How do you torque brake fittings?
05-24-2010, 09:39 AM
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How do you torque brake fittings? Maybe I'm missing something, but how are you supposed to use a torque wrench on brake lines? 
For example, in the service manual I have it says to torque the brake pipe to the brake hose to 11 lb ft. Not sure how to do this since it's not a bolt.
For example, in the service manual I have it says to torque the brake pipe to the brake hose to 11 lb ft. Not sure how to do this since it's not a bolt. 
That's probably what I'll end up doing. I just didn't know if they made a tool for this, or if there were some way of adapting a torque wrench to the fitting. I guess just as long as it's not too loose. 
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05-24-2010, 09:55 PM
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Should've known there was a tool out there for this!
I can see where both bpittman and ZForce1 are coming from. The engineer in me made me look into this some more, so I found a picture online, and a formula that came with my Craftsman torque wrench:
TW = TE*[L/(L+E)]
The E and L in the picture are the same as the E and L referred to by the Craftsman formula. TW is the torque set on the wrench and TE is the torque applied to the fastener. The A is the angle of the crow's foot, which is not used in this formula.
In the case of a crow's foot at a 90° angle, E=0, so TE = TW because [L/(L+0)]=1. This basically tells us that no correction is required. Very interesting.
Another question: Would this crow's foot perform the same task as a flare nut wrench? (as far as not allowing the edges to get rounded off). This way I wouldn't have to buy as many tools.
I can see where both bpittman and ZForce1 are coming from. The engineer in me made me look into this some more, so I found a picture online, and a formula that came with my Craftsman torque wrench:
TW = TE*[L/(L+E)]
The E and L in the picture are the same as the E and L referred to by the Craftsman formula. TW is the torque set on the wrench and TE is the torque applied to the fastener. The A is the angle of the crow's foot, which is not used in this formula.
In the case of a crow's foot at a 90° angle, E=0, so TE = TW because [L/(L+0)]=1. This basically tells us that no correction is required. Very interesting.
Another question: Would this crow's foot perform the same task as a flare nut wrench? (as far as not allowing the edges to get rounded off). This way I wouldn't have to buy as many tools.
05-24-2010, 10:34 PM
#11
Snug is fine - if it leaks, tighten it a little more. You'll know right away if it leaks when you pressurize the system.
I once tightened a banjo bolt to the recommended torque spec in the Helm manual, and ended up stripping out the threads in the brake caliper (which had just been newly powder coated). A $50 helicoil kit and a lot of cussing later, I learned my lesson - tighten it so it's snug, and if it leaks, tighten it a little more until it doesn't. Beyond that, if you are tightening a nut on a hard line, use a line wrench (as has already been stated). I learned my lesson the hard way on that one too.
I once tightened a banjo bolt to the recommended torque spec in the Helm manual, and ended up stripping out the threads in the brake caliper (which had just been newly powder coated). A $50 helicoil kit and a lot of cussing later, I learned my lesson - tighten it so it's snug, and if it leaks, tighten it a little more until it doesn't. Beyond that, if you are tightening a nut on a hard line, use a line wrench (as has already been stated). I learned my lesson the hard way on that one too.
05-24-2010, 11:04 PM
#12
Brake lines fittings need to be tight, but as others mentioned, too tight and you will pull the threads right out of an aluminum caliper.
The critical part is getting the copper crush washers to seal. As you are tightening the bolt, the washers deform slightly, creating a seal. If you don't tighten the bolt enough, you won't "crush" the washers, and it will leak. Too much, and you'll be buying a heli-coil or new caliper.
The critical part is getting the copper crush washers to seal. As you are tightening the bolt, the washers deform slightly, creating a seal. If you don't tighten the bolt enough, you won't "crush" the washers, and it will leak. Too much, and you'll be buying a heli-coil or new caliper.
05-25-2010, 05:07 PM
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Snug is fine - if it leaks, tighten it a little more. You'll know right away if it leaks when you pressurize the system.
I once tightened a banjo bolt to the recommended torque spec in the Helm manual, and ended up stripping out the threads in the brake caliper (which had just been newly powder coated). A $50 helicoil kit and a lot of cussing later, I learned my lesson - tighten it so it's snug, and if it leaks, tighten it a little more until it doesn't. Beyond that, if you are tightening a nut on a hard line, use a line wrench (as has already been stated). I learned my lesson the hard way on that one too.
I once tightened a banjo bolt to the recommended torque spec in the Helm manual, and ended up stripping out the threads in the brake caliper (which had just been newly powder coated). A $50 helicoil kit and a lot of cussing later, I learned my lesson - tighten it so it's snug, and if it leaks, tighten it a little more until it doesn't. Beyond that, if you are tightening a nut on a hard line, use a line wrench (as has already been stated). I learned my lesson the hard way on that one too.
