I purchased a torque wrench today to tighten the lugs on my wheels to the factory spec of 103 ft/lbs. After getting the wrench home I realized I grabbed the wrong one as it only goes up to 100 ft/lbs. I dialed the torque up all the way and tightened everything and it seems secure.

Maybe a dumb question though curious what people think... Is it worth returning the torque wrench over the extra 3 ft/lbs (meaning getting one that goes up to 150 ft/lbs, etc)? Is there really a difference between 100 and 103?

 

I think you will be all right with 100 # . The allowed tolerance on the wrench is about 2-3%. I have similar Kobalt wrench graded to 100. You can tighten a hair more if you have a feel of those three pounds. Important thing when tightening lugs is not overtorqueing them to the point of stress. Usually people overtorque. They (lugs) may not snap immediately but crack eventually when lugs are experiencing tension fatigue.
You will be good with 100.
Motor on,

 

You will be fine but it would be best to get a different torque wrench because they are most accurate in the middle of their range. I would suggest getting one that goes at least to 150 ft/lb.

 

You actually need 2 for the MINI because the oil plug/trans plugs are only in the 35ft/lb range and the wheels are 103ft/lb which can be completed by very few wrenches on the market. Plus they are not as efficient in the maximum or minimum #'s in their range. Honestly, for the wheels, make them tight and give them a good tug and they are good. I have an Ingersoll Rand Thunder Gun air impact set to the middle setting and it puts them on perfectly. Your wheels are not going to fall off because you under torqued them 3 ft/lb though so don't sweat it.

 

Agreed on 100 ft-lbs being good (heck its probably really 140N-m), but most torque wrenches aren't anything close to 2-3% accurate at full scale. 4-5% error at 20% full scale is a common rating with no rating at all for error at other torques. REALLY good instruments will go down to +/- 1% error over a wide range, but almost nobody buys them to work on cars. We need the accuracy and send our wrenches out for calibration (they aren't used on cars).

 

Thanks for the feedback. N666BK, I have the same Kobalt wrench, probably from Lowes. Interestingly enough it has a lifetime warranty. I have an older one from Sears that didn't and never seemed to work right. I'll keep this one for now and invest in another one down the road. They had another wrench that went up to 250 though it had a 1/2" drive. Probably better for 103 ft/lbs anyway.

 

One point about checking tightened fasteners:

Do NOT tighten them to check. Loosen them a bit and then re-tighten. If you periodically tug on the fasteners to check them, you will over-torque them. The correct procedure is to back them off and re-torque...

 

I don't know where the bad info comes from, but the three different tire dealers I checked with listed 88 instead of 103 ft.-lbs. for a 2007 MINI. They specifically list it for models up to 2009, not 2006 as it should.

 

confusion is based on the model. Because the 'vert stayed a GEN1 'til 09, the trq stays at the lower figure. Tire dealer computers don't seem to be updated to dif' the vert and hardtop model year difference in the changes.

Page 112 of the owner's manual for my 07 S hardtop says 103.3 ft/lb

 

What a simple and logical explaination! Thanks. That explains it.

 

The torque setting should be based on whether the lug bolts are 12mm or 14mm. MINI changed to 14mm sometime in 2006, so some 1st Gen 2006 models need 103 ft-lbs., and some need the lower spec. I would think that the convertibles made this change in 2006 with the coupes. I had to show the guys at Discount Tire in Santa Monica the 103 spec in the manual of my 2007 Coupe to convince them their data was wrong.

 

1.) the spec is 140 Nm or 103.3 Lb-ft, from the TIS.

2.) You really need to get a bigger torque wrench. A 3/8 wrench with a 100lb-ft scale is way over range, and you have no idea what torque you are applying. Get the 0-250 1/2" drive model. You can check how accurate the wrench is by hanging a weight from the end, while the socket end is clamped in a vise.

Torque is a cross product, and is calculated by (weight times the distance of application, times the cosine of the angle). (a 90 angle has a cos of 1)

So measure how long the handle is, (feet) and hang the weight at 90degs, and check. You will surprised how far off most wrenches are...

Me? I bought an electornic torque load measuring system. (Craftsman) digital display, and accurate to +- 1 lb-ft. over full scale, (it's 1.2" drive). But I really like tools...lol I've got a GT1 in the garage too.

 

So torque for my 2004 is 88 ft lbs?

 

 

Wouldn't a 0-150 1/2" drive be more accurate for a 103 setting?

 

Most inexpensive deflection beam and calibrated clutch type wrenches are only rated for accuracy at 20% full scale and loose accuracy as torque is increased.

 

I would strongly recommend that you avoid using a torque wrench over 7/8 of it's maximum range. Most professional codes and standards (ASME, ANS, etc) don't allow use of a torque wrench beyond this value.

In commercial and naval nuclear power applications, use of a torque wrench beyond 7/8 scale will void its calibration unless you can prove it hasn't been overranged. I've had a micrometer style 0-150 ft-lbf Craftsman torque wrench for over 20 years. Its seen heavy use but I'v e never used it beyond 7/8 scale and it has always passed calibration checks when I've found the time to get it checked.

HTH, YMMV.

 

I agree with what the others have written, get the 1/2" drive 150 lb wrench, use the other one for your pan bolt if you feel the need.......

Even torquing of the wheel bolts is important, not only for safety but also to make sure you don't warp the hubs and rotors - but 3 lbs isn't going to matter that much.