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Ball Joint Hardware/Torque Specs
Was doing a front end nut and bolt check the other night and managed to snap 2 ball joint attachment bolts in the process. Strangely enough the GM service manual calls for 25 ft lbs, but it snapped with only 20 ft lb. Anybody know the torque spec for these bolts? I'm assuming basic grade 8 hardware is acceptable here? They appear to be black oxide grade 8 1/4" fine thread w/ a metal lock nut, but just want to verify what is correct for the application.
These are on DSE arms for 67-69 Camaro/68-72 Nova's and are stock replacement Moog ball joints. Any help is appreciated..... |
I doubt their grade 8, at least the bolts that came with my Moog more resembled China specials. Should be able to grab suitable replacements at a local hardware or farm supply store. My local Wilco store has an incredible fastener selection up to grade 8 1" fine thread.
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I also doubt they were grade 8 bolts. They would not have broken at 20# of torque, even if they were cross threaded. I use grade 8 bolts everywhere on my cars with two exceptions ...
1. When I need the bolt to break first in a crash to save the part. We usually run grade 5 in these situations. 2. When I need something stronger than grade 8, in which case we run NAS or something engineered like ARP. I would suggest you use grade 8 bolts everywhere ... especially on such sensitive areas as ball joints. Only as a guideline ... "usually" ... * Grade 8 bolts are gold iridited. * Grade 3-5 bolts are silver cadium plated * Grade 1-3 bolts can be black oxide coated. The common exception is allen head cap screws which are "usually" black oxide coated even in grade 8. The best tell-tale are the markings on the head of the bolt. Refer to the chart below ... and note the strength differences in the ratings. |
Appreciate the responses above, looks as though they are grade 8 black oxide...... kind of an oddball bolt. I went ahead and picked up some new grade 8 zinc coated bolts and all metal lock nuts as replacements. Anybody know the acceptable or correct torque spec for these? Seeing differing info online and can't confirm what is needed. Seeing a range of 10-25 ft lbs.
http://i16.photobucket.com/albums/b1...a/image-71.jpg |
Anybody have any insight on torque specs for these bolts?
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These are a 5/16" bolt I think? Grade 8 5/16" is torqued to 25 ft. Lbs.
3/8" grade 8 bolts torque to 45 ft. Lbs. |
Maybe the nut seized on the bolt. I see this frequently with bolts that do not have lubricant. Usually its a stainless fastener.
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From my research seems a 1/4-28 grade 8 bolt should be torqued to 14 ft lb dry. Going to roll with that for the time being. That probably also explains my broken bolt trying to get the 25 ft lbs the factory assembly manual called for.
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My chart calls for 12 ft. Lbs. for a 1/4" fine thread. This would definitely explain the broken bolt.
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