DudeBud

damn i guess i will be using bolts on my 3.0 engnbldr on ebay has a head set with bolts for 114.00 not a bad deal. has DOA given you any sort or refund?

gwhayduke

I'll bet those threads were cut, not rolled. There are boltmakers here in El Paso and spring break starts this week. If someone can get me the specs on these or ship me an original one (I'll pay the shipping), I'll go shopping to see what they would cost for a set.

Babypig

Toyota head bolt are torque to yield. Yield strength is the point at which the bolt will no longer stretch and becomes deformed permanantly. This permanant stretching is called plasticity and the metal hardens as it streches. Steel crystals have certain kinds of structure that allows them to stretch and snap back called elasticity ( modulus of elasticity or youngs modulus) or ductility. Past that the steel crystals them selves begin to deform and the steel loses it's ductility or elasticity and this is called the plastic deformation state. The bolt still has a ways to go to it's tensile limit but will not be reuseable. If the bolts were torqued to 5ft/lbs less theywould stay in the elastic state and not deform. Toyota head bolts are streched and will not return to the original shape after they have been torqued to spec's there are they are torque to yield. Now there is alot I don't know about this as I am just learning, but it's fun.

mt_goat

[QUOTE=Babypig]Toyota head bolt are torque to yield.QUOTE]

How do you know? I know what yielding is, I just don't know if Toyota head bolts do in fact yield when torqued to spec and I'm wondering how you know that they do.

Babypig

[QUOTE=mt_goat] Cause toyota calls them torque to yield bolts and they deform when torqued. They aren't supposed to be reused.

mt_goat

[QUOTE=Babypig]I can see the DOA studs are deforning from the pictures of them, but I've never seen a OEM Toyota head bolt deform, but I'm not saying it doesn't happen. Has anybody out there seen a OEM Toyota head bolt deform from torquing to spec?

mt_goat

[QUOTE=Babypig]

Cause toyota calls them torque to yield bolts [QUOTE]

Where does Toyota call them torque to yield bolts? Again, I'm not saying they don't, I'm just wanting your source of info. This on-line FSM just says "if any bolt is broken or deformed, replace it." (on page 29 of 41) http://personal.utulsa.edu/~nathan-b...68cylinder.pdf

Babypig

[QUOTE=mt_goat][QUOTE=Babypig]

Cause toyota calls them torque to yield bolts If you go ask any toyota dealer or mechanic they are known as torque to yield. The dealer is who told me this. This is also proven by the fact that they deform when torqued. Thats how they work apparently. They should'nt be deformed before you use them but after they can't be reused.

mt_goat

[QUOTE=Babypig][QUOTE=mt_goat]Has your class done some tests showing they are deforming when torqued to spec? Also, if you have it handy, what were the Rockwell test results on the OEM bolts? Thanks for the info.

Babypig

[QUOTE=mt_goat][QUOTE=Babypig]Okay,
For the last time, they stretch when torqued. Thats why Toyota says not to reuse them. If you take a used one and put it next to a new one the old one is longer. Check it out.

MTL_4runner

[QUOTE=Babypig][QUOTE=mt_goat]Here is a good article to follow up on what you are saying:
http://www.robbos.com.au/myweb/Tech_Bolts.htm

engnbldr

>>>*Morning!

*Quite a discussion. We always replace the head bolts on the 3VZE, mostly because of early on we had two cases of breaking them. This spoils a day quickly...

*Ever notice it is nearly always either the last one or the next to last one?...*LOL**

I personally won't make the studs, I do not own the equipment to roll the threads during the forming process. Sure, I could set up and cut the threads, this is much weaker than a formed and rolled out piece. *More work, too and I'm lazy.......All it takes is one little stress riser and the stud can break.

Usually breakage with bolts is due to the threads creating resistance, they stop turning. The same can happen with a stud if the nut end threads are not completely free and lubed. Once they stop slipping as they are torqued, you are now twisting the shaft of the piece. I have had a couple of cases of folks breaking brand new bolts, this is the cause of that.

If the shaft of the fastner is actually twisted rather than tightened into the block, it is not creating clamping force at all, even though the torque wrench may read accurate load.

Yep, it can break. So before we even think of going to maximum torque, we clean the threads in the block with a chaser, (NOT a tap)..Then we oil the threads and spin the bolt all the way in and out with our fingers. This assures they are clean and lubed.

Then we pull them to 50%, all of them. ... back off 1/4 turn and repeat, note each time it will turn a tad more before 50% is reached. This is because the threads are bedding in. We do this 5 times, then we go to 75%, then to 100%, all done. We do this with ALL new fastners...it assures a more even clamping force, inconsistant clamping force is the number 2 cause of early head gasket failure..(heat is number one)

It takes some time, sure, but it takes less time than pulling the head back off...Hope this helps.....*EB

MTL_4runner

I do agree to chase and oil all the threads but also be sure to remember to derate the torque when doing this.
I use roughly 20% LESS torque with oiled threads than if they were dry.
.....this may be why some are snapping headbolts even with proper torque reading.

