Auto body repair & detailing: Car makes high pitched noise when in reverse

Question
My 2006 Kia Spectra is making a high pitched sound (almost like metal scrapping against metal) every time it is driven in reverse. Once it is put into drive it continues for a short bit (but at about 85-90% less intensity) and then stops. I just replaced all 4 brake pads less then a year ago. Any ideas what could be the cause?

Answer
Hi Rebecca!....Unfortunately, this type of issue has a multitude of various causes. The first thing that comes to mind though, is the transmission. Especially since you mentioned the sound is  more prominent when driving in reverse. In regards to a manual transmission, a high pitched sound  or whine, or even a grinding sound is very common with manuals, especially while driving in reverse. The reason being, is that reverse has the lowest gear ratio. Even lower than first gear. Also because the gears are meshed physically. Hence the whining/grinding sound. With regards to automatic transmissions, they generally use the same gear ratios as a manual, do still have gears, but the sound is less noticed due to the fact they use hydraulics, clutch packs, a torque converter, etc. to accomplish shifting. The best advice I can give to you, would be to take your vehicle to a mechanical shop that you trust, or have a good reference to, and have them put it up on a hoist. This way, the car can be run in forward and reverse, and the transmission could be checked out. One other common issue for grinding/scraping while driving in forward or reverse, is wheel bearings. Once on the hoist, each wheel can be isolated individually to verify a problem or not....Hope this helps you out, and gives you some direction as to where to look....Please drop me another line if you have any other questions or concerns.....Thanks....Dave.