aaddpp

I did not want to take Glenn M's fuel line thread off topic, but was wondering what sort of tool you use to torque a bolt you can not get a socket on but rather would need some sort of wrench to turn the fitting?

Thanks,
Dave

blown 87

They make things called Torque adapters, kind of a cross between a half a wrench with a square drive hole in the other end, then you have all kinds of Crowsfeet.

Glenn M

I used a four sided crows foot, got it at Harbour Freight.
http://www.harborfreight.com/cpi/cta...emnumber=93137

aaddpp

Greg, Glenn

Much appreciated info! Do you know if the torque value remains the same if you put an angle adjusting bit between the torque wrench and the crows foot? I think my 1/2 and 3/8 torque wrenches would be a bit long to go after some of the fuel fittings straight on.

Thanks again,
Dave

Glenn M

The complication with a crowsfoot on a torque wrench is that the scale is calibrated to its center of rotation (where you would normally put a socket), but the lever arm (the perpendicular distance from the center of the bolt to the hand grip on the wrench) will be longer or shorter than that depending on how you apply the crowsfoot. To make it just a bit more complicated, the more force you put on a torque wrench, the more it twists--this doesn't effect the length of the lever arm in normal application where a socket is centered on the rotation point, but when using a crowsfoot, the length of the lever arm could actually increase or decrease as the wrench starts twisting.

In the example if the 18" torque wrench reads 100 foot-pounds torque, the actual torque with the crowsfoot (now 20" long) is 100 x 20/18 = 111 foot-pounds.

If the crows foot is at 90 degrees then the torque is still 100 foot pounds.

Hope this helps.

borland

Never use a torque wrench on fuel lines. Fuel line fittings should only be removed and installed using two flare wrenches. One wrench to counter hold the other in order to prevent twisting of the fuel line tubing. Any other tools with likely damage the thin wall nut.

Always check the joint for leakage before running the engine for any extended period of time.

M. Requin

Crows foot wrenches are available in flare nut configuration.

jon928se

Use the crows foot at 90 degrees to the torque wrench.

If you are using a bendy beam torque wrench (the type with a long pointer that extends to a scals by the handle) the error is as Glen decribes and to be honest is not crucial - 10 or 15% on a torque of 20 or 25 ft lbs is probably within the range of accuracy of the wrench anyway.

If you're using a click type torque wrench the actual measuring point could well be a lot closer to the centre of rotation (where you put the socket on) than the handle. I know for example that my old torque wrench (handle about 18" long) had the "click" measuring point 3" from the centre of rotation. This would make the error around 60% increase in applied torque.

To be honest I wouldn't use a torque wrench for this type of joint. Just do it by feel - should be able to feel as all the mating surfaces come together then just tighten a little bit more - a bit of squeeze of the two wrenches against the friction of the mating surfaces - you'll feel them bind together then stop .

If you are torsionally challenged, practice using a scrap nut and bolt - start with the bolt held in a vice and torque the nut holding the torque wrench at the point where it is the same length as the flare nut wrench you would use and get a feel for the amount of force you would need to apply. I suspect it will be a lot less force than you expect.

aaddpp

Glenn, Jon, excellent explanations both. Thanks. Dave

blown 87

I am in the process of trading in all my standard 2% torque wrenches for 1% ones.

10-15% on a torque wrench is just not acceptable.

Rob Edwards

Doc Brown's shop is littered with these Snap-On Techwrenches, they toggle between ft-lbs/Nm and degree readings, accurate to 1% above 20% of max torque. Someday after I hit the lottery...

http://buy1.snapon.com/catalog/item....re&dir=catalog

Jim Morton

Not to rain on the Snap On Techwrench as they are a very convenient general torque wrench, but for real torque work at 1 pct., the dial torqometers are far better... at least IMO from managing ISO production lines. As example, here a link to the Snap On 0-100 ft-lb torqometer wrench:

http://buy1.snapon.com/catalog/item....re&dir=catalog


There is also the ASTM / SAE based opinions for how the click or vibrating torquewrenches can introduce an influence to the true screw torque / thread stretch.... comment here is that achieving 1 percent margins of error go beyond the bench rating of the torque wrench and how 1 percent accuracy is completely achieved should be considered within the assembly procedure. items such as oil / lube or not, washer / no washer, etc.

One last comment is that if you work on general part assemblies as well as engine internals, you may find that you need several styles of torque wrenches to meet your needs. As example, I own the Techwrenches for general assembling, click type for lugs / larger, crider stuff and torqometers for fine assemblies, head gaskets, rod nuts-bolts, etc.

YMMV

Rob Edwards

Hey Jim-

I will happily defer to your expertise on this one, I'm just easily impressed by machines that go 'BING' It's why I went into medicine!

blown 87

That is what I am getting a full set of, the dial type, man Snap-On is proud of those.
I think I have three of them now, a 0-25 inch pound in 1/4 drive, a 3/8 drive low torque FT/LB and one that goes up to 125 FT/LB I think.

I kept having battery issues with the digital types, even though I am keeping two of them for general stuff, just take the batteries out every time.

The twist the handle work great as long and the torque wrench is level, not so much if it is vertical, even Snap-On has warnings about them if you dig deep enough.

I am going to keep a couple of the "Y" types, but all of the spring types are getting sold, if any one wants some Snap-On torque wrenches I will let them go for what Snap-On is willing to give me on trade in.

I am in torque wrench hell right now.

Jim Morton

Greg:

I hope we are not too far OT, but I think the torque questions are good ones. Sorry to hear of the wrench dilemma.

As a FYI, I have four different torqometer wrenches. With them, I can cover in-oz. to 100 lb-ft. For larger stuff or cruder specs, I use the clickers or Techwrenches. I also have the angle gauge for those types of specs.

With all these tools, there is a "torque" drawer dedicated for the torqometers in my big roll cab and yes, it's cost the pretty pennies. I view the torque wrneches as the cost of admission for taking on the more complex bolted assemblies like head gaskets, etc. I love having the tools, but I think about the expense everytime I read a burglary report.