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Old 6th September 2010, 10:51 PM   #1
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Torque wrench recommendation?

I am rebuilding a Ferrari 360 drive-train in hopes of putting it an SLC and I am thinking an engine this nice deserves a better torque wrench than the one I have. Recommendations anyone?
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Old 7th September 2010, 07:05 AM   #2
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Re: Torque wrench recommendation?

Probably doesn't need a better one. Really. Grassroots Motorsport Magazine (either that or the SCCA's SportsCar) did a test of torque wrenches, from the lowly $19 Harbour Fright unit up to a $XXX Snap On piece. While The Snap On wrench was nice, the low end and mid-range units got the torque values right too and if I recall correctly the cheap HF was the MOST accurate. At least for the test they ran it looked like a decent wrench could be had for not much coin.

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Old 7th September 2010, 10:38 AM   #3
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Re: Torque wrench recommendation?

John

I agree with Ron. The only thing I would add is to get a clicker-type wrench, not the deflection-needle type. While there are a few things you can do with the deflection-needle type that you cannot do with the clicker type, I personally feel the clicker type is far better for 95% of the tasks for which a torque wrench is required.

I've had a Craftsman clicker-type wrench for two decades and am happy as can be with it. I've even known a couple of mechanics to use it in their service bays.

I think where the higher-priced wrenches set themselves apart from the crowd is in durability for everyday production use, but that is really speculation on my part and may not even be true. As a home hobbyist, you probably do not need to spend the extra money for that durability.

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Old 7th September 2010, 10:49 AM   #4
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Re: Torque wrench recommendation?

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Originally Posted by Bock350Dog View Post
As a home hobbyist, you probably do not need to spend the extra money for that durability.

Eric
Especially not for an F-car drive train....
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Old 7th September 2010, 12:07 PM   #5
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Re: Torque wrench recommendation?

Thanks guys! I have a "clicky" one that I have had since high-school but I imagine the calibration is suspect by now. I will try to track down that article. As for the durability of F-cars? I have owned Italian cars for the last 25 years - it's clear I don't learn from my mistakes
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Old 7th September 2010, 12:13 PM   #6
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Re: Torque wrench recommendation?

I'd just calibrate what you have and roll with it.
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Old 7th September 2010, 07:24 PM   #7
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Re: Torque wrench recommendation?

Quote:
Originally Posted by Ron Earp View Post
I'd just calibrate what you have and roll with it.
Where do you go to get your torque wrenches calibrated? Sears used to do it but they quit years ago, I believe.
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Old 7th September 2010, 08:15 PM   #8
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Re: Torque wrench recommendation?

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Where do you go to get your torque wrenches calibrated? Sears used to do it but they quit years ago, I believe.
Good question and heck if I know. The last time I saw one calibrated it was at Sears, but that was more than ten years ago. I bet there are some interwebz articles about performing your own calibration.
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Old 7th September 2010, 09:14 PM   #9
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Re: Torque wrench recommendation?

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Originally Posted by Ron Earp View Post
I bet there are some interwebz articles about performing your own calibration.
Indeed there are... the simple-minded ones have you clamp the square drive in a vise and hang a known weight a known distance from the drive. Easy enough but doesn't work very well for a short wrench that you want to calibrate at a high torque (unless you happen to have a barbell set).

There's an intriguing but to me incomprehnsible one at Calibrating A Torque Wrench - How-To - Stock Car Racing Magazine
I spent about 10 minutes trying to figure out what the hell he's talking about and then gave up. Among the problems is that at least two of the captions are exchanged.

My first google hit was this place: Torque Tool Service, Repair and Calibration Lab - Team Torque Inc. whose rates are reasonable. Anybody used them?
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Old 8th September 2010, 12:36 AM   #10
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Re: Torque wrench recommendation?

Looking at Team Torque, with a calibration fee ranging from $35 on up plus shipping both ways, it's probably less expensive to get a new wrench ( unless you have a Snap-On or similar).
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Old 8th September 2010, 09:48 AM   #11
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Re: Torque wrench recommendation?

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Originally Posted by x19.driver View Post
... it's probably less expensive to get a new wrench ( unless you have a Snap-On or similar).
On the Sears site the cheapest clicker type I see is $70. I have four, and the only time ever I bought one for less than that (Harbor Freight) it was wildly inaccurate.
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Old 8th September 2010, 10:16 AM   #12
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Re: Torque wrench recommendation?

The last Craftsman torque wrench I bought at Sears was a complete POS. Something broke behind the little plastic window through which you read the torque value and the display was illegible, so the wrench was completely useless, other than as a socket drive. The mouthbreather behind the counter at Sears even told me I couldn't return it, and that torque wrenches were exempt from the Cratsman lifetime warranty. I went to his supervisor and got my money back. I don't think I've bought a Craftsman tool since then. I got a Kobalt torque wrench for a good price at Lowes and have been happy with it for 8 years now. It came with a certificate of calibration.

Personally, I'd avoid the low-end stuff.
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Old 8th September 2010, 10:34 AM   #13
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Re: Torque wrench recommendation?

How about getting a HF unit and finding a friendly garage with a "quality unit"

socket the 2 together (2 sockets and a piece of hex bar) and see how close the 2 are.

I bet not that far out

after all you get a torque setting to use and most people will just assemble the unit put in a bolt and washer and tighten. Then another will add locktite, another will add copper grease, the next an oiled bolt etc - you got it every bolt will torque to a different clamping force - even if you used the same wrench.

