High Tensile bolts.

[Alex Blair (RIP)]

Originally Posted by Phil Waterman

Try this out fit http://www.fastenal.com/web/home.ex they are a commercial outfit that I've had good luck with. They seem to have a pretty good international distribution system, though I don't see listed an outlet in Australia or New Zealand.

The only problem is generally they only sell in bulk qunatities of 50 or 100 but their prices on grade 8 bolts is low enough that your buying a box of 100 for what you pay in the hardware store for 25.

One heavy equipment dealer near me has put is bolt bins out front in the parts area and sells Fastenal Grade 8 bolts by the pound. (about $4.50USD) I go in and buy bolts, nuts, flat washers, and lock washer taking a handfull or two of each size I need to restock my bolt drawers. I worked out the cost and it comes out that I'm using all grade 8 bolts for lot less than what cheep (quality) grade 5 hardware store bolts cost.

Cheers

Hi Phil..
For those that think that the bolt grade is not that important ..I can relate an example of the importance..
A few years ago I replace a few refrigeration compressor head bolts,OEM Grade 8 with some I had around the shop ..(Grade 5)....After a month or so ,on monthly maintenance I noticed the torque check revealed they required tightening..so that was done..

The next month on the torque check..I was surprised to see that they required re torquing.....again done...

I was curious and took a good look at some new grade five bolts similiar to the new ones installed..and compared to the ones I had replaced ,but still had on the workbench in a little box(Never throw any thing out untill the missus gets on the war path..)..
I thought that the thread pitch or diameter may be slightly different,,but they checked out..OK..
With the compressor still running I pulled one of the new bolts and cranked in the old original bolt and measured the new grade 5 against the one I just pulled out and low and behold it had stretched at least an 1/8 of an inch!!!!

At 80 pounds torque and the insessant vibration ..the bolts stretched and loosened..
The same thing will happen on a carrier ..or similiar piece of vibrating machinery...Don't cheap out and save yourself a lot of hassle..use grade 8 bolts or better when it comes to your loved ones..
Bolts only stretch so far before they break..
I my case the stretched bolt caused the headgasket to leak and that is not a good thing on a refrigeration compressor..