rod bolt streeeetch gauge

Alan Roehrich · 09-22-2012, 10:43 PM

Rod, one of the most important things is the dial indicator, it needs to have a really strong spring, and the tip needs to have a small radius. The Proform piece is okay, but like all the inexpensive version, the dial indicator spring is weak.

I make sure mine repeats by taking it off and putting it back on several times, then use my regular socket for rod bolts on my torque wrench.

By the way, you can calculate the portion of a full turn needed to stretch a bolt correctly, using the number of turns per inch of the threads. If the bolt is 7/16" -20, for example, then it takes 20 turns to move an inch. So one turn is 0.050". That means 1/8 of a turn will give you about 0.006" of stretch. Use that to know about how far to turn the bolt to get the desired stretch, and to make sure the gauge is reading close to correct. If you had the bolt just seated, turned it 1/8 of a turn, and got 0.010" stretch, you know something is off.

09-22-2012, 10:43 PM	#2
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,116 Likes: 1,573 Liked 1,829 Times in 414 Posts	Re: rod bolt streeeetch gauge Rod, one of the most important things is the dial indicator, it needs to have a really strong spring, and the tip needs to have a small radius. The Proform piece is okay, but like all the inexpensive version, the dial indicator spring is weak. I make sure mine repeats by taking it off and putting it back on several times, then use my regular socket for rod bolts on my torque wrench. By the way, you can calculate the portion of a full turn needed to stretch a bolt correctly, using the number of turns per inch of the threads. If the bolt is 7/16" -20, for example, then it takes 20 turns to move an inch. So one turn is 0.050". That means 1/8 of a turn will give you about 0.006" of stretch. Use that to know about how far to turn the bolt to get the desired stretch, and to make sure the gauge is reading close to correct. If you had the bolt just seated, turned it 1/8 of a turn, and got 0.010" stretch, you know something is off. __________________ Alan Roehrich 212A G/S Last edited by Alan Roehrich; 09-22-2012 at 10:53 PM.