SD, AST 2021+ BMW M3 G80 / M4 G82 Xdrive 5100 Comp Series Coilovers

[50shadesofhockenheim]

Quick online search shows these are around $5k.. Is that right? If so, why would someone go with these over KW for example?

[HP Autosport]

Originally Posted by 50shadesofhockenheim

Quick online search shows these are around $5k.. Is that right? If so, why would someone go with these over KW for example?

Can't discuss price here, but free to visit this link for pricing info:

https://hpautosport.com/product/ast-...bmw-g8x-m3-m4/

Monotube and digressive damping just to name two pros of the AST 5100. Penske dampers has a great article on monotube vs twin tube, a very good read.

Feel free to PM with any specific questions regarding this kit.

[VIERsr]

HP Autosport 4x linear springs, do you confirm?

[HP Autosport]

Originally Posted by VIERsr

HP Autosport 4x linear springs, do you confirm?

Yes, linear 10K front and 8K rear springs. Both RWD and X-Drive are available to ship right away.

PM if you any specific questions.

[juicy]

Originally Posted by HP Autosport

AST SUSPENSION 5100 SERIES COILOVERS: 2021+ BMW M3/M4 (G80/G82)

Achieve optimum handling and stance with the 5100 Series Coilovers for the 2021+ BMW M3 (G80) and M4 (G82) from AST Suspension. Available for both xDrive-equipped models and those without, the kit features an inverted front shock and converts the rear suspension to a true coilover configuration. Top mounts are included, and the front pair allows for camber adjustment. The shock bodies are threaded for height and preload adjustments, and an easily accessible rebound adjustment knob is located at the base of the shock.

AST Suspension specializes in producing suspension components for vehicles serving regular street use and competition purposes such as race, rally, autocross, and more. The company has continuously evolved since its establishment in 2000 and has always taken pride in its work. By combining in-house design and production with technical know-how, industry experience, and road-and-track testing, AST Suspension consistently produces exceptional suspension components at a competitive price.

*1-Way Adjustable, the 12 positions give clear feedback with each adjustment, each offering a different driving experience.
*Inverted strut design to cope with (heavy) side load and braking loads.
*Improved handling and consistent performance due to Monotube technology
*Ride Height adjustable
*Gas Pressurized (i: gas and oil are divided by a floating piston)
*Included front and rear top mounts
*True coilover rear (spring over damper)
*10K front and 8K rear springs
*Adjustable sway bar links [...]

Can G8X handle true coilover rear for both street and track use? Any reinforcements needed? Thanks

[specced]

Originally Posted by HP Autosport

Yes, linear 10K front and 8K rear springs. Both RWD and X-Drive are available to ship right away.

PM if you any specific questions.

Is that spring rate x drive specific, seems really odd for rwd.

[HP Autosport]

Originally Posted by juicy

Can G8X handle true coilover rear for both street and track use? Any reinforcements needed? Thanks

Yes, perfectly fine. MCS and Nitron are set up for true coilover rear on the G8X as well.

[HP Autosport]

Originally Posted by specced

Is that spring rate x drive specific, seems really odd for rwd.

The 8K rear is a true coilover spring rate.

[M3SQRD]

Originally Posted by specced

Is that spring rate x drive specific, seems really odd for rwd.

Why do you think these are odd? The 5100 is using a true coilover rear damper setup vs., say, the Ohlins R&T which uses the oem divorced rear spring setup.

The 5100 uses a front 10 kgf/mm (560 lbf/in) and rear 8 kgf/mm (448 lbf/in, coilover rear) springs. R&T uses a front 100 N/mm (571 lbf/in) and 190 N/mm (1085 lbf/in, divorced rear). The only way to compare spring rates is to use the wheel rate (effective spring rate acting on the tire):

Wheel rate (WR) = motion ratio^2 * spring rate (SR)
where motion ratio (MR) is defined as the ratio of the displacement of the spring/damper location to the displacement of the wheel location wrt the same pivot point (control arm).

