Loose lugnuts

[badassmav]

Does any body else out there have a problem with their lug nuts coming loose? We run the stock lug nuts on OMF wheels, which are machined to match the lugnut taper, and we torque the nuts to 78 ft. lbs. After setting the car on the wheels, I drive it for a mile or so, then I re-torque the lugs again. If this process is not repeated at least once everytime I put the wheels on, the lugnuts will loosen to around 60 % of their original torque value. In the hectic day before the IV 250, I failed to re-torque the lugs, and they came loose, allowing the rim to move and chaffe against the cast iron hub. The results were that we broke the center section out of that wheel on the second lap. I've seen other teams that use nylon, top locking nuts instead, but I prefer to stick with the countersunk lugnuts to better index the rim on the wheel studs, if possible.

 

[JoeyD23]

I just weld them on! Never had one come loose!

 

[Cwb from moval]

Never had a problem either. I put mine on with an impact.

 

[Bret901]

1/2" impact tight with ant-seize here!

 

[GOVACHO]

I learned my lesion with the impact gun and will never again.. After my lug failure I torque them to 80 lbs. an add anti-seize and haven't had an issue since.

 

[badassmav]

Impacts (1/2"), be it DC or pneumatic, torque in the 150-450 ft. lb. range. Factory specs are 75 ft. lbs. We vuse an impact on the course, but avoid laying into it for too long. I'm probably over thinking it as always. Weld 'em on. Funny dude !!

 

[badassmav]

I learned my lesion with the impact gun and will never again.. After my lug failure I torque them to 80 lbs. an add anti-seize and haven't had an issue since.

The lugs are a good application for anti-seize compound. I need to find out if the torque spec is for dry or lubricated threads. I'm with you about not using an impact. If the studs were at least 1/2" in diameter maybe. I live and die by a torque wrench. In last weekends case, I died by it because I didn't re-torque the lugs like usual, and it cost us valuable time, a broken $750.00 wheel, and perhaps even a win.
Thanks for your responses. I could always weld 'em (Joey D' Sarcastico!!)

 

[NIKAL]

Reid are you sure the lug nut taper is the same as the wheel? The only reason I ask is I have seen wheels come loose, even though they were impacted or torque wrenched on due to the taper not being the same. This allows the wheel to shift back & forth on the studs ever so slightly, which either hogs out the wheel holes or brakes a wheel stud. This is also more common on the thinner spun aluminum wheel vs the thicker cast wheel where the lug is recessed in the wheel face. That would be my first look.

How often do you replace the lugs? Could the threads be getting worn or stretched, allowing them to back off? How many threads are sticking out past the rim for the lug nut to grip? Can you find or run a acorn (VW style) lug nut that is open end vs the stock closed end? Look at the wheel studs and see if the threads are being pulled. If the material the manufacture used is somewhat soft you could be pulling or rolling over the threads on the stud vs the lug nut. Is the hub face mating up flush with the rim? If not this could cause a wobble and allow the wheel, to come loose. I have seen guys pitting class 1 cars and in the heat of the pit they dont get the wheel face flush with the hub and they impact the wheel on, only to have it come loose, shearing the wheels studs 20+ miles down the road.

 

[badassmav]

Reid are you sure the lug nut taper is the same as the wheel? The only reason I ask is I have seen wheels come loose, even though they were impacted or torque wrenched on due to the taper not being the same. This allows the wheel to shift back & forth on the studs ever so slightly, which either hogs out the wheel holes or brakes a wheel stud. This is also more common on the thinner spun aluminum wheel vs the thicker cast wheel where the lug is recessed in the wheel face. That would be my first look.

How often do you replace the lugs? Could the threads be getting worn or stretched, allowing them to back off? How many threads are sticking out past the rim for the lug nut to grip? Can you find or run a acorn (VW style) lug nut that is open end vs the stock closed end? Look at the wheel studs and see if the threads are being pulled. If the material the manufacture used is somewhat soft you could be pulling or rolling over the threads on the stud vs the lug nut. Is the hub face mating up flush with the rim? If not this could cause a wobble and allow the wheel, to come loose. I have seen guys pitting class 1 cars and in the heat of the pit they dont get the wheel face flush with the hub and they impact the wheel on, only to have it come loose, shearing the wheels studs 20+ miles down the road.

Yeah Todd, we had the wheel centers custom machined to match the degree of the lugnut taper (countersink). Since I'm the guy installing them, I guarantee the nuts are not tightened until the wheel is evenly seated against the hub, and the nuts centered within their respective tapers. I am considering thread deformation as a culprit. Using a nut for even a second time, can reduce the clamping force it applies by as much as 30%. The current lugs have been on and off at least 20 times. Minimum. I checked the wheel studs, and no, they have not been yielded. There is also a minimum of 1 1/2 times the thread diameter in thread engagement. An engineering rule I never violate!

 

[NIKAL]

I am considering thread deformation as a culprit. Using a nut for even a second time, can reduce the clamping force it applies by as much as 30%. The current lugs have been on and off at least 20 times. Minimum.

Yeah my team had rules regarding hardware. Nylocs can be used on a bolt twice. After that it goes in the used pile. Top Lock (aka Pinch Nuts) get 1 time. If you put a pinch nut on a bolt and 10 minutes later you have to remove it for something, that nut is now used and goes in the used pile. When we were racing full time, we had a nut & bolt sponsor. Our car was re-hardwared before each race. We might re-use some small skid plate or misc accessory bolt, but that was it. After each race we took that race's hardware, including washers, put them together so the bolt, washer & nut were fastened and put them in a box. Each pit crew or chase truck got a box that had all the hardware to re-bolt the entire car. There was never a reason for us to not have a bolt, nut or washer. BTW they were all F911 bolts, hardened nuts & washers! Nice!



