Nuts and Bolts
I'm kind of a nut when it comes to bolts (pun
), so here's the deal...
First, it's FAR, FAR better to over tighten a bolt than it is to under tighten one. FAR.
There are two primary ways to know if you've significantly over tighten a bolt (i.e. reduced the strength of the bolt). There are other ways, but these are good for most practical purposes...
1) The thread spacing expands. This is essentially an indication that a bolt has been torqued to yield. The bolt at this point is functional but should not be reused. How to tell: Upon removing the nut, and you VERY closely inspect the threads of the bolt, if you notice that the spacing of the threads has expanded (any of the threads that were in tension). If you see any irregular thread spacing, you should do the Carrol Smith "float test". Toss the suspect bolt in a near by pond/lake. If it floats, reuse it
2) The bolt breaks
. The most stress a bolt will experience is the stress of tightening (short of over loading it and causing a failure). Not only is it in shear stress, but it's twisted as well. This is key because if the bolt survives the tightening process, then you don't have to worry about it breaking soley from being over tightened during use. Again, over tightening is far better than under tightening.
Tightening 101... MOST mechanical tq wrenches are only accurate to about +/-25% of the indicated torque. Given this statistic, you have 3 options, IMO. Annually recalibrate your tq wrench (Send it off), buy a digital tq wrench (expensive, but are typically more accurate and stay more accurate than mechanical), or cross your fingers and slightly over torque every bolt you're supposed to torque to X to X+10% or so (depends on the fastener size and use) to hedge your bet that your tq wrench may be reading much over what is indicated at the "click"... You now know it's better to be too tight than too loose (remember if the bolt doesn't break you're likely OK), so you always hedge up in tq rather than down if you question your equipment...
You should always use a hard washer with a bearing surface under the nut to be torqued at critical joints/unions (like the toe links). I'm not sure how I feel about those locking washer that come with some of the kits... I'd rather use a nyloc nut (yes, those are reusable). Remember is not the nut or the "lock washer" that keeps things tight. It's the bolt stretch...
MOST tq specs are for dry and clean threads unless otherwise specified (like the toe links- dry and clean).
All the above is especially importantly for things like suspension/driveline components.
I'd bet a fair penny that every failed toe link failed due to improper tq. Those that claim they always tq'ed their toe links prior to a track event and still experienced a failure (Which would be few) probably had something wrong with the tightening procedure like a torque wrench that wasn't calibrated, or were using the *old* tq spec opposed to the new one for the links, or perhaps retorqued a toe-link that had been previously been torqued to yield by mistake, or possibly the joint could have been loose at one point in time and damage occurred to the stud at that time. It could be any one or combination of those items...
IMO, I think the after market solutions do more for awareness than anything, which causes people to check them more frequently. That really helps the most (more than that "double shear" thing-uh-muh-jig connecting rod)... IN full disclosure, I do not personally run the stock toe links... but I also don't run the so-called double shear rod that connects the joints either...Not that there's anything particularly wrong with the aftermarket solutions out. They obviously work just fine:up:
Hope that helps,
Phil