Spherical Rod Ends

[rjwoods77]

What do people use for spherical joints at the upright, the a-arm mounts and the the pushrod/pullrods.

[rjwoods77]

What do people use for spherical joints at the upright, the a-arm mounts and the the pushrod/pullrods.

[Colin]

there has already been a discussion on this
do a search for the topic "Wishbone Manufacturing".

[rjwoods77]

I meant what sizes do people use.

[jack]

most use 5/16 everywhere, some gamble with 1/4.

[rjwoods77]

Now do people avoid .25 rod ends or .25 spherical bearings. If it is rod ends it would be understandable beacause of the body size. But if it is .25 spherical then what would be the issue. I was talking with Denny and he was talking about deflection in sphericals but I dont know if he was speaking of the housing deflecting or the actual ball in its own body.

[Akos]

Guys be realisting about your rod end/spherical sizing.

Our Formula Renault cars run 1/4" sphericals at most inboard joints. That is an 1100lb car.

Sit down, do the math, and figure out roughtly your loads in your suspention links.

Decent 5/16" rod ends on the inboard side, if loaded properly, are way overkill.

On an FSAE car you should be able to use 1/4"rod ends or 3/16" sphericals in most places. 3/16" rod ends can definately be used in some places.

The one you have to watch for is the lower outboard sphericals with a pushrod setup. If these are too small they will tend to wear out fast.

Cheers,

Akos

[rjwoods77]

I wanted to do the whole car in .25. Figured that was light enough and there is no difference in dimensions between .25 and .1900. The load rating difference confuses me but i bet those ratings are based on a bolt with a identical shear strength for all the sizes. That might account for the difference in listed radial strengths. So i figured just use .25 all around. They weigh the same and the bolt weight difference in negligable. Reduces inventory for sure. People in baja use 3/8 rod ends and they survive massive one time load conditions. Also all my load calcs say that .25 should survive. Also who gives a shit about life. The competiton is only 2 days of driving.

[Lyn Labahn UW-Madison]

If you do not aim to have your car last more then two days driving, it is unlikely you will get in any reasonable test time. Therefore it is also unlikely you will be able to get your car prepared to pass even the brake test, let alone an event.... food for thought.

[rjwoods77]

Yeah, thats what i meant. I am sooooo stupid to really think this. I just puked your food for thought. People here just have absolutly no sense of humor.

[rjwoods77]

Also it was colin chapman who said a properly designed race car is one that falls apart when you cross the finish line. There is an obviously leeway to this statement that people understand. I guess colin chapman should listen to you if he were alive. Get real.

[Cement Legs]

Rob I've been reading a lot of your posts in different categories and I'm wondering why you go so quickly to insults in your comments?

[EgyptianMagician]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Rob Woods:
Yeah, thats what i meant. I am sooooo stupid to really think this. I just puked your food for thought. People here just have absolutly no sense of humor. <HR></BLOCKQUOTE>

Grow up.

I thought we were suppose to stop using extended vowel sounds to express 'anger' way the hell back in grade 4.

Seriously, it's a techincal site where engineers chat, so be an engineer and stick to the technical jargon. If you don't agree, why not just say, I don't agree because. This is isn't a typical gamers site to post junk.

Food for thought, people are gonna ask a million questions and try to knock you off your guard at the competition and (later on) during your thesis defence, so get used to answering politely.

cheers,

[rjwoods77]

Because people are quick to comment with snide, idiotic answers so they get an equal reaction. Golden rule. Treat me like an idiot or talk down to me and i'll do the same back. This is far from a professional site and far from professional conversation. This site is more of a social gathering that trades ideas. Besides, I am just mean at heart.

[Charlie]

It used to be a professional site. Where is that ignore feature admins??

[jack]

i dont think you get it. what lyn labahn said was not rude at all, in fact, it was good advice. you were the one who was rude, when your design was criticized, instead of offering a counter point of why you think your idea is valid, you insulted, and quoted a quote that frankly has nothing to do with the type of cars we build.

this site is what you make of it. if you have technical questions and no one to turn to, it can be a good resource. if you turn it into what egyptianmagician refered to, i think it will lose alot of value.

to echo earlier comments, practicing for what you say to design judges is a much better idea than being negative. you might understand this more after your first competition.

so, do you think that you wont fail rod-ends in testing, or not? why?

