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I've had my Bolt since March and love it. However, yesterday it began making a loud "scraping" noise. The noise appears to be coming from the left front wheel and sounds like metal-on-metal. I've looked under the car and around the wheels but can't see anything. Befor having it taken down to the local dealer I wanted to know if anyone has had a similar issue.

Thanks!
 

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I've had my Bolt since March and love it. However, yesterday it began making a loud "scraping" noise. The noise appears to be coming from the left front wheel and sounds like metal-on-metal. I've looked under the car and around the wheels but can't see anything. Befor having it taken down to the local dealer I wanted to know if anyone has had a similar issue.

Thanks!
Do you see any pronounced scoring on the rotor for that wheel? It is possible for a small rock to get wedged between the rotor and a pad, and make a pretty nasty noise. You might have to use your hand to feel the back side.

Don't do this if recently driven, the rotor could be hot.
 

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Discussion Starter #3
I don't see any scoring on either front rotor. I used my endoscope to look around the brake calipers but couldn't see anything there either. However, the small rock hypothesis seems plausible. I may try to hose out the rotors.

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Also check to see if it's just something really simple like the backing plate touching the rotor at some point. That typically happens.
 

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I found the "rock." It was about 1/8" in diameter and very irregularly shaped--the kind of rocks they put on the road around here before repaving. It had settled into the bottom of the inside lip of the backing plate, between the plate and the rotor. It may be common, but it looks like a bad design to me. For this to happen the rock has to be of a particular size--and being irregularly shaped helps! Next time it happens (and I suspect it will) I know just where to look.

Now I have another question: how tight should the wheel lugs be torqued? I set them all at 80 lb ft, which seemed to be close to where they were originally. Maybe it's in the manual, but I couldn't find it.
 

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Discussion Starter #7
Actually, I owe Martin a "big" one since this would NOT have been covered under warranty had I taken it to the dealer.

Thanks Martin!

Jim
 

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Sweet ! Glad it was something so minor and didn't cost you anything or cause any damages :)

For the lug nuts, 80ft-lbs sounds good to me. I think anywhere between 80-90 should be ideal. Drive it around and re-torque after a few days just to be sure nothing has backed off at all
 

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Page 320 of the Bolt owner's manual. Under Capacities and Specifications.

Lug nut torque- 100 ft lbs. (140nm)

No surprise here. It's almost always 100 ft lbs with alloy wheels.

I recommend using a criss crossing pattern (see below) to first torque them to about 50 ft lbs and then do them again in the same pattern to 100. Proper torque and uniformity are very important to keep your brake rotors from warping and also to keep your alloy wheels on. If you've ever seen a car by the side of the road with aftermarket alloys on and it's clear one came off and spun down the road, now you know why.

In the old days with drum brakes and steel wheels you could get away with whatever, but today's cars require a little more care.

 
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