Author Topic: Fastner material and grades ?  (Read 10958 times)

Offline PSweeney

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Fastner material and grades ?
« on: June 03, 2014, 03:39:12 AM »
On my previous cars I've used mostly Grade 8.8 BZP fastners and over time the corrode and go cloudy white.  I' intend to chrome all my axles and links and was wondering if stainless grades A2 or A4 are acceptable on higher load components such as motor plates, torsion bars, radius rods, steering links, rod end half nut and through bolts ?   Would I be better off using chromed steel nuts and bolts ? problem with these is they do not have markings ?

Offline rooman

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Re: Fastner material and grades ?
« Reply #1 on: June 03, 2014, 05:06:40 AM »
Phil,
     I use NAS bolts on all of my builds. They are plated to military specs, come with full shanks and short threads and are about the best thing readily available. When I first settled permanently here in the US I worked for a well known chassis shop and their practice was to use (as spelled out in their marketing blurbs) "Grade 8 bolts". The problem was that they were using fully threaded bolts to hold the rear end in place. My issue with that is that the threaded portion of the bolt does not totally fill the hole in the brackets so you are relying on the clamping force on the bolt to hold the rear end in place rather than the fit of the bolt through the mounting holes. After enough hard launches the tendency is for either the bolt to "machine" out the id of the holes or the threads to be worn down and neither scenario is good.
   I hate stainless because of the galling issue and chrome plating also has its own issues (hydrogen embrittlement, diameter change on shank etc). Any business that supplies the aircraft industry should have the NAS hardware Or Euro equivalent) on your side of the water.

Roo
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Offline Dolmetsch

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Re: Fastner material and grades ?
« Reply #2 on: June 03, 2014, 06:06:11 AM »
I didn't know about NAS bolts (thanks)but also have had great concerns over using the thread portions of bolts for anything other then holding a nut. To that end I often used a longer G8 bolt with a longer smooth shank and chopped the excessive threads off leaving of couse enuf that even if the in the unlikely event the nut came loose it would have to unwind quite a bit before it could fall off.
don
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Offline Lorbiecki

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Re: Fastner material and grades ?
« Reply #3 on: June 03, 2014, 07:26:05 AM »
Agree with the stainless comments. If stainless to stainless is used, the use some type of anti sieze compound. Stainless hardware should not be used in high load areas as grade 8 has a much higher shear then SS. Note that there are many grade of SS (304, 316, 406, etc) and each has its use. And, of course, stay away from chromes hardware in any high load situation as hydrogen embrittlement can take place after a time which can lead to hardware failure.

ARP is of course the best you can get and they have the quality control in place to minimize hardware failure. Remember that the way a screw works is that it is deformed (stretched) when tightened. This is where the stress in the hardware is induces. Each type of hardware will react differently when stressed and this is when the failure will take place.

Also, any bolt in a shear position (rear end, 4 link, etc) should have the proper length in which the shank of the bolt (un threaded) is placed into the various bracketry. This means the threads should actually be outside of the mounting bracket (or flush) and the proper flat washer used to insure that the nut does not bottom on the thread.

Good luck!

Offline PSweeney

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Re: Fastner material and grades ?
« Reply #4 on: June 03, 2014, 07:54:55 AM »
thanks guys, I always use bolts with the appropriate shank, only ever use machine screws into castings.   

Roo, how well does the plating hold up on the NAS bolts and what finishes do you get on them ?  I'm happy that bolt sizes are sufficient for the load, I'm just loathed to spend a fortune on chroming then use black oxide or bzp fastners which corrode.   Fpund one place in the UK doing NAs bolts, one 3/8 UNC 2" bolt nearly $10 :o

dreracecar

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Re: Fastner material and grades ?
« Reply #5 on: June 03, 2014, 08:42:37 AM »
Aircraft Spruce (www.aircraftspruce.com) 1-877-477-7823
They have international reps all over the world , give them a call for your hardware needs.
Since most people dont engineer their fasteners, they tend to overbuild the requirments. 
The only place that one really needs a NAS bolt is for the rear end mounting, everything else can get by with a properly sized AN bolt
And on chroming your front axle, make sure the plater understands about post bakeing of the axle to remove the Hydogen embritalment that will occur durring process.

Offline LZ

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Re: Fastner material and grades ?
« Reply #6 on: June 03, 2014, 12:46:34 PM »
On my previous cars I've used mostly Grade 8.8 BZP fastners and over time the corrode and go cloudy white.  I' intend to chrome all my axles and links and was wondering if stainless grades A2 or A4 are acceptable on higher load components such as motor plates, torsion bars, radius rods, steering links, rod end half nut and through bolts ?   Would I be better off using chromed steel nuts and bolts ? problem with these is they do not have markings ?

