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sooooo, my wheel fell off. damage ensues
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timichango
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PostPosted: Tue Oct 23, 2012 7:11 pm    Post subject: Reply with quote

denwood wrote:
Bentley says 123ft/lb. for VW stock fasteners
Aftermarket stuff usually 90..as is all three of our other rides. Vw, Honda,Audi.

Using antiseize increases effective torque via thread lubricity (and I use it on all wheel bolts, particularly the winter drivers) so if you do this, 75 to 80 is good. The important thing is that you have a torque wrench, and that they are equal.

^ What he said.

From T3Technique's literature:
Quote:
As a rule of thumb, any aftermarket stud or lug bolt should be torqued to 90 ft-lb and all factory VW lugs should be torqued to 123 lb-ft. Why the difference? There is a difference in the material make-up as well as a difference in heat treating. The aftermarket wheel hardware that T3 Technique is still rated at grade 10.9, just as the factory parts, but the manufactures of the aftermarket products specify a lower torque value.


http://www.t3technique.com/media/pdf/Vanagon_Syncro_Wheel_Facts.pdf

Since the torque question was asked in conjunction with CLK wheels, which don't use stock VW nuts/bolts, the 90 lb-ft spec should apply, no?
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timichango
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PostPosted: Tue Oct 23, 2012 7:18 pm    Post subject: Reply with quote

Or is it specifically related to studs/bolts, and not to nuts?

In which case, if he's running CLKs on the stock rear studs, but with aftermarket bolts up front, then the torque settings would necessarily be different front/rear (90 lb-ft front / 123 lb-ft rear).

Confusing.

Now I wanna know the answer to this, since I'm running stock studs out back, with T3 conversion studs up front, so I'm in the same boat...
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rubbachicken
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PostPosted: Tue Oct 23, 2012 7:22 pm    Post subject: Reply with quote

i would do them all to 120 ftlbs and be done with it
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timichango
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PostPosted: Tue Oct 23, 2012 7:27 pm    Post subject: Reply with quote

rubbachicken wrote:
i would do them all to 120 ftlbs and be done with it


T3's literature that comes with the conversion studs warns against exceeding the 90 lb-ft threshold on pain of fastener failure and impending death. I'm apprehensive about not taking that to heart.

How much margin for error is there in torque specs? I'm pretty certain that the $30 torque wrench I got from Princess Auto isn't the most accurate measuring device in the universe, and there's got to be some variance in people's tools, so I'm imagining the specs are spec'd on the conservative side, but how much is too much? Or too little...?
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rubbachicken
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PostPosted: Tue Oct 23, 2012 7:33 pm    Post subject: Reply with quote

most half decent torque wrenches have at least a + or - 4% range or better
i would still go 120 ftlbs, i have done on all my VW's even running porsche aluminum space savers with aluminum lug nuts
i've never ever had a wheel come loose not in 29 years



i better go out and re check lucy now i've said that Wink
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denwood
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PostPosted: Tue Oct 23, 2012 7:41 pm    Post subject: Reply with quote

Too much torque = potential catastrophic failure of the fastener. Please don't torque to 120 unless you have bone stock, dry threads. That said, You may strip the fastener first if you attempt 120 with aftermarket hardware. You can feel this in the threads if you try it. I used 80 with the antiseize on my Westy this weekend.

If you're not sure, 90 across the board. In 12 years with the van, always used 90. Zero issues. If you use antiseize that 90 is effectively ~ 110.

With regard to cheap tools, equal is more important than exact (I'm only talking wheel bolts/nuts). Torque wrenches require regular calibration I believe by the FAA, however DIY have never heard of it. ha. One thing I will say is that click type wrenches should be stored set at zero.
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jmranger
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PostPosted: Tue Oct 23, 2012 8:39 pm    Post subject: Reply with quote

<off-topic>
Using anti-seize on wheel studs/bolts is controversial. Before deciding to do it, be sure to understand the rationale used by both sides.
</off-topic>
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denwood
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PostPosted: Tue Oct 23, 2012 8:51 pm    Post subject: Reply with quote

Apparently so..so yes, read and decide for yourself. With the salt here, and +35 to -35C temp swings, I use it on anything I've wrestled with in the past Smile That's wheel bolts and anything external exposed to heat cyclying, salt spray.

The important thing is understanding its effect on torque specs. and compensating accordingly. Dry vs lube torque.

Btw, jm, your comment is very much on topic. Dude lost his wheel!
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timichango
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PostPosted: Tue Oct 23, 2012 10:57 pm    Post subject: Reply with quote

Agreed. Another thing that I would imagine factors into the whole wet/dry torque equation, and the related 'lube-or-no-lube' question is related to the issue of conversion studs, like T3 sells, which I imagine some folks are using.

