Clunk noise

[Keoke]

So are the high quality Marine stores omly stocking that China crap its all about the bottom line.---Keoke-- :hammer:

 

[Bob_Spidell]

I buy (nominal) Grade 5 or 8 nuts, bolts and washers at OSH. I haven't checked for any 'Made in' labels on the packaging, but I have always wondered if I was getting quality fasteners. I think you just have to go by the label and hope for the best; I suspect even McMaster-Carr and others may be sourcing from China or India, etc. At any rate, I haven't had any fail on me (yet). The bolts on the shocks--the rear ones, at least--aren't what I consider critical. I use Grade 8 flatwashers almost everywhere I need a flatwasher because they are less likely to deform and, well, they're cheap insurance.

If it makes you feel any better, there has been a problem with counterfeited aerospace fasteners. Some of the critical, 'yellow-tagged' fasteners--like the ones that hold wings and engines onto the aircraft--can cost hundreds of dollars apiece. It's tempting--and too easy--to substitute an automotive quality--or worse--fastener for one of the 'special' ones. I just try not to think about this too much.

 

[Keoke]

BOB!!!
I just did a shower stall in an expensive home. I had specified to the wholesale plumbing outfit I wanted all top grade SS for the assembly screws, drain covers,soap dishes and support bars. When the items arrived they were blazoned with "STAINLESS STEEL" on the box covers . In very small print was a list of countries where the items were made one country was China , as i took my magnet out of my pocket all the items jumped on to it and clung. I sent it all back and told the supplier send me ss and they did. Interesting too the invoice price did not change .---Fwiw--Keoke

 

[Bob_Spidell]

That's a good test for stainless--at least for material--but unless you have the ASTM testing equipment I don't think you can tell if you're getting quality Grade 5/8 bolts. I wouldn't use stainless for any critical fastener on a car (I've got stainless exhaust manifold-downpipe studs and they seem to snap easier than the ancient mild steel studs I had in there before).

If you can't get what you need locally, I've ordered from here before--service was good: https://www.boltdepot.com

Useful chart here: https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx

 

[tahoe healey]

Thank you for that chart. Is there a comparable nut marking and chart?

 

[John_Progess]

Just remember that grade 400 SS is magnetic and grade 300 (304,316, 310 etc) are not magnetic. Just a thought and have a good day!

John

 

[Keoke]

Just remember that grade 400 SS is magnetic and grade 300 (304,316, 310 etc) are not magnetic. Just a thought and have a good day!

John

Stainless markings vary.
Most stainless is non-magnetic.

Usually stamped A-2

 

[Bob_Spidell]

Thank you for that chart. Is there a comparable nut marking and chart?

Never seen one (doesn't mean there isn't). As a general rule, use the same grade nut and flatwasher as the bolt grade. Again, I usually use grade 8 flatwashers unless it's inconsequential because, well, plain steel washers are pretty much worthless.

 

[tahoe healey]

Okay, I acquired the grade 8 nuts, bolts and washers. Has anyone tried using some blue lock-tight on the washer to frame to prevent any movement? I intend to use lock-tight in addition to the lock washer.
Again, thanks for all the advice.
TH
One more question, can grade 8 bolts be cut to shorten them or will that effect the strength as in case hardened material?

 

[Keoke]

Yeah TH, you can cut them just make sure there are at least three full threads showing outside the nut after tightening.--Keoke

 

[Bob_Spidell]

I use grade 8 flatwashers under the bolt head on the shock side and lockwashers on the chassis side. Here's the reasoning (using 'random' numbers--not actual calculated--to illustrate the principal):

A given bolt at a given torque produces, say, 10,000psi of tensile (clamping) force. If the area under the bolt head is (ex. only) 1/2" sq, then the clamping force applied will be 5,000 pounds (0.5in sq. X 10,000psi--the square inches 'cancel' out and you get the 5,000 pounds). If you put a rigid washer under the bolt head that increases the area to 1" sq, you increase the clamping force to 10,000 pounds. That's why you use a grade 8 flatwasher: to increase the area of the shock that is clamped by the bolt while not releasing pressure by deforming. In addition, since the shock body is some sort of crummy aluminum/(zinc?) alloy, the flatwasher prevents the bolt head or, worse, a lockwasher from digging into or compressing the metal and releasing the pressure. Grade 8 flatwashers just fit in the recess around the bolt hole on the shock.

This is one of the few times I've found that using a split lockwasher works well (note that lockwashers are not used under head nuts or bolts--it's not a coincidence). Threadlocker won't hurt, but if you torque the bolts properly--35ft-lbs IIRC--they should hold. If not, you have other problems.

If you end up cutting the bolts--a cutoff wheel works best (you'll be all day with a hacksaw)--put a die or at least a nut on the bolt first so when you remove the die/nut you'll chase the threads. Otherwise, you probably won't have a decent 'starter' thread on the bolt.

 

[tahoe healey]

Thanks, Bob. That explains a lot and I like the idea chase nut.

 

[roscoe]

Perhaps I missed it in this thread, but don't you folks use loc-tite or similar brand thread lockers? Ny-loc (plastic insert) nuts are pretty good, but there are also the crimped or high-temp slotted self locking nuts that are used for non-cotter keyed installations that work very well. Look at the Aircraft Spruce catalog on line for a good cross section of what is available. I also had the exact same clunk and now use the internal wrenching bolts, nylon insert nuts and loctite.