I'm about to re-assemble my front suspesnion with the SC&C stage 2+ parts. The supplied fasteners are all Grade 8 nuts & bolts. Except for the upgrade to 17-4 stainless n&b's for bolting the upper cross-shaft to frame rails.

The bj's are fastened to each upper bj plate with [4] 5/16" grade 8 bolts to nylocks.

The adjusting sleeve connections to the cross shaft and bj plate is with grade 8 - 7/16" bolts and nylocks to lock the sleeves in position.

Would standard 304 stainless bolts be strong enough for these upper arm connections?

The entire assembly looks great, but living so close to the pacific will garuantee surface corrosion in 6-12 months. After spending $$$ on all this upgrade metal, I've POR 15'd all the individual parts, except the fasteners. A little too tedious a task, so I thought standard 304 stainless fasteners [about $25 worth] would be an easy solution, unless they're not up to the strength of material required for these static connections.

BTW: I'm using an Alan Grove ps pump bracket set, and would also like to know if I can go with standard 304 stainless bolts to the engine for mounting the brackets as well, eventhough stainless is more brittle than standard steel and engines create harmomic vibration?

Thanks in advance to everyone.

jps

jps,
SS threads have terrible properties, regardless of the grade. Gr 8 bolts have a min, 150k tensile and only high grade SS fasteners, e.g. A286 can come close. Even so, SS tends to be around 80k/100k tensile. Also, SS makes very poor thread profiles and have a tendency to seize (gaul) much more often than black-oxide coated Gr 8's.

I live along the beach in socal and I would only use Gr. 8, blk-ox coated in high load areas. For intake manifolds, brackets and other more visible areas of lower loads, you can go with the SS but a quality blk-ox coated fastener will resist oxidation just as well and give you far better performance.

Trust me, I'm an experienced mech engr. and expert in bolted joint design. I'm forced to use SS in space applications, but they really suck.

Put the right anti seeze on the stainless and torque to stainless spec and you will be fine, if you don;t drive through salt water and do Dukes of Hazzard stuff :)

Thanks for the info; never considered black ox and didn't see it at the local supplier. Is the 50K-100K pound tensile strength for basic stainless based on a specific cross sectional area or diameter?

Not intending to derail this thread into a lecture on strength & materials [never took that course in my engineering background- now wish i had] but in determining the correct fastener material for an application, are the most important strength ratings two values: tensile & shear or failure from side load or torsional loads?

Also, do repeated vibration cycles contribute to metal fatigue?

In the case of a steering box, are the loads mainly based on the torque placed on the box in relation to the input and feedback from the output shafts?
In the case of an engine appendage, such as a support bracket [ps pump, alternator] is torsional load minimal and vibrational harmonics the larger factor contributing to fatigue of the fastener, especially the farther or longer the appendage is, such as a 3-1/2" bolt fastening thru a spacer?

I don't know how to calculate the various strength factors for a fastener of given material, [and maybe I don't really want to either] but I think it's all published in something like "Peters tables" or a "CRC book" ?

Put the right anti seeze on the stainless and torque to stainless spec and you will be fine, if you don;t drive through salt water and do Dukes of Hazzard stuff :)
Agreed. If you really want the SS, makes sure you use the antiseize and you'll likely avoid the gauling. Although you won't have near the strength, most, most, applications will be fine with 80k fasteners.

When it comes to suspensioin pieces I wouldnt recommed compromising on strength anywhere. All grade 8 stuff here. Stainless for mounting fenders, intakes etc fine. Just my .02c

Thanks for the info; never considered black ox and didn't see it at the local supplier. Is the 50K-100K pound tensile strength for basic stainless based on a specific cross sectional area or diameter?

Not intending to derail this thread into a lecture on strength & materials [never took that course in my engineering background- now wish i had] but in determining the correct fastener material for an application, are the most important strength ratings two values: tensile & shear or failure from side load or torsional loads?

Also, do repeated vibration cycles contribute to metal fatigue?

