Torque on wheel bearing bolts

[our1vue]

Could someone please tell me why the bolts that hold the wheel bearings to the knuckle have to be torqued to 92 ft/lb ? Those bolts aren't that thick. The wheel lugs get torqued to 96 ft/lb and they are much thicker. Is it to stop the bolt from backing out ? Seems like some loctite or some lock washers could fix that with much less torque. The 90 something holding the disc calipers seems pretty high too. Is there something I'm missing ?
Signed,
Still sore from trying to tighten them to 80 ft/lb

[OhioVueBoy]

Because when they come loose, a bucking motion will ensue that will make you want to commit suicide when in traffic.

A lot of early owners, myself included have dealt with this. Mine have backed off a couple of times... some dealers even started LocTiting the nuts. Saturn issued a TSB early on regarding it.

~D.J.~

[our1vue]

Ohio,
What did the TSB say to do ? Just to check the tightness ? I torqued mine to 80 ft/lb (as tight as I could do it).
I was afraid the bolts were going to break. Then I checked the other side and they weren't even on 65 ft/lb. So I backed off the other side to 65 ft/lb and that is where they are now on both sides. I was tempted to put loctite on the threads, but wanted to check here first to see why they were so tight to begin with. Maybe I'll take the bolts out again, put on some loctite and put them back in at 65 again. That should hold them. Did you change your bolts when you replaced the bearings ? Thanks, Our1Vue

[OhioVueBoy]

I've never had to replace bearings *knocks on wood*... they just back off normally. I believe they are putting something on the new ones from the factory, but this was an issue with early VUEs.

If at 65ft/lb you are able to accelerate smoothly and idle in traffic without it bucking, you should be fine. When those bolts get loose - this bucking action will begin, and it will escalate (if you don't stop or push the clutch in on manuals) to the point that the tach will start moving with it. At this point, people for a 1/4 mile radius will forever think you are a drunk, or a manual n00b.

~D.J.~

[1saxman]

our1VUE; Get yourself a torque wrench that is rated for 150 ft. lbs. It will have a long handle and you should be able to get 90+ fairly easily. If I needed one and had no plans to use it more than once or twice a year, I would get a cheap one from Harbor Freight. You shouldn't be messing with critical components if you don't have the equipment to do the job properly. You're playing with your life here.

[scotted73]

I second 1saxman's comments...
Check out Sears, their Craftsman tools are usually on sale. Pick up a Ft/lb & Inch/lb torque wrench and keep them handy if you plan to work on your car. In the event you do have problems, you can at least state you torqued the nuts to their proper specifications.

[our1vue]

1saxman,
I do have a 2 foot 150ft/lb torque wrench. There wasn't much room to swing it in the wheel well. Three of the bolts I could have tighened up to 92 with a lot of effort, one was a pain to get to and put that much force on it. I was more concerned about the bolts breaking. Those bolts aren't that thick. That was why the question did they have to be so tight. If it was just worry about loosening, then some loctite should fix that without the high torque.

Ohio,
I don't have any bucking. Everything is nice, quite and smooth. But these are the back, so maybe they aren't as critical. The fronts get changed this weekend. Maybe I'll up it to 70 ft/lb and loctite the bolts. I'll try and see what torque they are on there when I take them off.

Thanks everyone for all the info. This is a great forum.

[2004NJVue]

Originally Posted by our1vue

1saxman,
... I was more concerned about the bolts breaking. Those bolts aren't that thick. That was why the question did they have to be so tight...

Sometimes the size of the bolts may be deceiving. I’ve seen real thin bolts rated at a higher strength than some real thick ones. For example, my girlfriend’s father pulls a 25-foot boat with a 91 Suburban. He uses a bolt thru the tow hitch to hold it on (instead of the locks that came with his hitch). When he first started towing (being a novice) he went to the store and purchased the thickest bolt that would fit…did not pay attention to strength ratings…he assumed bigger was stronger. Thankfully, it bent in his driveway. He went back to the hardware store and asked why. Needless to say he purchased another one that does not look nearly as strong, but its rated much higher than he needs. That setup has been working since 1991.

If its speced to be a certain torque, chances are, the bolts can take it and I would do my best to get it correctly. There are reasons to their madness when they come up with those numbers.

[vue-vtec]

Originally Posted by our1vue

...Those bolts aren't that thick....

What diameter are they? Or what size socket do they talke? If it's around a 1/2" screw, 90-something ft/lbs is not really that tight for a clean, well-lubricated, good-quality alloy steel screw.

[our1vue]

They have a 13mm head on them. I know there is a meaning to their madness, but sometimes they live in a different world. When they design a car it has to be easy/cheap to put it together. Taking the time to add some loctite to a thread would take longer than just tightning it up a little more to stop it from coming out. Me, I would choose the loctite (I'm only doing 4 bolts). They have to do thousands. So the trick is to find out what problem they were trying to solve and make sure your solutions still solves it.

[sspeer]

You can check the 'hardness' of the bolts by how many 'lines' the head has on it. The lines are raised and are aligned radially out from the center of the top of the bolt. I would think that these bolts would have 6 lines in it if they are that small and need such a high torque

Some info:

http://www.engineersedge.com/hex_bol...tification.htm

[2004NJVue]

Originally Posted by sspeer

You can check the 'hardness' of the bolts by how many 'lines' the head has on it. The lines are raised and are aligned radially out from the center of the top of the bolt. I would think that these bolts would have 6 lines in it if they are that small and need such a high torque

Some info:

http://www.engineersedge.com/hex_bol...tification.htm

Thanks, I never knew that.