Specifically, with the conversion studs threadlocked into the hubs, should anti-seize be used on the nuts-side of the studs in order to prevent the studs spinning out during a wheel change due to a seized nut?

If so, then presumably the wet torque spec is what's needed in this scenario?
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denwood
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PostPosted: Wed Oct 24, 2012 7:13 am    Post subject: Reply with quote

I'll let Chris chime in on that specifically. I wrestled with the stud thing on my autocross car finally tacking them from behind with my MIG. In that case i needed a weird length and deep nuts to accommodate three different rim options. Thread locked studs I'd predict poor success with. Press in studs (with the knurled base) work much better in my experience over threading.

Loctite Red releases quite easily with some heat...and the brakes supply plenty of that. That's likely why it doesn't work so well in that application.
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Christopher Schimke
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PostPosted: Wed Oct 24, 2012 9:11 am    Post subject: Reply with quote

Man, books have been written on this stuff. It can get very, very complicated. Below is a minor breakdown of what you need to know in order to be safe.

Yes, the maximum amount of torque applied to either the lug bolts or the lug nuts follows the recommendations of the fastener manufacturer (not the wheels) and always applies to the male portion of the threaded fastener. In other words, you could change wheels and/or lug nuts (aluminum lug nuts are not always included in that statement) and the recommended torque value would stay the same.

Almost every aftermarket stud/lug bolt manufacturer that I have spoken to has recommended 90-95 ft lb for torque. And most of us know that the stock studs have a much higher torque value than that (122-133 ft lb, depending on the source).

As I have mentioned before in other threads, and as denwood mentioned, over torquing any fastener can result in catastrophic failure. Here is the reason why:

When you torque a fastener, the male threaded portion elongates and the female threads compress. The interference fit between the elongated male threads and the compressed female threads, combined with the residual tension left in the bolt, is what gives you the proper clamp load that holds the wheel in place.

The specified torque value given to a particular fastener ensures that the male threaded portion stretches to a point that maintains elastic deformation. Elastic deformation of a fastener is below its yield point and is sort of like a rubber band. You can stretch it out (to a certain point) and it returns to its original length when the torque load is removed.
If you over torque a fastener, the male threaded section can reach a point where plastic deformation occurs. This is an irreversible state where the metal has stretched beyond its yield point and will no longer return to its original length. At that point, the fastener is junk and can no longer be considered safe to use.

Now luckily for us, and just like a rubber band, there is a reasonable range between where the wheel fasteners are torqued enough to keep the wheels on tightly and the yield point where the fasteners will fail. This means that there is decent range of tightening specs that can allow for varying torque wrench values (or lack of any torque wrench at all), varying forms of thread lube (each lube changes the friction between the threads differently) or anything else that may have an impact of the torque of the lugs. While this range is forgiving, it is not infinite. This is the exact reason why it is so important to use a decent torque wrench when tightening lugs. Without a torque wrench, you have no way of knowing if you have stretched the fastener tight enough to stay tight long term or if you have over-stretched the fastener resulting in damaged parts (seen or unseen).

As mentioned by others, adding any form of lubrication to the fastener will allow the fastener to easily be over-torqued. Here is why:

With 100% clean and dry threads, roughly 85-90% of the torque that you apply to the fastener goes into overcoming the friction between the male/female threads and between the head of the fastener and the surface beneath it (this would be the lug seat area of both the lugs and the wheels). That leaves only about 10-15% of the torque value that is actually applied to the clamping load that puts tension in the fastener and keeps the wheels clamped in place.
If you were to add any sort of lubrication to the threads and the head of the fastener, the amount of friction between those two areas will be reduced during torquing which will translate to more of the torque value being applied to the threaded/shank area of the fastener. In other words, lets say that you reduce the friction between the head and the threads by 20% by adding lubrication. This means that now only 65-70% of the torque value is being used to overcome friction and 30-35% of the torque value is applied to the threaded/shank area of the fastener. This would result in a fastener that is over-torqued by roughly 20%, which could result in the fastener reaching plastic deformation and therefore rendering it unsafe for use.

Now here is where it gets a bit tricky when this information is applied to lugs and wheels.

Most of the charts and information that I have seen about how much to reduce a given torque value when adding lube to the mix seem to assume that lube is added to both the threaded portion of the fastener as well as the head/clamping surface. Most of the information and charts suggest somewhere around a 15-20% reduction in torque value when lube is included.

When talking about wheels, we don't (shouldn't) ever add lubrication to the head of the lug nuts or bolts.