In the case of a steering box, are the loads mainly based on the torque placed on the box in relation to the input and feedback from the output shafts?
In the case of an engine appendage, such as a support bracket [ps pump, alternator] is torsional load minimal and vibrational harmonics the larger factor contributing to fatigue of the fastener, especially the farther or longer the appendage is, such as a 3-1/2" bolt fastening thru a spacer?

I don't know how to calculate the various strength factors for a fastener of given material, [and maybe I don't really want to either] but I think it's all published in something like "Peters tables" or a "CRC book" ?

All what your'e talkin' about here is engineering the application, and that engineering was done by GM engineers 40 years ago, and re-done by the supplier of your grade 8 fasteners with your new parts. Do you really think anybody here can add anything to that? And this might seem silly: but suppose your shade-tree engineered suspension fails and you run into somebody and they are killed or permanently and totally disabled, do you suppose that their insurance company will not sic a bulldog lawyer on you, complete with expert witnesses e.g. metallurgists and automotive engineers? Just my two cents...

All what your'e talkin' about here is engineering the application, and that engineering was done by GM engineers 40 years ago, and re-done by the supplier of your grade 8 fasteners with your new parts. Do you really think anybody here can add anything to that? And this might seem silly: but suppose your shade-tree engineered suspension fails and you run into somebody and they are killed or permanently and totally disabled, do you suppose that their insurance company will not sic a bulldog lawyer on you, complete with expert witnesses e.g. metallurgists and automotive engineers? Just my two cents...

Wow! This sounds like respect for engineers!:hurray:

We don't get much of that....:sad:

Thanks!

Ron

Thanks for the info; never considered black ox and didn't see it at the local supplier. Is the 50K-100K pound tensile strength for basic stainless based on a specific cross sectional area or diameter?

Not intending to derail this thread into a lecture on strength & materials [never took that course in my engineering background- now wish i had] but in determining the correct fastener material for an application, are the most important strength ratings two values: tensile & shear or failure from side load or torsional loads?

Also, do repeated vibration cycles contribute to metal fatigue?

In the case of a steering box, are the loads mainly based on the torque placed on the box in relation to the input and feedback from the output shafts?
In the case of an engine appendage, such as a support bracket [ps pump, alternator] is torsional load minimal and vibrational harmonics the larger factor contributing to fatigue of the fastener, especially the farther or longer the appendage is, such as a 3-1/2" bolt fastening thru a spacer?

I don't know how to calculate the various strength factors for a fastener of given material, [and maybe I don't really want to either] but I think it's all published in something like "Peters tables" or a "CRC book" ?

What you're asking is hardware specific expertise. I'm a space hardware guy and cars are just a hobby for me. Others have stated very well that GM engineers have done this work. Much of it published in SAE journals that you could review, if interested.

A bolted joint is engineered for the load specifics- it's not a blanket approach. I.e. some joints see far more oscillating tension than torsion, or more shear...etc. Some have heavy shoulders, other fat washers.

Bottom line, if you're re-engineering a joint, better think twice. Or at least reconfigure the joint to be stronger than the original. To sub SS for a Gr. 8 that an engineer previously looked at is asking for trouble.

Hey, I am ready to read/listen to any and all of y'alls insignt into bolted fastener joint and material design-fire away.

My current practice is to put anti sieze on everything, lug nuts, suspension bolts, accessory bracket bolts, and yesterday, the tailshaft bolts and speedo clamp bolt. I did put grade 8 stuff in the rear control arms. Engine fasteners, I generally use motor oil and try to follow the recommended install proceedure.

