designer
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| posted on 11/8/12 at 09:53 PM |
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Where do you get the idea that MNR are the only cars with rod ends?
And why do you call it an untested joint?
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eddie99
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| posted on 11/8/12 at 10:19 PM |
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As above what designer said... why do you think there dangerous? Like that on a lot of race cars as mentioned beforehand.
http://www.elitemotorsporteng.co.uk/
Twitter: @Elitemotoreng
Facebook: http://www.facebook.com/pages/Elite-Motorsport-Engineering/153409081394323
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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rodgling
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| posted on 11/8/12 at 10:23 PM |
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I'm not really well-informed enough to have a strong opinion on this. But why do most manufacturers stay away from rose joints here?
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tegwin
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| posted on 11/8/12 at 10:50 PM |
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quote:
Originally posted by rodgling
I'm not really well-informed enough to have a strong opinion on this. But why do most manufacturers stay away from rose joints here?
Cost and durability..... a "normal" off the shelf sealed ball joint type thing would be much cheaper and last longer... but be much
heavier and harder to adjust....
------------------------------------------------------------------------------------------------------------------------
Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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deezee
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| posted on 11/8/12 at 11:11 PM |
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quote:
Originally posted by grissley
thanks for your comments on my engineering abilities !!
but a decent suspension designer would do it properly I dought he has ever studdied suspension design in fact I,m sure.
happy motoring 
been a laugh thou
I'm 150% with you! I once used these dangerous and untested, standard suspension components. I know you have your doubts but after a week of
mopping up the blood, I can tell you how crazy they are! If all the well documented failures aren't enough proof* then the lesson I've
learnt (RIP Rover) is take the word of internet trolls as gospel !
* no actual sources available
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gottabedone
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| posted on 12/8/12 at 09:05 AM |
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Is this Nigel Whatshisface under a different name is it?........The one that's bitching with Roadrunner because he wants their chassis design
calcs by telling them that their chassis isn't safe
....or perhaps Mr Henderson is back 
Steve
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grissley
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| posted on 14/8/12 at 12:22 PM |
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lets stick to road car design here, if you,d spent the time to seriously design the suspension correctly for camber/caster/roll centres etc and I
might add steering rack here as its vital they are all designed together . then accurate drawings and manufacture of the suspension components using
correct road bushes and ball joints becomes very simple to use.
rose jointing is a scapegoats idea in my opinion because they are unable design it correctly or accurately.also as far as I,m aware rose joints are
not designed for road use.
this simply isn,t just a knock at your mnr cars, theres poor compoments on quantum xtreme too .
I simply wouldn,t do it myself and you are entitled to do you own cars.Thats what kit building is all about but don,t get caught up in poor design for
the sake of it being done by others.
Forums are for helping not falling out , there is always an option, don,t take the word of the kit manufacturer that his design is good, challenge
them, most of the seven kits are just coppies of collin chapman and they haven,t designed theres as well.
Finally I,m not a poo stirrer or want anything form the manufacturers regards design,calcs or anything. I can do it myself and have.
thanks
[Edited on 14/8/12 by grissley]
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daviep
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| posted on 14/8/12 at 02:09 PM |
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quote:
Originally posted by gottabedone
Is this Nigel Whatshisface under a different name is it?........The one that's bitching with Roadrunner because he wants their chassis design
calcs by telling them that their chassis isn't safe
....or perhaps Mr Henderson is back
Steve
No way is it Mr Henderson, he'd have a fit if he saw the spelling, punctuation and grammar used by the OP 
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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phelpsa
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| posted on 14/8/12 at 02:12 PM |
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I really wouldn't expect to hear such comments from 'an engineer of 40 years'.
I dislike the standard line of 'Rod ends must not be put in bending', it is completely unfounded. I don't know where this massive
fear of bending and shear has come from. Materials behave just as predictably in shear and bending as they do in tension and compression.
Yes there are more material efficient methods, but for a simple system rod ends work just fine. Just because you would do it differently doesn't
mean that is can't/shouldn't be done.
And as for 'rod ends aren't designed for use on the road'.... you think they were 'designed' for use on cars at all?
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MikeRJ
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| posted on 14/8/12 at 02:46 PM |
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quote:
Originally posted by grissley
I listen to you on your comments , but there is another issue here that putting an untested joint on a road car for the general public to use could be
a serious legal issue. As you will well know and I stand corrected that no other road car kit uses this idea and use well tested manufacturers std
ball joints for the uprights for a very good reason.road cars are a differnt animal completely to track used cars, maybe safety is my priority but I
was just very concerned when I saw this. I,ve been an engineer for over 40 years and this is my opinion and many others I,m sure,but don,t be
missunderstood by my intentions here its just me.
regards phil
How about backing up your hand waving with some actual numbers since you have an engineering background? Take a look at the specifications of the rod
ends used and the forces involved on an upper wishbone and prove to us that it is dangerous.
