TORQUE!!!!!

milktree

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.... values, that is.

Doing suspension work. There's one bolt that everyone says "dude, you gotta replace that": the strut pinch bolt. So that's a no brainer.

But there's a bunch of bolts that

A) VW says you should replace (but nobody does)
and
II) have a torque spec. that includes something like " + 180°"


For the ones without (II), above, I'm comfortable re-using a "must replace" bolt, tightening to the specified torque.

But what about the ones that include a "this much more"? Do you do exactly that, even on a re-used "must replace" bolt?

The ones I'm thinking (probably too hard) about:

top mount bolts, #13:



LCA mount bolts and ball joint lower nuts, parts #7, 8, and 4:


and parts #1 and 10:


I'm conflicted because usually "+xxx°" means "tighten to yield", which means "don't reuse" and more explicitly, "if you keep tightening to yield, they'll end up like this: (motorcycle brake caliper mounting bolt. I had the torque wrench set to "lb-ft" instead of Nm. I caught it before riding.)




+180° seems like "to yield", so .... what does everyone do here?
 

Cuzoe

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I have replaced all the +xxx degree bolts every time. Needless to say I've been through over a dozen sets of hardware. Your last picture is frightening. I guess in my paranoia mind that happens instantly any and every time a "to yield" bolt is re-used, haha.

That being said, lots of people pick and choose which bolts to replace, always replacing certain ones while seldom replacing others. Does a bolt that was originally +90 get +120 the second time around? I can't logic my way through making those determinations so I replace them all.
 

milktree

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I have replaced all the +xxx degree bolts every time. Needless to say I've been through over a dozen sets of hardware. Your last picture is frightening. I guess in my paranoia mind that happens instantly any and every time a "to yield" bolt is re-used, haha.

That being said, lots of people pick and choose which bolts to replace, always replacing certain ones while seldom replacing others. Does a bolt that was originally +90 get +120 the second time around? I can't logic my way through making those determinations so I replace them all.
That stretched caliper bolt got that way because the torque wrench never clicked. I backed off and thought, "wait, that's not right" when the resistance to turning stopped increasing. Oops. so, it's an extreme example. I can't imagine that people who don't replace them have that experience.

I don't suppose you ever compared the OAL of the new vs old bolts, did you?
 

740GLE

Top Post Dawg
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the lower control arm has very tight tolerances for the ball joint bolt so I don't think it's about keeping it aligned (i think mk4 had some slop for alignment play).

I have reused the rear shock bolts and rear LCA lower bolts when i installed helper air bags on the alltrack (which has IRS) and just used 1 uggadugga and has been fine since.

Worse case reuse everything and toss on some red loctite and call it good.
 

nicklockard

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Loctite won't stop them from fracture failing. The issue is that they get work hardened @ yield. When you relax the tension on the bolt (take it out) then re-use it, you are entering brittle fracture regime, or at least flirting with disaster.
 

benshaw

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i would never angle tighten a bolt into shallow cast iron or any aluminium thread because after its done at first build it will pull the thread away next time out, only a steel nut is safe for tty in my opinion. tty must of been a cent cheaper then loctite for vw.

vw want to sell new parts.
 

milktree

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Loctite won't stop them from fracture failing. The issue is that they get work hardened @ yield. When you relax the tension on the bolt (take it out) then re-use it, you are entering brittle fracture regime, or at least flirting with disaster.
I guess the question is more about if they're actually "to yield", or is that just a VW way of more precisely setting torque?

For instance: The nuts that hold the bottom of the ball joint on have a spec. of "40Nm +45°". But what's yielding there? I've never heard of a a torque to yield *NUT*. VW doesn't say anything about replacing the ball joint, just the nuts. So what's going on here?

Likewise, the torque on the strut top mount bolts is only 15Nm, or 11 lb-ft. That's tiny for bolts that size. But 15 Nm +90° seems (to my gut) to be a reasonable torque value for an 8x1.25 bolt.

I just did a quick test using some 8x1.25 motorcycle hardware and a quality torque wrench and measured 15 Nm+90° to be 37 Nm, with zero measurable plastic deformation on that 20mm bolt. It wasn't scientific for sure, but it suggests the +90° is probably OK to reuse with the factory

70 Nm +180° is a lot higher starting torque, and a lot more extra rotation, so I'm not as confident about reusing those.
 

milktree

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i would never angle tighten a bolt into shallow cast iron or any aluminium thread because after its done at first build it will pull the thread away next time out,
You mean like studs in an aluminum cylinder block?

I don't think any of the aluminum suspension hardware has threaded holes that require "interesting" torque. Am I forgetting some?
 

Nuje

Top Post Dawg
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i would never angle tighten a bolt into shallow cast iron or any aluminium thread because after its done at first build it will pull the thread away next time out,
cf. The aluminum mount brackets on the Mk4 cars. Original torque spec on the big M12x1.5 bolts that screwed into them was 44ft.lbs + 90°, then in later manuals showed simply 100Nm (74ft.lbs). Same with the dogbone mount - used to be a ___Nm+90°, since changed to 50Nm on the 16mm head bolts and 25Nm on the 13mm ones that bolt into the subframe. ¯\_(ツ)_/¯
 
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740GLE

Top Post Dawg
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Loctite won't stop them from fracture failing. The issue is that they get work hardened @ yield. When you relax the tension on the bolt (take it out) then re-use it, you are entering brittle fracture regime, or at least flirting with disaster.
My understanding was the TTY was causing tension of the fastener under a "spring" type method (soon as the spring is stretched, it can't be "re-stretched" and serve the same clamping/spring force) which will prevent the fastener from backing out. Loctite should provide the same thing, prevent a fastener from loosening.
 

