02 OBW Lug Nut Torque?

[gbhrps]

Twice in the last three months my 02 OBW LTD has developed a rubbing/wow..wow type of noise from one of my front wheels, that would disappear when I applied the brakes. Both times I traced the problem to loose front wheel nuts, that I had personally torqued to 85 ft lbs. (Curiously, the rear wheel nuts were all tight and correctly torqued.) If they continue to work themselves loose then they must need to be torqued tighter than I've been setting them. What is the correct torque? (It sure would be nice if Subaru would sell a reasonably priced service manual.)

[GLCraig]

The torque spec should be listed in your owners manual in the section about changing a flat tire. The manual for my Legacy says the spec is 58 to 72 foot pounds.

[nickb21]

For some reason 67.5 ft-lb's comes to mind as an avg. Craig's range seems about right.

 

Do you have any penetrating oil on the threads or anything? Tighten them in a star pattern? Sounds pretty odd... maybe your wheels are allergic to your hubs.

[Andyjo]

Wow.. you guys are so nice to your lug nuts... i crank those puppies down to 100 or so ft-lbs sometimes around 80 if i'm feeling nice... and the roo' isn't pissing me off that day :-\

but i also had a problem with a wheel almost falling off on the highway once.. so i do thing a bit much now-a-days

[fastwgn286]

maybe your torque wrench isn't calibrated correctly. 85 should be plenty. i usually just use the lug wrench supplied in the car and step on the end of it. at least 100 lb-ft, probably much more.

 

i realize its probably not the best way, but then i know that wheel won't fly off....

[1 Lucky Texan]

EDIT!; please check near the bottom of this page;

 

http://www.cars101.com/recalls.html

 

 

wasn't there an alloy wheel recall? I forget which year but I THINK it was the Outback.

 

Anyway - that is crazy. Is the rim cracked? I'd definitely swap that wheel with another one and see if the problem stays at the hub or follows the wheel.

 

Actually, I'd probably try to get opinions from some tire/wheel guys and the dealership.

 

get that investigated.

 

Carl

[Setright]

Yes, have the torque wrench calibrated if you can.

 

Also, whilst 100 ft/lbs isn't vicious over-torque, over tightening can also lead to lost wheels if you stress the studs to far! They'll snap suddenly under load.

 

Remember that the wheel/hub undergoes thousands of heat cycles.

 

 

(Of course the main reason for the low torque range is to protect the soft alloy wheels.)

[kimokalihi]

Yeah 100 lbs is crazy for a car. I put my truck lug nuts at like 80-90max. That's a 5 lug toyota on 31" mud tires!

 

I bet the book probably says something like 65 lbs maybe 75 tops for the subaru. I would never do them by hand without a torque wrench. You'll warp the rotors in no time. I totally warped mine. What happened was my car was in the shop at my friends house for like a week while installing a tranny(didn't have time due to school and work so it took a while)and neither of us have a torque wrench so I had to torque them by hand. Apparently I torqued them too much and not evenly because I later went to another friends house like probably a couple months later lol and used his torque wrench when I was putting in a new knock sensor and all of them were way past 80 lbs. The car shakes when you apply the brakes somewhat. I don't know if it was like that before or not because I had just gotten the car back then so I can't say for sure that I did it but it's definately a possibility. Oh well, it stops.

 

But now that I think of it, when I got the car, the front driver side wheel had a broken lug at the surface of the rim. So whatever jackass had it before me had it WAY too tight.

[fastwgn286]

EDIT!; please check near the bottom of this page;

 

http://www.cars101.com/recalls.html

 

 

wasn't there an alloy wheel recall? I forget which year but I THINK it was the Outback.

 

Anyway - that is crazy. Is the rim cracked? I'd definitely swap that wheel with another one and see if the problem stays at the hub or follows the wheel.

 

Actually, I'd probably try to get opinions from some tire/wheel guys and the dealership.

 

get that investigated.

 

Carl

 

i think he's in the clear. he has 02, recall for 03 h6's.

 

but, yeah, that torque wrench needs some calibration. or rotate tires and see what happens, but i think its the wrench. how old is the wrench you used?

[1 Lucky Texan]

Twice in the last three months my 02 OBW LTD has developed a rubbing/wow..wow type of noise from one of my front wheels, that would disappear when I applied the brakes. Both times I traced the problem to loose front wheel nuts, that I had personally torqued to 85 ft lbs. (Curiously, the rear wheel nuts were all tight and correctly torqued.) If they continue to work themselves loose then they must need to be torqued tighter than I've been setting them. What is the correct torque? (It sure would be nice if Subaru would sell a reasonably priced service manual.)

 

Did you buy your car new? Does it have stock wheels? Ever been wrecked or 'tagged' a curb hard?

