So is there a good reason to use the vastly more expensive tty bolts on the manifold and plenum over a sturdy grade 8 bolt?
What kind of loc-tite do you recommend?

 

I just went to the dealership and got them for like $16. And theres a tiny "m" stamped on the top! Lol

 

I had the same dilemma and ended up choosing TTY. I wanted to do it right the first and forget about it.

 

IIRC, I went to Ace Hardware and bought some Grade 5 and installed them with red Locktite. Worked great as they were a bastard to remove this last time I tore into the engine.

 

Grade 5 are even cheaper. Any issues with damaging the threads? Another disadvantage of the tty bolts seems to be that they break, I am confident that grade 8 will hold up, just don't want to damage the threads.

 

from what I've read, the grade 8's are fine.. the purpose for TTY is to hold the low torque, and not pull out.. if you're using something more- DON'T over torque, and use some sort of thread lock.. blam- you're good.

 

Grade 8's and red or blue locktite do you think?

 

I think grade 5 will be even better than grade 8; a little more elastic, which is what you're looking for IMO. And I'd definitely go with medium strength (blue) loctite. It will hold just fine for what you're doing, and the fasteners will come back off a whole lot easier than with the red (high strength) stuff.

 

Here's a great article to articulate Grade 8 vs Grade 5 bolts from the Fasteners perspective ONLY.

http://www.rockcrawler.com/techrepor...ners/index.asp


It's not wise to assume that the stronger bolt is the better/improved/upgraded path for an application. The significant part of the equation is the actual type of joint. More specifically, how the fastener is loaded. Some joints are tension only or dominant, while others are shear dominant. Read the article carefully as it has great analogy.

To highlight drewactual's point about over torqueing....this could not be further from the truth. Example, you use the greater capable fastener and torque it to x% of its yield. You now have potentially overtorqued for the application b/c it requires more torque to reach that load.


Use what the specs define for fastener size/threads/lube. Lube has a significant impact on the torque as well.

(I'm not familiar with the manifold bolts specifically, and only wanted to help clarify a need to be careful about just thinking about the fastener. That is misleading)

 

dig this: you're working with aluminum.. that is the material of the intake.. you're dealing with steel (most often), which is the material of the heads.. you've sandwiched a gasket between them.. the tty bolts stretch and conform to the chase, which is in effect what all bolts do, it's just they do it quicker and more completely.. we're talking 12lbs of torque- not much..

if you want to crack your manifold, by all means- crank a grade 5 or 8 to 80% tension of the bolts design..

if you want to skimp on the tty's (which, personally, I wouldn't, but that's me.. others do it all the time and with good results), use either 5's or 8's, but for the sake of the manifold, don't torque it anymore than 15lbs.. that thing needs to be held tight enough to maintain seal, but loose enough to float through heating cycles..

the 5's and 8's aren't softer metals with almost pliable tension strengths like the tty's, they are much harder, and therefor the threads won't conform and 'bite' like the tty's.. so, you gotta hedge your bet by using thread lock of some sort..

will the 5's or 8's suffice? yes.. are they easier to use than the tty's? yes, because you can re-use them at least once or twice more.. are they better? no.. they don't conform to the chase they are in, and they will have a tendency to want to loosen over several heating cycles.. loosen more without a thread lock, loosen less with..

there is more in play in this particular fasteners topic than the torquing ability of the fastener alone.

edited to add- the tty's made by design for this purpose are shanked before the heads.. and, about the thickness of the manifold where it is tapped.