[Denny Trimble]

Rob,
Pre-emptive strikes are not a part of the golden rule. I think you come out swinging a little early...

[rjwoods77]

I always swing first. Guess i'm an ass. hahahaha. This forum hasnt been as interesting until I started posting. Check you e-mail. We built a mockup of the chassis. Found it was way too big. Dropped 3.5 inches of height on the main roll hoop, 2 inches of height on the front roll hoop and 4 inches of height on the front bulkhead. We found that we have a 54 inch visability of the ground measured from the fornt bulkhead plane. Really cool. I'll be in touch.

[Amos]

Ummm... Don't really agree with all this back and forth comments about snide remarks but would like to post something about rodends and sphericals.

Being an Australian team we tried to have a completely NORMAL... (oops i mean metric) car.
Unfortunately due to availability of Aurora rodends and sphericals in metric we had to make some last minute changes. But previously we were using M6 (little less than quarter inch) on most members with M8 (about 5/16) on lower wishbones.

I think that these parts can deal with the loads fed to them considering the formula fords in Australia only run something slightly bigger (much heavier car, much quicker).

If you design all the spuds with enough meat you can just uprgrade the size (assuming you left enough clearance on clevices etc). This is something we had to do, luckily we'd designed enough room everywhere to update all parts to 5/16.

I personally think 5/16 are fairly overkill for some of the lighter loaded members. Of course you are welcome to completely ignore me.

[Cement Legs]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Amos:
Being an Australian team we tried to have a completely NORMAL... (oops i mean metric) car.
<HR></BLOCKQUOTE>

HAHAHA... hey Amos without thinking about it how tall are you? http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Amos]

178cm my friend, which i think is just under 6 foot i think!!
Seriously though anyone that tries to do all metric should have any orders in about 3 months in advance as this turns out to be a major setback!

[Big D]

Just some thoughts...

I don't like the idea of having a threaded rod holding things onto the side of the chassis... screws are best for clamping parts to one another. The stress risers created by the root of the thread worries me. Unless you are using the insert bearing style... We ran 1/4" male rod ends on our A-arms, and one or two were broken after riding in the trailer coming home from Detroit. In the trailer, of all things! Anyways, this has me thinking of ways to eliminate as many sperical ends as I can, I'd like to only see them at the uprights, and steering/toe links.

[Infinity]

our team is totally new to this competition so we had consulted the previous teams from our country-India. They suggested the use of Female rod ends over male rod ends. I have been searching net for long but i havent been able to figure out the difference between both. Could anyone please help out??

[J. Vinella]

Do you mean the physical difference?

Female: you screw something into the rod end (http://www.thebigbearingstore.com/catalog/femalrod_end_bearing.gif)
Male: you screw the rod end into something. (http://aurora.thomasnet.com/ImgMedium/a1213.jpg)

If you question was about where you would use each?

Well for a push rod, I would rather make a tube with treaded parts on either end and screw a male rod end into it. If I were to use a female rod end: I would have to put a treaded type bolt on the end of the push rods and from a machining stand point the male way is better. (No sexist remake intended)

Come to think of it we only have two female rod ends on our car and they are used as an ARB control arm.

Hope that all helped.

[Infinity]

Thanks for that. But is there any difference of strength between the two? i have heard that female can bear a lot of stresses than males? Is it true?

[vreihen]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Infinity:

i have heard that female can bear a lot of stresses than males? Is it true? </div></BLOCKQUOTE>

Have you ever heard of PMS??? http://fsae.com/groupee_common/emoticons/icon_smile.gif

Sorry, couldn't resist.....

