Wrenching Tip: The Importance of Calibrating Your Torque Wrench


Grabbed this from over on StangTV.com

John Gibsonby on September 19, 2012

Before we dive into what is one of the most often overlooked tools in the average man’s garage, ask yourself the following questions: Where is my torque wrench stored right now? When was the last time I used it? What is the current torque setting at on it? How accurate do I believe my torque wrench is?

We’ve seen a torque wrench be as far as 16 ft-lbs out of calibration – Chris Raschke

Every garage, engine builder, or race team has a torque wrench, and we all use it a considerable bit! But when was the last time you gave more than a moments glance at your torque wrench? Without a doubt one of the most often overlooked and most used pieces of equipment in any race teams or home garage has to be their torque wrench.

A torque wrench is a relatively inexpensive piece of equipment when you consider how often we use it to create serious horsepower or to ensure our wheels don’t come flying off when we put the car on the ground. A typical “click-style” torque wrench will usually run between $100-$400 and if cared for properly can last quite sometime.

Ensuring Your Torque Wrench Isn’t lying to you

What happens though when your trusty torque wrench has seen a few years, and you are starting to doubt the results it’s giving you. “We’ve seen a torque wrench be as far as 16 ft-lbs out of calibration,” explained Chris Raschke of Automotive Racing Products.


NHRA Teams can walk over to the ARP tent and quickly see just how accurate their favorite torque wrench is.

ARP understands how crucial it is to have a torque wrench that is calibrated correctly. ARP works closely with many of the top NASCAR and NHRA teams as well as numerous engine builders across the country to supply engine and driveline fasteners.

ARP has spent 2012 traveling across the country to every NHRA event offering a special service to the teams and mechanics in attendance. ARP brings a torque indicator that allows teams to test their torque wrench settings. Teams can walk over to the ARP tent and quickly see just how accurate their favorite torque wrench is simply by giving it a couple of pulls.

“We test the torque wrench at 50 ft-lbs and 100 ft-lbs to give teams a proper reading,” continued Raschke. “We encourage and stress that everyone to bring their torque wrench to our tent and see just how accurate the wrench really is.”

Torque Wrench Maintenance Tips from Harbor Freight

  • Before each use, inspect the general condition of the tool. Check for loose hardware, misalignment or binding of moving parts, cracked or broken parts, and any other condition that may affect its safe operation.
  • After use, wipe external surfaces of the tool with clean cloth.
  • If the Torque Wrench has not been used for some time, turn the knurled handle (clockwise and counterclockwise) several times to re-lubricate the internal workings. Then, operate at a low torque setting several times. This ensures proper operation.
  • Do not turn knurled handle below the lowest torque setting.
  •  Wipe Torque Wrench with a cloth to clean. Do not immerse in any cleaning solution. This would damage the internal lubrication.
  • Periodically have the Wrench calibrated and serviced by a qualified technician.
  • Store inside case in a clean and dry location.

Why It’s So Crucial To Check Its Calibration

ARP explained to us that they have seen torque wrenches as far as 16 ft-lbs out of calibration. It’s easy to think how dangerous it would be if it a wrench was -16ft lbs, but the important thing to remember is +16ft lbs would be just as dangerous, especially for engine builders.

For example, let’s say you are working on a Chevy Small Block and are installing the cylinder head bolts for a 18 degree standard port cylinder head. ARP recommends torquing their hex bolt kit to 70 ft-lbs in three increments of torquing.

This means at three different steps you are going to torque each individual head bolt first at 20 ft-lbs, then 40 ft-lbs, and then finally 70 ft-lbs. If you are torquing 16 ft-lbs to much or to little, you are setting yourself up for serious problems. You are either going to under torque or over torque your head bolts by 22% versus ARP’s recommended level!

Torque wrenches are often used to torque the lugs on a wheel before a car ventures on the track as well. We don’t have to go into a lot of detail here, you can imagine just how dangerous it would be to have a torque wrench that was under torquing your wheel lugs.

What To Do If Your Torque Wrench Is Off

Even if you take immaculate care of your torque wrench ARP advised us that mechanics should have their torque wrench tested once a year to ensure that it is calibrated correctly. If your torque wrench does happen to be off by a few ft-lbs then what is the best option?

“We don’t actually calibrate the torque wrenches that are a few ft-lbs off,” Raschke explained to us. “Most all of the popular tool trucks like Snap-On and others will send the wrench in for calibration. In fact Sears provides service for their torque wrenches.”

How To Avoid A Wacky Torque Wrench

The next question has to be, how can you avoid ending up with a Torque Wrench that is out of whack?

ARP explained to us that the biggest mistake they see people making is not taking proper care of the torque wrench, and offered us a few tips to ensure that you get the maximum life out of your torque wrench.

  • If possible store in the manufactures case inside a dry area. Treat it as a delicate piece of equipment.
  • Always remember to back off the torque indicator to a low torque setting before storing it for the next use. The click style torque wrenches contain a spring and by having a high torque setting compressing that spring for an extended period of time will cause the spring to “set” at that length.
  • Purchase a torque wrench that operates within your torque range. If you are going to be checking torque levels at 80-100 ft-lbs on a consistent basis then you need more than a typical 100 ft-lbs torque wrench. You should be looking in the 200 range. This will allow the torque wrench to give you a more accurate reading as the torque wrench will not be nearing it’s max torque setting.
  • Do not turn knurled handle below the lowest torque setting.

