I have been looking for some info on the front bolt that is used for the rear leaf spring. A few months back, I replaced the rear springs on my truck and replaced these bolts with hardened zinc plated bolts from the hardware store. After reading about bolt grades and hardness, I am wondering if the bolts that I used are strong enough. It seems as if the majority of the shackle kits on the market use hardened zinc plated bolts. So this makes me believe I will be fine. Any knowledge on this topic would be appreciated.

 

You made me curious so I looked at all the bolts I could look at. Some of them are very hard to find grade markings on anymore but they all appear to be grade 5 bolts. I suspected this would be the case. Bolts you got at the hardware store are likely grade 2 or grade 5. What grade did you use?

 

I would think 40 year old grade 5 bolts will be like a grade 8 bolt today. I would use all grade 8 on the frame. but i am no pro!

 

A 40 year old grade 5 bolt is still a grade 5 bolt.

 

I disagree . The steel is not as strong as it once was.

 

Steel made the same way is the same and bolt grading hasn't changed.

 

Ok u use grade 5 I'll use grade 8 problem solved.

 

I disagree. I could be wrong here, but I don't think the ASE standards for strength grades of bolts would change in 40 years. You don't hear people say "Get me 5 pre-1991 Grade 5 bolts, please". And if a bolt is marked as a Grade 5 or 8, it has to hold up to strength testing when they mfg the bolts so I personally don't worry about cheap China steel in bolts, it's usually cast pot metal stuff you have to worry about.

 

Actually if anything steel should be stronger than it was 40 years ago.

 

just use grade 8 bolts and you'll be fine.

 

Sorry to cause any anger over my concern. The bolts that I installed were grade 8 zinc plated hardened bolts. The reason I brought this up was because I read that some bolts are 10.9 grade and if I should have used those. But if it was a grade 5 before, the new grade 8's will work fine. Thank you for the replies.

 

And fyi, over 88% of steel today is recycled. So yes, steel today is a mixture of different manufacturers thus giving us weaker steel. Not all countries share the same regulations which is the reason American made steel is stronger than Chinese made steel. I read that there are "laws" that required fasteners be made of non recycled metals. As for grading, there is a load of info on the web about it but I can't find anything about changes in history of grading.

 

I may be mistaken but, I believe a grade 10.9 is the metric equivalent of a US grade 8.........Newer stuff uses metric bolts therefore the 10.9 designation.

 

i used grade 8 bolts over 20 years ago when a put a spring lift in all four corners of my 78 f250. never had an issue. i'm in the process of rebuilding her and replaced all the rubber spring bushings with poly bushings and once again used grade 8 hardware.

 

Are there any more steel plants in America?