That stems from a few tries at outboard motors and boat trailers. And I have not seen any fasteners that I did not have to remove down the road.

if you really want stainless and not sacrafice strength aircraft ms or nas fasteners are available with better shear and tension strength than grade 8

When it comes to suspensioin pieces I wouldnt recommed compromising on strength anywhere. All grade 8 stuff here. Stainless for mounting fenders, intakes etc fine. Just my .02c

All what your'e talkin' about here is engineering the application, and that engineering was done by GM engineers 40 years ago, and re-done by the supplier of your grade 8 fasteners with your new parts. Do you really think anybody here can add anything to that? And this might seem silly: but suppose your shade-tree engineered suspension fails and you run into somebody and they are killed or permanently and totally disabled, do you suppose that their insurance company will not sic a bulldog lawyer on you, complete with expert witnesses e.g. metallurgists and automotive engineers? Just my two cents...

look at the stock suspension bolts- they are grade 5, i believe. the GM engineers figured that grade 5 was more than strong enough for the application- they even neck down the diameter thru the center of the bolt for some reason, which has to make them weaker- and how many stock suspension fastener failures has anyone ever heard of over the last 45 years or so, even with modern aftermarket tires, springs, and shocks putting greater loads on them?
i've heard of mounting holes on the frame getting elongated and mounts tearing off the frame, but i've never heard of a problem with the oem fasteners until someone broke them off or couldn't get them out when they were doing suspension work. but by the time that happens, they are 35-40 years old and have seen a lot of different weather conditions- a problem that i'm pretty sure the car will never experience any more.

grade 8 or it's stainless equivalent should be just fine for pretty much anything anyone is ever going to do with their car.

All what your'e talkin' about here is engineering the application, and that engineering was done by GM engineers 40 years ago, and re-done by the supplier of your grade 8 fasteners with your new parts. Do you really think anybody here can add anything to that? And this might seem silly: but suppose your shade-tree engineered suspension fails and you run into somebody and they are killed or permanently and totally disabled, do you suppose that their insurance company will not sic a bulldog lawyer on you, complete with expert witnesses e.g. metallurgists and automotive engineers? Just my two cents...

JJ65,
Not trying to slam you, but IMO, what was done 40 years ago, or for that matter, today, was based on market economics- the safest product based on Federal reg's, and produced for the lowest cost possible. They [the auto industry] produce what they believe will keep them off the hook with federal reg's and insurance companies, at the least cost possible and still stay in business- your personal safety and well being is likely third place, or lower.
When 'those' GM engineers or any other auto builder, perform their design & engineering, it's a compromise of cost and safety requirements [never mind environmental regs for the moment]. They could never, either then or now, market a vehicle with stainless fasteners and be cost competitive, unless all builders were doing it.
By the way, as far as "re-done by the supplier of your grade 8 fasteners with your new parts": every single aftermarket part I've ever seen sold publicly has a standard disclaimer attached to it stating that the manufacturer does not warrant safety reliability or suitability of use or in the purchaser's vehicle.
So much for their certification of grade 8, or any other fasteners or products' safety reliability.
Factoring in strength, it could well be that most stainless fasteners are within the tolerance range of strength required for their use in automotive applications, but most of the time they're too expensive when compared to other types of steel which may yield a measure of strength not legitimately required.

Team Chevelle, like any other source of information, is also subject to one of lifes most important golden rules: "caveat lector".
Because I refer to this blog for opinion doesn't mean I substitute that opinion for fact. Moreover, if I truly believed that opinions expressed here are, across the board unqualified, then I would have to ask myself, why do I even bother ? [Off hand, I know of at least 5 things more entertaining and fulfilling than trawling the car enthusiast websites to keep my old iron rolling- no offense intended to anyone here].
But I don't roll that way, so here I am seeking opinion on what others might know of.
I ask because there is the possibilty that someone here may be a metallurgist and may actually know more than auto engineers know. It's not out of the realm.
There appears to be a few engineers and knowlegdeable mechanics who contribute here at Team Chevelle, but again, I always invoke, "caveat lector".
I guess I would rather base my actions on consideration of all the opinion, data, thereom, etc. available, instead of limiting my automotive universe [and other things in life] to a narrow source or whatever my worst fears may dictate.
Although there's something to be said for that too.

When I experience a mechanical failure, either due or undue to my 'shade-tree' retro-engineering, and a life is lost in connection with it, even with all of my cars' original engineering intact, I expect that any insurance company, their counsel, with expert witnesses in tow, would file suit anyway. If only on the basis of the car's age; they would focus on its age and current auto safety standards and whether or not I used responsible judgement in the determination of its fitness for safe use in traffic. Given that likelihood, and the fact that I still like driving my dated car [doing my part in the environmentalism of recycling], all I can say is "you pay your money [even if it is only 2 cents worth of tensile strength] and take your chances." There are few guaranties in life.

