are you in a cold sweat yet?
[Edited on 11/8/12 by blakep82]
seen a bmw engined car for sale on e bay thats fitted with rod ends for top ball joints,?????? who the hell would design that idea.?
those things are deffinatelly not designed for that USE.
they want locking up. how bloody dangerious is that ?
f1 designers for one (depends on their orientation though) and most formula type cars
are you in a cold sweat yet?
[Edited on 11/8/12 by blakep82]
quote:
Originally posted by grissley
seen a bmw engined car for sale on e bay thats fitted with rod ends for top ball joints,?????? who the hell would design that idea.?
those things are deffinatelly not designed for that USE.
they want locking up. how bloody dangerious is that ?
look yourself item ebay 320946643498
you dont use them for top ball joints .unless your stupid ?
looks perfectly ok to me, and in the correct orientation too. could do with some of the rubber boots you get for them to keep grit out and grease in,
but perfectly acceptable.
perhaps more suited to track cars, but on a road car, with limited mileage and regularly inspected, not an issue at all
I guess the pictures are all home made efforts ?
The joint only has lateral forces, perfectly fine.
If you used on the lower bone so it was carrying the weight of the car then it's a different answer as in danger of popping out.
^but you'd have a big flat washer either side of the joint to hold it, in case it did pop out
quote:
Originally posted by grissley
I guess the pictures are all home made efforts ?
how many times do you see the suspension fall off an F1 , 
never for me thou.
I don't think you have understood the forces involved - there is no issue with them at the top.
I'd be more concerned about them being used at the bottom as there is a bending force on the threaded portion which could lead to fatigue
cracking and possible failure there.
you haven,t convinced me this isn,t on dangerous ground for road use .but each to there own !
SVA gestapo must not have had an issue with it, and he's managed nearly 4000 miles without killing himself......
so put the wooden spoon away and get it bought.
Al.
No way hozza, 
Applies equally well to the Transit drag link.
Upper ball joint only gets fairly light loads in comparison to the lower joint.
a rod end is essentially the same as a ball joint, just with both ends open and a hole (and an optional rubber cover) instead one closed end a stud
through the middle and a rubber cover...
never mind not convincing you its not safe, you've not convinced us its dangerous yet. why do you think its dangerous? isn't someone in
their garage welding a few bits of metal together, usually without any proper training, and driving it about dangerous?
its ok for IVA, its good by racing car designers, race cars corner much faster than road cars, putting higher forces through the suspension, and
they're ok with it.
fair enough you perhaps don't understand WHY and how they're perfectly ok to use, but don't go dismissing them, try to understand why
they're ok, because believe me, they're perfect for the job.
on a road car they might be subject to wear, but the owner just needs to keep a regular check on them, and even better get some of the rubber covers
on them. not a hard job.
[Edited on 11/8/12 by blakep82]
Standard practice, no problem.
i think theyre DESIGNED by the factory , ie MNR , perhaps you should contact them and tell them.........
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
This might be more your scene http://www.volvoforums.org.uk/ 
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
My MNR had those top joints, on Mazda MX5 uprights. Absolutely deadly they are. I was once rolling the car into the garage using the front wheel, and
I caught the back of my finger between the inside lip of my wheel, and top of the rod end. Oh it did bleed!
As for the structural integrity... No problem what so ever. I'm no engineer, just a bloke who built one following the exact instruction given by
MNR. Marc knows what he is doing.
Lee
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
This thread has given me some brilliant ideas for the suspension for my next project
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 always wondered what the difference was between track rod ends and drag links.
Lets not feed the trol
Where do you get the idea that MNR are the only cars with rod ends?
And why do you call it an untested joint?
As above what designer said... why do you think there dangerous? Like that on a lot of race cars as mentioned beforehand.
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?
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?
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
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
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]
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
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?
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
quote:
Originally posted by grissley
look yourself item ebay 320946643498
you dont use them for top ball joints .unless your stupid ?
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.
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]
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]
ummm just seen this.
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.
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.
quote:
Originally posted by grissley
ummm just seen this.
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.
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.
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]
NO, I said its fine by me IF YOU WANT TO USE THEM you think there ok.
no more to said.
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]
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
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.
Actually if you take time to do a mental calculation the loads normally experience by the top ball joint including under braking are not that
enormous.
The loads a rod end will survive under combined single shear and bending will always be considerably lower than under pure axial tension but it
just a matter of doing simple calcs and using Mhor's circle to select a joint to give an adequate FoS and ensuring the design ensures a
minimum length of the shank of the rod end is exposed to minimise the peak bending moment. Of course it easier just to follow the proven
path and follow the example of a M18 thread Transit drag link.
In the 40 odd years I have been around racing cars I have never seen a rod end on a top wishbone fail unless under major impact with the Armco ,
in a surprising number of those the ball joint shank bent rather than snapped.
