M4 Comp. 666m OEM WHEEL BOLTS?

[Fan.]

Hello guys! I am new here, I just got a F82 M4 Competition with 666m wheels.
The car looks great except for the annoying H&R spacers. I wanna remove them but unfortunately, I do not know the OEM(Stock) wheel bolts for it.
I searched on the eBay but there are too many ... need help


CAN anyone tell me about the size? What length of bolts are the OEM style?

Thanks !!!

[M3SQRD]

14x1.25 27 mm is the correct oem diameter, thread pitch and length. However, I wouldn’t buy replacement bolts off of ebay for ~$28 USD when an oem set is ~$90 USD. Do not skimp on a major safety item by buying a set of bolts made from poor/unknown material, etc. - you don’t want a wheel flying off on the highway due to lug bolt failures! Buy them from a local BMW dealer or, even better, an online bmw dealer that sells parts at discounted prices (typically 20% off list).

[Fan.]

Originally Posted by M3SQRD

14x1.25 27 mm is the correct oem diameter, thread pitch and length. However, I wouldn’t buy replacement bolts off of ebay for ~$28 USD when an oem set is ~$90 USD. Do not skimp on a major safety item by buying a set of bolts made from poor/unknown material, etc. - you don’t want a wheel flying off on the highway due to lug bolt failures! Buy them from a local BMW dealer or, even better, an online bmw dealer that sells parts at discounted prices (typically 20% off list).

Sounds reasonable! Thanks for the reminder, mate.

I think I would purchase a set from the local dealer and get it done. Btw, does the spacer really matter in terms of driving (suspensions, steering etc.). Cuz I think the previous 15&20 mm HR spacers are too wide ... it seems to be nice with a 12&15 mm combinations on M4 (seen from a YouTuber). Thanks again for your help

[N1rve]

Originally Posted by Fan.

Sounds reasonable! Thanks for the reminder, mate.

I think I would purchase a set from the local dealer and get it done. Btw, does the spacer really matter in terms of driving (suspensions, steering etc.). Cuz I think the previous 15&20 mm HR spacers are too wide ... it seems to be nice with a 12&15 mm combinations on M4 (seen from a YouTuber). Thanks again for your help

Just buy OE or OEM from FCP Euro. When they start rusting just get a new set for free.

Spacers affect turning diameter and adds additional stress on the bolts.

[M3SQRD]

Originally Posted by N1rve

Just buy OE or OEM from FCP Euro. When they start rusting just get a new set for free.

Spacers affect turning diameter and adds additional stress on the bolts.

He’s in the UK. Does the FCPeuro warranty apply to people outside of the US? That would be great and still with it even with high shipping costs.

How much does the turning diameter change with the use of 5-20 mm spacers?

How does running a spacer increase the stress on the lug bolts? BMW runs 30-40 mm spacers on the F82 GT4 race cars. Someone better tell BMW about the added stress on the bolts.

[N1rve]

Originally Posted by M3SQRD

He’s in the UK. Does the FCPeuro warranty apply to people outside of the US? That would be great and still with it even with high shipping costs.

How much does the turning diameter change with the use of 5-20 mm spacers?

How does running a spacer increase the stress on the lug bolts? BMW runs 30-40 mm spacers on the F82 GT4 race cars. Someone better tell BMW about the added stress on the bolts.

"Yes. FCP Euro will cover the replacement cost of the part only. We do not cover shipping, duties/taxes, or other fee's applicable to an international purchase (ex: currency conversion, etc)." - FCP Euro Site.
https://www.fcpeuro.com/page/lifetime-guarantee

As you increase your track width you increase your turning radius.

As you push the wheels out further the stress is more pulled outwards (distance away from the suspension). It won't just be on the bolts, it would also be on the wheel bearings. However there are benefits as it increases stability, allows for wider brake calipers, bigger wheels/tires. I am pretty sure BMW out weighs the performance gains of increased wear and tear. It's a racecar after all and meant for abuse.

