alistairolsen
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| posted on 18/3/10 at 02:29 PM |
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My basic requirement was that they should not be the weakest component in the system of the top wishbone and from memory they fail at a lower
thensione than:
the pin of the balljoint in shear
the threaded section of the balljoint in tension
the two tubes of the wisbone in their component of lateral tension
the suspension mounting bolts in shear.
As all of those items are proven I don't want to add an item which is weaker.
My Build Thread
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DavidW
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| posted on 18/3/10 at 02:56 PM |
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This does look scary but wouldn't you usually expect when driving normally that most the forces on this adjuster would be pushing inwards
towards the car i.e. pushing the steel half nut against the wishbone, not trying to pull the ali apart?
I admit I could easily be wrong....
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eddie99
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| posted on 18/3/10 at 03:03 PM |
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Yeah its an interesting topic, and i've had a bit of fun trying to work it all out....
I think that overall everything will break eventually and mathematically it looks pretty safe, if you can show the maths to show that this isn't
the case then please do.
Talking doesn't really solve anything without the maths/figures to back up the argument in this case, otherwise its just opinions. Also the fact
that everything could be safer, and it is safe in terms of the normal job.
I personally just think that AshG was unlucky and it was a one off. If it happens again, then it'll be interesting to look into it some more.
Plenty of things break on everyday road cars but they aren't always recalled. One failure out of a couple of hundred seem to suggest that its a
one off rather than a general conceptual problem.
I could be wrong though 
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procomp
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| posted on 18/3/10 at 03:14 PM |
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Hi
The thing to remeber with a lot of products that are now supplied into the kitcar market. Is was made in China for less than £2.
The Trouble with theses items is that they are just crap quality material. There have been some near failures where simply by tightening the lock nut
up to a suitable pressure has seen the threads pulled out. And thats before they have ever been used.
Get them made from a suitable material. And expect to pay twice what they are else where. Sure theres a guy on here who could supply if asked. Not
sure what his name is as i only ever look at his avatar. 
Cheers Matt
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Toltec
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| posted on 18/3/10 at 03:56 PM |
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The cross-sectional area is about the same as that of a solid rod of 12.6mm diameter, this is similar to what a 14mm bolt would have depending on
thread pitch. Given the ball joint thread is 18mm and subject to bending and sheer as well as tension then the equivalent of a 14mm bolt to take
tension only does not sound too far out. Providing it is manufactured properly from the correct material.
The idea behind this design is probably sound, it is just the execution that could be causing the problem. As mentioned earlier ensuring the plane of
the inner rim of the tube in the suspension arm is perpendicular to the axis is going to be important. As is machining in some stress relief between
the cylinder and nut faces of the adjuster.
As also mentioned this appears to be the first instance of failure and it did not in itself cause any critical problem.
[Edited on 18/3/10 by Toltec]
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Liam
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| posted on 18/3/10 at 04:37 PM |
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quote:
Originally posted by Toltec
As also mentioned this appears to be the first instance of failure and it did not in itself cause any critical problem.
On the other hand, someone's front suspension coming apart could very easily have resulted in a fatal crash.
I'm totally with alistairolsen when he says you don't introduce a new weakest link into a proven system unless you absolutely know what
you're doing! The choice of material and surface treatment in this case indicated this 'designer' doesn't know what
he's doing. This part in ally (probably totally unknown untracable ally to touch on Procomp's comment) is the weakest link in a locost
front suspension by some considerable margin.
IMHO the fact one has failed in normal use indicates all the others out there may well be sailling very close to the wind. And in ally it's
just a matter of time anyway! Who knows how long? Certainly not the 'designer' that's for sure.
Having seen the numbers I'd retract my earlier statement about not even trusting a well made steel version, but that ally one, those dimensions,
that critical application, wouldn't touch it.
Liam
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AdamR
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| posted on 18/3/10 at 05:44 PM |
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Right... Who's up for manufacturing a batch of steel camber adjusters to identical dimensions?
I've always had my doubts about these, and the pics and discussion have me convinced I need something different. I think there'll be quite
a good market for a better version.