Today's Tech Tip: On high stressed parts, like suspension, steering, shocks ect. Don't measure & buy a bolt by its overall length. Measure the componite and buy your bolt measuring the bolt shank length. The weakest part of a bolt is where the threads end & the shank begins. You want the load to be solely on the shank of the bolt, as the threads are only there to lock the bolt down. To do this is very time consuming as you are then cutting bolts down to size, but if you use good quality hardware and do this you will most likely never have a bolt failure. In all the years I have raced & prepped, I have never had a single bolt failure.

 

[badassmav]

Foremost makes quality hardware. Rick and I used them while in our driveway, but changed to Bowman hardware when we opened the shop. I remember Carroll Smith saying that they (Foremost F 911's) were "glorified grade 8 bolts" in his book Engineer to Win. I always treated them as such, but I believe they were 150,000 lbs. tensile strength, which puts them in between grade 8 and aircraft grade.
The "Bowmalloy" series hex cap screws are about as good a bolt as you can find, and they offer a couple of different metal, top-locking nuts to boot. Like you, we never re-use metal locking nuts, and whenever a critical load bearing bolt is removed (90 % of the time), we re-install a new one. Got a pile of good used bolts that I'm too cheap to throw away, but smart enough not to re use! I spent many hours learning, in the field as well as in the classroom, about hardware technology and applications. Call me "nutty", but one can never know too much regarding the marriage between hardware and racing applications of it.

 

[GOVACHO]

Well if either of you have a bag or two of them so called used nuts and bolts I'll be more then glad to take them off your work bench and put them to good use...lol.. Just saying that's all..

 

[badassmav]

Well if either of you have a bag or two of them so called used nuts and bolts I'll be more then glad to take them off your work bench and put them to good use...lol.. Just saying that's all..

If you can stop by our shop, I'll be happy to give you some used hardware. Most of it is 1/2"-20 shock and suspension pivot bolts. 1 3/4"-4" in length. I keep some around for misc. uses, but I can afford to lose a few as well. PM me, and I'll hook you up.

 

[BiggJim]

Hmmmm, I try'n avoid Loose Nut's at all cost

 

[Blue Coyote]

Sounds like a lug nut angle issue. We put DWT wheels on the Maverick with stock lugs (SnapOn torque wrench, etc) - could not keep them tight. Ordered DWT lug nuts, and so far so good.
Any paint / powder coat in the tapers will cause issues as well.

 

[badassmav]

Hmmmm, I try'n avoid Loose Nut's at all cost

Don't you have somewhere you need to be? Lol! Hey, is the new chassis ready to race? You sure grabbed the bull by the horns on that project! Hope all goes well for your team and car this weekend.

 

[badassmav]

Sounds like a lug nut angle issue. We put DWT wheels on the Maverick with stock lugs (SnapOn torque wrench, etc) - could not keep them tight. Ordered DWT lug nuts, and so far so good.
Any paint / powder coat in the tapers will cause issues as well.

Yeah, it took awhile to remove the powdercoat from the countersunk holes, as well as the rear wheel surface where it mates to the hub. It was a timely hand process, and the bore angles may have been compromised a bit because I dont have a radial arm drill press or milling machine to assure a square cut. I carefully used the proper degree countersink in a hand drill, along with paint remover and 220 grit sand paper to clean out the countersinks in the rim. The replacement wheel centers I ordered had a plug placed in the lug nut bores to keep the powder out of the countersunk area during powdercoat. .

 

[BiggJim]

Don't you have somewhere you need to be? Lol! Hey, is the new chassis ready to race? You sure grabbed the bull by the horns on that project! Hope all goes well for your team and car this weekend.

Is it ready? Its as ready as its gonna get!! I just did a small part on that car, We had 2 full Time employee's working on it for the last 3 weeks non stop to make it happen....as well as Justin and Myself here and there.

 

[crazywatson]

Something is not right keeping them tight shouldn't be a issue. Imo the nuts should only hold the rim onto the hub. The hub should be manufactured so the machined center fits over the hub and supports the weight so the nuts are only holding the wheel on the hub and not holding up any weight. Are the Can Am hubs manufactured in this way I know polaris is my wheel get stuck to the hub and I have to kick them off.

Sent from my SM-N900V using Tapatalk

 

[badassmav]

Something is not right keeping them tight shouldn't be a issue. Imo the nuts should only hold the rim onto the hub. The hub should be manufactured so the machined center fits over the hub and supports the weight so the nuts are only holding the wheel on the hub and not holding up any weight. Are the Can Am hubs manufactured in this way I know polaris is my wheel get stuck to the hub and I have to kick them off.

Sent from my SM-N900V using Tapatalk

No, the Can-am wheel hubs have no center "ring" or raised casting to locate the rims onto the hubs. By factory design,. the stock rims have a step on the back side of the casting that loosely fits the major diameter of the hub. Mfg. tolerances allows the interface almost 1/8" of slop, so in the end, the countersunk lugs are what's holding the wheel true to the hub. You make a valid point. I never thought of the wheel not being indexed to the hub as an issue. Now, it hits me like a ton of bricks! How ignorant of me! Thanks for the enlightenment.