Bolt mounting Question...

[hotrodrookie]

Hi guys, this is kinda of a beginner question but when using bolts through a double shear situation, can you mount one side on the threads or do all the threads have to be on the outside and require the use of a washer?

Im mounting end bushings for my 4 link bars, I just dont like how there is so much thread sticking out as shown in the drawing( using a 5/8-18-4.5" grade 8 bolt)

Can I buy shorter bolts or do I need them full length so as to not damge the threads for any reason?

[smashingchuck]

Obviously, having a bolt that is sized perfectly would be the best option. Check aircraft supply catalogs. Or a bolt specialty store. WagAero, as well as Fastenall and Grainger come to mind.

[hotrodrookie]

Well, Im going off of standard sizes that I can buy from Fastenall. If I were to buy a 4" bolt, the threads would be seated in the hole.

Can somebody help me out?

[Turbo85GMC]

In a critical application, you want the bolt long enough so that the full diameter protrudes through the other side. You should have just enough so that a washer will take up the slack but not enough that the nut bottoms out before fully clamping.

[Shane]

I agree with Turbo85GMC ... you would want the shear load on the "shoulder" of the fastener and not on the threads.

Here is an AWESOME pdf file that I have used for years on proper use of fasteners.

http://gltrs.grc.nasa.gov/reports/1990/RP-1228.pdf

[Tx Firefighter]

The fellows are right, you want the shoulder carrying the weight not the threads. I understand you're having trouble getting the exact length through your sources, so I'd run the 4.5 inch bolt and cut it shorter before running a 4 inch and having weight bearing down on the threads.