I'm pretty certain you won't be able to do this, because it's been done before by various engineers on here and it showed that even
quite small rod ends have adequate safety margin in this position. However, it wouldn't be a bad thing to have another engineer run the figures
independently to prove or disprove this.
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emwmarine
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| posted on 14/8/12 at 04:17 PM |
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quote:
Originally posted by grissley
look yourself item ebay 320946643498
you dont use them for top ball joints .unless your stupid ?
Why is it stupid? It would be good to know your thinking.
Many people, usually with the intention of track use as well as road use, rose joint their suspension.
A standard modification for the Lotus Elise is to replace the track rod ends that are used as tie rods in the rear suspension with rose joints that
are under double shear. The only issue with rose joints is that they need more maintenance as they are exposed.
Building a Dax Rush.
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FuryRebuild
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| posted on 14/8/12 at 05:40 PM |
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I suggest people take a look at Carroll Smith's book "Nuts, bolts and fasteners" which goes into this at some length, as does the
SAE formula student regs wherein people who design wishbones with rod-ends in bending get marked down heavily.
It boils down to putting the bolt shaft in shear at it's most vulnerable point, where the shank becomes the thread. They do snap.
For instance, in my fury I think the bottom ball-joint is a transit or LDV Van link, grossly overengineered in the right application, but because the
forces are going around a corner it does the job. However, if you have really well engineered and set up suspension, and are on slicks or semi-slicks
even this overspecification will give.
Losing your steering at 100+ is a nightmare.
If you're passing the force down the suspension component in a straight line, you won't snap the shaft - they should be loaded in
compression.
How the rose joint goes into the link is also important - welding a nut on is worse, whereas the best way is to get a specific weld-in bung which
transfers the load to the entire head of the tube and fully supports the shaft for a considerable part of its thread length, rather than a welded on
nut.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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grissley
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| posted on 14/8/12 at 06:59 PM |
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well I,m pleased some understand, I don,t have any calc books anymore but look at one and take your own opinion as to how much SIDE loading you think
a rose joint is likely to take in place of a good ball joint in pull and compression. !
if you are happy to use them its fine by me.
thanks for your input.
[Edited on 14/8/12 by grissley]
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daviep
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| posted on 14/8/12 at 07:22 PM |
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quote:
Originally posted by grissley
well I,m pleased some understand, I don,t have any calc books anymore but look at one and take your own opinion as to how much SIDE loading you think
a rose joint is likely to take in place of a good ball joint in pull and compression. !
if you are happy to use them its fine by me.
thanks for your input.
[Edited on 14/8/12 by grissley]
"Side loading" not exactly an engineering term, presumably you mean axial load? The joint shown in the ebay add you linked would not be
loaded axially so why worry about it?
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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grissley
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| posted on 14/8/12 at 07:39 PM |
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ummm just seen this.
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FuryRebuild
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| posted on 14/8/12 at 07:42 PM |
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Really good picture. The one on the left is not great design - the force has to go through two bends before getting from the upright to the chassis.
The first bend of which puts the rod-end in bending.
The second is way better, and carries no bending load to speak of, and it's obvious it's of less metal, but for its specific application,
much stronger.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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MikeRJ
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| posted on 14/8/12 at 07:45 PM |
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quote:
Originally posted by FuryRebuild
I suggest people take a look at Carroll Smith's book "Nuts, bolts and fasteners" which goes into this at some length, as does the
SAE formula student regs wherein people who design wishbones with rod-ends in bending get marked down heavily.
It boils down to putting the bolt shaft in shear at it's most vulnerable point, where the shank becomes the thread. They do snap.
They do if not adequately specified and especially if the locking nut is over torqued (which is why the GTS style adjuster is better, as long as
it's not made from alloy). However, thousands of kit cars have used (no doubt Chinese-made) Transit drag links for years with no problems, and
rod ends are usually made from much higher spec. material.
Loading the shank in bending is not an ideal engineering practice since it means the joint has to be larger and heavier than it otherwise would need
to be, but that certainly doesn't mean it has to be dangerous, despite all the baseless hand waving being done by the OP.
The OP also seems to be very confused as to the direction of loading that would be seen by the upper balljoint - there is no danger of the ball
popping out of the housing in this situation - the shank would fail first.
[Edited on 14/8/12 by MikeRJ]
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daviep
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| posted on 14/8/12 at 07:47 PM |
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quote:
Originally posted by grissley
ummm just seen this.