But to be fair, I admit that it is in the realm of worst case scenarios.

If using stainless, make sure it is for Automotive applications.

Fasteners are a pretty big deal in my trade. Here is an article I copied several years ago from an automotive web site. Our mechanics ask every now and than about fasteners Grade 8 vs Grade 5

Page 3 is a chart that sums up everything you would ever need to know about bolts on a car. When you see what Grade 5 bolts are rated at, it should put everyone mind at ease.

I see people ask if they should use Grade 8 bolts on their engine stand.........A 1/4" grade 5 bolt has a shear of 3682lbs and tension capability of 4007lbs

So you can see, the use of Grade 8 bolts will be a waste of money in most applications on a car. I hope everyone gets as much out of this article as I have.


http://i288.photobucket.com/albums/ll182/rocks66ss/Boltspg1.jpg
http://i288.photobucket.com/albums/ll182/rocks66ss/Boltspg2.jpg
http://i288.photobucket.com/albums/ll182/rocks66ss/Boltspg3.jpg
http://i288.photobucket.com/albums/ll182/rocks66ss/Boltspg4.jpg


Rocky

So you can see, the use of Grade 8 bolts will be a waste of money in most applications on a car.

This I would dissagree with. The cost difference between 5 and 8 for a single car isnt that much. My main backround is the offroad industry so Im a little biased to overkill applications, but in the end peace of mind is worth the extra money for grade 8. Obviously there are some acceptions as you dont need grade 8 to hold your fender on, But I would say for anything suspension, steering or brake related the small increase in money for grade 8 is well worth it. Not to mention you get a nice gold zinc plated look for the standard Gr8 fastener. :D

http://www.mcmaster.com has a great selection of bolts (all grades)

Yeah ,gr8.

This I would dissagree with. The cost difference between 5 and 8 for a single car isnt that much. My main backround is the offroad industry so Im a little biased to overkill applications, but in the end peace of mind is worth the extra money for grade 8. Obviously there are some acceptions as you dont need grade 8 to hold your fender on, But I would say for anything suspension, steering or brake related the small increase in money for grade 8 is well worth it. Not to mention you get a nice gold zinc plated look for the standard Gr8 fastener. :D

http://www.mcmaster.com has a great selection of bolts (all grades)


That's why I posted the chart, so you can look at your application and use it accordingly. My point was the manufacturer used mostly Grade 5 bolts, because there isn't a need in most applications in an automobile.
Most people have a big misconception, or I should say lack of knowledge when it comes to fasteners.

Of coarse your probably better off using grade 8 fasteners, it's just a stronger bolt but most applications it's not needed.




Yeah ,gr8.

I see, That's a mighty profound statement! Any substance to add to that to help educate someone on application of fasteners.



Rocky

just to add to the info on the chart... CRES = stainless for those that don't know that.

Yeah ,gr8.


I see, That's a mighty profound statement! Any substance to add to that to help educate someone on application of fasteners.Rocky

No,you pretty much covered it so I saw no need to elaborate.

One thing I didn't see posted here was that these are also all perfect scenarios for a fastener, but in reality fasteners are subjected to combined loading, shock-loads much greater than static loads that cause fatigue damage, corrosion that takes material away from that which was used to calculate the joint strength, etc. As an engineer I can't simply design something to survive just static loading, I have to take these other things into account so that it doesn't fail in the life of the vehicle.

One thing I didn't see posted here was that these are also all perfect scenarios for a fastener, but in reality fasteners are subjected to combined loading, shock-loads much greater than static loads that cause fatigue damage, corrosion that takes material away from that which was used to calculate the joint strength, etc. As an engineer I can't simply design something to survive just static loading, I have to take these other things into account so that it doesn't fail in the life of the vehicle.

