Rear Wheel Stud/Wheel Hub Bolt Distress
 

Well, sooner or later, I was going to join the wheel stud broken club. Broke one of my rear wheel stud clean after finishing up an event. My standard practice is as follows:

1)Leave the car in 1st gear and rear parking brake on
2)Lift the car up in the air one wheel at a time via jack
3)Apply cordless impact wrench (rated 170ft/lb) to loosen OEM lug nuts,
vinyl-enclosed-deep socket all the way down making contact with rim hole
4)Swap whee/tire
5)Hand thread the lug nut back on
6)Re-apply cordless impact wrench until 2 clicks heard
7)Drop the jack and hand torque to 95ft/lb on the ground

The practice has served me well until this past weekend. One of the rear lug nut would not give, impact wrench or torque wrench (CCW). When it did eventually, the lug nut took the regularly exposed wheel stud section along with it. The broken piece is still stuck inside of removed lug nut. The fracture point is fairly clean and straight.

So what did I do wrong? Too much torque (on a freshly charged battery)? Bad OEM lug nut? The still-to-be-learned lesson will cost $110 plus parts per side at the dealer since the rear wheel stud is anything but DIY-friendly. Attached PDF shows the steps and SSTs required to do the job right.

Another solution is to use torque socket or the combination of torque stick and socket. Frequent wheel swappers please respond :dunno: :wtf:

I've been changing my wheels a couple times a month for the last 1.5 years and haven't had a problem yet, other than the stud threads getting a little tweaked. Your procedure is pretty much what I do, except I usually use a cordless drill with socket attachment rather than an impact wrench so I can't really overtorque anything.

Did you let things cool down after your runs before trying to change the wheels? The studs will expand with heat and could cause problems if you try to force the nuts off. That's my only guess...

You sure are going to have problems.... Mazda says max tq of 86 ft lbs for lugs.

Actually, they revised the torque specs awhile back and upped it to 108 ft/lbs: http://www.finishlineperformance.com...2-04-1301b.pdf

Either way, does 10 ft/lbs over spec really cause any harm?

Do you use any anti-seize?

^^^^^^^^^^

What he said. I broke a couple of studs on my S2000. Started using anti-seize, and never had a problem again.

Sigh...

The problem is the horrible OE lug nuts. We found out the hard way last year too. The OE nuts are soft and dirty. Take a brand new unused OE nut and screw it on a brand new unused stud and you can feel how rough it is. Add a little dirt, osme metal shavings from the wheel, and a bunch of wheel changes, and it's only a matter of time until the stud and or nut are galled up enough to have a problem.

When we figured this out last year, we bought some McGuard nuts from Summitt Racing (Part#: MCG-64002. The difference is like night and day. We also started using anti-seize and haven't had any problems since.

Looks like I'm living on borrowed time. No antiseize. Stock lugs. But I only torque to around 75 lbs. Didn't know it was higher than that.

1) Leave the car in 1st gear and rear parking brake on
2) Hand loosen lugs on one side of car.
3) Jack entire side of car up
3) Apply cordless DRILL to remove OEM lug nuts, rear wheel 1st.
4) Swap wheel/tire
5) Hand thread the lug nut back on
6) Re-apply cordless DRILL as far as it will go.
7) Drop the jack for back tire until wheel has contact with ground and hand torque to 75ft/lb
8) Repeat 3-7 for front tire.

I find 100+ ft/lb to be in the high range for lugs. Heck, my Subaru with AWD rally-x capabilities was 70 ft/lb. 100+ IMHO, could warp stuff if they get hot...

I haven't had any issues, nor have I had any loose lugs, even after driving my car to/from events these past couple years. Even all the way out to national events.

--kC

Anti-seize is your friend. I'd keep the same procedure but add anti-seize every couple of months and you shouldn't have any more problems.

A few suggestions so far:

1)Better lug nuts (McGard lists 64002 as 21mm, http://www.mcgard.com/deutschland/en...e_konisch.html)
2)Anti-seize on the thread
3)Watch out for heat with proper cool-down
4)Less torque (80 seems to be a good figure)

Should I continue break the lug nut loose using the cordless wrench with the tire off the ground? On or off the ground makes any difference?

For those who were brave enough to change rear wheel stud on your own, was it worth the aggravation/time/swearing?

That is insane... You would kill those things at that tq. Might be okay for the regular guy that takes wheels off once a year, but if you do it every weekend they will not take it.

I have done one of each, it is easy. Give it a wack with a hammer and it will pop out. Then use a spare nut and some washers to pull the new one in. If you rotate it to the right spot both front and rear can be done with only taking off the wheel.

Is that so? The bolts sit atop of brake shield in the attached pdf. How would hammering affect the wheel bearing? If I was to cut the damaged bolt short, than backing it out should by easy. The problem is putting the new long bolt in with limited clearance space.

I think the board will benefit in a huge way, if Jason can do a DIY on the rear. The front is here in case anyone is interested: https://www.rx8club.com/series-i-do-yourself-forum-73/diy-replacing-front-wheel-studs-73670/

I did it like a year ago and it went so quick I can not remember. I took nothing off but the wheel. There is room to fish a new full size one in there. I will have the tires off later today and will look at it. I tend to like to find ways to do things with as little work as possible, I am lazy and I like to know I could do it at an event without special tools. Kind of like I am the only one doing rear shocks without taking the rear suspension apart. :mdrmed:

As far as the wheel bearing if it can not take a couple of hits with the hammer I don't think we should race the car with sticky tires on.

