Since these threads tend to get buried and not everyone uses the track feature here I thought I would initiate a second note with an update...The initial A4 thread is below...

Tonite I pulled my summer wheel bolts from storage to measure them. These are bolts supplied with mt SSR Integrals by TireRack. I also use McGard bolts so I happen to have 4 bolts that are unused. The remainder have probably been removed and reinstalled 10+ times in the past 18 months...probably a little higher than average, even among Audi nuts.

I used a caliper to measure the length of all the bolts. Assuming close manufacturing tolerances, if there is an issue with 90lbft and anti-seize improperly deforming the bolts, the ones that have been used should be longer. What I found was there is no meaningful difference between the bolts, new or used - they were all the same length +/- .001" and the used ones did not as a group measure longer. I did have one bolt that was .004" shorter than the rest - it is a used one. This suggests to me that at 90 lbft we are not stressing the bolts whether they have some form of lube or not.

In my previous update - at the end of the previous thread - I indicated that as far as I can determine so far the bolts we use should have oiled/dry maximum torque ratings of about 110/150. I am waiting to hear back from TireRack and McGard regarding bolt grade. Audi responded with "ask your dealer" - which I guess I expected (disapointed but not surprised).<ul><li><a href="https://forums.audiworld.com/a4/msgs/987318.phtml">https://forums.audiworld.com/a4/msgs/987318.phtml</a</li></ul>

 

you could be damaging the wheel. Too much torque and something is gonna give. Will it be the steel bolt or the aluminum wheel...
The wheel face of course. I've seen some peeoples cars with wheels where it was obvious the bolt was on to tight.

 

I know there have been a few case here where it seemed the bolts had been way overtightened and things felt funny until they were re-torqued, I dont remember anyone saying they had to replace 1 or more wheels, or any other parts over it. Has anyone?

 

If you have some persistence, I'll bet you could get through to someone in Audi or VW engineering to discuss this matter. I'll bet it turns out that in practice, the anti-seize doesn't causes enough overtorquing to make a real difference due to over-engineering. Still, it would be useful to know what is really going on, and I'll bet the right car engineers know exactly what's going on here.

 

I have heard back from Eddie at TireRack and McGard. Both use 10.8 DIN spec bolts for our application. Fron the online data I can gather the 10.8 DIN is a bit above SAE grade 7-8 but quite close. The max "slightly lubed" torque to reach 90% of deformation point is 120 lbft and dry is 150 lbft.

Further, I have read a couple corporate sites and .org (particularly BMW sites) that anti-seize paste can reduce friction up to 50% (a lot of variance depending on the paste used) where as the "lightly lubricated" assumes a light oil and a reduction of about 20%.

If we assume the best case friction reduction with anti-seize we should probably not be torquing over 75 lbft (50% reduction) and 90 lbft would be an appropriate max for a 40% or less reduction in friction. I would be surprised if any of us were getting 50% reduction.

One more point I saw online but didnt look into. One fastener manufacturer referred to differenced in max torque according to the primary forces applied to the joint. A primarily sheer load called for a lower max torque than a stretch load by about 20%.

Oh, here is an interesting bit. If you look up the anti-seize paste at griotsgarage, the photo is of someone applying it to a wheel bolt...


I dont know about you all but for me, the more tech data I get, the less clear this whole thing becomes.


For me...
I havent seen anything (experience or tech data) to make me stop using anti-seize (we cant all live in California and the snow belt is hell on corrosion with these fasteners) or change the torque (90lbft - well 89lbft is the conversion from NM) I apply.

I think I need something important to come up and suck up my free time...standing around in a cold garage measuring bolts with a precision caliper must be one of the signs of someone with way too much time on their hands.