Bolt Grade for Fan Assembly

[Jons340Dart]

I have put a larger spacer on my fan asembly and now require a move from 5/16 x 2"' to 5/16 x 2 1/2".... is a grade 5 bolt adequate? If not what grade should I use and what do the markings look like?

Thanks

 

[RedFish]

Grade 5 is fine for that application.

 

[Jons340Dart]

Thanks Redfish

 

[SSDA67]

The GRADE of a Bolts is for STRETCH SHEER Factor.a Standard Bolt is adequate and what was used on most applications.I use a 4" Spacer on mine with NO failures over 30 years..

SS

 

[dgc333]

Gee! For the extra buck or two it will cost I would go with grade 8 bolts. They are ready available at the local hardware store and will also have chromate finish in addition to the zinc or cad for improved corrosion protection compared to the typical grade 5.

Grade 5 bolts have three radial lines stamped on the head, a grade 8 will have 6 lines. A grade 8 is 50% stronger than a grade 5.

I use grade 8 for everything that supports weight or fastens something that moves.

 

[SSDA67]

Gee! For the extra buck or two it will cost I would go with grade 8 bolts. They are ready available at the local hardware store and will also have chromate finish in addition to the zinc or cad for improved corrosion protection compared to the typical grade 5.

Grade 5 bolts have three radial lines stamped on the head, a grade 8 will have 6 lines. A grade 8 is 50% stronger than a grade 5.

I use grade 8 for everything that supports weight or fastens something that moves.

Yea...You wanna Know Something...LUGs and LUG NUTS are Standard Grade 3 UNLESS they are Aftermarket...Don't believe me...?Ever Twisted a Stock Lug off or Stripped the Threads?...That's how I found out...ALSO MOST Nuts are Standard Grade...
The Grade 5 is actually Overkill,and the grade 8 sure is over kill...BUT I bet you are the one I could sell Polyurethane Bushings for suspension too aren't ya..?

SS

 

[dgc333]

Having been an engineer for the past 30+ years I do know how various grades of materials fail and grade 3 fasteners will stretch a huge amount and neck down 30% or more before they break and the few lug nuts I have snapped over the years have had little or no visible necking before they break which is indicative of a high strength steel fastener. Also, the typical recommended torque for a 1/2" grade 3 bolt is 55 ft-lbs and a grade 8 is 90 ft-lbs, with recommended wheel lug torques in the 75 ft-lb range the fasteners have to be much stronger than grade 3 or you will be yielding them every time you torque them. The ones I have snapped only happened after putting a pipe on a breaker bar. I can snap a 1/2" grade 3 with a wrench without any extra leverage.

So, I don't believe for a second that a wheel lug is a grade 3.

FWIW, I am not in favor of poly bushings on one of our old mopars because they are not sealed and will wear out much faster than stock rubber bushings. This is because the poly bushing slides on the shells and with nothing preventing road grim from getting in between they will grind away vs the bonded to the shells rubber bushing which twists for its motion.