more crank bolt....

Ameer Antar antar at
Tue Dec 2 07:56:38 EST 2003

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.


---Original Message---
Date: Mon, 1 Dec 2003 19:06:03 -0700
From: "Al Powell" <apowell at>
Subject: more crank bolt....
To: <quattro at>
Content-Type: text/plain;	charset="us-ascii"

I think Ameer is missing the point and confusing his math. And this is
really scary to me, as I am never the first to grasp math, but.......

In the first and mostest basic place, WHO CARES whether you're a few pounds
off??? As  explained in the first post, it simply doesn't matter because you
have considerable margin for error with no impact on the outcome. You're
thinking too much and making it too much work. Audi is terminally anal, and
we already know we all learn to disregard their instructions at
times that make sense to us.

Second, the math is simple enough even for me....

Torque = force x distance
T1 = F1 x L1 = 10 lbs x 2 ft = 20 ftlbs
T2 = F2 x L2 = 20 lbs x 1 ft = 20 ftlbs
Therefore, T1 = T2
Therefore, 85 pounds at 4 feet = 340 pounds at 1 foot.
And as I said earlier, 340 pounds = close enough!!!!!!!!!!!

Since the desired torque on the bolt is around 350 bs/ft, get the four foot
pipe, slide it over the breaker bar, apply a good grunt worth of effort to
tighten the bolt, and unless you're either relatively weak or a weightlifter
who bench presses extraordinary weight, you're going to be in the right
range. After that, just drop it - you're done.

In the third place, I don't really care whether Audi wanted me to do, nor
whether they would get their panties in a wad if I was off by 10 lbs/ft when
I tighten the bolt. As long as I get the bolt torqued close enough to stay
put and do its job, the rest is immaterial.

Al Powell
apowell at
1958 Fiat 1200 Transformabile Spyder
1983 Datsun 280ZX Turbo
1993 Audi 90Q
1997 Chebby Blazer
1999 Chebby Blazer


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