Turbo fasteners: Stainless vs 8.8 vs ??
10-09-2007, 05:09 PM
#1
Turbo fasteners: Stainless vs 8.8 vs ?? I see alot of turbo companies use stainless fasteners on their turbo system. I think I read somewhere that Stainless has less tensile strength compared to grade 8 bolts, what is the better fastener to use? Do they choose stainless for the corosion resistance?
10-09-2007, 05:17 PM
#2
Stainless is actually weaker than Grade 5, something along the lines of grade 3.
I use Grade 8 whenever possible only thing is it is hard to find grade 8 in some of the smaller fine pitch bolts.
I use Grade 8 whenever possible only thing is it is hard to find grade 8 in some of the smaller fine pitch bolts.
10-09-2007, 05:38 PM
#3
You are telling me, This is my second car from the US and third on its way this month. I live in Canada and its always fun to find some bolts, usually set me back a bit running around finding the damn things. Metric fine thread is fun stuff 
Also agree on the grade 8, never had a problem except on my turbo'd eclipse. The bolts were to narrow, but the grade 8 would stand up to the job allot better.
Also agree on the grade 8, never had a problem except on my turbo'd eclipse. The bolts were to narrow, but the grade 8 would stand up to the job allot better. 
10-09-2007, 09:23 PM
#7
You guys need to be careful in your descriptions of fastener strengths...there are multiple grades of stainless fasteners too...18.8 and 316 are the common ones (but there are others too)...18.8 is weak, 316 (and other 300 series though 316 is the common one for fasteners) is stronger than grade 8.
Here's a good chart to use for quick comparisons
http://www.arp-bolts.com/Tech/T2_Met...ialSpecs2.html
It is worth it to note that stainless fasteners sometimes can be more likely to gall threads and seize...a quality moly lube helps with that a lot...there are even stainless specific lubes to use.
Also, for anything that'll get hot (exhaust) that is through bolted...like a turbo to a flange, use the mechanical style lock nuts rather than nylon...the ones with the slots cut into them that pinch in just enough to lock work out really well. Whenever you need to remove a stainless fastener, I suggesst putting some of the above mentioned lube onto the exposed threads so as you loosen, the nut works up over the lube and it gets easier and less likely to gall a thread on the way out.
Here's a good chart to use for quick comparisons
http://www.arp-bolts.com/Tech/T2_Met...ialSpecs2.html
It is worth it to note that stainless fasteners sometimes can be more likely to gall threads and seize...a quality moly lube helps with that a lot...there are even stainless specific lubes to use.
Also, for anything that'll get hot (exhaust) that is through bolted...like a turbo to a flange, use the mechanical style lock nuts rather than nylon...the ones with the slots cut into them that pinch in just enough to lock work out really well. Whenever you need to remove a stainless fastener, I suggesst putting some of the above mentioned lube onto the exposed threads so as you loosen, the nut works up over the lube and it gets easier and less likely to gall a thread on the way out.