Sure, go ahead and notify BMW that they will have extra wear and tear on their components but they're a big company that probably wouldn't blink an eye if they need new lug bolts or need a wheel bearing done.

[M3SQRD]

Originally Posted by N1rve

"Yes. FCP Euro will cover the replacement cost of the part only. We do not cover shipping, duties/taxes, or other fee's applicable to an international purchase (ex: currency conversion, etc)." - FCP Euro Site.
https://www.fcpeuro.com/page/lifetime-guarantee

As you increase your track width you increase your turning radius.

As you push the wheels out further the stress is more pulled outwards (distance away from the suspension). It won't just be on the bolts, it would also be on the wheel bearings. However there are benefits as it increases stability, allows for wider brake calipers, bigger wheels/tires. I am pretty sure BMW out weighs the performance gains of increased wear and tear. It's a racecar after all and meant for abuse.

Sure, go ahead and notify BMW that they will have extra wear and tear on their components but they're a big company that probably wouldn't blink an eye if they need new lug bolts or need a wheel bearing done.

I doubt a 0.25” spacer, or a 0.50” increase in track width relative to stock track widths of F/R 62.2”/63.1” (<1% increase F & R), is going to have much practical impact on turning diameter if you can still turn the steering wheel lock to lock.

A quick rounded down calculation for a grade 10.9 lug bolt shows its preload is 23500 lbf. There are five bolts so total compressive preload per wheel is 94000lbf. The bolt radial distance from the hub centerline to bolt centerline is 4.409”/2 = 2.204”. Now assuming all of the applied wheel torque is reacted at the bolt circle diameter, the shear load per faster is

Fsb=Tw/(#bolts*bolt radius)=Tw/(5*2.204)=0.0907*Tw

where Tw is torque applied at the wheels. Tw is equal to engine torque, Te, times the gear ratio in 1st gear, FG1, times the differential FD ratio which is

Tw= FG1*FD*Te
FG1 = 4.806
FD = 3.463
So torque at wheels, Tw, is
Tw=4.806*3.463*Te=16.64*Te
Te is 406 lbf-ft

So

Tw=16.64*406=6757 lbf-ft=81806 lbf-in
Tws=Tw/2=81806/2=40903 lbf-in
Finally, Fsb is

Fsb=0.0907*40903=3710 lbf per bolt

Or the shear running load, Fsl, on the bolt circle is

Fsl=Tws/(3.14159*Dbs)=40903/(3.14159*4.409)=2953 lbf/in

(conservative running load because more torque is carried above the bolt circle diameter).
The applied axial compressive preload line load at the bolt circle, Fal, is

Fal=Fpre/(pi*4/3*Dtc)=94000/(3.14159*2.204)=13576 lbf/in.

Assume a conservative COF for Aluminum on Aluminum, mu_al2al, is 0.5 (can be higher). So

Fslip_al/al=mu_al2al*Fal =0.5*13576=6788 lbf/in

So an applied wheel torque running load of 6788 lbf/in has to be exceeded for the wheel to rotate relative to the brake rotor hub:

Slip Margin=6788/2954-1=1.30

which means you can more than DOUBLE the applied torque before the lug bolt would see any applied torque.

As for the vertical shear load, if a hubcentric wheel spacer is used, no vertical shear load is applied to the lug bolts regardless of spacer thickness. Additionally, the lateral bending load applied to the lug bolts doesn’t change with wheel spacer thickness (actually this reduces the vertical load due to cornering by increasing the track width), it’s only the tire rolling diameter relative to stock rolling diameter that affects the lateral bending load.

So where is the added stress on the lug bolts coming from?

[M3SQRD]

Originally Posted by Fan.

Sounds reasonable! Thanks for the reminder, mate.