Absolutely, all you mentioned is very true, but remember, this thread is concerning automobile fasteners. But wouldn't you agree that most of the fasteners holding an automobile together, are actually stronger than the material being held together? That's why it would appear that grade 8 bolts are overkill for MOST applications in an automobile, not all.

Of course putting grade 8 in suspension assemblies gives one a certain piece of mind.


Rocky

I am retired as a staff engineer, Product Engineering, Saginaw Steering Gear formerly a Division of General Motors. We designed all of the steering gears and steering columns for all GM cars and light trucks from 1967 through many of today's vehicles. We NEVER compromised steering system safety over cost.

Jim Shea

Absolutely, all you mentioned is very true, but remember, this thread is concerning automobile fasteners. But wouldn't you agree that most of the fasteners holding an automobile together, are actually stronger than the material being held together? That's why it would appear that grade 8 bolts are overkill for MOST applications in an automobile, not all.

Of course putting grade 8 in suspension assemblies gives one a certain piece of mind.


Rocky

I am not actually making a statement for or against Grade 8, just saying to not forget that the performance of a bolt/joint design when first put together is not the same as the performance of the same over a period of stress cycling and environmental exposure.

I also factor in the fact that this civil engineer, in his auto hobby merriment, is prone to installing bolts with the large Ford tool, fixing the damaged threads with a threading die, and installing the nut with an impact wrench, several times for each mistake. Factor in liberal use of automotive assembly fluid, and grade 8 stuff still has an adequate factor of safety. Working on late model stuff, Yamaha waverunners, and Ford engines, I note that many accessory fasterners are much smaller, the metric version of 1/4 in or so, and seem to be easier to remove and reinstall than the larger stuff on older iron like Chevelles and old Mustangs. I do not know who designed the bolts for Evinrude but he and I will have some words if I ever meet him. He was not as good as they Yamaha guy.

I am retired as a staff engineer, Product Engineering, Saginaw Steering Gear formerly a Division of General Motors. We designed all of the steering gears and steering columns for all GM cars and light trucks from 1967 through many of today's vehicles. We NEVER compromised steering system safety over cost.

Jim Shea


Thanks for standing up Jim.

More GM employees should tell us why we should buy GM products. You just gave us a good one.

Ron

.A 1/4" grade 5 bolt has a shear of 3682lbs and tension capability of 4007lbs

So you can see, the use of Grade 8 bolts will be a waste of money in most applications on a car. I hope everyone gets as much out of this article as I have.
Rocky

No offense there, Rocky, but how much data do you have to support this claim? Again, no offense, because I have a HUGE appreciation for hands-on experience, but when you have a preloaded, bolted joint of say, 1ksi,....when it hits a pothole and sees 3-4 G's, well, the math is obvious.

Most folks don't understand, and I certainly don't expect them to since I don't understand brain surgery, why people starve or women in general,... but momentary loads at points of impact can easily (CAUTION: NOT a general comment) exceed several thousand pounds. So, don't let those high numbers impresse you. Those loads can easily be seen.

Bolted joint engineering 101: What does the joint see (tricky part); shear (as in body panels and suspension joints), vibe (as in everything) tensile/compression oscillations (as in primary suspension joints), peel (as in wheel joints), thermal expansion loads (as in head bolts, manifold bolts)...and multiply by the SAE standard of 1.3, 1.6 prefered. Engineer that joint. That's what they did or they would not have published the standards we engineers, engineer by.

Thanks for standing up Jim.

More GM employees should tell us why we should buy GM products. You just gave us a good one.

Ron

From another mechanical engineer...TOTALLY AGREE. Love the work the engineers did. Problem is, the management did not equate their skills!

I am retired as a staff engineer, Product Engineering, Saginaw Steering Gear formerly a Division of General Motors. We designed all of the steering gears and steering columns for all GM cars and light trucks from 1967 through many of today's vehicles. We NEVER compromised steering system safety over cost.

Jim Shea

Jim,
I'm your protege. I worked in awe of you and your work and became the engineer I'm proud of today. I'll say to all that can read this; the same thing I said to the S. Koreans when I consulted on their recently launched spacecraft and they asked..."Why can you do all these things the world doesn't know about?"....I looked around for a manager that might be offended and said - "We're American engineers. The best in the whole damn world!!".

