Im am about to do a wheel replacment on my x andsee in the manual thay have a tourque wrench setting of like 78.5 or something..to tighten..Do I reallly need to use one..cant i just use the crowbar that come with the car and tighten it as hard as i can..trust me im not super strong.lol...gonna do a brake jog as well,but dont want to start if im gonna make more work for myself..lemmie know guy's

 

I would use the torque wrench.

 

Irish, I have 2 things for you to consider when trying to come with an answer for this:

1) when taking things to "as tight as I can take them" (I call this spot torque, ie, you twist till you see spots), it is very easy to push things to beyond what they are designed to do. Think of it this way, the studs/lugnuts serve a few different jobs. Not only are they there to apply a clamping force for holding the wheel to the rotor, but they are also there to overcome the stress applied when the car is pushing to the side when turning. They also absorb the shock of hitting a pot hole. You can factor in a few others. So, take a stud/lugnut that has a breaking point (called fracture point) of say 100,000 pounds/inch. The stud only has about a 1/4" of surface area. So, the stud will break if you exceed 25,000 pounds of force. By torquing the stud to say 100 ft-lbs, you may apply a force of about 3-4,000 pounds as seen by the stud. In the big scheme of things, this isn't that much since the stud won't fail until a much higher force is applied. Hitting a pothole can subject the stud to forces in excess of 10,000 pounds of force. When you turn, a force of say 1,000 pounds can be applied (the law of the lever is your enemy with this). When you start adding up these forces, you can start to get close to the 25,000 pound magic line. Now, you start going to "spot torque", that puts you that much closer to your magic line of breaking a stud (or 2, or 3). So, as you can see, having a good idea of where you are torquing things to is important so you don't break things.

2) Applying the same torque to all the lugnuts is critical. By tightening some more than others, you are applying different amounts of force to the rotor (remember, it is sandwiched between the rim and the hub). This will cause part of the rotor to want to bend out towards the outside of the car and other parts to want to bend towards the center of the car. As you apply your brakes and let them cool over and over, this uneven force setup in the rotor will cause your rotor to want to relieve these stresses, resulting in a rotor that won't spin in a nice straight line (ie, warped rotor). So, unless you are good at being able to tighten things to a given amount and being able to do it over and over, having something that shows you how tight things are is a great help. Working around system that were responsible for keeping people alive (gotta love hull work on a submarine), we used the "feel" method of torquing as a last resort. Then only certain people could do it after getting special permission.

So, as you can see, spending some money on even a cheap torque wrench can save you money in the long run from having to do other repairs. Hence why I have 3 different torque wrenches in my garage to handle just about anything I do.