 

Carl

[OB99W]

[...]Both times I traced the problem to loose front wheel nuts, that I had personally torqued to 85 ft lbs. (Curiously, the rear wheel nuts were all tight and correctly torqued.) If they continue to work themselves loose then they must need to be torqued tighter than I've been setting them. [...]

As others have suggested, checking your torque wrench for accuracy might be a good idea. Lug nuts on alloy wheels tend to reseat a bit as driven, due to wheel flexing (front wheels typically do more of this than rears), etc., and will loosen somewhat. You should probably recheck the torque after driving a few (50-100?) miles after the initial tightening, and retighten as needed. If you wait until the lug nuts are loose, you are still only doing the initial tightening.

 

As 1 Lucky Texan mentioned, there may be other issues.

[blitz]

I bring mine up to 90 ft./lbs. - anything less feels like it's gonna work itself loose.

 

**** ******!

[DerFahrer]

Don't torque down too much, or you'll ruin your wheelstuds. One day when you wanna take a wheel off, the threads will just strip or the stud will break off completely. That's not fun, believe me.

[gbhrps]

Gentlemen,

There are obviously a great many ideas out there as to how tight to torque a set of alloy wheels! I've always set the standard at 75 ft lbs for alloys and 90 ft lbs for steel wheels on any car I've ever owned, and I've never had this situation before. The alloy wheels are stock for this LTD OBW, and are not cracked or abused in any way. In fact I even switch them over for steel wheels and ice grip tires for the winter. There is no lubrication of any kind on the wheel studs, and yet twice within the last 3 months one or both of my front wheels has worked itself loose, while the rears have maintained their torque. The click type torque wrench I use is dead on, as I have a second pointer type torque wrench that gives pretty close to the same readings. For now I'll leave things at 85 ft lbs and check them again weekly, for all of the time it takes.

[OB99W]

[...]The alloy wheels are stock for this LTD OBW, and are not cracked or abused in any way. In fact I even switch them over for steel wheels and ice grip tires for the winter. There is no lubrication of any kind on the wheel studs, and yet twice within the last 3 months one or both of my front wheels has worked itself loose, while the rears have maintained their torque. The click type torque wrench I use is dead on, as I have a second pointer type torque wrench that gives pretty close to the same readings. For now I'll leave things at 85 ft lbs and check them again weekly, for all of the time it takes.

It's good that the torque wrench you're using agrees closely with a bending beam type (assuming that's what you mean by "pointer type"), which tend not to go out of calibration to any great degree.

 

Do keep in mind that torque measurement is only an indirect indicator of bolt (stud) tension, which is what really determines the clamping force. Unfortunately, a torque measurement is very dependent on frictional forces. Lug nut torque specs are usually given for dry threads, but that also assumes the threads are clean and free of corrosion. It's possible for torque reading to be "correct", but for the tension to be too low, if there is any significant dirt, rust, etc. in the threads or on other contact areas.

 

Since you're using steel wheels in the winter, I assume that you're changing to the Subaru OEM lug nuts when the alloy wheels are reinstalled. If the nuts used with the steel wheels have open ends, as they typically do, some rust may be forming at the exposed end of the lug, which may affect the performance of the Subaru nuts. I'm not saying that's the situation in your case, but it might not be a bad idea to take a wire brush to the lugs and make sure they're clean, for the reason I mentioned above. This may be obvious, but lug nuts should spin on fairly freely; any significant resistance may indicate thread damage that could cause torque measurement to be a false indicator of tension.

[1 Lucky Texan]

I would definitely confirm that the stock wheels were NOT those '02s that someone pulled outta the dumpster or something and put on your car at the dealership - there must be a number or code on them to confirm they are not the recalled ones.

 

From what I've read at tirerack, lug nuts can make a big difference, number of threads engaged, depth, angle/shape of the contact area. Maybe you need different nuts for the winter vs summer rims?

 

Have any enemies?

 

I dunno

 

 

Carl

[Wayne Boncyk]

One thing that does happen to lug nuts that are used a lot (and in this case I mean "normal" tire rotation constitutes a lot), and if they've been routinely overtightened (which may have happened at some time in this car's life), is that the threads in the nuts fatigue. Usually they stretch a bit, and thin out as a result. Once the nuts have been stressed past a cerain point, they will not hold and will naturally loosen up with time. At that point you are best off just chucking them and getting new replacements. This fortunately happens to the nuts more often than the lugs -- nuts are easily replaced, lugs are obviously a little harder to replace!

[gbhrps]

Gentlemen,

Thanks for all of the input. For interest sake I'm using the same chrome acorn nuts that came on the car for both sets of wheels and tires, and there is absolutely no corrosion on any of the nuts or the studs. As I stated earlier, I'll monitor the lug nut torque very carefully over the next couple of months, and if the wheels show any tendancy to loosen up again, I'll junk the original wheel nuts and put on a new factory set. Thanks everyone!