Why you don't want to use impact gun to tighten wheel lugs

G

GP20

Senior member
Brought my Z4M to a local Discount Tire store a couple of months ago to get my wheel re-balanced. After they were done, they used an impact gun to initally tighten the wheel lugs before they used a torque wrench to manually tighten the wheel lugs to spec. I had just taken off the wheels a couple days ago and everything was fine. The impact gun must have somehow badly cross drilled one of the rear wheel lug holes. Last week when I tried to take off the wheels, one wheel lug would not loosen up. On my 2nd try, the wheel lug broke and left the rest of it inside the wheel hub. I found one other wheel lug on the same wheel hub that was not loosening up either but this time I didn't want to break it as well. It's bad enough to have to drive around with 4 lugs on a wheel; I didn't want to have to drive around with only 3 - not to mention it was the rear wheel. Inspected the other 3 wheels and at least they were fine.

Took the car back to the Discount Tire store, and surpringly they didn't give me an hassle at all. They agreed to take care of it about as soon as I explained the situation to them. They even let me take my car to a shop of my choice, Truline - who's very reputable and do very good work but not known to be cheap either.

Turned out that I would need to replace some parts (parts are for a Z4M-roadster):

wheel hub: 33412229120
Axle nut: 33411133785
Angular contact ball bearing: 33411090505

The parts cost about $270 at the local dealer, or about $170 from Tischer BMW. But it'd have taken too long for the parts to arrive if we ordered from Tischer BMW so we got the parts from the local dealer. Discount Tire is paying for the parts anyway. I dropped off my car at Truline today and probably won't get it back until next Monday (need to wait for the parts to arrive at local BMW dealer). After talking to the owner of the shop and understanding the process of the repair, my guesstimate is the labor alone will probably at least 1~2 hours.

So the moral of the story - always hand-tigthen your wheel lugs. Even if you bring your car to a local tire store, tell them in advance NOT to use an impact gun.
 
IF the lugs are started by hand till well seated, then an impact wrench shouldn't affect it. Unfortunately, most tire shops hire a kid fresh out of school that does not know better and starts with the impact wrench instead of by hand :cry:
 
I hand tighten all my bolts, and then finish with the torque wrench. But I will remember to tell the people at the tire shop to do the same. Nice writeup, GP20. :thumbsup:
 
Thanks for the warning! A lot of trouble for you!
Should end well due to a honest shop -

Best!
Jack
 
I use a Black and Decker cordless Drill set on it's lowest torque setting with a 3/8" drive adapter to do the work after I get it started and know the threads are aligned by hand. The torque is so low in this case that it won't even make 1 ft/lb before it starts chattering which is all the work I want the drill to do before I finish the job with my torque wrench.

The Tire Factory is just as bad or worse - they refuse to even use a torque wrench and when I objected I was informed that "we are professionals at this - we know what we are doing". I had to use an extender on a breaker bar to get the lug nuts off so I could torque things down correctly after I got home. I was lucky they didn't break anything. That was a number of years (and cars) ago but I have never even considered going back to them after that.
 
I often use an air impact gun to remove but not to put on.... :)

Z41101.jpg
 
AlanL said:
Oh yeah - I do have one at home and I use it to remove only as well.
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X2 or 3.. :)


Someday (if it ever warms up again) I'll put my GS-D3's back on and terrorize the neighborhood again. :headbang:
 
Yeah I can't believe the idiot cross threaded the nuts. That's just lack of experience. Glad to hear they aren't giving you a hassle on it. What is the torque on our wheel lug nuts anyways?
 
You raise a good point in the tightening of lug nuts, shame it proved so inconvenient to have to get the issue fixed.

Once started manually I see no problem at all spinning them up with an airgun or my personal choice is the drill on low torque setting spinning a suitable socket. Trouble with many tyre shops is there equipment is abused and settings very rough and the shop junior who puts the nuts on has no idea what he's doing.

The key to me is to torque them and then AGAIN after some miles have been put on. They very often loosen up as they settle in

As an off road driver I could tell you so many stories of loose lug nuts, wheels coming off due to the stresses and strains such use causes and so on. Performance cars are not disimilar in what we ask of them in hard cornering and braking Vs the average 4 door saloon.

Heres' what I use in a variable speed drill on low torque setting to spin sockets quickly once start threaded:
http://www.screwfix.com/prods/17228/Screwdriver-Bits/Nut-Drivers/Nut-Socket-Driver-Bit-Set-3Pc
 
I always give the guy a $20 tip prior to installing the wheels, and request that he uses a torque wrench. Seems to work :thumbsdown:
 
Thanks for all the responses and some very good advice. :thumbsup: I dropped off my car on Wednesday, and actually got a call from the shop around Thursday noon that the repair was completed. Great work by Truline in Bellevue, WA. For local people here, the Discount Tire I used was the one on Bel-Red Way and 130th ave (I dealt with Sean). I'm still impressed by how stand-up they were. It had been a couple of months since they worked on my car and they could've easily denied responsibility.
 
Zeefour said:
mattholecko said:
What's the torque spec so I can tell them when I get my wheels changed?
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BMW has upped wheel torque specs for all BMWs (except X5s) to 87 lb ft., +/- 7.
Click to expand...

I believe the official torque spec has always been 88lb-ft.
 
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