mbackhand

So my wife and I were headed home last night about 11:30pm and the car started shaking violently at about 50mph. Thankfully the wheel did not fly off as we were about to get on the highway in which we would have been going 75-80 !

I pulled over thinking I had a flat and discovered that 2 lug nuts had snapped off and the remaining 3 were literally finger tight.It was the rear drivers side wheel.

I made a few phone calls and decide to tighten the 3 remaining nuts and CRAWL home.

So now what? What is involved in replacing these? I imagine the hub needs to be replaced ?

slvr993

That could have been very ugly...
As far as the broken lug bolts, they can be replaced individually without replacing the hub.

Jeff

larpy

I would replace them all. The stress put on the remaining lugs could have damaged them. With your car being a 95 it may be a good "piece of mind' to replace them all since it is pretty inexpensive DIY project.

Garth S

As Jeff said, the studs can be replaced. First, determine why they are broken ..... usually, it is due to lug nuts that were not torqued correctly, or worked loose: that could erode the conical nut seat in the wheel - but from the pic, yours appear OK.

The studs are 50mm oal ( head included), with 37mm of exposed thread above the flange face - ~ 10mm of splines 'bite' into the holes in the flange to secure them. They are replaced by pressing them inwards - but to do so, the rotor/disc and the shoe assembly of the parking brake must be removed. There is one 'well' in the hub carrier behind the shoes that is deep enough to allow the full length studs to be pressed out, or inserted.

The easy way to fit new ones is to slip a stack of large washers or oversize nuts ( yea, I know what it sounds like ) down over the new stud, and reef on a correct lug nut to draw the splines into the flange .... no big deal to get yourself running again!

ReinerFink

I have an extra 993 front hub in my garage... used but in good shape. Make me a reasonable offer?

Note, you'll have to get a new wheel bearing if you go this route.

-reiner

User 122821

The studs can be pressed out and new ones pressed in once the hub is removed. Fairly straight forward job if you have access to a press. I've banged them out before with a heavy mallet when I had no other choice.

vertex carries the individual studs. I would definitely replace all of them and probably on both front hubs.

http://www.vertexauto.com/ShowItem/1...0-%2066mm.aspx

David in LA

if you've ever considered running small spacers then you may want to go ahead and install the longer studs.

Tango635

Glad to hear that you and your wife are OK. I got a scary story about lug nuts...

My wife's cousin invited my wife, mother-in-law, and I drive out to Louisiana from Houston in their suburban for a night at the casinos. There was a couple of others going, but they still had room for the 3 of us. I said, no we'll take our car just in case. Just before we took off, as they pulled the suburban from the opposite side of the street to the residence side for loading everyone up, we heard some clanging coming from the right rear wheel. It happened to be one loose lug nut in the hub cap, checked the others, they were loose too. Tightened all the lug nuts on, then took off. On the way back to Houston, I was following them, I saw one of the most surreal things. If you've been in an accident, you know, everything seems to suddenly go into slow motion. I saw that rear wheel shoot off to one side, then next thing the suburban rolling down I-10..... Everyone was eventually OK, but yeah, I would say change all of them on that wheel for now.

I completely agree with trying to figure out if they were left loose or if they were over-tightened. However, it maybe more reassuring and safer to just replace them all. If the car was taken to some discount tire type place, then the lugs/studs could have easily been over-tightened. Some people think the tighter the better and don't know anything about materials and ultimate yield strength.

Has someone tightened your lugs on that wheel recently?

bart1

Also, get yourself one or two open ended steel lug nuts to remove and reinstall the studs.

Robin 993DX

How did this happen? Were they not tighten to the right torque from the start?

mbackhand

I am not sure what caused it. I check tire pressure and the lugs pretty regularly so I am don't know.

I do know that I will be checking them even more often now.

Steve Weiner-Rennsport Systems

In the majority of cases, broken studs are caused by overtightening.

This can be due to the use of an impact gun or a torque wrench thats lost its calibration. I'd kindly recommend having your wrench tested and calibrated in case its off.

Ours are all tested annually.

autobonrun

From M4hand's description, it seems that the nuts were not torqued down. If all 5 are torqued correctly, and two were to break for whatever reason, it seems to me at the speeds he was driving, the other three hold the tire on and would not be finger tight when inspecte; unless they were finger tight from the beginning.

My opinion is all 5 were loose, these two took the brunt of the wobble and snapped first. I agree with the others, replace all 5 and torque them to spec.

It is possible a shop just forgot to torque them down. It would be easy for someone to go reach for the torque wrench, have the phone ring, then forget to go back. It's hard to say.

Have you checked the other three tires?

By the way, glad you and your family are ok.

jscott82

Thats a really good point.... Mines 5 years old and never been tested....

bart1

Torque wrench calibration is not a bad idea, I bet 25 lug nuts that's not what happened here. I would bet on left loose at last service or tampered with(?).