That's a true story that happened in 1997. I grew up dreaming of following you and your colleaques. You made us all proud. Thank you!!

No offense there, Rocky, but how much data do you have to support this claim?


Considering the fact I have had every nut bolt and screw from my car in my hands at one time or another over the last Eleven years, I dont think I have ever seen more than a few Grade 8 bolts period, and I think those were the lower control arm bolts and I'm not exactly sure those were from the factory.

I'm not exactly sure how this thread turned from a fellow asking about SS fasteners to the engineering community here defending their prospective trades.

My point to all this was, I see people all the time asking about Grade 8 hardware, Hell yes, replace everything you see bolted together with grade 8 fasteners and it will be better. But the fact remains is, the car didn't come from the factory all bolted together with grade 8 fasteners!

The reason being it wasn't needed. He also asked if 304 would be strong enough for upper arm connections, considering my PST front end kit came with grade 5 ZP hardware, I would say.......well make up you own mind.

I posted this information so when people take something apart, they can see what it was put together with, and make an educated decision on what kind of fastener they have, and what if any they want to replace it with.

I'm not trying to re engineer anything. I'm trying to give people who don't know anything about fasteners some information to work with.

Like I said, I see people who ask if they should use grade 8 fasteners on an engine stand. now they can make an educated decision based on the chart provided if a bolt rated at 9888lbs shear, will hold a 700lb engine.



Rocky

I still am campaigning against flexible coupling rebuild "kits" that use common bolts to assemble the rubber disc to the steering column flange. The OEM flexible coupling has 5/16-24 and 3/8-24 shoulder bolts that are used to connect the two together with nuts and lockwashers. You must have a metal to metal connection in order to be secure. You cannot just squeeze directly upon the rubber disc and expect to create any tension in the joint.
http://i2.photobucket.com/albums/y38/JIML82/FlexCplgFeatures.jpg
If you reuse the rusty shoulder bolts that came in your OEM assembly and throw away the common fasteners that comes in the kit you will have an acceptable metal to metal connection.

Many of their catalogues have pictures of the components in their rebuild kits showing the common fastener bolts. I wrote letters about a year and a half ago to many of the major automotive suppliers outlining my concerns. A few responded that they would take it up with their supplier(s). No one has gotten back outlining any changes. One did state that their supplier felt that the parts were acceptable. (I am not going to debate someone that flunked fastener theory 101!) The pictures in the catalogues have not changed.

Thank you for allowing me to stand on my soap box. BTW, I was a Senior Project engineer at Saginaw Steering Gear Division with a Product Engineering group that had responsibilities for the flexible coupling assemblies during the 1970s and early 80s. So I do have some background on the subject. I am now retired after a 39 year engineering career at Saginaw.

Jim Shea

So JIML82, you are the daddy of rag joints! Cool. Any more info you can provide this poor civil engineer is appreciated! I thoroughly enjoy hearing the story behind stuff like this, since I have many stories as to how stuff gets built like it does! My latest one is "This is how rednecks do nuclear medicine!" from recent completion of a radiation oncology clinic! Ain't nothin' to this linear accelerator business!

I agree with keeping the shoulder fasteners, but all of the Ford units I have changed have had rivets that had to be ground out. Iirc, the Help repair joint came with some shoulder bolts to provide the steering contact to the box if the rag part failed. Is this the metal to metal contact you are referring to?

I'm not exactly sure how this thread turned from a fellow asking about SS fasteners to the engineering community here defending their prospective trades.



Like I said, I see people who ask if they should use grade 8 fasteners on an engine stand. now they can make an educated decision based on the chart provided if a bolt rated at 9888lbs shear, will hold a 700lb engine.

Rocky

Those of us who are engineers are not defending our trade. We are warning this forum that many of the decisions that are made about what fasteners are used are made by business people who do not have the expertise, experience or knowledge to make these decisions.

