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2009 2.5X EJ253 Manual
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Discussion Starter #1
Service Manual states torque spec on wheel lug nuts to be 100Nm/73.8Lb-ft. I dialed up 76lb-ft on my clicker ratchet so that if its +/- 4% margin of error fell on the minus side, the torque on the lugs would still be at or above spec.

76 lb-ft just felt a bit weak for lug nuts. I'm used to putting 100 lb-ft on lugs, I guess.
 

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2017 VW Golf SportWagen 5MT
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80lbs is good. If you really want to do 100lbs do it, but it's not necessary.

I used to over-tighten the **** out of my lugnuts, but learned not to.

Stan
 

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The Sub kit guy
2005 Forester X & XT VF39
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13,008 Posts
I always do mine 75-80. If you do them too tight you can warp your rotors and cause a horrible braking feel and uneven wear.
 

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246 Posts
Steel wheel and alloys need different recommendations. The way the lug nut distributes its pressure is different and you can see how the lug shape is different.
 

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2019 Crosstrek 2018 XT
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14,129 Posts
I put the slightest, slightest silicon grease coat on the nut bevel so that I get a more consistent value...it avoids the heavy friction that robs clamping force....Again the amount is not even perceptible.

And I don't use a torque wrench. Wrenching for 50 years gives me a pretty consistent feel. Not saying my way is right for everyone.

Friction on the dry nut surface is so unrepeatable that clamping force is not a real good correlation to torque. (IMHO)
 

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07 Forester XT
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6,758 Posts
I know what you mean by feel. I take my wheels off so many times for track events I can pretty much set it by hand at 85lbs.
 

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2009 2.5X EJ253 Manual
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2,802 Posts
Discussion Starter #9
When I re-check torque in a few days I'll probably just set my torque ratchet to 80 lb-ft then.

Thx all.
 

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Premium Member
07 Forester XT
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6,758 Posts
If you're gonna do that I suggest you break the all a bit loose (one turn) so there's no chance you'll overtorque any of them.
 

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2007 Forester Sports XT 4EAT
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38,719 Posts
My research for 12mm iron bolts says:
grade 8.8 - 60 ft-lbs
grade 10.9 - 85 ft-lbs
grade 12.9 - 95 ft-lbs
The above torques are for "lubricated" threads.

If you installed subframe locking bolts, you might have noticed they're 12mm iron, grade 12.9. :wink:

I torque my lug nuts to 85 ft-lbs. I always recheck the torque after the vehicle has been driven on newly installed wheels, until no nuts need to be retighten. If you don't do a retorque, you'll be surprised how many loose lug nuts you'll find, especially on the front wheels. Once the lug nuts have settled in, no loose ones will be found. Rechecking was recommended to me by my trusted tire & wheel guy. Strongly recommended for alloy wheels. :smile:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2018 2.5i Premium CVT
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18,733 Posts
Retorquing after 100 miles is specified on the shop report any time they've done something that caused the wheels to be removed. I always do it anyway, and it always needs it. Things just take a bit of time to settle in and assume the most comfortable position.

I'm happy with the factory numbers and have settled on 68, because that's the year I got married so it's easy to remember. Some here use 69, as it too is somehow a number easy to remember. :icon_wink:

Even with the 24" breaker bar we have in both our Subarus, my wife does appreciate the low torque figure. She's never had to change a tire in the wild, but we've had some practice runs at home.
 

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2008 FSXT 4EAT
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4,143 Posts
I employ the "Turn of the Nut" method, since I don't own a torque wrench. I'd be interested in seeing what kind of torque is reached based on this method. Basically, you get all of the nuts snug-tight, and then turn the nut an additional amount, which is based on the bolt length. This additional turn pre-tensions the bolt, which causes the bolt to elastically stretch, while remaining below its yield limit. This pre-tension is what creates the clamping force. Too much torque causes the bolt to exceed the yield limit, where it begins to in-elastically stretch and deform, which in this case is not desirable.

Based on the AISC for Pre-Tensioned Connections (16.4-48, Section 8.2.1, Table 8.2):

Bolt Length not more than 4 * Db: 1/3 turn

Bolt Length more than 4 * Db, but less than 8 * Db: 1/2 turn

Db = Bolt Diameter (12mm or 0.47" for us)

Bolt Length = Length of stud beyond the face of the hub
 

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2019 Crosstrek 2018 XT
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Bolt Length not more than 4 * Db: 1/3 turn
Of course this is the most accurate way. That way you have equal clamping force. You might get some deformation in the area of where the lug seats on the wheel seat. As long as it stays tight you are good to go.

