Knurled wrote: That is what Da Boss suggested, although my tentative, rapid search of ARP's catalog proved fruitless. Head studs aren't listed by length, just application. I'm thinkin', just get another set of yellow bolts, torque to 60, call it a day. The M10x1.25 bolts in the Mazda case haven't blown out after all. I found that *those* yield at about 40 ft-lb, when I mistakenly tried to torque them to 60 one time. Ooops. Stretched the first one like taffy
Contact them directly.
BrokenYugo wrote: In reply to tuna55: TIL, (you got any further reading on that handy?) might not be a good idea then. I think the application here is through bolting the carrier bearing caps to the center section, so one end would be outside.
Only sort of:
https://www.fastenal.com/content/documents/FastenalTechnicalReferenceGuide.pdf
FastenSome wrote: There are three main ways in which hydrogen embrittlement can be fought. • Hardness: Harder, stronger materials are more susceptible to failure than weaker, softer ones. In general, if the hardness of the fastener is less than 35 HRC, you’ll probably encounter little difficulty. If, however, the fastener has hardness above 40 HRC, problems are more likely to occur. • Coating: Use a coating process that does not introduce hydrogen into the material (particularly those free from acids used for cleaning). If electroplating is still desired, ensure to use the proper plating procedures and baking the fasteners correctly based on the hardness of the fastener. • Environment: Your application environment should play a crucial role in the fastener material selection. The potential for hydrogen embrittlement cracking for even fasteners below HRC 35 is accelerated if the fastener is acting as the cathode in a galvanic couple. Caustic or sour environments may require much lower hardness levels to lower the susceptibility to hydrogen embrittlement.
Here is a document on hydrogen embrittlement if you want to do some more reading:
http://www.boltcouncil.org/files/HydrogenEmbrittlementInSteelFasteners-Brahimi.pdf
SHCS are also more susceptible to corrosion as they are not (typically) plated due to a tighter thread fit (3A vs 2A with HHCS) and there isn't tolerance for plating.
In reply to EvanB:
Thanks for linking that. I was having trouble finding documentation which I could share.
Maybe this is a stupid question, but is there some other element (your comment on the silicone made me think of this) that starts to compress noticeably at the 75-80 lb ft mark? Gasket/bearing/whatever?
I just ran the numbers using the formula in the Machinery's Handbook for an SAE grade 8 bolt and even with lubricated threads you shouldn't have any problems at 85ft lbs.
Not that it couldn't happen but I've also never gotten a bad fastener from McMaster-Carr and I buy thousands of fasteners from them.
You're using a calibrated torque wrench so that's not the problem.
Have you either continued to torque to failure or measured the bolts after you've had the problem? I'm wondering if something else is giving and that feels like the bolts are stretching.
Are you holding the bolts and torquing the nuts? If you do it the other way and the bolts are a tight fit then that could mess up your torque reading.
What are you using for washers? Could they be giving?
APEowner wrote: I'm wondering if something else is giving and that feels like the bolts are stretching.
That's what I was getting at.
bluej wrote:APEowner wrote: I'm wondering if something else is giving and that feels like the bolts are stretching.That's what I was getting at.
Good idea. Take the new bolt threads and lay them alongside the old bolt threads and check for necking. You will be able to see it if they are yielding.
tuna55 wrote:bluej wrote:Good idea. Take the new bolt threads and lay them alongside the old bolt threads and check for necking. You will be able to see it if they are yielding.APEowner wrote: I'm wondering if something else is giving and that feels like the bolts are stretching.That's what I was getting at.
Oh, the bolts are visually stretching, and you can't spin a nut all the way to the shoulder as further proof that the bolt has stretched there. The 6" or whatever bolt under the pinion support can easily take a nut to the shoulder so I am assuming that it hasn't yielded, as its pitch hasn't changed anywhere.
I guess I had been HOPING that I was just feeling the aluminum case get squidgy... which really shouldn't be encouraging if that really were the case.
A different brand of fastener is on the way. And I'm going to only torque them to 60.
Have you checked with Yukon yet? It would seem this is a problem they should have an answer for.
Yukon never answered me after multiple attempts, going all the way back to when I bought the rearend, what, 2 years ago? I don't have time during the day to make a phone call. (Makes dealing with Mazda Motorsports a pain, too, since they never acknowledge the online results forms until I manage to get time to call them) If I can't contact them by e-mail then I can't contact them.
I bought the housing from a eBay retailer (Yukon doesn't sell directly, and the retailer I bought from had a package deal that had the pinion support and bearings that I wanted/needed) and it didn't come with instructions. They never answered any of my inquiries regarding what the torque should be, too. The only info I have about it is from searching on my own time.
You'll need to log in to post.
