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Old 09-16-2010, 08:26 AM   #1
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impact guns (wrenches) on porsches

[rant on]
just doing some minor work (currently underway) new set of discs (rotors) and pads and some minor suspension overhaul has turned into a hell of hells and need to vent....

who ever did work on my car prior to my ownership had a mechanic that seems to have taken joy in using an impact wrench to tighten everything up and is now involving routine trips to by replacement bolts, nuts everything else.

why oh why do people not use a torque wrench and use the correct torque settings rather than wind things up with an impact wrench till the bolts distort.

and with the ally/steel mix, it makes things even more 'interesting'.


by the way, mine has main dealer service history. go figure !

[rant \off]
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Old 09-16-2010, 08:53 AM   #2
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I feel your pain. People use air tools because they are lazy and/or in a hurry.

Be especially careful about this at the tire stores. Although they supposedly have and use torque limiting tools.

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Old 09-16-2010, 09:08 AM   #3
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Mark

dont even get me started on that. you ever seen a tyre (tire) shop adjust the torque on an impact gun i sure as s... havn't. doesnt matter if its truck with steel wheels or performance car with rare alloys.. wind it & 'up git 'er done'


just bought a complete new set of stainless wheel bolts and lock nuts as the cups are distorted and chewed to heck...

... as well and having the wheels restored (pick them up tomorrow) so nice new bolts too.

oh by the way, this thread broke my virginity.. this is my second post on the forum.

Last edited by Bruce Wayne; 09-16-2010 at 09:12 AM.
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Old 09-16-2010, 09:49 AM   #4
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A tire shop gunned on and managed to round the nut holding the pad carrier on my Mountaineer. Now months later, I can't service the brakes because of the rounded nut, just for digs they lost my wheel bearing dust cover too, thanks for the meticulous work, I mean 70.00 an hour what can one expect?
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Old 09-16-2010, 10:35 AM   #5
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Air tools save time and make servicing your car more affordable. Wanna pay an extra 2-3 hrs. labor because someone disassembled/reassembled your car with hand tools? Even if you do, the shops don't - it's all about revenue per bay/hr. They need to maximize this and air tools help them do this.

That said, there are many types of air tools. An impact wrench is supposed to used only for removing stubborn fasteners. To attach a fastener, you are supposed to use an air ratchet wrench. Any torqueing s/b done by hand. There are breakaway torque sticks which use a sort of calibrated clutch to stop the force of the tool at a certain torque. These are very inaccurate, yet this is what many tire shops use. Also, they're made for use with an air ratchet wrench only. If you use them with an impact wrench (which uses pulses of air), the torque stick 'resets' between the pulses and so never releases the force of the tool.

Air tools are also at the mercy of the compressor and it's regulating valve. These are almost never recalibrated (though they s/b with great frequency, esp. in shop use).

Air tools are a good thing if used properly, but few shops do and even fewer do so consistently.

I have a full set of air tools and use them all the time - properly.

If you're going to farm out the work on your car, there are two things you should do. First, look around the shop and see how they're using their air tools. If the only thing you see being used is an impact wrench, pick another shop or assume the risk.

Also, when having work done, specify in writing on the service order that you do not want air tools or torque sticks used to tighten the fasteners. This way you have their agreement in writing before the work begins. Again, any shop unwilling to do this would be one to avoid, or as I said above, assume the risk.

Cheers!
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Last edited by Lil bastard; 09-16-2010 at 10:38 AM.
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Old 09-16-2010, 11:54 AM   #6
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A few years ago, when I first got my Boxster I was having my snow tires taken off and the tire guy used an impact gun to take things easier and stripped the screw holes on one of my hubs. They had to spend about $1200 to replace it. Now if anyone is taking my rims off, I make a point to tell them, "No impact guns."
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Old 09-16-2010, 01:19 PM   #7
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Quote:
Originally Posted by rick3000
A few years ago, when I first got my Boxster I was having my snow tires taken off and the tire guy used an impact gun to take things easier and stripped the screw holes on one of my hubs. They had to spend about $1200 to replace it. Now if anyone is taking my rims off, I make a point to tell them, "No impact guns."

As lil B correctly pointed out, in most places the gun torque is at the mercy of the inherent air system. I'm sure when you are out of sight, anywhere that repairs vehicles is gunning the lugs...
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Old 09-16-2010, 03:14 PM   #8
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A couple other points:

Stainless lug bolts are not a great idea on our cars with alloy wheels. There is a high potential for galvanic corrosion which could cause early failure. Stick to OEM quality.

The op discussed really stuck bolts when changing his rotors. This may not have been an air wrench problem at all. The top bolt on our caliper is often frozen in place due to high heat and corrosion over time. It is a common problem and much worse in damp seaside communities or regions with salted winter roads.

Yes an impact wrench is a useful tool when used correctly. Just finish with a hand torque wrench.
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