Wheel Lug Strength During Tracking Duties

[S65V8]

Unlike most, I didn't go stud kit since I didn't want my dealer to blatantly know I'm tracking the M.

Suggestion/heads-up for newbies: after about 9 track events this season, one of the lug nuts snapped (Macht Schnell Spacers Kit). Makes sense since these aren't supposed to be removed and torqued that often over shorter periods of time.

If you're tracking often, remember to switch out the lug nuts after a certain period of time so you're experiencing a snapped lug. Better yet, get a stud kit if it works for your situation.

[dmw16]

It should also be noted that you shouldn't torque your wheels (or really even check the torque) when you've just come in from a session. You want the check everything when it's cool. Torquing a hot lug is a good way to over-toque it and break it.

[Groundpilot]

Its a good idea to change lug bolts every 10 or so track days.
Also, if you notice that one lug bolt is damaged, dont just replace that one. You must replace all 5 on that side.

[jphughan]

Originally Posted by SROC5

Unlike most, I didn't go stud kit since I didn't want my dealer to blatantly know I'm tracking the M.

Suggestion/heads-up for newbies: after about 9 track events this season, one of the lug nuts snapped (Macht Schnell Spacers Kit). Makes sense since these aren't supposed to be removed and torqued that often over shorter periods of time.

If you're tracking often, remember to switch out the lug nuts after a certain period of time so you're experiencing a snapped lug. Better yet, get a stud kit if it works for your situation.

Thanks for the heads-up. I'm a little confused as to what happened to you, though. Did a lug break while you were out on track and you just discovered it in the paddock later? Or did a lug break off while you were trying to remove it? Did you end up with part of a lug stuck in the mounting hole without the head attached and have to drill it out?

[S65V8]

Originally Posted by jphughan

Thanks for the heads-up. I'm a little confused as to what happened to you, though. Did a lug break while you were out on track and you just discovered it in the paddock later? Or did a lug break off while you were trying to remove it? Did you end up with part of a lug stuck in the mounting hole without the head attached and have to drill it out?

Should have mentioned, happened while my car was being torqued at a shop. One lug nut snapped randomly in front of me while they were torquing it. It then dawned on me (), "oh ya, I track this car like I senna, must be wear and tear....note to self, change all lug nuts before this happens to me on the track!". End rant.

[surlynkid]

Originally Posted by SROC5

Should have mentioned, happened while my car was being torqued at a shop. One lug nut snapped randomly in front of me while they were torquing it. It then dawned on me (), "oh ya, I track this car like I senna, must be wear and tear....note to self, change all lug nuts before this happens to me on the track!". End rant.

I don't let any shop mount my wheels. They get loose rims and tires. I bring them home and do it myself.

[Groundpilot]

Originally Posted by surlynkid

I don't let any shop mount my wheels. They get loose rims and tires. I bring them home and do it myself.

I do exactly the same when i can

[skxf430]

Did your lug nut or the stud snap off?

[MilehighM3]

You should also avoid spacers as much has possible, especially under high stress circumstances like the track. They're just another added variable that can cause issues.

[jphughan]

Originally Posted by surlynkid

I don't let any shop mount my wheels. They get loose rims and tires. I bring them home and do it myself.

Hmm, I immediately loosen and retorque them to spec after it's been in a shop just to make that exactly right, but I certainly don't mind them mounting them initially.

[CSBM5]

Originally Posted by jphughan

Hmm, I immediately loosen and retorque them to spec after it's been in a shop just to make that exactly right, but I certainly don't mind them mounting them initially.

The problem lies in a shop that over-torques lug bolts past their yield-point, even if they "fix" the problem right away...it's too late for that bolt. Then it is only a matter of time until that fastener fails in service (which is probably what happened in the case mentioned).

[dmw16]

Originally Posted by CSBM5

The problem lies in a shop that over-torques lug bolts past their yield-point, even if they "fix" the problem right away...it's too late for that bolt. Then it is only a matter of time until that fastener fails in service (which is probably what happened in the case mentioned).

Sad but true. Most shops just run the lugs on with an air wrench and they are usually not calibrated or set with a clutch set at the proper torque rating.

[jphughan]

^ Interesting, the indy shop I go to (and have since developed a great relationship with the owner) always uses an 80 ft-lb torque limiting stick when they're attaching the lugs to my car, and they mentioned without my even asking that they periodically check the accuracy of those sticks by using torque wrenches on the fasteners afterward and consistently find the sticks to torque within 1-2 lb-ft of their spec.

I also generally go into the shop with a typed page describing the services I want. I figure between the aftermarket parts I have and the fact that I have time to geek out over the details of my one car whereas they have to know all kinds of things for lots of different cars, if I can provide more information for them, it will ensure the job gets done right or at least save time and effort for them if it would have gotten done right anyway but with more work on their end. So on that page I have a note that the torque spec on the lugs is 88 lb-ft. I have a master Word document I keep with all kinds of other notes, including torque specs for various fasteners that are part of the StopTech BBK, notes about the Vorshlag camber plates, and even some stock stuff like a reminder of the existence of the secondary oil sump and the request to intentionally underfill during an oil change because an overfill is easy with these stupid dipsticks and can only be solved by draining from the bottom rather than running a fluid extractor down the non-existent dipstick shaft. Whenever the car needs service I just pull the relevant details from that master Word doc into a new one for the specific things I need done at that visit, and all is well.