If you're commenting on the camber adjuster.
Been done to death already, do a search.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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FuryRebuild
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| posted on 14/8/12 at 07:48 PM |
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Hi Mike
I agree with you that it doesn't need to be dangerous - I've run the transit/LDV links top and bottom for years on the road, and never had
an issue. When I had an off at harewood I snapped a top one and bent a bottom one, but that had more to do with the armco than the high lateral G. I
would even argue that for most road use, it's adequate.
If however, you're proper hooning it on the the track, pulling high lateral G with good suspension and tyres, then you're vulnerable to
having it go really wrong.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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phelpsa
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| posted on 14/8/12 at 09:19 PM |
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quote:
Originally posted by FuryRebuild
Hi Mike
I agree with you that it doesn't need to be dangerous - I've run the transit/LDV links top and bottom for years on the road, and never had
an issue. When I had an off at harewood I snapped a top one and bent a bottom one, but that had more to do with the armco than the high lateral G. I
would even argue that for most road use, it's adequate.
If however, you're proper hooning it on the the track, pulling high lateral G with good suspension and tyres, then you're vulnerable to
having it go really wrong.
You're only vulnerable if you haven't specced it correctly though
See my previous post...
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phelpsa
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| posted on 14/8/12 at 09:21 PM |
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quote:
Originally posted by grissley
well I,m pleased some understand, I don,t have any calc books anymore but look at one and take your own opinion as to how much SIDE loading you think
a rose joint is likely to take in place of a good ball joint in pull and compression. !
if you are happy to use them its fine by me.
thanks for your input.
[Edited on 14/8/12 by grissley]
You've posted a thread stating that someone else's design is dangerous, then you say it's fine by you? You, sir, need to make your
mind up!
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grissley
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| posted on 15/8/12 at 07:31 AM |
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NO, I said its fine by me IF YOU WANT TO USE THEM you think there ok.
no more to said.
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ffrgtm
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| posted on 1/12/12 at 08:17 AM |
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Come on guys... 2 solid pages and no one has come up with the correct answer yet?
Outboard rod ends are just fine under all of the major handling modes... pitch, heave, roll... hell you can jump the car over a bus for all they
care... but you are all forgetting one critical condition the vehicle sees.
BRAKING
Think about the load paths under braking.. you are creating a MASSIVE bending load through the upper rod end. And guess where the stress must flow
through? The thread roots, which are perfect stress raisers.
Using rod ends on the outboard is a mortal sin, even if you were to oversize them (we're talking a factor of safety for yield in axial of 3-4)
it doesn't matter. The fatigue cycling you're forcing the rod end to endure will eventually develop crack propagation in the thread root.
I don't care what the endurance limit is, it's been proven time and time again (often with death) that it will fail at the worst possible
moment... Usually at your braking marker at the end of the straight under highest aero loading.
Sure, you may see professionally built race cars running rod ends here... but let me reassure you: these are "setup" control arms. Only
used to validate predicted suspension geometry optimizations. Once a race team has hashed out the tire behavior, they swap these control arms out for
proper encapsulated spherical bearing arms.
The two reasons I bought an MNR were the diligent use of tubular members, and the encapsulated spherical bearings in the outboard control arms. These
two facts told me that MNR understood the physics of materials better than the others... or at least were smart enough to emulate those who did.
I am heavily involved in formula SAE in my country, and I'll let you the design judges won't even let you on the track if you use
"rod ends in bending". Too many failures have injured too many spectators.
Stop this rod end in bending shit... please... before someone gets killed.
edit: forgot to say thank you grissly.
[Edited on 1/12/12 by ffrgtm]
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Mr Whippy
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| posted on 1/12/12 at 10:04 AM |
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Although I'll all for posting freely this thread seems to be about provoking reactions based on unfounded opinions of one man vs everyone
else
I think you have made your point on how superior your engineering wisdom is and I look forward to seeing the car you build
Good bye
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ffrgtm
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| posted on 1/12/12 at 10:44 AM |
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Look... the mere fact alone that we are haunting the same forum suggests that we have many of the same intrinsic qualities. I'm not trying to
swing a big engineering wang around, I just don't want other people that I have so much in common with to get hurt.
I see now that I said "MASSIVE load through the upper rod end" which completely skewed my intention. What I was really trying to get
across was that using rod ends in bending in all locations is pretty damn stupid, but MNR uses the correct encapsulated spherical bearing in the lower
a-arm, which is in this particular case going to be the highest loaded point in braking.
I get that MNR uses a threaded rod end in the upper position... they can't account for the dozens of tires constructions that customers are
going to use... they will all require totally different suspension geometries that would be impossible to accommodate with all encapsulated
sphericals.
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