First time user of a torque wrench

[oldcorollas]

plastic region

when torqueing up a bolt, you are in their elastic region.
when doing the 90deg yield thing, you move from elastic to plastic region, it deforms, and then moves back into elastic only region (just)

TTY are single use because you will never know or remember how many times they have been yielded before. from memory, someone here did soem tests with the diameter and length of the bolts on multiple yields, and they could be safe for 5-10 uses, but you can never be 100% sure.
PLUS, when they yield, the bolt necks down and gets thinner at some point, so the next time you torque and yield, it gets thinner.. and weaker, since the load (per unit area) on the bolt in that necked point is higher

something like this


from here http://www.peachparts.com/shopforum/...d.php?t=274556

[JZA70 R]

good reading, thanks guys.

[jondee86]

this is wrong. way wrong.

torque-to-yield (TTY) bolts are designed to be tightened to a specific torque setting - then
rotated a specific amount.

If you use the 90 degree method, you snug the bolts down to some minimal starting torque,
and then make two passes with a power bar, turning the bolt 90 degrees at each pass.

Its the same f**king thing

EDIT: OK... my bad I took it that the original post was simply comparing the traditional way of torquing
down a head, with the torque to yield method. So yeah, stay with the TTY method if that is what is specified
for your engine.

EDIT: Unless you change to ARP head bolts, and then you are back to the old way of torquing !!

Cheers... jondee86

[jondee86]

I think you'll find it is more like just assumed knowledge.

There is a saying about assuming things... I'll think of it later

I am well aware of the difference between torquing dry, oiled and ARP style lubed bolts.
My comments were for the benefit of the original poster (self-professed noob), and anyone
else who may not have a mechanical background. And given the ready availability of
Service Manuals on-line, having a little note about lubing threads might be helpful

Cheers... jondee86

[T.C.N]

senn do you have a copy of MR2_AW_1988_REPAIRMANUAL.pdf?, i find the exploded diagrams easier to understand then the Hayes manual.

[senn]

yup i have the 88 and 89. but the torque specs are different between bgb, hayes, and the head gasket kit i had (ACL) i ended up using the ACL figures for Pre-94

[CELICASUPRA7M]

Assume, it makes an ASS of U and ME

[trdee]

the 4AG/AW11 manual implies (but doesnt explicitly state anywhere i can see) that you can reuse the head bolts even though they are TTY, so long as you measure the bolts and they are within the allowable spec.

also, FYI



As you can see, they talk about bolt stretch sorta-kinda, and also explicitly state to LUBE THE BOLTS. No secret squirrel mechanical knowledge required so long as you just follow what toyota says to do

[CLG]

In regards to oiling and torquing, I use the following procedure:

1: clean the threads out in the block - use a tap to suit the thread to ensure they are clean
2: take a head bolt that has been oiled up and screw it into the block by hand - the oil will distribute along the thread providing lubrication for the final install.
3: place the head on the block - don't forget the head gasket!
4: place oil both under and above the head bolt washer, this will reduce the friction against the head and bolt which can give a false result
5: torque down in sequence - place one hand on the end of the torque wrench, and the other hand on the head to steady yourself as you pull through the sweep in one continuous motion, do not start and stop through a movement - this will give a false reading as the momentum to overcome the friction during a steady state will give a false "higher" reading.
6: Job done, have a beer, and worship the head in it's clean state.

Should you need to retorque:

1: loosen the individual head bolt, oil the washer as best you can, and pull through to the desired torque. You losen the head bolt to eliminate the friction between the headbolts and washer, which would give a false reading.
2: repeat process for all other headbolts in sequence.
3: job done, have a beer, and stand there disappointed that the head is no longer brand new clean and slowly getting dirtier!

[allencr]

EDIT: OK... my bad I took it that the original post was simply comparing the traditional way of torquing
down a head, with the torque to yield method. So yeah, stay with the TTY method if that is what is specified
for your engine.

Thanks jondee86 but you have nothing to apologize for, the OP has a 4AG, it DOES NOT have TTY bolts, and unfortunately the constant crap from the confused about TTY fasteners & angle-control method of tightening any non-TTY won't stop here.
http://www.boltscience.com/pages/tighten.htm

[thechuckster]

having worked on jap motors for ~15 years I have observed that they either:
- torque up bolts conventionally (in either 1 or multiple steps)
- use TTY requiring users to tighten in steps up to a known torque then apply a specific rotation.

The later process is an extension of the former and will only work as designed if the first steps are followed.

Nowhere have I seen "snug the bolts down to some minimal starting torque" (or equiv wording) which implies that angle-control or TTY starts from some random level of torque applied to each bolt.

I called out jondee86's comments as they suggested that TTY bolts do not require tightening to a specific torque setting - they were adding to the confusion not helping.

[StuC]

Im with you chuckster. They all give an initial torque setting, even if it is only minimal such as 25 0r 30Nm. They will then have another 1,2,3 stages of rotation. I think my last 3s was 30Nm, then 60 degree then 90 degree.

Every motor i have done heads on (going back to mid 60s benzes) have all been TTY. They have some huge amounts of strecth on their bolts (45Nm then 3*90 degree) and arent necessarily a one-use bolt. They have minimum/max specs that can be used safely within. I however always suggested an 99% of the time replaced to be on the safe side.

AS for what torque wrench to use i used to have a kingchrome? clicky type but it broke. I used snap-on and stahlwille at work(clicky type) and have just about finishing making a deflection beam type with a setting range from 10Nm to 170Nm. I'll get some pics up when its done fully. i just need to finish engraving and polishing/electroplating.

[StuC]

So heres my torque wrench that i made. I ended up marking 15,25, 40, 60, 80, 100, 120 and 140 Nm markers. I found it too large for anything under 15 Nm and would set off without basically moving. I can actually have it set to about 180 but again it was a little fiddly and being a deflection beam it was more than likely going to end up with overtightened bolts.

Please excuse the shitty phone pics

[JZA70 R]

You made that? ...nice work!

[af300e]

One interesting one. The lower shock mount on the dirtbike is an M8 and torqued to about 50Nm (from memory). I smear a little waterproof grease on the unthreaded section to make it easy to remove next time, but if the grease makes it into the threads (and probably a little on the nut face fron greasy fingers too) the bolt strips before the torque wrench indicates correct torque. I assume that Yamaha provide the 50Nm rating to compensate for dry tensioning?

Before anyone asks, the wrench is a calibrated W+B operating around the middle of its range and it's not the only wrench that has stripped this particular bolt. They never strip when the threads and nut are dry.

So I'd say, lube when indicated and don't when not indicated.