Heim question

V8Ranger

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I was wondering how large of a heim you can get with a 3/4" or preferably 7/8" thread. The heim is going to be threaded into a sleeve which will be welded inside 1 1/4"x .095 tube and I want to run as large of a heim as possible but I'm limited to a smaller thread size. Any suggestions or part numbers are greatly appreciated.
 

FABRICATOR

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Generally, the bore of a swivel rod end is never bigger than the male thread section. Someone may make them, but it would be for a particular purpose or convenience, not strength. High strength rod ends usually have the male thread larger than the ball bore. An common example would be a 3/4" bore with a 3/4" thread or a 3/4" bore with a 7/8" thread. If you are using a good quality 3/4" rod end and proper mounting (double shear and a good bolt), it will be stronger than the tube size that you mentioned. A quality 7/8" bore rod end on that size tube is really just a waste of rod end. Check out www.bakerprecision.com</A> for tons of information on rod ends.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>
 

V8Ranger

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For comparison what size heim does camburg run on their radius arms and I-Beams? I know that it is quite bigger than the heim that I had in mind of using. The heim that I have in mind has a thread diameter of 7/8" and the I.D. of the ball is .622. Do you think these are strong enough for I-Beams/Radius Arms? I'd feel more comfortable running a larger heim but if I am understanding you corretcly you think it would be pointless. Thanks for your feedback.
 

Kritter

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Matt:

Camburg uses 1.25" heims.
Hit me up at school and I will show you what I have.

KRis

When in doubt, GAS IT!
 

singlehanded

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I would rather have an 1 1/4 an not worry about it ever having problems, its whats on my truck. I know Kreg Donahoe uses 7/8 heims on his arms(or at least use too) had some on my last truck. Maybe he can tell you if anybody has had a problem with that size heim on similair applications.

local
 

V8Ranger

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How about running a uni-ball rather than a heim? Radially speaking, they are stronger plus you can attach the uniball to both the upper and lower I-beam tubes rather than just the top one. Any comments? Also, why isn't this more common? Am I missing out on something?
 

FABRICATOR

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V8, This again goes back to application. Oversized rod-ends are used on various components that may bear, on their side, the weight of the vehicle contacting the ground or absorbing impact from large rocks. This is because of the high side load applied to the threaded portion of the rod-end. Rod ends are not designed with this in mind. That is why grossly oversized ends are used.

The other time larger than necessary (for the load) rod-ends are used is when extra high angle is needed. A huge swivel (rod-end or uniball) is used with inserts to adapt to a smaller bolt. The inserts are shaped to allow the ball to go beyond the intended (design) angle limit. A lot of cars use 1 1/4" uniballs in the front but most only have a 3/4" to 7/8" bolt.

If you want to use a larger rod-end, you can design your tube insert so the threads are beyond the end of the tube. In other words, at least part (the section with threads in it) of the O/D of the insert is the same size as the tube. This section can even be larger than the tube O/D. This is very common on racing tie rods. This still needs to be inserted and not just butt welded to the end of the tube. It's a good idea to make plug welds through the side of the tube and/or angle cut the tube end (rounded angle or sort of a fish mouth) to distribute the load.

If you look at a line of off-road race cars, even in a particular class, you will see major variations in rod-end sizes for the same application. It's a matter of doing your homework and having an efficient design or taking the reliable, easy and HEAVY route. The grossly oversized rod-ends usually do not need to be the best quality ones, which helps keep the price tolerable. The design of the arm itself and surrounding components also affect proper selection, such as if the arm is in a protected area or not, etc.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>
 

Donahoe

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Single handed, In six years of building our radius arms we have never had a hiem fail, The hiems on a radius arm are in (PUSH/PULL) and a 7/8 hiem is plenty stong to hold up.Think about it this way the bolt we use to hold the radius arm to the frame is 3/4. Camburg uses a 3/4 bolt as well. Where is the weakest link in both companies radius arms?? Its in the bolt. The bolt will shear before the hiem will fail. So why go with a big hiem unless you are trying to impress the chicks.... "HAY BABY SEE MY BIG HIEM????

NEVER LIFT!!!!!
 

Kritter

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What size is the bolt through a 7/8 heim? How about a 1 1/4" heim? It seems to me that the weakest point would be the bolt through the heim on the 7/8" and the bolt through the beam on the 1 1/4". I am not sure how much surface area is in contact with the bolt that goes through the small heim, but unless it is larger than the beam/arm bolt contact area then the bolt through the smaller heim would be the weak link. Stress is inversely proportional to area, so if the heim bolt has a smaller contact area it is going to see a larger stress.

Kris



When in doubt, GAS IT!
 

Greg

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Just a note: After spending countless hours under the Herbst's Truggy I noticed that the rear, lower trailing arm is held by a 5/8 bolt although they use some monster heims. I'm sure if someone broke one of Kreg's radius arm heims it would be a secondary action to something like hitting a curb at 90mph and the arm would be the least of your promlems. You'd most likely destroy a frame rail before crushing the heim.

Greg
 

ntsqd

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I'll venture that if we put some numbers on that 5/8" bolt we'd find that things like the bracket it goes thru or the bracket's welds are likely to fail first. At least if it's a real bolt sized properly for the application and not some G-8 pos. Assuming that is that it wasn't sized to be the fuse.


"Teach you all I know and you're still stupid"
-- Howdy Lee
 

Flea

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G-8 POS? i thought grade eight was fine for most applications. what would you recommend for this application? I agree that the mount or frame would fail first. but not your mounts matt.

GOD BLESS AMERICA! and hopefully my poor truck too.
 

Kritter

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F-911 hardware. 180,000 P.S.I. Minimum is at least 20% stronger than the best Grade 8 bolts


Don't skimp on the things that seem little.

Kris

When in doubt, GAS IT!
 

ntsqd

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G-8's are comparitively very brittle too. When I don't have the option of MS/NAS/etc or even SHCS fasteners I size appropriately and run G-5 as they are more likely to bend than break. Shear strength is less than 60% of tensile strength, so don't let the large number mislead you.

"Teach you all I know and you're still stupid"
-- Howdy Lee
 

ntsqd

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Prefer them, usually when even a SHCS is ruled out it's because of the yahoo (insert stronger expletive here) customer, not space/design considerations.

"Teach you all I know and you're still stupid"
-- Howdy Lee
 
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