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Dahoopd
05-07-2009, 08:54 PM
I want to replace the water pump bolts and JS pulley bolts with stainless. The SS bolts are only grade 2 and both pulley bolts have grade 5. Do you think its going to create a problem down the road? Any help is greatly appreciated.

89SCBoosted
05-07-2009, 09:04 PM
i Dont think so, personally id prefer even higher grade over SS, it does look better for ascetics. i Dont think the torque required on them will break em, thread chase all you're female threads in the timing cover and use moly g. for even torque application and go from there,check the book for proper torque.

Mike8675309
05-07-2009, 09:24 PM
I'd shoot for the properly rated bolt with a black-oxide coating. Especially if the things you are bolting on are polished.

Flex
05-07-2009, 09:51 PM
Stainless automotive bolts are considerably stronger than regular bolts. They are not rated the same. A regular stainless bolt is stronger than grade 12. Just don't get the shelf grade bolts from a hardware store but go to a bolt house,

Dahoopd
05-07-2009, 09:58 PM
Stainless automotive bolts are considerably stronger than regular bolts. They are not rated the same. A regular stainless bolt is stronger than grade 12. Just don't get the shelf grade bolts from a hardware store but go to a bolt house,

I went to a bolt distributor, thats all they sell. The guy said ALL stainless bolts are grade 2. He said no one makes a stainless bolt any stronger. Last year when I was trying to find stainless bolts for the same reason. I contacted a distributor that sells the ford kits on ebay. He also said the same exact thing.

I am assuming but of course that always comes back and bites me in the ~~~. Since its only mounting the pulley to the shaft, the stainless bolts I got would work. I figured I might ask you guys first before the pulley flies off going down the road.

Flex
05-07-2009, 10:03 PM
Oops I goofed, the bolts I ordered were a special industrial grade still a little weaker than grade 8. The traditional bolts were A2's which are weaker.

Flex
05-07-2009, 10:04 PM
Well if you think about it, the sheer strength is still above 40,000 so it would take some effort.

http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx

DLF
05-07-2009, 11:41 PM
You can get 5 packs of SS bolts from ARP, which is what I used on my JS pulley.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=ARP-712-1000&N=700+4294922918+115&autoview=sku

You can also buy A4-80 SS bolts from http://www.totallystainless.com/ which are stonger than the typical A2-70 bolts.

Flex
05-08-2009, 03:26 AM
Great post. The ARP 300 bolts are super strong at 170,000 psi. That is about 55,000 more than 316's

S_Mazza
05-08-2009, 10:19 AM
Now I'm not a metallurgist, but I believe I have read that stainless steel bolts have high strength numbers, but tend to be much more brittle than regular steel. Is this correct?

kpatton
05-08-2009, 10:54 AM
ss bolts are fairly soft. If you are worried, try and locate stronger bolts that are chrome plated. However since the pulley doesn't have any tension/compression forces once torqued down. probably not a problem.

kenewagner
05-08-2009, 11:05 AM
Now I'm not a metallurgist, but I believe I have read that stainless steel bolts have high strength numbers, but tend to be much more brittle than regular steel. Is this correct?


I beleive you are right. I would have to check but I think SS is around 90,000 lb tensile strength and the stuff is harder than hell, not soft. Just try drilling a SS plate sometime. You can burn up a drill bit in seconds. I would have to beleive that brittleness is a problem giving it such a low grade bolt wise

Ken

fastsc92
05-08-2009, 01:31 PM
Unless you buy APR stainless bolts....any SS bolt you get is going to be inferior to grade 8+ bolts. With that being said, in those applications, any SS bolt should be fine as you're worried about shear strength.

Flex
05-08-2009, 02:34 PM
I beleive you are right. I would have to check but I think SS is around 90,000 lb tensile strength and the stuff is harder than hell, not soft. Just try drilling a SS plate sometime. You can burn up a drill bit in seconds. I would have to beleive that brittleness is a problem giving it such a low grade bolt wise

Ken

The problem to get around is sheer strength. In most cases, the stronger a metal, the more brittle it is. I know it makes no sense. Stronger metals don't twist, they just snap.

In the case of low grade stainless, there is no carbon in the mix which is what gives normal bolts their strength. Without carbon, the bolt can't be tempered for strength.

A grade 8 bolt has a yield strength of 130,000 psi and a tensile strength of 150,000 psi. An A2 or 18-8 is typically about 80,000-90,000 and 100,000-125,000.

The ARP300 material is different. ARP stainless steel components are made from a special stainless which is processed by hot and cold working which gives a material with a tensile strength of 170,000 PSI.

Flex
05-08-2009, 02:45 PM
Unless you buy APR stainless bolts....any SS bolt you get is going to be inferior to grade 8+ bolts. With that being said, in those applications, any SS bolt should be fine as you're worried about shear strength.

There are bolts made from 316 stainless and 410 which are considerably stronger than A2 (302,304,305 etc.) due to the addition of other metals like molybdenum but they cost more.

rzimmerl
05-08-2009, 02:47 PM
I've just used zinc plated grade 5 bolts on my WP and JS pulleys for the last few years. Never broke a one of them, even after being removed and installed many times. Remember you can divide the shear stress by four since there are four bolts, if I remember my joint calculations correctly. Without the shaft to positive locate the center, it might be a different issue using high strength bolts.