740GLE

Top Post Dawg
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Timing belt?

Also front steering knuckles on most VW worth owning are aluminum,
 

milktree

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Timing belt?
Not really a suspension part. :)

Also front steering knuckles on most VW worth owning are aluminum,
(I think) The steering knuckles on GTIs, Rs, and Alltracks are aluminum, but not on the diesels. All the drop-in Audi knuckles are aluminum.

But do any of them have threaded holes? I thought they were all through holes. (I'm not super confident of this, which is why I'm asking)
 

Cuzoe

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That is correct, aluminum knuckles on the GTI/R/Alltrack... all 55mm front struts too. I'm running them on my car, about 90% sure they're through holes though. I don't think there was anything threaded. Running the aluminum subframe as well and the only threaded hole I remember is for the level sensors. Very light torque on those screws of course.
 

thundershorts

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I think the tty hardware may have a lot to do with the assembly at the factory using preset torqueing power tools. I've never seen high quality hardware like ARP being tty. You could just buy arp and be able to reuse as many times as youwant with no worries.
 

740GLE

Top Post Dawg
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They are through holes with nut and bolt set up, darn!

What about dog bone mounts into the transmission, DSG or MT? that's an aluminum case right and sortta suspension/driveline related? Those are TTY.
 

milktree

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I think the tty hardware may have a lot to do with the assembly at the factory using preset torqueing power tools. I've never seen high quality hardware like ARP being tty. You could just buy arp and be able to reuse as many times as youwant with no worries.
I don't know what "ARP" means in this context.

Would you use the XXX Nm + YYY° method?
 

thundershorts

Top Post Dawg
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ARP is a company the makes high quality hardware. Bolts, head studs, nuts, etc. People that don't want fastener failure buy their stuff, its very high quality.
 

Nuje

Top Post Dawg
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What about dog bone mounts into the transmission, DSG or MT? that's an aluminum case right and sortta suspension/driveline related? Those are TTY.
That used to be the case on the Mk4 at least; they're now straight-up Nm / ft.lbs.
 

740GLE

Top Post Dawg
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if only we were in the mk4 thread :sneaky:
 

Nuje

Top Post Dawg
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Ah yes - the peril of launching a browser tab from an email notification: not being sure which sub-forum you're in. ;)
 

milktree

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For anyone following along at home:


I attempted to install the Bilstein shocks in the rear of my car last weekend (I failed because I fat-fingered and bought the non-TDI shocks that don't fit, the bottom mount is 14mm too wide)

Anyway...

For science, I tightened the left lower shock mount bolt (M12 x 1.5) to the factory spec. of 70 N•m +180°, incrementing the torque wrench after the initial 70 N•m until it clicked at 180°. I got to about 190 N•m.

For the right side, I tightened to 70 N•m, then set the torque wrench to the left side's final setting of 190 N•m, and tightened until it clicked. This time, the bolt only turned 90°!

So, *something* is wicked different. If I'd tightened the right side to +180°, it would have been *WAY* more torque than the left side.

'course, I foolishly didn't look at the standard torque charts before starting. 190 N•m is kind of a lot more than the 130 N•m the online tables for class 10.9 bolts show.

Oops..
 

Nuje

Top Post Dawg
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I attempted to install the Bilstein shocks in the rear of my car last weekend (I failed because I fat-fingered and bought the non-TDI shocks that don't fit, the bottom mount is 14mm too wide)
I think @Cuzoe encountered the same issue with the shocks he got for the rear of his car (don't think it was 14mm too wide, though; might have only been 55mm vs. 50mm); anyway, he worked around it by pushing out the rubber bushing and swapping in the bushings from the stock shocks.
(And if I recall, had a lot of "fun" doing so. :D )
 

milktree

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I think @Cuzoe encountered the same issue with the shocks he got for the rear of his car (don't think it was 14mm too wide, though; might have only been 55mm vs. 50mm); anyway, he worked around it by pushing out the rubber bushing and swapping in the bushings from the stock shocks.
(And if I recall, had a lot of "fun" doing so. :D )
Shocks == rear
Struts == front

The front struts on the TDIs and regular Golfs and GSWs are 50mm, but the GTI, R, and Alltrack struts are 55mm.

The rear shocks on the TDI (with the torsion beam suspension) are 14mm wider than any of the multi-link rear shocks.

I'm 100% sure I could have put the shocks in my mill and narrowed them down to fit, but chose not to since I could just buy the correct ones and (hopefully) sell the wrong ones to someone with a Golf or GTI.
 

Cuzoe

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Fun is right, haha... a mill would have been the much easier way to go, but I don't have (or have access to) one

But yes... 55mm struts on the cars you mentioned, along with aluminum steering knuckles
And the lower bushing on the rear shock is wider for IRS (59mm) as compared to our torsion beam (45mm).

I measured the same 14mm difference as @milktree, but the IRS shocks are larger. You can see my pictures in post 69 of my thread about DCC retrofit...
I assume the difference in shock body size is because I was going form standard shocks to DCC, but you can clearly see the bushing difference too.
 
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