    ARP encourages and stress that everyone to bring their torque wrench to their tent at every NHRA event, and see just how accurate the wrench really is.

  • Never turn the wrench past the “click”.
  • If the Torque Wrench has not been used for some time, turn the knurled handle (clockwise and counterclockwise) several times to re-lubricate the internal workings. Then, operate at a low torque setting several times. This will ensure proper operation.

Top engine builders and mechanics understand the importance of having a torque wrench that is measuring properly. This is why so many are now opting for the high dollar (some as much as $4,000) digital torque wrenches that can provide extremely precise measurements. But even these need to be checked often to ensure that the number you are seeing is the correct amount of torque that is being applied.

A torque wrench is a valuable tool, but if it is not properly used and cared for it can become your worst enemy. Don’t place your hard earned dollars and more importantly your lives at risk by assuming that the torque wrench you have is reading correctly after all these years. Get it tested and ensure that “tight” bolt is actually tight!


Right after I read this I went out and checked on my pair of torque wrenches.

One of them is old school.  Looks like this:

This one is just laying around in one of my Mac Tool  toolbox drawers.

The other that is similar to the one here in the article is in its plastic case.

Wonder which one I’ll use again?
Thanks for reading.




Spec Clutches


This is the Clutch I’ve added to my Corvette.
I have the stage III
check out video:


Auto Factoids for the week of Sept 23

We have a couple of debuts’ this week and a couple of Birthdays.

First up on Sept. 23 in 1969 the iconic and now recreated Dodge Challenger.

From this:

1969 Challenger

And this:

The Iconic General Lee

To this:

The 2012 version.

Virgil Exner was born on the 24th of Sept in 1909.  Who was “Ex”?    A car designer.  Oh…ok…of what?  Just a couple of designs, like all of these:

Studebaker Champion
Studebaker Starlight
Chrysler C-200
Chrysler 300 letter series
Chrysler 300 non-letter series
Chrysler New Yorker
Imperial 1955-1961
Chrysler Diablo Concept with Ghia
Plymouth Savoy
Plymouth Belvedere
Plymouth Fury
Plymouth Suburban
Plymouth Valiant
Dodge Coronet
Dodge Firearrow Concept
Desoto 1961
Desoto Adventurer
Bugatti 1965 concept with Ghia
Mercer-Cobra 1965 concept
Duesenberg 1966 prototype with Ghia
Stutz Blackhawk

Bill France was born on the 26th in 1909 in our nations capital.  Mr. France was an American race car driver. He is best known for co-founding and managing NASCAR, a sanctioning body of United States-based stock car racing.
The final debuts was on Sept. 26, 1967 when AMC released the Javelin.

1967 Javelin

Thanks for reading


Tucson Cars and Coffee



Tucson Cars & Coffee July 2012

We were lucky enough to have a cloudy morning for this month’s Cars and Coffee. The diffused light that the clouds provide makes my job really easy! Enjoy the photos.























15 Jul This entry was written by Otis, posted on July 15, 2012 at 13:49, filed under Automotive, Photography and tagged , . Bookmark the permalink. Follow any comments here with the RSS feed for this post. Post a comment or leave a trackback: Trackback URL. View EXIF Data

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07 Corvette – When a good clutch goes bad!

Few post back I mentioned the issues with being able to shift the C6 into reverse and then generally the shift began to get worse.  Additionally the clutch fluid would become low.

As most Corvette owners know, the C6 has a separate hydraulic clutch.  I had the fluid flushed numerous times and eventually we found a small leak at the clutch slave cylinder.

Replaced the cylinder and stopped the leak.  This stopped the fluid usage and shifting improved, but only slightly.

Eventually it began getting much worse.  With the ignition on the car would not go into reverse at all.  The only way to get it into reverse was to turn the car off, put the that trans in reverse and start the car. Even then, it would sometimes kick itself out of gear when started   Then highway shifting began slipping and RPM when up.

I do auto cross the car and I guess some spirited street driving.  Here is what my clutch and flywheel now look like, yes… I saved them!!!



Clutch 2


Those shiny rivets – not a good thing!!!!

The Flywheel, interesting coloration, don’t you think?



Yes it was time for a replacement.


What was the replacement?

That is coming up next.

Thanks for reading.





Engine Line-up 1952 Desoto

Up until 1952 the only engine available was the L6 cylinder and it again was the main power plant for the ’52 production year.

This engine for 1952 was an iron block with a bore and stroke of 3.438X4.50 with a compression ratio of 7.0:1.  With 5 main bearing and topped with a Stromberg 380359 or 380349 or a Carter E9AI it produced 116 hp.   This was pretty much the same for all the L6’s but bore and stroked changed through the life of the company as well the number of main bearings (most numbering four) and the  displacement fluctuated between 236.7 and 250.6 CID. The engine disappeared from Desoto line-up in 1954.

L6 Engine

But the really big deal for the 1952 Desoto was the addition of what would become one of the most famous engines every produced.  It was the spherical segment combustion chambered engine, the  Desoto Hemi V-8.

It was an overhead value hemispherical combustion chambered iron block.  It displayed 276.1 cid and it’s bore and stroke was 3.626×3.344 inches and a compression ratio of 7.0:1.  It had hydraulic lifters and five main bearings.  Topped with a Carter 2bb (models 884S, 884SA and 884SC it produced 160 hp.  The Firedome V8s were the same but used the Carter models 908S,909S and the 910S.

A restored 52_DeSoto Firedome (museum photo)

1952 4 door Desoto

Thanks for reading.