Confused About Torque Values - Page 2 - PeachParts Mercedes-Benz Forum

cornemuse · #16 09-28-2017, 11:08 AM

75 to 85? Set your wrench to 80, , , ,

Clemson88 · #17 09-28-2017, 02:07 PM

Quote:

Originally Posted by Squiggle Dog

I've been searching the internet for answers and have given up. All I get is irrelevant information. My question is, what does it mean when a service manual says the torque value for a bolt is 75-85 ft-lbs? Does that mean 75 ft-lbs? 85? Somewhere in between? Tighten it to 75 and then tighten it to 85?

I'm working on an old Ford truck and almost every torque value they give has two numbers (30-35, 12-15, 45-50, 100-110, etc.). I want to make sure I understand torque values before I mess up something.

I always view the average of a specified range to be the goal. It seems to me that engineers would want to accommodate a user's error and that error of a torque wrench too. Setting a goal of 80 if the window specified is 75-85 lbs-ft might do just that.

I may be way off base here because I'm not even a good shade-tree mechanic.

DeliveryValve · #18 09-28-2017, 04:50 PM

Quote:

Originally Posted by Squiggle Dog

....

I store my torque wrenches at nearly 0, handle them carefully, and use them with my hand on the handle and do a smooth, steady motion until it clicks, after having the bolts just snug.....

I was told by the torque wrench calibration shop I use that you don't want to store your mechanical clicker torque wrench to zero. When at zero, the spring tension is unloaded. This can cause the other components within the wrench may move fractionally relative to each other. When you set the torque number and load/compress the spring, the orientation of these components can change and affect accuracy.

The calibration shop says to store it at 20% of the top of the range. So if your clicker's max is 200 ft lbs. Store it at 40 ft lbs.

Just in case if someone else is reading this, on the other end spectrum, you don't want to store your torque wrench loaded in the upper range. You can keep it loaded if you use it often. But extended storage, like several days, weeks, etc., leaving it set/loaded will weaken the spring over time and again affecting accuracy.

My two cents...

.

tangofox007 · #19 09-28-2017, 05:44 PM

Quote:

Originally Posted by Clemson88

Setting a goal of 80 if the window specified is 75-85 lbs-ft might do just that.

Then why not just specify the mean torque value?

If "75-85" really means 80, why not just say 80?

Dubyagee · #20 09-28-2017, 05:59 PM

Torque to yield bolts are specific. Regular bolts have a safe range.

Sent from my iPad using Tapatalk Pro

dieselmania · #21 09-28-2017, 08:25 PM

Quote:

Originally Posted by DeliveryValve

I was told by the torque wrench calibration shop I use that you don't want to store your mechanical clicker torque wrench to zero. When at zero, the spring tension is unloaded. This can cause the other components within the wrench may move fractionally relative to each other. When you set the torque number and load/compress the spring, the orientation of these components can change and affect accuracy.

The calibration shop says to store it at 20% of the top of the range. So if your clicker's max is 200 ft lbs. Store it at 40 ft lbs.

Just in case if someone else is reading this, on the other end spectrum, you don't want to store your torque wrench loaded in the upper range. You can keep it loaded if you use it often. But extended storage, like several days, weeks, etc., leaving it set/loaded will weaken the spring over time and again affecting accuracy.

My two cents...

.

Good info. I wonder how many of us home mechanics actually get their torque wrenches calibrated?