Torque Wrenches - my answer... (Fifield, Douglas)

[megara at mac.com]

OK, so using your numbers SJ and my formula:

TW = (NT * LT) / (LT + L2079)

TW = 258 * 1.46 /  (1.46 + 1.0)
TW = 153 ft-lbs

So  instead of using the 258 ft-lbs on the torque wrench, you will use 
153 ft-lbs when you have the 2079 tool on the end. It makes sense - the 
2079 tool extends the torque wrench by ~60%, so there is a reduction on 
the setting by 60%.

Now you have to make sure you are measuring you tools correctly. You 
can't measure end to end, you measure from pivot point to pivot point. 
For the torque wrench, it is from the handle end (actually where you 
are going to hold the thing...:), so make a mark at the point of the 
center of your hand on the handle) to the center of the square drive. 
For the 2079 tool, it is from the center of where the square drive is 
accepted to the center of the 2079 tool socket.

However....what the heck is that 2084 tool? I quote from 
http://www.zdmak.com/audi_tools.htm  :

(from description of the 2079 tool)

"Used in conjunction with Counter Holder 2084"

I have no idea how the 2084 tool is used with it, and if it would 
affect my equation.


Your interesting footnotes are actually contradictory. One says to use 
a lubricant and the other says to use loctite, if I read them 
correctly. I would just use the loctite---if you paint it on the 
threads near the bolt head, it will seal the bolt and not allow any 
substantial corrosion to begin.

--Greg



On Wednesday, December 3, 2003, at 12:54  PM, SJ wrote:

> I think we understand the general theory by now. The problem lies in 
> the
> data details.
>
> The best way to illustrate this problem would be with an example using 
> real
> numbers.
> Tell us what the the torque on the crank bolt should be. Use your 
> formula,
> and whatever numbers you have available. Just give us the primary 
> source for
> any of your data.
>
> I'll help you out.
> Length of 2079 tool = L2079 = 1.0 ft (from a lister that has the tool, 
> I'm
> tracking down this number)
> Length of the torque wrench = LT = 1.46 ft (I measured my torque 
> wrench,
> Sears Craftsman Digitork)
> Setting for torque wrench = TW = 258 ft lbs (Bentley 5000S 84-88, pg 
> 13.13)
>
> Assume that all the tools will be in line perfectly so we can 
> eliminate the
> alignment complications from the discussion.
>
> Does this sound like a setup? :-)     It is, but this is the best way 
> to
> illustrate the problem. Go along with me.
>
> Interesting Footnote:
> Bentley 5000S 84-88, pg 13.13 >>> "..apply corrosion inhibitor AMV 186 
> 011
> 02 to top threads and contact surface of bolt head."
>
> pg 13.18 >> Turbo Diesel > "...258 ft lbs . . .coat threads and contact
> surface of bolt head with Loctite 573 or equivalent."
> No direct reference to tool 2079. Warning says to see pg 13.16. Nothing
> there of importance. Showing how to use tool 2079 is on pg 13.15. I'll
> assume this is a typo error in the Bentley.
> Loctite 573 Gasketing Product
> Fills gaps up to 0.1 mm. Slow cure. Easy disassembly. High resistance 
> to
> loads and vibrations.
>   a.. Medium strength, bright green colour
>
>   b.. Applications:
>   For sealing rigid flange faces on transmissions and engine casings,
> differential housing covers, bearing caps, etc.. Fills gaps up to 
> 0.1mm max.
> Hmmmm . . .seems using loctite is incorrect, unless you have a diesel.
>
>
> SJ
> 85 Dodge PU, D-250, 318, auto
> 85 Audi 4k - - sold but still on the road
> 88 Audi 5kq
> 90 Audi 100q
>
>
>> From: Gregory Megara <megara at mac.com>
>> Subject: Re: Torque Wrenches - my answer... (Fifield, Douglas)
>>
>>
>> Torque is Force x Length of lever arm. So, to figure the torque on the
> crank bolt can be done with the derived equation:
>>
>> Needed Torque on the crank bolt = NT
>> Length of the torque wrench = LT
>> Length of 2079 tool = L2079
>> Setting for torque wrench = TW
>>
>> TW = (NT * LT) / (LT + L2079)
>