more crank bolt....

[Al Powell]

I didn't mean to be unkind to Ameer - my apologies if the tone was perceived
as aggressive.  It was intended to be joking. The other lister did so in a
more appropriate manner than I. Let's get over it.

To respond to your question - the source for the numbers 85 x 4 is extremely
simple.

To re-cap; the best number I could get for tightening the bolt without use
of the special Audi tool was about 350-360 lbs/ft. This rounds to 350 for
convenience. Although I needed to apply about 350 lbs/ft of torque, I had no
wrench calibrated that high, nor enough muscle to lean over the fender and
apply it in an awkward position with a normal length torque wrench (maybe
18-24" long).  The easy, and to me very intuitive, solution is to make the
handle longer! This allows you to reduce the amount of force needed at the
end of the bar, and still apply lots of force at the bolt.

So - the question quickly becomes how much pipe to use in extending the
lever.  (350 divided by X, with X=the length of the wrench handle). Simple?

Here's a MUCH more detailed version of the decision-making process than I
actually used....

350 divided by 2 = 175 pounds, but 2 ft. is the normal length of a torque
wrench and my back didn't like the idea of bending over and applying 175
pounds to a wrench.  Not a good solution at age 53.
350 divided by 3 = 117 lbs.  I could certainly apply that much force, but
the placement of the bolt made a 3 foot extension somewhat awkward (IMHO).
350 divided by 4 = 87.5 pounds.  THAT works.  4 feet of pipe (a standard
length available at the hardware store) gets me far enough from the bolt
that I can work past the fender easily, and the force needed is easily
within my ability to apply.  Also, with a force in this range, I can make a
better physical guesstimation of the force I'm applying than if I have to
apply over 100 pounds of push...so I have the chance to be more accurate
when relying strictly on muscle power.

The 85 figure is easy to arrive at by the process above - and totally
approximate - and I'm pleased to have gotten so much positive reinforcement
that my logic holds water.

So the thought process is easy, and here's the summary, about the way I
worked it out: can't do it with a standard torque wrench - acceptable margin
of error is very large - so get a long bar in a practical length and cinch
the sucker down. How long? 4 feet will reduce the push to something I can
do, and in a position where I can do it.  Use 4 feet.

The math is really window dressing; its only function is to give me a
ballpark for how hard to push on the pipe.

************************
Al Powell
Fort Collins, CO
apowell at gocougs.wsu.edu

"To announce that there must be no criticism of the president, or that we
are to stand by the president, right or wrong, is not only unpatriotic and
servile, but is morally treasonable to the American public." Theodore
Roosevelt, 1918, during WWI.
************************

-----Original Message-----
From: Ameer Antar [mailto:antar at comcast.net]
Sent: Tuesday, December 02, 2003 5:57 AM
To: quattro at audifans.com
Cc: Al Powell
Subject: Re: more crank bolt....


Yes, I agree when torque is that high close enough is close enough, but I
was worried that it was a much higher number. I was just bringing up a
concern, and I wasn't sure that I was doing the physics right (the math was
fine). The point that I got wrong was that it does matter how long the
t-wrench is. I assumed this b/c in the manual it makes no mention of the
length of the wrench. Now, I guess that's b/c there must be an unspoken
industry standard for torque wrench lengths for a given range. So now, I can
calculate and match the numbers in the original post. I have seen 2 250
ft-lb wrenches that are 30", so I will assume that's what Audi used. So, to
get 258 ft-lbs of torque at the wrench head, you need 258ft-lbs/2.5 ft =
103.2 lbs. Then add the 1 ft extension and you get 3.5ft * 103.2lbs = 361.2
ft-lbs. Now I feel much better that the numbers match.

So exactly where are you getting these numbers: 85 lbs and 4 ft? I haven't
seen these in any Audi manual. Now, what's w/ the attitude? I don't really
see that I've done such a bad thing. I wasn't worried over a few ft-lbs,
more like a hundred or more, and that would be enough of a difference to
cause problems. Also, there was another lister who I won't mention who had
the same exact thinking/concerns as me, but you decided to focus on my post.
Another lister noticed my mistake and was able to point this out in a much
more palatable way. Everyone makes mistakes and it's important to help each
other see them but there are more reasonable ways of doing this.

-Ameer