Losing My Wheel Bolts

At a recent track day at Donnington Park I was getting a thudding noise from the front of the car. I did suspect a driveshaft or cv joint issue but it actually turned out to be my front left wheel wobbling about as the bolts had become so lose!

I left to cool, tightened them back up and headed back out again. Four laps later I had the same.

Has anyone else had a similar issue? Initially I guessed it was all the heat generated from the R888’s and brakes, but then realised this probably isn’t the case. Wheel bearing past its best maybe?

Help and advice much appreciated.

Oh and a big thank you to John (Johnny Bravo Turbo). He turned up and helped me out with a couple of problems. Without him and a trip back to his workshop I would have been going home early on a flatbed for sure. Wouldn’t even let me buy him a beer either, top fella!

Cheers
Phil

Loose wheel nuts can occur for a variety of reasons, including undertorquing, overtorquing, differential thermal contraction, and improper mating surfaces.

Both undertorquing and overtorquing are common when air impact wrenches are used because the actual torque that gets applied depends on so many variables. A common approach is to purposefully overtorque wheel nuts, in part to combat this variability and in part based on the reasoning that "more is better". However, overtorquing actually reduces (not increases) clamping force in many cases, by stretching the studs or threads beyond their ability to respond - especially when this is done repeatedly. Overtorquing can also cause other problems such as cracked, seized, or cross-threaded nuts (which cannot apply the appropriate clamping force), and increases the frequency of stud failure and cracked wheels.

Differential thermal contraction can occur when wheels are mounted at shop temperatures in cold climates. As the wheel components cool to ambient temperatures, clamping force is lost. Wheel nuts which experience any rotation (i.e. back off) during this time will not regain their original torque / clamping force values.

Improper mating surfaces include both damaged and contaminated mating surfaces. Proper clamping force cannot be achieved with non-flat mating surfaces such as damaged or bent hubs and wheels, or worn or elongated bolt holes (raised metal). Contaminants such as excess dirt, sand, rust, metal burrs, and paint on mating surfaces can wear away with use, causing a settling effect. When present on the threads or between a nut and the wheel surface, these contaminants can also change the clamping force / torque relationship, resulting in "false torques" where much of the torque applied is used to overcome friction and is not converted into clamping force.

A loose wheel nut can originate from any of these sources individually, or more probably, from a combination of these sources - which makes the task of eliminating all loose wheel nuts very difficult.

Great post Patrick

Rule of thumb on a trackday is to check them as much as possible.
We have had a fair few loose bolts at Spa on various powered coupes.

Just ask Mario at Donington

As above ... re-torque them after every session. It's the only way to be certain!

Also you shouldn't grease the bolt threads or seats as it causes applied torque to have a bigger stretching effect on the bolts, potentially exceeding their elastic limit.

whats you opinions on using some stud-lock/locktight??

bloody donington!

check the hub centric rings or if you have original wheels the size of the wheel and hubs if there is play the wheel bolts can get loose or worst case break