Mazda specs them at 108ft-lbs, so 108ft-lbs is what we torque them to. And yes, doing it every weekend they will take it, assuming you use anti-seize and decent lug nuts (not the factory ones). I think we only applied the anti-seize once and the lugs have not given us any problems since.

I've always used 108 lb-ft torque with aftermarket nuts, never an issue and I won't run less :dunno:

Same here. Good aftermarket nuts and I torque at 105.

Clyde - thanks for the tip on the lug nuts. I have had to replace 2 front lugs and had a rear lug fixed. I just ordered some McGard lug nuts as I had no idea the stock lugs are what may have caused this. I started using anti-seize recently and all is well so far.

Situational update: dealer replaced the rear wheel stud, due to not being able to find any clear instructions on DIY. According to the dealer, wheel bearing, brake caliper, and hub assembly all had to be removed to get one little bolt replaced. Thanks to great Mazda engineering! 2 hr labor charge ~!@$

Bought the good-quality McGard 64002 (M12x1.5) from PepBoys for $8/4-lug-nuts and anti-seize. Torn about applying anti-seize due to overwhelming recommendations from those of you who swear by the lubricant, while tons of warnings can be found against the practice. See:
NASA Stress Test
http://www.tundrasolutions.com/forum...lug-nut-studs/
ScoobyMods
http://www.scoobymods.com/forums/arc...hp/t-2884.html
TireRack
http://www.tirerack.com/tires/tirete....jsp?techid=39
MotorAge
http://www.findarticles.com/p/articl...4/ai_n15692083

One thing for sure, I will try to use air compressor to clean the stud thread and enclosed lug nuts.

with the McGard lugs it looks like they will fit my 21mm socket, I would like to confirm that? Anyone who has em.

Yes, it's fine. 13/16in = 20.6mm. Close enough.

umm, I would like to make sure I don't round em off with my impact gun tho, that thing makes like 300 lb/ft

I've been using a 21mm impact socket with cordless impact gun for at least the last 30 wheel change cycles. No issues yet.

BTW, the $90 (after $10 mail in rebate) I spent at PepBoys for their 24v Goodyear Racing cordless impact gun is probably the best $90 I've ever spent on autocross related "stuff." Only twice have I had to resort to a breaker bar in those 30 wheel change cycles (=1200 lugnut removal instances) with the wheels up in the air.

hmm, my Milwaukee one was significantly more expensive. Maybe when/if it dies I'll look into that one.

+1 for Pepboys' 24v Goodyear Racing cordless impact gun. One NiCd charge lasted 9 wheel change cycles (off and on as 1).

yeah, it's a great buy

I've been using anti-sieze on the RX-8 and Miata, and I won't stop using it, as long as I am swapping the wheels on a semi-weekly basis.

Theoretically, the lube reduces the amount of torque required to get the correct pre-load in the bolt. So, if you use anti-seize and use the full 108 ft-lbs specified by Mazda you are stretching the studs by a greater amount than Mazda intended and putting greater forces into the hub.

Whether or not this is a problem is hard to say. Fatigue failures are notoriously hard to predict. But it's equally hard to predict how quickly the studs will degrade due to friction & contamination in the un-lubed state. Galling can also cause failures, as already noted.

I run 90 ft-lbs with anti-sieze as a compromise. Don't know if it's right or wrong, just a guess. :dunno:

Agreed.


I worry more about galling threads than breaking the stud through over-torquing.

How would a hammer affect it?

How would hitting your average hole in the highway at 80mph with a 3000lb car on top of it affect it.

:)

Wondering whether you can remember how to get the rear studs off while not taking more than just the wheel off (certainly not the hub). I have had issues at the track. I found out how to do the fronts with only removing the tire and was surprised to read your experiences.

Please help a fellow racer with issues at the track. This experience has made me hate and fear tire changes. Right now, if there were issues at the rear, I'm done for the weekend....which is an awful feeling.

Thanks.

anti-seize your studs, use 90-95 ft-lb torque, replace the OE nuts with a set of McGard or Gorrilla lug nuts, and pray

otherwise the rear hub will need to be disassembled

one member did manage to swap one out without disassembly by grinding down the stud heads on one side so that it could be slid out/in from behind the hub

:uhh:

Count me in for the stripped stud club. My local mechanic autox buddy helped me change out my rear stud yesterday. A HUGE PAIN. We did it w/o disassembling the rear hub, but had to:

1) Cut the disc cover
2) Filed down the stud head on one side to get past the rear knuckle
3) Used a hammer. Lightly ;)

Even after rotating the hub, cutting the disc cover, and filing the stud head, it still was a huge pain to get the stud past everything. If I had to do it over again, I would consider just disassembling the hub.

I will do everything I can to prevent this from happening again. Tommorow, I'm buying McGard lug nuts for my autox wheels and some anti seize...

I already picked up a fresh set of Dorman lug nuts to replace my crappy street lug nuts. Any experiences w/ Dorman lugs? Should I go online and get a real set? The Dormans were the only set the local store carried that fit my silly heavy bling SSWs.

cutting the disc is not what most people want to do, but it would prevent having to remove the hub

get the Gorilla nuts with the small 17mm hex if you can, these are what Tirerack provides with SSR wheels, they are great and relatively light, lets almost any socket fit in the tightest wheel holes

So after some digging, I found an old set of kyokugens in the garage, but the key/spline is stripped (common apparently). Is this set worth replacing the spline and using for my autox or street wheels? The lug nuts look like they are still in good condition.

I hate spline lug nuts ...