Are grade 5 bolts good enough for my water pump pulleys?

[babyface]

Are grade 5 bolts good enough for my water pump pulleys or do I need to use grade 8?

Thanks,
BF

 

[cantwell.colton]

should be fine -
might put on 1 or 2 grade 8s just for good measure
i wouldnt go below 5 though thats for sure.

 

[pistolpete]

I always figured if I had to stop and think if I needed grade 8 bolts, might as well use em. Even if it involves driving 20 minutes outta my way to get em. But then again I tend to over think and over design most of what I do.

 

[Unkl Ian]

Grade 5 is PLENTY.

 

[dmw56]

No stresess involved with a pump. Grade 5 is just fine.

 

[donsrods]

Grade 5 is fine, but I use grade 8 on everything, mainly because I like the pretty gold color.

Don

 

[cantwell.colton]

Grade 5 is fine, but I use grade 8 on everything, mainly because I like the pretty gold color.

Don

[cl
hooray

 

[rdixiemiller]

Use grade 8

Sorry guys, I always use grade 8 bolts anymore. The original bolts were heavy enough for GM engineers. No idea what grade they were. I have had some really bad experiences lately with CCB's (Cheap Chinese Bolts). I always try to find American grade 8 bolts and use them. I have had several cheap bolts pop the heads off here lately on some machinery we built. The water pump bolts can have a fair amount of pressure on them, especially if you have several belts pulling on them.
Just my $.02 worth!

 

[35Mastr]

Grade 5 is just fine. But use grade 8 when doing anything suspesion and brake related.

 

[Crossfire]

bolt grades

Grade 5 bolts are fine for the fan. found out something about bolts that really helps on different applications,Grade 5 bolts will bend and stretch under stress where grade 8 bolts will snap and break.

 

[King Herald]

Grade 5 is just fine. But use grade 8 when doing anything suspesion and brake related.

There is a school of thought that says grade 8 are too brittle for suspension, as they have very little flex and will snap rather than give a little in a shock loading situation. I have no idea if that is factual. [S

My general opinion is that if I have doubts about a bolts strength, or where the grade of a bolt may mean the difference between failure or survival, I will use a bigger bolt, in situations where that is possible.

For suspension, such as four bar bolts, I will use a bolt that has just enough thread for the nut to tighten down,so the shear loads are on raw steel diameter, not across the thread of the bolt.

This alone doubles the strength of the fitting.

I am a failure freak: if in doubt, go large young man, go large. [cl

 

[nunattax]

bolts

why take the chance.over here on the other side of the atlantic high tensile unf/unc bolts are hard to find.when i need them i order arp stainless high tensilebolts from jegs.never had one break yet see (http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx)

 

[Sam_Fear]

There is a school of thought that says grade 8 are too brittle for suspension, as they have very little flex and will snap rather than give a little in a shock loading situation. I have no idea if that is factual. [S

I would say false. Did a bit of reading. This is directly from the K-T Bolt Mfg. Inc. website: "Grade 8 bolts have been hardened more than grade 5 bolts. Thus they are stronger and are used in demanding applications such as automotive suspensions. Grade 8 bolts have 6 evenly spaced radial lines on the head."

Argument over in my view.

Also found this somewhat technical, but interesting read:
http://www.rockcrawler.com/techreports/fasteners/index.asp

 

[King Herald]

I would say false. Did a bit of reading. This is directly from the K-T Bolt Mfg. Inc. website: "Grade 8 bolts have been hardened more than grade 5 bolts. Thus they are stronger and are used in demanding applications such as automotive suspensions. Grade 8 bolts have 6 evenly spaced radial lines on the head."

Well, direct from the manufacturer eh. Can't argue with that. [cl

I remember from my engineering apprenticeship days:

Toughness: The ability to withstand repeated blows.

Hardness: The ability to withstand indentation.

 

[26Troadster]

we work on rotary blast hole drills, and the rotary head is mounted with grade 8 bolts, after awhile the bolts break out and we have to go get them out and fix what ever got messed up, when we put them back together we use grade 5 with hardened washers, we have alittle better luck that way, and when they break out again and they will with either grade it is easier to get them out. i do like a harder bolt for brakes and sep. so it is a dilma, and everybody has a thought about it. i think i always go over kill on anything i build, just like most people use 1/2" heim joints on their cars i use 3/4", like instead of using a 5/16" bolt i can use a 3/8" bolt instead, so i guess you should not listen to me on this one.

[

 

[Sam_Fear]

You have a good reason for using the grade 5's, but it's a replacement issue, not a failure issue. Easier to replace grade 5's more often - makes perfect sense. The only way to keep the bolts from failing would be to use bigger bolts, but then what would fail instead?

 

[26Troadster]

i agree with you sam, i sure wouldn't want anything like pulleys, are the fan coming off, that would be bad. if i'm not mistaken the studs that you get from the parts store are grade 8, for the fan and pulley, atleast for cheby's.

 

[Sam_Fear]

Another plus of grade 8's is your a little less likely to round off the head when you get lazy and reach for the handy visegrips instead of walking over and getting the proper wrench out of the drawer.

 

[cantwell.colton]

Another plus of grade 8's is your a little less likely to round off the head when you get lazy and reach for the handy visegrips instead of walking over and getting the proper wrench out of the drawer.

that makes them worth their price right there

 

[toms26t]

Also remember when torquing bolts, Plated bolts are to be used with the wet torque, Non-plated bolts use the dry torque from the charts.