I meant to post this a while ago, but forgot to with the holidays etc. Anyway, it took me a lot of time and research and wasted money to figure this out, so I thought I would pass a long the information so it may help people here. (If you just want to know the cheapest source I found for replacement lower ball joint bolts, scroll down to the 2nd to last paragraph)
When I was replacing my CV boots last month I had a ton of trouble removing my lower control arm bolts (see thread http://vehicross.info/forums/showthread.php?t=25048). I marred up the bolts quite a bit and needed to get a new set. "No problem" I thought, "surely I will be able to find replacement bolts at Lowes or Home Depot, etc."
This started a 2-3 week battle in trying to find a proper set of replacement bolts. The first problem was that my bolts didn't have standard markings on them so I could tell what hardness rating they were. Not sure if these were the original bolts or not. After searching around a bit and trying to decide what hardness rating to get (metric 8.8 vs 10.9) I then realized that replacement lower ball joints include the bolts in the kit. Since I needed to eventually change out my lower ball joint anyway, and it was going to cost me almost $20 to buy just the bolts online, I decided to just buy the ball joint up front and use those bolts to ensure I was using the proper bolt.
Not a good idea. I bought mine from Autozone and got the Duralast brand. The hardness on these bolts were rated at 8.8, so I naturally assumed that this was the OEM spec. When I went to install them, there were two longer bolts and two shorter bolts, which makes sense when you look at the lower ball joint. However, there is a shield type piece on the lower control arm that among making my removal nearly impossible (see the previous post mentioned) also allows the bolt head to recess further and thus extend further down. The (first) problem with the bolts in the Duralast kit was that the heads were bigger than the original bolt heads, so it wouldn't recess into this area, making one bolt too short to start to be threaded.
At this point I was pissed, but not super pissed because I only needed to get a replacement or two at Lowes for the one bolt that was too short. But now that I "knew" I only needed the more common 8.8 hardness bolt it wouldn't be too hard to find.
I buy the longer replacement bolts, put it together and start cranking down. I get out my trusty torque wrench to torque it back to factory specs, 76 ft-lbs IIRC, and start. First bolt... stripped. Second bolt, click, got it to spec. Third and fourth bolts, stripped.
So I turn to the internet. Turns out for that size/thread bolt, there is very little chance that a 8.8 hardness bolt won't strip out when trying to get to the factory torque setting. I can try to find the resource again if anyone is interested, but basically the maximum strip torque was in the 70 to 75 ft-lb range. The minimum for 10.9 is in the 80 ft-lb range.
So, long story short, if you want to torque back to factory specs, you're going to need 10.9 hardness rated bolts. I'm an engineer so I'm anal that way.
Luckily, if your aftermarket ball joint doesn't come with the proper bolts, I found the cheapest replacement option. http://www.allensfasteners.com/searc...tnSearch.y=-42 It ended up being about $12 total and they shipped quickly. I bought 2 50mm length and 2 45mm length per side to help recoup some precious pennies after I just wasted a bunch of $$ on the incorrect bolts, but feel free to splurge on all 50mm bolts, they will fit.
I hope that prevents someone from the pain in the #%$ that I went through.
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