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eddie99
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| posted on 18/3/10 at 05:45 PM |
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Lol not sure if David (flak monkey) could do these... He might be busy for a while if he can
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boggle
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| posted on 18/3/10 at 05:53 PM |
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just put in an order with the flak meister
just because you are a character, doesnt mean you have character....
for all your bespoke parts, ali welding, waterjet, laser, folding, turning, milling, composite work, spraying, anodising and cad drawing....
u2u me for details
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ReMan
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| posted on 18/3/10 at 06:15 PM |
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I got mine from Darren GTS, I expect he supplied them to Rally Design.
No problems yet, but as said if the prpoerly considered opinion, is that ally is not adequate, then I'd be up for a set in steel or stainless
better still as the spanner has taken the anodising off mine.
Though better still, perhaps I should commision a new set altogether with some extra caster built in?
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ashg
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| posted on 18/3/10 at 06:37 PM |
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i ordered some bar stock today. when it turns up i will be making 4 new ones in steel and upping the wall thickness by 1mm.
the tubes were perfect, i specifically turned them on the smaller precision lathe to make sure they were perfect!!
and this is the fabrication of the wishbones. as you can see there were no corners cut on my side of things
Anything With Tits or Wheels Will cost you MONEY!!
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Exocet (Finished & Sold)
New Project (Started)
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hicost blade
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| posted on 18/3/10 at 07:32 PM |
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Does anyone know if somone could turn me up a set out of this \/ \/ \/
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Liam
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| posted on 18/3/10 at 07:56 PM |
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I'd have to advise against that ^^^. The internal void defects within that material could be nucleation points for cracks to propogate from,
eventually leading to a failure. You would be better with a tougher more homogenous material such as a good Comté.
Liam
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ashg
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| posted on 18/3/10 at 08:34 PM |
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found this old thread posted up by darren at gts showing how they are meant to be used which is exactly how i did it.
here is the picture
http://www.locostbuilders.co.uk/viewthread.php?action=attachment&tid=9013&pid=87256
here is the link to the thread.
Click
so i was using it as designed.............
[Edited on 18/3/10 by ashg]
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Exocet (Finished & Sold)
New Project (Started)
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eddie99
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| posted on 18/3/10 at 08:36 PM |
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I've spoken to Darren today and he originally designed it about 5 years ago. Made a batch of 1000 In stronger ally stuff, he gave me all the
details and had it tested etc.. and was all good.
Rally Design when remade just remade from a given item, no drawings or anything and he doesn't know what they've made it from either...
He's going to speak to them and try and find out however.
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MikeRJ
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| posted on 19/3/10 at 01:02 PM |
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quote:
Originally posted by ashg
i ordered some bar stock today. when it turns up i will be making 4 new ones in steel and upping the wall thickness by 1mm.
I started making steel replacements for my Locost when I bought the GTS bones years ago, because it just seemed a bad idea putting a thin alloy
section under significant tensile load. Also there was a clearance problem with the hex head on my bones, the points of the hex hit the wishbone
tubes.
I'd forgotten all about them actually, I didn't have a tap to finish them and I haven't touched my poor old locost project for a
long time.
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mistergrumpy
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| posted on 19/3/10 at 01:17 PM |
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Eddies can I just verify then that if these items have ben bought from GTS they should be the stronger, tested ones? That's where mine are from
that's all.
Incidentally the nuts on my drag link are very close to the upper wishbones too but just about clear them.
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eddie99
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| posted on 19/3/10 at 01:21 PM |
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That should be correct, When did you get them from GTS? Long time ago or very recently?
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mistergrumpy
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| posted on 19/3/10 at 01:46 PM |
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Around 2006/2007.
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eddie99
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| posted on 19/3/10 at 01:49 PM |
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Then im pretty sure that would have been GTS own ones!
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ghostrain
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| posted on 20/3/10 at 12:37 PM |
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Why has ashg not rang Rally Design
I rang up Rally Design and was surprised they did not know about this problem,their attitude is if ashg has a problem with the camber adjusters why
has he not contacted them directly instead of posting alarmist threads on this forum. I have the same setup on my GTS so was very worried about this
failure.
