Crank Pulley
#17
the only ones i had to replace on the 93 lt1 was the head bolts. 93 3.4 part number for center bolt is 14102649 and,,, holey crab,,, 26 bucks and shows as off a 87 2.8 v6 on nalleygmc. does not show as a tty but then head bolts dont either so parts book must not show that. not the 93 version anyways.
#18
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Let say you have a 1/2” long bolt and you bolting down something ¼” thick. Let’s say this item heats up quickly and expands .015”. Because the bolt is so short, .015” is too much for the metal of the bolt to handle so it permanently stretches. Now when everything cools down the bolt is loose. Since the TTY bolt is in spring mode this expansion is no problem.
Ever unbolt an exhaust manifold and see a real thick washer under the head for no reason? That is the engineer’s way of dealing with expansion. Ever wonder why cheaper thin flanged header bolts always seem to come loose? Now you know why. Also note, most carbon steel bolts react the same way to heat and use the same young's modulus so going from TTY bolts to High end ARP bolt will not work. It will come apart. You can try to lock tight the thread but once the bolt stretches whatever it is holding will be lose cold.
I do understand the engineering better than this but it gets real complicated fast so this is the easiest way to explain it in a thread. TTY bolts where used in air planes long before showing up in cars. I was a little surpised to see TTY on the flywheel of my 3800. Some people confuse torque angle requirement with TTY bolts. Torque angle is just a more accurate way to torque a bolt and most TTY bolts do use torque angle but it is also used on standard bolts also.
#19
The bolts fbodyrs96 posted are TTY, and it appears that the one you removed isn't. The telltale sign of a TTY bolt is the self washered head, and the stepped-down diameter between the head area and the threads; thread portion is larger diameter than non-thread portion. Conventional bolts aren't like that. Which then begs the question...are the factory bolts conventional type, and the replacement bolts for whatever reason are TTY?
#20
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The manual should call out if it is a TTY bolt. On my 96 every where it mention bolting up the fly wheel it had in red (one time use bolts) or something like that.
The step down feature makes the bolts easier to manufacture. The smaller the "control" area the easier it is to monitor but it is not a requirment of design. Even a bolt that is theaded all the way to the head can be TTY.
The step down feature makes the bolts easier to manufacture. The smaller the "control" area the easier it is to monitor but it is not a requirment of design. Even a bolt that is theaded all the way to the head can be TTY.