This is why bridges fall, aircraft crashes, space craft blows up and lawyers get rich. It is also why engineers get fired, even though their decisions are overridden by management.

You would be well served to to ask yourself if what you are doing is reasonable, like in your last paragraph.

Ron

To the OP, SS 410-HT and 416-HT as well as regular A286, regular meaning not calling a specific SAE Standard(there are a few variations) have the same strength as Gr8 with A286 yield being a hair lower at 148Ksi.

Cres isn't strong enough in yield to compare (95Ksi).

We use A286 and Cres (in space). A286 for all our bolted joints.

A A286 bolt will be nearly as strong but the thread quality sucks...oh does it ever.

First64, you may know how much space qualified lube is used (e.g apiezon, etc.) just to make those fasteners work! PIA. On the ground, blk-ox, alloy steel every time.

Could you quantify the "thread quality sucks" description, relative to stainless steel bolts? I keep thinking ss bolts would be good since they have less chance of rusting solid before I need to take them out again?

What are talking here, rough threads or variations in thread uniformity, etc?

I'm about to re-assemble my front suspesnion with the SC&C stage 2+ parts. The supplied fasteners are all Grade 8 nuts & bolts. Except for the upgrade to 17-4 stainless n&b's for bolting the upper cross-shaft to frame rails.

The bj's are fastened to each upper bj plate with [4] 5/16" grade 8 bolts to nylocks.

The adjusting sleeve connections to the cross shaft and bj plate is with grade 8 - 7/16" bolts and nylocks to lock the sleeves in position.

Would standard 304 stainless bolts be strong enough for these upper arm connections?

The entire assembly looks great, but living so close to the pacific will garuantee surface corrosion in 6-12 months. After spending $$$ on all this upgrade metal, I've POR 15'd all the individual parts, except the fasteners. A little too tedious a task, so I thought standard 304 stainless fasteners [about $25 worth] would be an easy solution, unless they're not up to the strength of material required for these static connections.

BTW: I'm using an Alan Grove ps pump bracket set, and would also like to know if I can go with standard 304 stainless bolts to the engine for mounting the brackets as well, eventhough stainless is more brittle than standard steel and engines create harmomic vibration?

Thanks in advance to everyone.

jps

Good question, I too live 3 blocks from salt water. IMHO I would just use the grade 8 fasteners and just coat there exposed parts with a light film of marine grease. Remember, you can still get rust when you combine different metals. Sounds like you got a great project going on there, but IMHO don't over-think it, just use a light coat on the bolt heads and nuts/shafts. You can also spray some boshield on the exposed fastener parts. I maintain a flats boat in a marine environment so I know first hand what salt water and air can do to parts :yes:. While I have GREAT respect for the engineering field(father was a mech eng. for Lockheed) this thread seems to be turning into a pissing contest:D. Just put your car back together and have some fun. It's not a trailer queen, right??:thumbsup:

and i just got ss bolts for my control arms.......

and i just got ss bolts for my control arms.......
So use them Andy, coat them well. I can see high tensile/shear strength on a suspension that travel's a long distance at high speed with lots of jumps (BAJA Truck race) but for street use its getting blown out of proportion.:yes:

Could you quantify the "thread quality sucks" description, relative to stainless steel bolts? I keep thinking ss bolts would be good since they have less chance of rusting solid before I need to take them out again?

What are talking here, rough threads or variations in thread uniformity, etc?

Take a SS bolt under a 15/20 mag and compare them to a quality alloy bolt. Or, you can R&R a SS bolt a few times (unlubed) and you'll see what happens first hand.

Rocky,
Didn't see the article or it's link. Can you try re-posting?

Thanks,
jps

My experience on 304 stainless or sometimes called 18/8 which is the typical stainless steel fastener material, is that it is equivalent to about a grade 2. I don't use them on high strength applications.

Could you quantify the "thread quality sucks" description, relative to stainless steel bolts? I keep thinking ss bolts would be good since they have less chance of rusting solid before I need to take them out again?

What are talking here, rough threads or variations in thread uniformity, etc?

I have to use stainless fasteners at work (food processing plant), and they do suck for the most part.

