Rocket

One of my Magnesium BBS 18 inch rears on a 993RS cracked across 4 spokes on a recent trackday. Is this a common occurrence, and is it advisable to have them X-rayed or checked regularly?



Rocket

Wheel here

Greg Fishman

Check them visually everytime they are off the car or before track events.

This is not an uncommon occurerence and these wheels have a shorter life span than alloy (forged aluminum) wheels do.

APKhaos

BBW Motorsports [here in the US, at least] will crack test/replace components and reseal these wheels. Not sure is they offer that service in the UK, but its worth checking.

Bill Gregory

You also need to watch for cracks in the wheel halves between the bolt holes. BBS Motorsports in the US will provide replacement seals and new bolts, at no charge. Unlike other wheel manufacturers, they'll even tell you what to torque the bolts to (install dry, 145 inch lbs)

Rocket

Thanks for the replies..........unfortunately we get charged for the seals and bolts whether direct form BBS in Germany or via dealers. I am surprised also that BBS are not even interested in taking back the old spoke section. Magnesium must have some scrap value?

Thanks for torque settings- I take it you divide 145lbs inch by 12 to get lbs foot.

Rocket

Greg Fishman

Rocket,
Don't do that! Use a proper inch/lbs torgue wrench only.

Bill Gregory

Greg is right on, use the proper torque wrench with an inch/lb scale. My inch/lb torque wrench is the dial type, rendering very explicit what the bolts are torqued to.

Danno

Anyone have a good source for rim-halves? I need to expand my rear wheels by about 1". Thanks