this weekend at the local autocross event there were two lug bolts on two different 04 models one an S and one a cooper that had the bolts twist off during tire changes torque to 80 ft lbs with two different torque wrenches,, these are the gold colored bolts,, i didn't have any problems with the 02 car that had the black lug bolts

 

Geez - 80 ft/lbs isn't all that much torque. Sounds like there might be a batch of faulty lug bolts flying around. I always torque my lugbolts to 81 ft/lbs and have never had a problem - My bolts are black (2002 MCS).

 

Thanks for the head's up about the gold colored bolts. I am using the black ones that came on my 2003 MCS, but have gold bolts that came with the wheels I am using for racing.

Have not tried the gold bolts, but won't now that I have heard this. . . . .

 

85lb/ft with my '02 for more wheel changes than I could ever count...
Yep, something's going on there with the '04's.

Brian

 

Gold bolts from an 02 MCS. 80 ft/lbs and no problems.

 

Argh, I have an '04 Cooper on the way. Guess I'll find some other bolts to use! I've been torqueing my Honda lugs to 85 ft*lbs (factory spec is also 80).

 

hmm, does this mean they may come off when driving? it does not affect my march 03. But i'd like to know.

 

04 S with a 10/10 build. Gold bolts no problems, owners manuel say 88.5 lb ft for torque. I usually run them to 90.

Harts it would be really good if you could find out the build dates.

 

my 04 cooper was built about the 2nd week of january,, and the other one an S i think was probably a november,, i had another bolt fail yesterday when i had it in to the dealer for some brake work,,, by fail i mean that when you go to torque them they get to about 70 lbs and then just start stretching and don't get any tighter ,, of course if you continue turneing them they will break,,, i don't want to alarm everyone but it's no fun to be at the track and have this happen and you don't have any spare lug nuts, so it would be wise to pick up some spares and keep them in your tool box,,, cheers

 

Everyone who knows of failing bolts, please call MINIUSA and let them know. Let's try to get a TSB/recall. Until then I have some 03 golds, if anyone wants them- PM me.

 

I had a black lugbolt on my new 05 MCS twist off at the track this weekend, (88.5 ft/lbs of torque) dumping me unceremoniously on my ***. The only opinions I've heard is that an air wrench was used on them at one time, weakening them, which I imagine would be on the assembly line.

Carrying spares will do you no good if the rest of the bolt is buried in the hub. My MINI dealer removed the remains and treated me to a new lugbolt under warranty, but my day at the track was shot.

Has anyone done a stud-and-lug nut conversion?

 

i was a grissom aeroplex in indiana at a test and tune event and after the day was done, i didnt check anything. so the next day i drive back to the actual event and all of my wheels were shaking, i felt insane vibrations through the steering wheel. ALL of my lugs were loose. I drive a 3/04 build cooper s.

scary when you think about it, if l i lost a wheel at 55mph!

 

Good to know the car gives you some warning before puking a wheel.

 

what kits where used??? =o)

 

What kits?? Stock S-lites with stock black lug nuts. I can't worry about this while changing shoes or re-torquing the wheels at the track.

Solution: replace with chromed Gorillas.

 

i wuz askin' the same question as above post "what lug kits have people used"

 

Oh. Sorry.

I heard kmickey did the change, but I haven't talked to him about it.

I decided to stay with the lug bolts for now.

 

The lug bolts on the 2003 MCS sheared at a time trial event 15 laps after they had been correctly torqued. Bolts were analysed at CO State and there were obvious signs of metal fatigue - think crystalization. Just too many heat cycles. Car had 10K miles, mostly track and autocross, just about 2 years old. Car is driven very hard most of the time.

The car runs in GS, so there is no option of better brake kit, and the tracks we run tend to be very demanding on the brakes.

Solution - replace all lug bolts annually. No problems since.

A word on the stud conversion kits. EVERY single MCS I have seen converted to studs has had problems with studs coming loose. The Mini hub is not very thick, and there is not a lot of thread depth for the studs to seat into. All studs had been treated with threadlocker. My advice for those considering a stud conversion, place a small tack weld on the back of the stud. This will prevent the stud from backing out, and the tack weld can be ground down if you ever need to change the studs.

Running stock wheels can exacerbate the problem.

 

Thanks for the report from the field, Bones. That's the kind of real world info I was looking for. My sheared bolt also looked like it had crystalized.

 

I have an early 03 MC. I made the switch to black lugs when I got some after market wheels. I keep some of the extra gold lugs in my factory tool kit. I autocross some in the DC area. If anyone here is at an event and needs to replace a lug bolt - let me know.

John
Silk Green/B Cooper

 

I just bought a set of studs and aluminum nuts from Tire Rack. Cost about $80 shipped for the set, with 4 extra nuts, just in case. Will install tonight and let you know how they work.

Per

 

 

I was with you right up until the last sentence. Heat cycles don't cause metal fatigue. And if your steel lug bolts got hot enough to affect their metallurgical properties then that would be the least of your problems: your wheel bearings and even tires would likely be on fire! Depending on grade and temper the mechanical strength of steel is unaffected until above the 550-600 deg C range, i.e. in excess of 1000 deg F.

Metal fatigue in steel is caused by repeated mechanical stress beyond the material's yield point. Think in terms of flexing a paper clip back and forth until it suddenly breaks. The equivalent for a lug bolt would be either:
a) Grossly overtightening so that it doesn't merely stretch, but yields.
b) Undertightening so that wheel torque (braking and accelerating) loads the lug bolts in shear. They may then be flexed back and forth until they fatigue. Normally these bolts should be loaded primarily in tension, with wheel torque loads being transferred via clamping friction between the wheel and hub.

Obviously (a) can happen if you hammer away at 600+ lb-ft max with your trusty IR2131 air impact gun, but that's not normally going to be the case. I hope.

You'd think that (b) wouldn't happen too much either, but there's at least one non-obvious way it can. If you have aftermarket wheels that don't seat nicely on the hub, or if there's the same problem with spacers or hubcentric rings, or if there's corrosion between the wheel mounting face and the hub, then you may not get proper clamping force between wheel and hub. In this condition cornering forces could also cause the wheel to rock slightly on the hub, unloading and overloading individual lug bolts in turn until they fail.

For a track or autocross car replacing the lug bolts periodically and preëmptively isn't a bad idea though. If there isn't a nearby Mini dealer when you need to you can buy them at any BMW dealer - lots more of those.

Neil
05 MCS - stock lug bolts
96 M3 - studs and lug nuts

 

Quick write-up on the Tire Rack stud conversion.
http://grmotorsports.com/news/catego...5-mini-cooper/

Per

 

Yeah, kinda skimpy coverage.

If you look at the pix you'll see that there's no hex recess on the outboard end of the stud, so there's no direct way to tighten the stud to the hub. It's quite important to get it threaded in firmly under tension; threadlocker alone isn't enough. The way to do this is by double-nutting, a procedure they didn't mention. Maybe they did in the print article?

BTW, I used to have those same aluminum nuts and would very much advise against them. Aluminum is a notably poor choice for fasteners, and the weight savings is trivial. The black finish mars quickly too. The main reason to fit studs is if you change wheels frequently, for track or auto-X. Aluminum nuts don't hold up well to that kind of (ab)use. If you even begin to cross-thread them they're toast.

Neil
05 MCS - boltly
96 M3 - studly