[Groundpilot]

Originally Posted by CSBM5

The problem lies in a shop that over-torques lug bolts past their yield-point, even if they "fix" the problem right away...it's too late for that bolt. Then it is only a matter of time until that fastener fails in service (which is probably what happened in the case mentioned).

That is exactly why i have a separate set of lug bolts for the track

[Z K]

Originally Posted by jphughan

^ Interesting, the indy shop I go to (and have since developed a great relationship with the owner) always uses an 80 ft-lb torque limiting stick when they're attaching the lugs to my car, and they mentioned without my even asking that they periodically check the accuracy of those sticks by using torque wrenches on the fasteners afterward and consistently find the sticks to torque within 1-2 lb-ft of their spec.

Torque sticks are just used so they do not over torque when using air tools. The torque spec should still be checked with a torque wrench afterwards. A lot of shops are just lazy and use the torque stick to torque lugs and call it torqued.

[S65V8]

Originally Posted by Bmw135er

You should also avoid spacers as much has possible, especially under high stress circumstances like the track. They're just another added variable that can cause issues.

I should've mentioned I don't use spacers on the track, I pop them off. Spacers on the street are a must hate that wheel gap - so fugly.

[bigjae1976]

You can over torque a fastener with a torque stick. Stud kit or OEM bolts are both subject to failure. IMO, a stud kit is more prone to failure because there's more room for installation error.

Over-torqueing once will not cause your wheels to fall off. Not properly seating the wheel against the hub or not having hub centric wheels AND over torqueing WILL result in failure of the fasteners pretty quickly. So that's why it is very important to keep your hubs and wheel bores clean.

Although if there's a car at the track that is stuck on the side with 3 wheels...its usually a BMW.

[CanAutM3]

IMO, over-torqued bolts/studs used at the track is the most probable cause for studs or bolts to fail (unless the wheel is coming loose). When torquing a nut or bolt, it is not the torque per se that is sought after, but rather it is the amount of stretch of the bolt or stud that is needed. The bolts/studs act like a spring that squeeze the two surfaces to me mated together. It is the friction between the two surfaces that actually carries most of the load. If the nuts or lugs are over-torqued, this means the lugs or studs are also overstretched. Combined with the heat expansion of extreme track conditions, the lugs/studs can be stretched beyond their tensile strength limit causing them to fail. Every time you brake, the bolts/lugs are stretched, which could also cause fatigue failure.

Implying regular torquing and un-torquing of the lugs/studs as the reason for failure implies a very low cycle fatigue failure, which I think is unlikely if they are properly torqued to begin with.

[1MOREMOD]

Originally Posted by surlynkid

I don't let any shop mount my wheels. They get loose rims and tires. I bring them home and do it myself.

i do the same as well. just haul them in the x5. otherwise would be driving all over on the nt01s also. i see those guys almost monthly for mount or flip.

[bigjae1976]

Originally Posted by CanAutM3

IMO, over-torqued bolts/studs used at the track is the most probable cause for studs or bolts to fail (unless the wheel is coming loose). When torquing a nut or bolt, it is not the torque per se that is sought after, but rather it is the amount of stretch of the bolt or stud that is needed. The bolts/studs act like a spring that squeeze the two surfaces to me mated together. It is the friction between the two surfaces that actually carries most of the load. If the nuts or lugs are over-torqued, this means the lugs or studs are also overstretched. Combined with the heat expansion of extreme track conditions, the lugs/studs can be stretched beyond their tensile strength limit causing them to fail. Every time you brake, the bolts/lugs are stretched, which could also cause fatigue failure.

Implying regular torquing and un-torquing of the lugs/studs as the reason for failure implies a very low cycle fatigue failure, which I think is unlikely if they are properly torqued to begin with.

I agree. What's odd is I've seen 4 cars loose a wheel at the track. One was a D-Force LTW5 splitting at all 5 spokes at 100mph...but I digress. The other 3 were old model BMWs using OE BMW lug bolts.

Those lug bolts might have been old. But I'm curious if the lug bolts offer any reliability disadvantage vs the studs and lug nuts that every other non-EU car maker uses. I'm sure there are plenty of older Japanese and US cars with owners that aren't regularly changing their studs and are regularly over-torqueing them.

[pkimM3r]

I always use hand tools for lugs. If a shop starts using air tools i will stop them immediately. Just a breaker bar for taking off and your hand with socket and then torque wrench for putting on.

Do these lugs break that often after 10 track days because there are plenty of ppl on here that are ok.

Maybe due to having spacers on some of the time??

[bigjae1976]

Originally Posted by pkim1079

I always use hand tools for lugs. If a shop starts using air tools i will stop them immediately. Just a breaker bar for taking off and your hand with socket and then torque wrench for putting on.

Do these lugs break that often after 10 track days because there are plenty of ppl on here that are ok.

Maybe due to having spacers on some of the time??

When you get studs...you won't be spinning all 20 lug nuts on by hand. I still use air tools. Just don't get the lug nut tight and lay on the trigger for 30 seconds.