Ditto what Mike said. My understanding is that (most?) stainless is about the equivalent of a grade 4 or 5. I'd use the grade 8.
some SS is better than others. I've had some SS bolts work great and other snap while installing them. Now I run grade 8-in the motor mounts, loader and droop too and just replace them every now and again if they start to rust.
Ditto what Mike said. My understanding is that (most?) stainless is about the equivalent of a grade 4 or 5. I'd use the grade 8.
Typical type 304 SS (18-8 Stainless) tensile strength is around 75,000 psi. By comparison, grade 8 bolts (43xx series steels) will generally be at or over 200,000 psi. Use the grade 8 if you want to be safe------ and safety comes first.
SteveM - Metallurgical Engineer.
Originally posted by Jetmugg
Typical type 304 SS (18-8 Stainless) tensile strength is around 75,000 psi. By comparison, grade 8 bolts (43xx series steels) will generally be at or over 200,000 psi. Use the grade 8 if you want to be safe------ and safety comes first.
SteveM - Metallurgical Engineer. Just out of curiosity how is the tensile strength of steel affected by rust?
Use olny g8 bolts!!! the ss DO BREAK. If your intake is taped for
.250 retap to .3125 . I drill and tap all the way through the intake
and use jam nuts on top.
Rust isn't very strong. That being said, it also would take a long time for a grade 8 bolt to rust to the point that the cross sectional area of the bolt is significantly reduced.
Also, check the major sanctioning body rules governing loader hardware. The rule books I've seen specifically prohibit stainless fasteners for jet boat loaders.
I know that some of the racers here replace their bolts religiously after each race (grade 8). A broken loader bolt could cost you your life. If you buy a box of them from McMaster or MSC, or somebody else like that, you can save major $$ as well.
It's not a matter of opinion or preference - the grade 8 bolts are simply stronger. If you are building a boat for show only, by all means use all the polished SS you can afford, but don't put your safety in jeapordy by using SS bolts on your loader.
SteveM
FYI, The NJBA requirements for all Jet Boat Intake Grates are Grade 8, Drilled through, and nutted up top. ABSOLUTELY NO Stainless bolts allowed. Now, that being said, that is what is in the rule book and I have never actually seen them check to see if stainless or not.
Just my .02, go with a grade 8, drill and thread all the way through the intake, locking nut up top, and replace them every year. You can get them at any good hardware store. If you've ever seen a Intake grate come out from the bolts breaking at a high speed, you'll know that it isn't a pretty sight. My family's and my life isn't worth risking it and I feel that it's more than worth it shelling out the $10.00 or so per year on new intake bolts.
When it comes to safety, don't be cheap!
ditto to squit gon and BBT..my intake is drilled and threaded all the way through and i've got lock nuts on the inside of the boat to hold the loader bolts and intake brace in place.
I've had SS loader bolts shear. On a 80 mph jet boat. I run black iron now. And I go a bit faster.
You want peace of mind? I can guarantee you if your loader lets loose for the cost of 4 bolts there's no peace of mind. Or be happy with whatever cheap overseas grade SS you get from the hardware store (after all they're SS and don't rust so they must be really strong, right?) or what your mfg installed. If you only do 60...no problem. Your loader most likely not stressed. Be happy with whatever.
On the other hand, if you want high performance or upgrading to get there...go with what Steve and others recommend.
jer
why not use grade 8 and then paint over em afterwards?
dont tell me you drive a delorean too?