[NetKev92]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Infinity:
our team is totally new to this competition so we had consulted the previous teams from our country-India. They suggested the use of Female rod ends over male rod ends. I have been searching net for long but i havent been able to figure out the difference between both. Could anyone please help out?? </div></BLOCKQUOTE>

A number of sites will list the strength of each, male and female separately. I figure the female parts ought to be stronger, but it may be more a difference in accounting than a real advantage. Female rod ends have that larger diameter female housing for a stud or bolt, so the neck should be stronger than the small diameter male parts. The weak point though is probably the male thread that you attach to with the female end, which is probably the same diameter as you would have with a male rod end. It probably doesn't matter much if you break the rod end or you trade parts and break the attach stud. I'd just pick the type that's easier to install. If it's a tough call, flip a coin.

Another example of accounting: some satellite parts makers intentionally build using only male connectors for external interfaces. The male connectors are lighter, so they make your box look lighter on the spec sheet and therefore more attractive to purchase. It turns out though that your box can't go in the satellite unless someone has female connectors, so no weight was really saved on the satellite as a whole. You just push the weight onto someone else's balance sheets so you look like a miracle worker and the other guy is a villain.

[Matador Motorsports]

Here are some thoughts on female rod ends. In order to use these you will need to use a thread rod that will be located on another suspension component.

Due to packaging issues most likely you'll just weld a rod to your a-arms and then cut the threads with a die. Thread cutting will cause a high stress concentration which will cause this cantilevered fastener to fail prematurely.

The biggest downfall of all rod ends is that they are really cantilevered at the threads. Even if you figured out a way to use a bolt that has rolled threads the female threads in the rod ends are cut, so there's a stress riser.

Well this is the same case for the application of a male rod end. The threads are rolled, and you cut the female threads. However, here the difference is amount of material between the two setups. Using a female setup, just by thinking of a basic one, just seems to be bulkier, thus heavier.

If you run some quick numbers you might prove me wrong. I would recommend a rod end based on strength to weight ratio. Be careful in using the stated material properties for all type of fasteners. Especially when they quote there strength is superior to SAE Grade 8, which is their highest rating for the fasteners.

[Infinity]

Weight is not the issue for us. How much wt will it matter- it is matter of just 100 gm per rod end..so it wont matter much on a heavy car. All that matter to me is Strength? If female is stronger than male then i Would prefer Female for it better to have bulkier car working rather than a light car with broken suspension. Our main aim is to complete the track successfully as its just the First year for us

[blister]

Hi there, I have a specific question to spherical BEARINGS: Has anyone used the bearing horizontally (pivot axis points in drive direction)? We use pullrods, and looking at the loads a the upper ball joint it`s best to mount the spherical bearing horizontally. The big problem ist the achievable misalignement angle. We go for 30? max. steer angle and the max. misalignement angle of the Aurora bearings are not bigger than 12-15?. I think about using some sort of high misalignement bushings (found in the chassisshop catalog on page 52).

Any recommandations? Should we mount both bearings vertically? How to increade the misalignement angle?

(Please excuse my small knowledge and my english, i`m from a first year team from Zurich, Switzerland)

[Marlin]

Male rod ends are better in bending because you can get the mating part closer to the ball.

[kwancho]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by blister:
Hi there, I have a specific question to spherical BEARINGS: Has anyone used the bearing horizontally (pivot axis points in drive direction)? We use pullrods, and looking at the loads a the upper ball joint it`s best to mount the spherical bearing horizontally. The big problem ist the achievable misalignement angle. We go for 30? max. steer angle and the max. misalignement angle of the Aurora bearings are not bigger than 12-15?. I think about using some sort of high misalignement bushings (found in the chassisshop catalog on page 52).

Any recommandations? Should we mount both bearings vertically? How to increade the misalignement angle?

(Please excuse my small knowledge and my english, i`m from a first year team from Zurich, Switzerland) </div></BLOCKQUOTE>

I think notably RMIT uses them in that orientation, and as long as you don't exceed the axial load capacity (which is about 10-15% of the radial load capacity). I do advise taking a look at the HXAM and HAB series from Aurora, which are designed to be high misalignment (like the bushings from chassis shop as part of the ball). The 1/4" go up to 23 deg for the rodend and 24 deg for the spherical.