I think I would purchase a set from the local dealer and get it done. Btw, does the spacer really matter in terms of driving (suspensions, steering etc.). Cuz I think the previous 15&20 mm HR spacers are too wide ... it seems to be nice with a 12&15 mm combinations on M4 (seen from a YouTuber). Thanks again for your help

If you plan on running 12 mm and 15 mm spacers then you need to buy lug bolts that are 12 mm and 15 mm longer - at least 39 mm long front lug bolts and 42 mm long rear lug bolts. I’d recommend buying spacers that comes with longer lug bolts so you know the correct length bolts are being used. Turner Motorsports or Future Classics make high quality wheel spacers.

[N1rve]

Originally Posted by M3SQRD

I doubt a 0.25” spacer, or a 0.50” increase in track width relative to stock track widths of F/R 62.2”/63.1” (<1% increase F & R), is going to have much practical impact on turning diameter if you can still turn the steering wheel lock to lock.

A quick rounded down calculation for a grade 10.9 lug bolt shows its preload is 23500 lbf. There are five bolts so total compressive preload per wheel is 94000lbf. The bolt radial distance from the hub centerline to bolt centerline is 4.409”/2 = 2.204”. Now assuming all of the applied wheel torque is reacted at the bolt circle diameter, the shear load per faster is

Fsb=Tw/(#bolts*bolt radius)=Tw/(5*2.204)=0.0907*Tw

where Tw is torque applied at the wheels. Tw is equal to engine torque, Te, times the gear ratio in 1st gear, FG1, times the differential FD ratio which is

Tw= FG1*FD*Te
FG1 = 4.806
FD = 3.463
So torque at wheels, Tw, is
Tw=4.806*3.463*Te=16.64*Te
Te is 406 lbf-ft

So

Tw=16.64*406=6757 lbf-ft=81806 lbf-in
Tws=Tw/2=81806/2=40903 lbf-in
Finally, Fsb is

Fsb=0.0907*40903=3710 lbf per bolt

Or the shear running load, Fsl, on the bolt circle is

Fsl=Tws/(3.14159*Dbs)=40903/(3.14159*4.409)=2953 lbf/in

(conservative running load because more torque is carried above the bolt circle diameter).
The applied axial compressive preload line load at the bolt circle, Fal, is

Fal=Fpre/(pi*4/3*Dtc)=94000/(3.14159*2.204)=13576 lbf/in.

Assume a conservative COF for Aluminum on Aluminum, mu_al2al, is 0.5 (can be higher). So

Fslip_al/al=mu_al2al*Fal =0.5*13576=6788 lbf/in

So an applied wheel torque running load of 6788 lbf/in has to be exceeded for the wheel to rotate relative to the brake rotor hub:

Slip Margin=6788/2954-1=1.30

which means you can more than DOUBLE the applied torque before the lug bolt would see any applied torque.

As for the vertical shear load, if a hubcentric wheel spacer is used, no vertical shear load is applied to the lug bolts regardless of spacer thickness. Additionally, the lateral bending load applied to the lug bolts doesn’t change with wheel spacer thickness (actually this reduces the vertical load due to cornering by increasing the track width), it’s only the tire rolling diameter relative to stock rolling diameter that affects the lateral bending load.

So where is the added stress on the lug bolts coming from?

https://letmegooglethat.com/?q=How+d...tear+on+car%3F

[M3SQRD]

Originally Posted by N1rve

https://letmegooglethat.com/?q=How+d...tear+on+car%3F

I thought we were talking about “adds additional stress on the bolts”?

However, for fun, I searched for damage spacers do and ended up getting quite a few links explaining why spacers are not as dangerous as most people believe as well as increased loads ON hubs, knuckles, spindles, etc. but nothing on increasing turning radius () and more stress on lug bolts.

[N1rve]

Originally Posted by M3SQRD

I thought we were talking about “adds additional stress on the bolts”?

However, for fun, I searched for damage spacers do and ended up getting quite a few links explaining why spacers are not as dangerous as most people believe as well as increased loads ON hubs, knuckles, spindles, etc. but nothing on increasing turning radius () and more stress on lug bolts.

https://letmegooglethat.com/?q=Does+...turning+radius


https://letmegooglethat.com/?q=Does+...ct+wheel+studs

Seems like you're the type that doesn't know how to google.