Being an Engineer/Maintenance Foreman/Instructor. Its a subject close to my heart.

With an unlubricated stud/nut (both thread and face) clamping values can be off by 50%. With lubrication and good threads nut face it gets into the 25% area. Fortunately the application is usually not that critical. As long as the wheels don't fall off. :) warped rotors?.... yea maybe.

Yea..I know you are an engineer. :D
 

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2007 Forester Sports XT 4EAT
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I employ the "Turn of the Nut" method, since I don't own a torque wrench. I'd be interested in seeing what kind of torque is reached based on this method. Basically, you get all of the nuts snug-tight, and then turn the nut an additional amount, which is based on the bolt length. This additional turn pre-tensions the bolt, which causes the bolt to elastically stretch, while remaining below its yield limit. This pre-tension is what creates the clamping force. Too much torque causes the bolt to exceed the yield limit, where it begins to in-elastically stretch and deform, which in this case is not desirable.

Based on the AISC for Pre-Tensioned Connections (16.4-48, Section 8.2.1, Table 8.2):

Bolt Length not more than 4 * Db: 1/3 turn

Bolt Length more than 4 * Db, but less than 8 * Db: 1/2 turn

Db = Bolt Diameter (12mm or 0.47" for us)

Bolt Length = Length of stud beyond the face of the hub
Say what? An engineer without a torque wrench? :icon_eek: Much easier with a torque wrench! :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Premium Member
2008 FSXT 4EAT
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4,143 Posts
Say what? An engineer without a torque wrench? :icon_eek: Much easier with a torque wrench! :wink:
lol, I must be an engineer if I'm tightening my bolts based on a structural code. The turn of the nut method was instituted for large structural connections and anchor bolts, where the nuts are the size of your fist. I don't think they make torque wrenches that big. :biggrin: But yeah...probably easier with a torque wrench.
 

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2015 Highlander AWD XLE 6AT
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4,255 Posts
Retorquing after 100 miles is specified on the shop report any time they've done something that caused the wheels to be removed. I always do it anyway, and it always needs it. I'm happy with the factory numbers and have settled on 68...
I also use 68 lb-ft (~95 N-m), and I re-check after 100 miles or so. Spec in the '09 OM is 58 - 72 lb-ft (80 - 100 N-m).

HTH,
Jim / crewzer
 

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1999 Forester L
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9 Posts
Torquing wheel nuts

I just got my winter tires put on my factory steel rims and the guys who put the tires on at the shop recommended that I retorque them after 100 km. they said they do it for free if I brought the car back up but I used it as an excuse to go buy myself a torque wrench. Shopped around a bit and found one for 35 bucks at an auto machinery store. After reading through this thread on the forum and using the advice from the guys at the tire shop retorqued all my wheel nuts at 80 foot-pounds. Most of the nuts clicked on the torque wrench without even moving but seven of them, a couple on each tire required additional torquing. I found this surprising was quite thankful that I had made the modest investment and now have a torque wrench that I can check my wheels at any time with. Thanks for all the info and insight on this thread, very educational.
 

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10 XT 4EAT
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893 Posts
I just got my winter tires put on my factory steel rims and the guys who put the tires on at the shop recommended that I retorque them after 100 km. they said they do it for free if I brought the car back up but I used it as an excuse to go buy myself a torque wrench. Shopped around a bit and found one for 35 bucks at an auto machinery store. After reading through this thread on the forum and using the advice from the guys at the tire shop retorqued all my wheel nuts at 80 foot-pounds. Most of the nuts clicked on the torque wrench without even moving but seven of them, a couple on each tire required additional torquing. I found this surprising was quite thankful that I had made the modest investment and now have a torque wrench that I can check my wheels at any time with. Thanks for all the info and insight on this thread, very educational.
a word of wisdom for torque wrenches:

Always reset the wrench to its lowest setting after use!!

If you don't the torque mechanism will fail and the torque wrench will no longer be accurate and you can severely over-torque to the point of breaking bolts/studs.
 
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