Since roughly 50% of the friction created during torquing comes from the friction between the head and the mating surface (and roughly 40% is used to overcome thread friction), and since we only lube the threaded portion of the wheel hardware, I feel that it is safe to assume that we can reduce the normally recommended 15-20% reduction in torque value (if using lube) to around 7-10% without getting into a situation where we are over-torquing our wheel hardware.

Now, since we are only talking about a 7-10% reduction in torque value when adding lube to the threaded portion only of the wheel hardware, and considering that there is a reasonable amount of tolerance within the limits of the wheel hardware in regards to what it tight enough and what is too tight, I usually don't make too much of a big deal between lubed or unlubed wheel hardware. In other words, if the recommended dry torque value is 90 ft lb and we add lube to the threads only, a 7-10% reduction in torque value would be roughly +/- a 6-9 ft lb difference. In my opinion, that is usually within the tolerance of most quality wheel fasteners and isn't really worth getting too worked up about.

On the other hand, under-torquing lugs can be just as bad as over-torquing. Tests have shown that under-torqued fasteners will loosen sooner than slightly over-torqued fasteners.

Everything above is based on theory combined with tests of known parameters. In reality, we deal with so many different variables when it comes to wheel hardware that its best to take the information above and combine it with experience to come up with a reasonable set of parameters for torquing our lugs. In my experience, torquing aftermarket 14x1.5 lugs to 85-90 ft lbs, lubed or unlubed, has proven to be a very reliable method of attaching wheels. For stock VW Vanagon hardware (bolts or studs), I usually increase the torque a bit just for peace of mind, but others have reported that they have years of reliable service when torquing to 90 ft lb, so again, there is some margin for manipulation here. My personal van has aftermarket front and rear studs with anti-seize and I have torqued the lug nuts to 90 ft lbs for years with no issues whatsoever.
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Christopher Schimke
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PostPosted: Wed Oct 24, 2012 9:31 am    Post subject: Reply with quote

timichango wrote:

Specifically, with the conversion studs threadlocked into the hubs, should anti-seize be used on the nuts-side of the studs in order to prevent the studs spinning out during a wheel change due to a seized nut?

If so, then presumably the wet torque spec is what's needed in this scenario?


denwood wrote:
I'll let Chris chime in on that specifically. I wrestled with the stud thing on my autocross car finally tacking them from behind with my MIG. In that case i needed a weird length and deep nuts to accommodate three different rim options. Thread locked studs I'd predict poor success with. Press in studs (with the knurled base) work much better in my experience over threading.

Loctite Red releases quite easily with some heat...and the brakes supply plenty of that. That's likely why it doesn't work so well in that application.



When it comes to conversion studs, the only reason that I recommend using red thread locker on the portion that is threaded into the hub is to help prevent the stud from backing out in the event of minor thread damage or corrosion. In the event of major thread damage, you would want the studs to come out since you would need to replace both the stud and the nut to ensure a clean, safe union.

In that light, a small amount of anti-seize on the main threads could be helpful in preventing the lug nuts from locking onto the stud.

As far as red thread locker releasing with heat, this is true. However, it takes 500 to do so and it returns to a locking state when cooled. While brake rotors will reach temperatures higher than that, I don't think any of use will be working on them when they are that hot and I don't think that the temperatures at the hub will normally be that high. 500 is at or above the maximum working temperature of most wheel bearing greases.

Again, I have been doing it and suggesting it for years now with no problems or issues of any kind.

If someone wanted to place a tack weld on the backside of the hub to help keep the stud in place, that would be fine. Just be sure to keep it a small tack and not a full weld. Too much heat put into the stud could result in altering the heat treatment which could then result in a failure. A small tack is fine though.
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denwood
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PostPosted: Wed Oct 24, 2012 9:57 am    Post subject: Reply with quote

What he said. Great breakdown. I'm fighting the urge to pimp the rims on my van after refinishing/powdering my OEM alloys. Your wheel threads aren't helping Christopher Smile

With regard to the loctite, my problem on the autocross car is that the stud sometimes came out with the nut. Normally a non-issue, however I switch between race/street every weekend during the season, and these rims have different hub thickness. The nut and stud combo was designed to deal with this, however pulling the stud caused a big problem as now I had to jam nut the stud to get the wheel nut off, re-loctite, yada yada. Zero issues since with the tack thing. On the front hub in my application alternatively the studs are pinned from the OD to prevent them backing out.

Regardless, no one should be loosing any wheels after reading this thread!
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PostPosted: Wed Oct 24, 2012 10:01 am    Post subject: Reply with quote

thanks chris.

posts like the 2 above are why i read the samba when i'm supposed to be doing work.
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