So how accurate can the reference torque setting actually be?



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Old 8th September 2010, 10:51 AM   #14
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Re: Torque wrench recommendation?

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How about getting a HF unit....and see how close the 2 are.

I bet not that far out

after all you get a torque setting to use and most people will just assemble the unit put in a bolt and washer and tighten. Then another will add locktite, another will add copper grease, the next an oiled bolt etc - you got it every bolt will torque to a different clamping force - even if you used the same wrench.

So how accurate can the reference torque setting actually be?
That's exactly what I did: checked the brand new HF wrench against the others (recently calibrated and they all agreed). Like I said the HF unit was WAY off, like 30%. It was relatively easy to disassemble and adjust, however.

As for all the different situations you list, yes those will introduce variations (around 20%), but they are well-known. They are accounted for and documented (or should be) in the corresponding equipment documentation.
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Old 16th September 2010, 10:54 PM   #15
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Re: Torque wrench recommendation?

So, to answer my own question about where to get one calibrated:

After some research I found a national calibration chain called Micro Precision (www.microprecision.com) with a branch a few minutes away. Their rates are about the same as the one mentioned above (under $50 for a normal wrench, $150 for electronic ones).

I took in my "best" but still several-years-old torque wrench (Craftsman 44598 "Torque Meter", no longer available, see Electronic Torque Wrench - Torque Sensor - webBikeWorld). A few days later I picked it up.

Since it's "electronic" it cost $150 for calibration. It came back requiring no adjustment, and in fact was well within spec. (3%): from 10 to 100 ft-lb it's within a fraction of a ft-lb of standard. From there to 150 it's off by a ft-lb or two. It's maximum error anywhere (at 120) is 1.6%

So now I can use it to calibrate the others.

Based on this experience I recommend Micro Precision highly.

Also, the (to me) irrational pricing for "electronic" torque wrench calibration might be a reason to stick with buying mechanical wrenches.
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Old 23rd September 2010, 06:27 AM   #16
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Re: Torque wrench recommendation?

During my time on the tools the most accurate wrench brand I have came across is the Gedore. They are pretty expensive and I dont know how available they would be where you are from. I have used wrenches made by snap on, proto, etc and always found that over time the calibration drifted out but the gedores were always within the alowable tolerances.
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Old 23rd September 2010, 03:25 PM   #17
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Re: Torque wrench recommendation?

I buy a new Craftsman clicker at Sears every five years or so...seems to be easier than tracking down a calibration expert, dropping off/picking up, and paying his fee, etc.

Frankly though, I only use a torque wrench on head bolts. Never used a torque wrench on anything else in my life. I trust my ability to feel the "right" torque value, which may not be the factory spec setting to be honest. There are a lot of variable which affect what's right in one setting v. another that aren't capable of reflection in a static factory setting. I know that sounds a bit vague but after restoring cars with my own hands for 30+ years, and doing a fair bit of machine work too, I seem to have acquired my own sense of what's the right setting. Have never had anything let go or warp or strip or leak yet!
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Old 23rd September 2010, 10:54 PM   #18
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Re: Torque wrench recommendation?

Cliff,

When you have that sort of experience, I think you are doing it perfectly correctly. Better, as you say, than the nominal factory figure because you have a feel for the actual situation with all its variables. Most of us have some confidence, but would still look to a torque wrench for many assemblies.
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Old 26th September 2010, 02:04 AM   #19
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Re: Torque wrench recommendation?

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Cliff,

When you have that sort of experience, I think you are doing it perfectly correctly. Better, as you say, than the nominal factory figure because you have a feel for the actual situation with all its variables. Most of us have some confidence, but would still look to a torque wrench for many assemblies.
Well, thanks Dalton. My practice is obviously somewhat "back yard" and "shade tree" but it seems to work well for me! There's more than one way to skin a cat and no doubt sticking to the factory torque specs is plenty effective too!
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Old 26th September 2010, 09:44 PM   #20
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Fastener Torque

Quote:
Originally Posted by Cliffbeer2 View Post
I trust my ability to feel the "right" torque value, which may not be the factory spec setting to be honest. There are a lot of variable which affect what's right in one setting v. another that aren't capable of reflection in a static factory setting. I know that sounds a bit vague but after restoring cars with my own hands for 30+ years, and doing a fair bit of machine work too, I seem to have acquired my own sense of what's the right setting. Have never had anything let go or warp or strip or leak yet!
To everyone who thinks fastener torque settings are optional and intuitive: I'm sorry but I'm not enough of a flower child and too much of an engineer to let this go by. I'll say this once and then drop it.
  1. The statement about variables not reflected in the factory setting is just plain wrong. There shouldn't be variables. That's what an accurate torque wrench, the right lubricant, the right shop practices and the right fastener are for. Fastener torque is not an adjustment to field conditions, it's a proven requirement for achieving design strength.
  2. The only reason you have gotten away with this so far is that some careful, hard-working and well-educated engineer built in design margins that you have been lucky enough not to exceed. So far. If you were to read up on how threaded fasteners work, what fastener torque is for and what happens when it is under or over-applied, you might change your mind. Carroll Smith's books are a good start. Playing games with fastener torque is a bad gamble with a street car because the design margins are very large, but even so smaller fasteners are easily over-torqued. On a race car that sees track time it's criminal stupidity either to under- or over-torque an important fastener. What's an important fastener? Any fastener for which the designer specified a torque setting. He didn't do that because he had nothing better to do; he did it because it's important.
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