Single Shear Bolt application, strength info required

In summary, the author is rebuilding a suspension arm to make it adjustable in length and to replace the ball joint. The new setup would use a 5/8 spherical rod end with a hole ID of 15.87mm (.625"), and they can only use an M12 bolt which would be about 55mm long plus the thread. They need to use 2x stainless steel spacers to mimic the taper on the ball joint stud, and also to space the head of the nut out so that it doesn't interfere with misalignment, it would only be spaced about 3mm or so. They also need to use a cotter pin to prevent the bolt from undoing over time. The load the bolt would see is
  • #1
Cazman
6
0
I have a suspension arm that I am rebuilding, the main reason is to make it adjustable in length, and the other is to replace the ball joint.

The original equipment is a standard automotive ball joint, greased and the shaft is 1 piece with the ball.

The new setup would use a 5/8 spherical rod end with a hole ID of 15.87mm (.625")
I can only use an M12 bolt which would be about 55mm long plus the thread.

I would need to use 2x stainless steel spacers to mimic the taper on the ball joint stud, and also to space the head of the nut out so that it doesn't interfere with misalignment, it would only be spaced about 3mm or so.

My question is, will this setup be as strong, stronger or weaker than the original setup?
To me it looks weaker but I am no expert.
Any advice on how to mkae it better, or advice on what can be changed etc.

The Rod end is Chromeolly
The spacers are stainless (I can use other materials if need be)
The bolt is eitehr 8.8 or 10.9, both are readily available.


My next question is, what can be done to stop the bolt undoing over time?
Standard they use a cotter pin through a castle nut, and the taper helps it stay in place in one direction.

I don't think I can buy an 8.8 or 10.9 bolt that has a hole in t for a cotter pin, so what can i do?
Should I use a nyloc nut instead?
Locking nuts?
Or can i drill a hole in the bolts without effecting strength? The way i see it the hole would be past where the load is, but I am not sure if this is safe.
Also are castle nuts even available in a 10.9 grade nut??

Thank you very much for any help you can give
My email is cazman@internode.on.net if you have any other specific questions, bu I will keep an eye on this thread, as I am trying to have these parts made within a week.
 

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  • #2
Cazman said:
... The new setup would use a 5/8 spherical rod end with a hole ID of 15.87mm (.625")
I can only use an M12 bolt which would be about 55mm long plus the thread...

WHOA! You're planning to stick a 12mm bolt in a 15.87mm hole? In a suspension component?

Are you familiar with the term "catastrophic failure"? (You will be!)
 
  • #3
No there are spacers in there, click on the pic to see them.

The factory joint was an m12 thread but had a large formed taper on it, what I want to know is, is a 12mm bolt through the middle going to be strong enough?

The hubs have a taper in them that i can't avoid, 12mm is the biggest bolt I can fit in there, maybe 12.7mm if I am lucky.
 
  • #4
It's tough without really knowing the magnitude of the loading this thing will see. The original design may have a factor of saefty of 5 built in. Who knows? From a strict comparisson standpoint, yes, the smaller bolt will be lower strength than the original. You can't get around the smaller cross sectional area of the new bolt. That being said, now the tough part is will that affect you?

Out of curiosity, why the restriction to an M12?
 
  • #5
I could use a large bolt, but it would mean drilling out the cast hub itself, not a difficult task, but when it comes to selling these parts as a "bolt on" item, its not something people will want to do.

The load the bolt would see is impossible for myself to measure. It is a rear toe arm on a multilink suspension, the car weighs aprox 16-1800kg.

This arm itself doesn't take as much load as all the others, it is only there to control the toe, but in saying that, I don't really know how much it takes.
 
  • #6
Cazman said:
No there are spacers in there, click on the pic to see them.
Oops... Didn't see that. :redface:

The factory joint was an m12 thread but had a large formed taper on it, what I want to know is, is a 12mm bolt through the middle going to be strong enough?

I would say no. In the original part, the taper is taking the active load. The threaded end is merely a retaining device.
 
  • #7
pantaz said:
I would say no. In the original part, the taper is taking the active load. The threaded end is merely a retaining device.

Thats what i was thinking and fearing.

Any ideas? I can get some shanks turned up and threaded, and probly in decent steel too. I don't know what grade would be decent though

The ones you can buy off the shelf look like this, but they all seem to have the wrong size taper and length for me
http://static.zoovy.com/img/stage3motorsports/-/M/mm5tr_1.jpg
 
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  • #9
No one has any ideas how to make it stronger?
 
  • #10
One of the main questions here is, what is the purpose of the taper? Does a tapered connection somehow reduce the cyclic tensile stress ratio on the threads, more than a highly-preloaded, straight-shank bolt? If so, could someone explain how it works? I don't readily see why it would, although I have not studied this.