Site has a good chart for derating torque:
http://raskcycle.com/techtip/webdoc14.html

engnbldr

>>>*Good point, but nearly all manufacturers do suggest lube when they offer specs. Many even supply the correct lube for their values. We use dry torque specs for fastners such as intake/exhaust manifold bolts, all externals in fact. For high-load fastners like rod bolts, we use the stretch method normally. This isn't really possible with head studs and main bolts, though, so installation technique becomes critical.

I remember running some tests a year or so ago when we were having the 10.9 Grade bolts made for the 22RE engines. That bolt at SAE grade 10.9 will take 110 ft lbs of load, right at 200% of spec. Yet lock the threads and they twist off at around 90#.

Pull yield or PSI strength is totally different than twist yield. We had some fun stuff way back when we were building NASCAR engines, we did quite a few actually. Some of the Alcohol classes allowed Aluminum heads and blocks. Being clever, I thought I knew all about it, but I started losing gaskets right and left.

*Got snickered at, too...Running hard for 30 laps of a 100 lap main didn't do much to win races.

I will say that I am used to winning my fair share of races and a few of some other good folk's share, too..., so failing is serious red-faced stuff...

Finally I swallowed my pride and hollered for help from a friend who built them with success. One night over a couple of Buds he showed me some things about clamping force and torque loads. It seems that Cast Iron heads (my Forte at the moment) and Aluminum are two different worlds, he spent a full hour setting the studs on each head, (good old ARP's, too) Yes, a world of difference between an 800 H/P engine and a 120 H/P engine, but the theory is the same.

Remember that torque is just a measure of twisting force, clamping force is what keeps things attached. It seems that variations across a series of fastners could be as much as 50%, sometimes more if one was not careful. I know he was right, it solved my problem.

The very best thing an installer can do using new fastners is repeat load at a percentage of final value, 5 times is good, my friend used 10 times. Get the clamping force right, gasket failures are almost never....*EB

mt_goat

Good stuff EB, thanks. What is a chaser and how do you gauge when your at 50% or 75%? Do you mean like 50% of a 90deg turn?

MTL_4runner

This is what a thread chaser set looks like:

engnbldr

>>>*Nice pic of a good chaser set in the post above. *Easy to make, too, I take an old bolt in good shape and cut a slot in the threads with "V" cut file or hacksaw.

Guess I was being a bit generic on torque loads, seating the threads properly can be done at about any mid-percentage value, it isn't really critical. Been a bit since I pulled on a wrench, but I believe the 3.0L calls for 33 lbs ft and two 1/4 turns? (Somebody post the spec if that isn't correct, I am sitting at my kitchen table with no manuals right now)

So I would use 33 as a value....*EB

MTL_4runner

It sounds like you have emperically come across the mechanical engineering "strength of materials" laws. You are referring to materal shear strength vs yield strength and yes, they are quite different as they are also calculated differently. They also differ depending on if you have a ductile or brittle material so you need to take that into account as well (most metals obviously fall in the ductile category). The calculations when done correctly can be quite complicated, but there are some general rules engineers do follow.

http://www.roymech.co.uk/Useful_Tabl...reloading.html
http://euler9.tripod.com/fasteners/preload.html

Now unless it specifically says in the manual that the threads should be oiled when torquing, then I have to disagree that they provide specs that assume lubrication.....it is usually assumed NO lubrication and that the torque should be derated properly for the reduction in friction between the 2 materials (something they don't usually mention either). You really need to be careful here because roughly 80-90% of the torque is used to overcome friction then this only leaves 15% to 10% for actual bolt tension so what this means is that a huge error in bolt prestress can occur with the use of lubrication and improper torque specs. In critical applications (such as designing stuff for aerospace, which I used to do) you use a bolt with an embedded strain guage. Now these are rediculously expensive and impractical for a vehicle head bolt but it underscores the need to be very careful to minimize the variation in torque you create by using the torque wrench method.

http://www.boltscience.com/pages/tighten.htm
http://www.boltscience.com/pages/bc1.htm

This also has some good training stuff if you launch the flash at the bottom:
http://www.boltscience.com/pages/boltcalctraining.htm

http://www.rockcrawler.com/techrepor...que/index.asp#

It does sound like you have some very good seat of the pants experience for getting around the need to read true bolt strain though.

mt_goat

So 33 ft-lbs would be 100% and 16.5 ft-lbs would be 50%....etc? Is that right?

mt_goat

[QUOTE=MTL_4runner]It sounds like you have emperically come across the mechanical engineering "strength of materials" laws. QUOTE]

I believe EB is a mechanical engineer. I also have the BS in ME.