It is a different matter putting loads into a road end that could pop the ball out out of the socket.
Isn't this the time that someone says that they used to be a F1 engineer with 20years of experience and all their kids design rally cars for
subaru, or have I missed that bit.
Surely someone. What is this forum coming to.
While I see where you're coming from, I argue that there are too many exceptions to the rule to maintain that stance in the long term. In fact...
if we move away from SLA suspension the torque reaction at the upper outboard mount could be much larger than the lower (for example in a trailing
link setup).
I would also argue that mohr's circle is going to give you a far less than complete picture. Like I said, this is a situation where stress
concentrations leading to crack growth in the thread roots in the primary concern. Even a modified goodman diagram is going to be pretty far off the
mark as dynamic deflections in the individual components are going to change the loading geometries.
If you want to design an optimized vehicle that uses a rod end in a bending location you'd need to use multiphysics simulation... and probably
magnaflux on a regular basis. At that point anyone sane would just us an encapsulated spherical in the first place.
On a broader level... using a high factor of safety to account for incorrect loading is sort of against the very essence of the car in question
(as I cross the fine line)
The provided the joint is correctly sized material used for forged rod end has a more than sufficient notch fracture toughness to cope with the load cases in all but the most extreme impact scenarios,
imho its the use of appropriate technology.
Formula Fords which have been the stalwart of motorsport for 40years use rosejoints in the method thats being slandered here, but they have a
different set of criteria than some home built road car. There are no potholes, icy roads, tractors pulling out on circuits, and an FF doesnt weigh
1500-2500kg like most modern road cars, and generally 30%-50% of a 7Type
in an FF, the rosejoint breaking in a shunt often dissipates the energy of a crash actually reducing the risk to the intrepid pilot. It also allows a
half hour change of a damaged corner, rather than ripping lumps out of the chassis.
Larger heavier race cars, often use spherical bearings in housings welded onto the wishbones. This removes the risk of the threads breaking (there are
none in this scenario) but also the simple camber/castor adjustment. The adjustment is usually added at the inboard mounting end my adding shims
between the wishbone mounts and the chassis. Bit more fabrication, bu easily replicated on a 7type.
by using 'road car' balljoints (maxi, cortina etc) the loads dont go away, they just move to the next weak point, often the design or
welding of the wishbone its attached to, there are plenty of horror stories on here of wishbones shearing etc.
if you dont like a particular method, dont use it on your car, but ensure that youve thought about the route that the 'breakage' will
follow. A minor shunt on a race car that didnt use a rosejoint as a mechanical 'fuse' could lead to the wishbone shearing and intruding into
the cabin with nasty consequences for the driver.
if the items are specced correctly, or over specced to move the failure elsewhere as is necessary, then i dont see the issue. As to which of us is
qualified to make that specificatrion call, well thats another 20 page thread isnt it?
one last point, the irony of us all worried about the load paths and relative safety of a 60year old design 7type built in sheds by amatuers isnt lost
on me!
if you want safe, drive the Euro-box thats almost certainly on all of our drives anyway and dont think of getting into 30metres of tube and GRP...
CNH
defo not an engineer...
[Edited on 1/12/12 by CNHSS1]
Years ago there was an article in racecar engineering about this.... basically they fail when used wrong. Otherwise they would not be used, as they
are, in critical parts of various machinery.
Seen a few fail in formula student. to be honest, most were no way big enough (top joint, 1/4" single shear...).
not used on road much because of cost (there is a reason good ones are the price they are) and they last about no time at all even on track. never
mind on potholes and hitting curbs,etc.
They fail if they are not specified correctly. If specified correctly they do not fail.
It doesn't matter if they are in bending, shear, tension, compression or what application they are in. You could use them to hang paintings if
you want, if it does the job then there is no problem.
The reasons why they are not used on production cars is (1) They are not self adjusting. (2) Even with dust boots they are not sealed against
water, grit and road salt. Any ball joint exposed to the hostile road environment would last a matter of weeks.
Before the 1930s the track rod ends used were pretty crude adjustable rod ends that had to be greased every 100 miles. In the 1930s with the
gradual introduction of independent suspension and fully enveloping bodywork more modern looking non-adjustable track rod ends appeared properly
sealed with dust boots to seal out road grit, however these still needed greased every 500 to 1500 miles. Just after WW2 GM used self-adjusting
track rod ends and ball joints which did not require regular greasing and over the next 12 years or so these completely replaced the non-adjusting
type and led to the gradual disappearance of king pins and trunnions from passenger car suspension.
A self-adjusting rod end or ball joint has a stiff diaphragm spring sandwiched between the bottom cup of the ball joint and the lower cap.
Occasionally you can see the effects of the diaphragm spring when checking a cars steering for free play you will find track rod end that has
little or no lost motion but exhibits vertical motion in that the ball jumps up and down in its' socket as the steering is moved.