Hi Phil:
Im not smart , but have had the privilege of some good experiences and working with great people. So just some info that I hope can be of help to you.

Sounds like by your post your mostly worried about looks as your are chroming some items. If you intend to chrome be very wary. As mentioned by our fine members here there can be issues and if correct processes are not followed the items are compromised. Hydrogen embrittlement is more of a problem by formed material and introduction of hydrogen molecules by welding. This is all exasperated by chroming. With economic , ecological and political issues. Plating industry has taken it hard. If you have a good plater, by him a great lunch or more.
You need to be proactive to make sure your item was fabricated correctly and to follow through with your plating.  You may need to get a steel treating place involved if the plater is not hooked up with one. Also plating within a timely period of the items processing. There was a web site that had plating engineers that would answer your proccessing questions. I will try and find it.
As you mentioned you would like to use SS hardware to compliment . There is nothing wrong with this but you need to make sure of a quality hardware and a correct lube. Torque correctly also.

As long as we are talking lubes here can I recommend one?? http://www.summitracing.com/parts/drt-lube
You can get this at  most MFG supply. As in example here in the states McMaster or Grainger. I have a tube of this stuff that got to be 30 years old. Works great on dead centers. Not messy.  Important on SS fasteners to use right lube. You will get unsatisfactory results if you just grab some wheel bearing grease or the like.
Now on the subject of fasteners. be very careful. There is a problem of .......lets say unworthy sundries getting into the mainstream. Sometimes you can just look at it and go OY. But sometimes it looks OK ,there are material and heat treat issues. This is a real problem. Especially for very engineered items like aerospace.
There are places that may charge more for there items but they have the pedigree. You have to research this. Dont know what you have in the mother country. Think next time you go flying that one of these things did not end up in a critical area of your plane.  :o

One other quick item of note. The higher the strength steel fastener, the more susceptible it is to corrosion and related issues. They do not take kindly to plating's. Fortunately in drag racing we are constantly messing with our cars and they are not subject to much exposure. But just because you have this high strength fastener does not mean it lasts longer. Think rod bolts.

I just scratched the surface of a very deep topic. We can be very thankful we live in this time of so much shared engineering. Very smart people out there doing things to improve our lives and make things better.
Sorry for any errors in writing but am a person that did not pay enough attention at English class.

good luck bud
Luke
"I am not a number.... I am a free man."

Offline Oldboy

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Re: Fastner material and grades ?
« Reply #7 on: June 04, 2014, 05:10:59 AM »
Anybody got any comments on the use of Grade 12.9 Cap head bolts ?

Offline Oldboy

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Re: Fastner material and grades ?
« Reply #8 on: June 06, 2014, 02:09:49 PM »
Re; Anybody got any comments on the use of Grade 12.9 Cap head bolts ?

Anybody ?

It's just that I have a good stash of 12.9's from a previous project. Using the old adage 'If some is good and more is better, then too much should be just right' I was thinking they might be better than 8.8's, probably wrong.

dreracecar

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Re: Fastner material and grades ?
« Reply #9 on: June 06, 2014, 03:55:27 PM »
Just not a lot of metric stuff used on racecars in the U.S. to give you a qualifyed answer

Offline Oldboy

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Re: Fastner material and grades ?
« Reply #10 on: June 07, 2014, 12:09:09 PM »
Sorry should have said, these are all imperial UNF and UNC threads.

Offline PSweeney

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Re: Fastner material and grades ?
« Reply #11 on: June 07, 2014, 03:21:37 PM »
Sorry should have said, these are all imperial UNF and UNC threads.

only issue you may encounter is their lack of markings.

Offline Oldboy

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Re: Fastner material and grades ?
« Reply #12 on: June 09, 2014, 07:59:07 AM »
Thanks Phil, I'll go check  em.

Offline janjon

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Re: Fastner material and grades ?
« Reply #13 on: June 09, 2014, 08:06:07 PM »
"unworthy sundries getting into the mainstream" How PC. We can't just say "Chi".. no we can't. Counterfeit, yes. It's probably not exactly the case these days, but at one time NASCAR dictated the use of Grade 5 over Grade 8 because of better ductility, in suspension applications.
Just keep the same amount of stuff on the right
as there is on the left. Seeing straight ahead is highly overrated....