You know the difference in feeling between a nice ARP stud and nut compared to threads you cut on round stock with a dull, worn out die; as you run a nut on with your fingers?
Not a technical description, but that about sums it up.

Brand new stainless bolts and nuts often don't feel good as you run the nuts on by hand. Very frequently I have to take the bolt to a wire wheel prior to using it just so I can run the nuts on with my fingers.

If I need a couple 3/8 nuts or whatnot for my car, I'll go buy some at the hardware store rather than borrow a couple stainless ones from work.
(not because of ethical issues regarding stealing $.25 from my employer)

Rocks66 copied in a very logically written and relatively well researched topic...that is to say, how long have cars been built now? It has to be one of the most gone over mechanical engineering fundamentals in our history.
Given that, I knew someone must have distilled it down to the essential rules of thumb and well founded engineering axioms/formulas [for those of us who like to know anyway].
Thanks Rocks66.

Thanks runway1, but I think Rocks66's chart/article reference raised the bar on you a little on answering the original query.

Just to be certain and Thanks to bikeron, but the statement: "You would be well served to to ask yourself if what you are doing is reasonable, like in your last paragraph." is somewhat the underlying point of my starting this thread, and in doing so, I've asked everyone their opinion/assertion on 'reasonable' use of fasteners. Hoping we all leave a bit more edified than before.

And to everyone else thanks for the input; the car is back together and performing well, but there's always room for improvement.

I will eventually post pics of finished products and a few unexpected side effects, but I'm short on time at the moment- give me a few more weeks.

BTW: the SS fasteners are still intact, as are the recycled LCA pivot bolts....but for how long? [just kidding]

Kind of an old thread, but I love the subject!

First, Comparing Grade 8 fasteners with SS fasteners is not a fair comparaison. Grade 8 determines the strength of the bolt and SS, the material it is made of.

SS fasteners come in many different grades just as regular steel fasteners. You have to pick the right one for your application.

For automotive use, ARP is the primary source for Hi-Strength SS fasteners. When it comes to buying SS fasteners for automotive application (Low & High Strength as well as decorative), Totally Stainless (http://www.totallystainless.com/) was my place of predilection. :thumbsup:

That being said, for those who think that GM overdesigned with the use of grade 8 bolts for suspension parts, let's just say that I was glad they did when I removed my rear control arms and I saw that the bolts had "necked" (is that a word?) due to rust! :yes: Sometimes you have to think ahead, with the worst conditions in mind.

from ARP's website: [they have a load of info there, from metallurgy to standards and everthing in between]

Quick Reference Guide to Fastener Materials

Material /ARP Uses? /Yield Strength /Tensile Strength /Used For

Grade 5/ No /90,000 /120,000 /accessory bolts and studs
Grade 8/ No /120,000 /150,000 /accessory bolts and studs
Stainless 300/ Yes /140,000 /170,000 /accessory bolts & studs, head studs
Custom 450®/ Yes /150,000 /180,000 /head bolts, accessory bolts
8740 Chrome Moly /Yes /160,000 /190,000 /rod bolts, head & main studs & bolts
A286 /Yes /170,000 /200,000 /head bolts, accessory bolts
ARP2000 /Yes /180,000 /215-200,000 /connecting rod bolts
L19 /Yes /200-230,000 /230-260,000 /connecting rod bolts
Inconel 718 /Yes /190-210,000 /220-240,000 /connecting rod bolts
Custom Age 625+ /Yes /235-255,000 /250-280,000 /head studs, connecting rod bolts
ARP 3.5 /Yes /220-250,000 /250-280,000 /connecting rod bolts
AerMet® 100 /Yes /258,500 /300,000 /connecting rod bolts
Titanium /Yes /160,000 /180,000 /head studs, accessory bolts

I ended up using 17-4 hardened stainless steel bolts to mount the UCAs to the frame and recycled the LCAs pivot bolts [since I couldn't find a shoulder bolt of the size required in 17-4], but they'll be replaced when I scrap the SPC LCAs in the near future.
Zinc plated steel grade 8s on everything else.