It seems to me the purpose of the taper is to create an extremely tight-tolerance shear connection. This would eliminate shear displacement in the connection, preventing impact of the bolt shank against the bolt hole. This would also eliminate bending moment on the threads. A simultaneous reason for the taper might be to resist a higher shear load on the larger-diameter cross section of the tapered shank.

If the larger-diameter cross section is required to resist the shear force, then your new design will be inadequate. It is logical to assume the larger-diameter cross section (and same material grade) is required to handle the shear load at the active end. Secondly, to meet the requirement of zero bolt hole clearance, your tapered spacer would need to be a slight interference fit on its inside diameter. Regarding locking the nut, I think it is OK to drill a cotter pin hole, if you deburr the hole edges well. I think a property class 10 castellated nut might exist. To machine your own shanks, I think you would need to consult with a materials expert who manufactures bolts; perhaps ask Arp (?).
 
  • #11
Couple of things to think about..reason OEM use taper BJs and the like is 1.cost
2.ease of maintenance, 3. quickness of assembly

takes line worker no time to slap in the taper BJ and run a nut on it ..no washers to fumble with, no requirement to hold a wrench on the bolt while the air gun runs the nut..easy to shoot grease to the zerk, relatively cheap and durable..
We run spherical rod end of all links of our cars suspension as does every other racer out there where the rules permit...
off hand , your application, being the rear of the vehicle that weighs almost 4000 lbs. means roughly 992 pounds is on that corner.. is the auto a front engine car?
if so, even less weight would be on the back end..

What ever you do..USE HIGH QUALITY BOLTS.. do not stick a SAE bolt from the hardware store into this application..I hate them..these are friking FARM BOLTS...mass produced crap with terrible thread quality..JUNK!

1. not strong enough, 2. these SAE bolts are typically .0015 to .002 inch UNDER size..when mounted in an AIRCRAFT quality rod end..that had an ID sized to .001" or less, there is too much slop..granted, this slop should be negated by clamping pressure but it is still there
I would much rather use a hi grade AN bolt and nut in this application..
NYlock lock nut I ok to use but do not take it off and put it back on more than two times. Will not back off as long as you do this.

Use High Strength Alloy Rod ends Aurora makes these...

things to watch for...Suspension Bind..the BJ may permit a lot more motion than the rod end..you can buy High-Misalignment high strength rod ends..check how much travel your application has..disconnect a shock if it helps when checking for bind..but you do not want a link that bind and snaps..even if on the rear end..
two..you will need to lube the rod end regularly and this must be done...this is the major draw back to using these..we have to tear down our cars suspension frequently to lube the rod ends properly..we race in the rain and rain is a major cause of rust..no way around it...it will ruin the rodend in short time if not lubed..just this is justification in my mind to stick with the crappy OEM BJ..who wants to crawl under the vehicle every month to lube the rod end

see www.PegasusAutoRacing.com for above bolts, rod ends etc...ask tech desk for help..they are all old racers..good people
 
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  • #12
Personally, I have had a lot of trouble with heim joints wearing out. I used them in a steering application and ended up replacing with tie rod ends.

For a steering knuckle, the most durable setup would probably be kingpin style. After that ball joint then heim joint.
 
  • #13
your right about king pin steering
it is totally bullet proof..circa 1910 thur 1960 ..pick up trucks
basic straight axel wit hbronze sleeve bushing inside..
ref - racing..which is all i care about in life...
i beg to differ as high quality rod ends..in certain racing applications are the hot set up
but considering street scene, daily driving..poor or zero maintneance schedule, cost and ease to grease..Bjs are tops for the street..
not for racing however..
 

1. What is single shear bolt application?

Single shear bolt application refers to the use of a bolt to join two or more components together by passing through a hole in the first component and being tightened against the second component, resulting in a single shear force being applied to the bolt.

2. How is the strength of a single shear bolt determined?

The strength of a single shear bolt depends on several factors, including the material and size of the bolt, the material and thickness of the components being joined, and the method of installation. It is important to consult with a professional engineer or refer to bolt strength charts to determine the appropriate strength for a specific application.

3. What information is required to determine the strength of a single shear bolt?

To determine the strength of a single shear bolt, you will need to know the material and size of the bolt, the material and thickness of the components being joined, and the method of installation. Additionally, the expected load or force that will be applied to the bolt must also be taken into consideration.

4. How does single shear compare to double shear in terms of bolt strength?

In single shear, the bolt is subjected to a single force perpendicular to its axis, while in double shear, the bolt is subjected to two forces in opposite directions. As a result, double shear can provide greater strength and load-bearing capacity compared to single shear. However, the specific application and factors such as bolt size and material must also be considered.

5. What are some common applications of single shear bolts?

Single shear bolts are commonly used in applications where two or more components need to be joined together, such as in construction, automotive, and machinery industries. They are also used in furniture assembly, electrical installations, and other household projects.

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