I don’t know the exact motion ratios of the g8x but for the f8x and e9x the spring MR is around 0.62 and the damper MR is around 0.84 so

WRohlins_r = MRspring^2*SRspring = 0.60^2*1085 = 391 lbf/in

WRast_r = MRdamper^2*SRdamper = 0.84^2*448 = 316 lbf/in

So the Ohlins 1085 lbf/in rear spring rate looks high but it has a poor MR whereas the AST 448 lbf/in rear spring rate looks soft but it has a much better MR. The BMW divorced rear spring setup makes it harder to compare suspension kits that use a coilover rear instead of a divorced rear because the spring leverages are very different.

The front strut MR is the same for both at roughly 0.96:

WRohlins_f = 0.96^2*571 = 526 lbf/in

WRast_f = 0.96^2*560 = 484 lbf/in

AST wheel rates are F/R 484/316 lbf/in
Ratio of wheel rates are 484/316 = 1.53

Ohlins wheel rates are F/R 526/391 lbf/in
Ratio of wheel rates are 526/391 = 1.34

Comparing wheel rates, the Ohlins R&T has a less-understeer-biased track setup compared to the AST 5100 or you could say the AST 5100 has a safer more compliant street setup compared to the Ohlins R&T. However, the damping curves will have a major effect on the ride quality and performance of the two setups. AST 5100 only adjusts rebound damping whereas the Ohlins R&T rebound and compression damping are adjusted together.

[specced]

Originally Posted by M3SQRD

Why do you think these are odd? The 5100 is using a true coilover rear damper setup vs., say, the Ohlins R&T which uses the oem divorced rear spring setup.

The 5100 uses a front 10 kgf/mm (560 lbf/in) and rear 8 kgf/mm (448 lbf/in, coilover rear) springs. R&T uses a front 100 N/mm (571 lbf/in) and 190 N/mm (1085 lbf/in, divorced rear). The only way to compare spring rates is to use the wheel rate (effective spring rate acting on the tire):

Wheel rate (WR) = motion ratio^2 * spring rate (SR)
where motion ratio (MR) is defined as the ratio of the displacement of the spring/damper location to the displacement of the wheel location wrt the same pivot point (control arm).

I don’t know the exact motion ratios of the g8x but for the f8x and e9x the spring MR is around 0.62 and the damper MR is around 0.84 so

WRohlins_r = MRspring^2*SRspring = 0.60^2*1085 = 391 lbf/in

WRast_r = MRdamper^2*SRdamper = 0.84^2*448 = 316 lbf/in

So the Ohlins 1085 lbf/in rear spring rate looks high but it has a poor MR whereas the AST 448 lbf/in rear spring rate looks soft but it has a much better MR. The BMW divorced rear spring setup makes it harder to compare suspension kits that use a coilover rear instead of a divorced rear because the spring leverages are very different.

The front strut MR is the same for both at roughly 0.96:

WRohlins_f = 0.96^2*571 = 526 lbf/in

WRast_f = 0.96^*560 = 484 lbf/in

AST wheel rates are F/R 484/316 lbf/in
Ratio of wheel rates are 484/316 = 1.53

Ohlins wheel rates are F/R 526/391 lbf/in
Ratio of wheel rates are 526/391 = [...]

Yeah makes more sense. I’m used to the divorced setups where on the rwd m3’s typically the rear is much stiffer 16-20k rates. But makes sense it’s not really comparable.

[M3SQRD]

Originally Posted by specced

Yeah makes more sense. I’m used to the divorced setups where on the rwd m3’s typically the rear is much stiffer 16-20k rates. But makes sense it’s not really comparable.

The MRs for the RWD and AWD are the same. The values i used are from the f8x and e9x which were RWD only. The only reason you’d want to run even higher rear rates relative to the front is if you’re going for a flat-ride setup. Flat ride is where you set the rear suspension to have a slightly higher frequency than the front suspension so that when the rear suspension hits a bump after the front suspension, the oscillation of the rear suspension catches up with the front suspension as they’re damped out.