Torque tò yeild question on large roller bolt

[Pedalsteel]

So I put the large roller in and thought i. Had torqued the bolt to the 30 ft lbs +1/4 and then questioned my torque wrench so I bought one of those digital torque devices that fit on any ratchet...I set my wrench to 30 ft lbs and also set the digital device to 30 and put that on my torque wrench so.i could check the two against each other...it turns out that in order to get 30 ft lbs on the torque wrench, I have to set it to 41 ft lbs... so that means the large roller has a mystery value...I know I could order one torque to yield bolt, wait a couple days, take the one in there now or and roller the bolt using my new dual beam wrench, but I'm wondering if anyone has the end value of the torque to yield bolt after it had been set to 30 ft lbs and 1/4 turn so i. Can just get this done?

 

[JETaah]

With that situation I would look for yet another quality tool to reference against and see which comes closer to the reading that you are getting.
Maybe the store where you got the digital unit will allow you to check it against another or another analog wrench.
I do that periodically with a couple of my torque wrenches to check if one clicks off before the other.
I probably don't have to tell you this but, whatever you do, get it right. It is crucial due to its place in the timing belt circuit.
Don't reuse the bolt in that position once you have stretched it.
Don't attempt to stretch it a second time.

 

[Vince Waldon]

Unfortunately there's no "final torque equivalent value", since the point of the bolt is accurate clamping force thru deformation, not finishing torque.

 

[Pedalsteel]

I'm hoping a trip to my vw dealer tomorrow will yield the correct TTY replacement and I can take this one out and put a fresh one in and correct it now that I have a new torque wrench I checked against the device

 

[Zak99b5]

Use the more accurate torque wrench and see how much more of a turn the bad ones needs to reach the real 30 ftlbs from the false reading. Turn the roller bolt that much more and be done.

 

[2004LB7]

You need to clamp the drive square in a vise or other unmovable bolt at a horizontal position and suspend a known weight of the same value as the value on the wrench exactly one foot from the drive square.

That will tell you which one is more accurate and how accurate

 

[Pedalsteel]

So using the new torque wrench I measured the torque value on the bolt and its around 38ft lbs with the old wrench and a 1/4 turn...I went ahead and bought a new bolt from my vw dealer and I'm going to remove the one on there now and replace it using the new torque wrench +1/4 turn just to be on the safe side...have the TTY bolts become the thing everyone uses bc they are indeed better at holding a torque value, or is it something the car makers are using to make more money? Why aren't we using steel everything plus a drop of blue loctite?

 

[BobnOH]

When possible we like to replace TTY bolts with standard.
Are the bolts from VW TTY?
You may be over thinking this. It sounds to me like you're good to go!

 

[P2B]

So using the new torque wrench I measured the torque value on the bolt and its around 38ft lbs with the old wrench and a 1/4 turn...I went ahead and bought a new bolt from my vw dealer and I'm going to remove the one on there now and replace it using the new torque wrench +1/4 turn just to be on the safe side...have the TTY bolts become the thing everyone uses bc they are indeed better at holding a torque value, or is it something the car makers are using to make more money? Why aren't we using steel everything plus a drop of blue loctite?

You cannot measure the torque of a TTY bolt once it has yielded, it should be replaced.

TTY bolts provide greater consistency of clamping force than standard bolts torqued to a specific value, particularly over time in applications subject to heat cycling. They reduce variations caused by inaccurate torque wrenches, dirty or lubricated threads etc. Engineers specify them when clamping force is critical.

 

[P2B]

When possible we like to replace TTY bolts with standard.
Are the bolts from VW TTY?
You may be over thinking this. It sounds to me like you're good to go!

It's a TTY bolt that was only slightly under torqued before the 1/4 turn yield force was applied, so it's *probably* OK, but given the consequences of a TDI timing belt failure vs. cost of a bolt ... why risk it?

 

[Vince Waldon]

have the TTY bolts become the thing everyone uses bc they are indeed better at holding a torque value, or is it something the car makers are using to make more money?

Pretty sure car manufacturers do everything possible to REDUCE the cost of manufacturing. If they could stick in a cheaper bolt... or, say, make the water pump housing out of plastic cough cough TSI cough cough...they would and they do.

They don't need to soak you on the bolts when they really can really soak you on the plastic bits.

The truth is that all manufacturers use TTY bolts, have been doing so for decades, and it's because (long story short) they are a superior engineering solution when accurate clamping forces are critical. Again, the game is not to hold an accurate torque value, it's to provide an known-accurate clamping force. Clamping is the function the bolt is doing, not torquing.

At least, that's my personal way of seeing the subject.

 

[Pedalsteel]

I meant more money for them to make off everyone... do funny cars and top fuel cars use tty bolts?

 

[Vince Waldon]

I've never bought any TTY bolts from VW, so if they used TTY bolts when they designed my car so that they could make more money off me they wasted their time.

 

[JETaah]

It is a bit puzzling the "why" and "where" they use the TTY bolts.
For example, the ALH intake manifold does not use TTY bolts but the oil filter bracket-to-block bolts do.

 

[Vince Waldon]

Or, they start with TTY but move to non-TTY, or visa versa. ALH IP sprocket bolts, IIRC?

 

[Matt-98AHU]

I've seen more than one of the large roller bolts break because they were stretched excessively when using VW's torque spec.

Realistically, anything between 35-51 ft-lbs is fine without the plus 90 step. It won't back off, and you won't be overstretched in that range. I think eventually the torque was revised to something around 37 ft-lbs without the +90. I've been doing it between 37 and 42 consistently just based on a feel I've developed over the years when the bolt is getting close enough to the point of not wanting to be torqued a whole lot further without substantially more effort. Generally that's just fine...

Towards that end, the engine mount BRACKET M10 bolts, same diameter and thread pitch as that roller bolt, are only torqued to 33 ft-lbs and VW says are re-usable because they aren't torqued so insanely high.

I've quite literally done hundreds of ALH timing belts this way and never had a belt I did have that bolt back off using this lower torque spec... And because I *have* seen multiple failures from people using VW's spec, I say you should probably do it my way rather than the ridiculous +90 degrees VW originally advised.

 

[Pedalsteel]

Well it's in there with the vw spec... so far it's good... the only bit of play I could feel in any of the components was the top small role had a tiny bit of play but not much at all... belt looked good and that was at mileage than the recommended interval...I replaced the rubber engine mount also which wasn't really bad but why not while I'm in there...