In the afternoon Darryn from GTS was just leaving, I understand that he was in discussion with Rally Design's designers about the problem.
I had a chance to discuss the problem with RD's MD,who was genuinely concerned. He advised that RD has sold 156prs of the adjusters last year
and over 50prs this year,over 4 years they must have sold over 800prs with no failures until this one. The material is HE30,type 6082 which is the
same as used by GTS,there latest supplier is an OEM who supplies Honda,ZF,TRW with ISO quality checks,they have just made another batch of 1000 camber
adjusters.
They showed me a simple test rig they had organised with Darryn where they mounted a wishbone with an adjuster and transit drag link mounted in a
vice,I was offered the opportunity to try to break the adjuster using 18" long pipe wrench. Despite using all my strength I could not break the
adjuster,a crude but impressive test I am happy to continue using the product,it certainly put my mind at rest. Their MD was surprised I could not
break the adjuster,the load I was exerting on the locknut was many times that which would be sensible in tightening that nut.
The photo shows an adjuster which appears to have ruptured in tension,we discussed it would be hard to exert high loads in that direction aside from
the load on the locknut.
The MD suggested other possible reasons for the failure and would really like to view the assembly including the wishbone and the drag link joint, it
would be a good idea if ashg were to take the assembly into Rally Design,I note his home is Rochester so it would be an easy journey,certainly help to
understand what caused this as yet one off failure.
GTS buys a lot of product from RD so it is possible that even if you bought a GTS product it could have come from RD and visa-versa.Also RD are a
wholesaler to almost every kit car manufacturer si if you bought elsewhere it could have come from Rally Design.
In the absence of sight of ashg set up the MD suggested the following possible causes of failure.
1. Too big an internal diameter in the wishbone tube,this would allow the adjuster to float inside the tube and cause a wear problem on the
adjuster.
2.Locknut loose,same effect as above.
3.Rough finish on inside of tube,same effect as above.
4.Tube inner not radiused or chamfered causing the tube edge to cut into the adjuster.
5.Tube not long enough to support the shank of the adjuster.
6.Locknut considerably overtightened,this we felt the most likely cause but after viewing the test it would have to be seriously loaded to cause
failure.
Rally Design's MD was so angry over this forum I can only repeat his words...'every kit car buider thinks he is an engineer but if you had
to answer some of the most basic questions that are asked by some kit car buiders I wouldn't trust them to build a kid's go cart, he is
very respectful of the depth of engineering knowledge of some and also respectful of those who are willing to learn,the dangerous ones are those who
have convinced themselves that they are engineers,convinced others that they know what they are talking about but actually know nothing, unfortunately
there are lots of the latter on these forums'...his words not mine,don't shoot the messenger!
I have some photos of the test which I will upload next week.
I have to say that I personally am most impressed by Rally Design,they have been so helpful in my build and their good stocks mean I am lucky they are
on my doorstep.
They were very worried about this failure and would produce a batch in steel if we ask for it but the test said for me it is not necessary,however I
would like to know why ashg adjuster failed.
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eddie99
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| posted on 20/3/10 at 12:41 PM |
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I had also been informed of this test they did.... And think that RD were going to put a post up here explaining it all. Not sure if this is still the
case..
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MikeRJ
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| posted on 20/3/10 at 12:58 PM |
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quote:
Originally posted by ghostrain
They showed me a simple test rig they had organised with Darryn where they mounted a wishbone with an adjuster and transit drag link mounted in a
vice,I was offered the opportunity to try to break the adjuster using 18" long pipe wrench. Despite using all my strength I could not break the
adjuster,a crude but impressive test
That gives you some idea of ultimate strength, but it does not replicate the fatigue cycles which are nearly always the cause of failure of stressed
light alloy parts...
I agree with your opinion of Rally Design however, they are always extremely helpful and I've received nothing but good service from them.
However I do think that if they have a problem with this thread they should either make a post themselves, or at least contact the forum owner or
moderators rather than going through a third party.
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ashg
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| posted on 20/3/10 at 02:21 PM |
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i havent had chance to go down to rally designs as i work all week in the complete opposite direction. i did invite darren to come and have a look
when he felt like it. i would much rather it be a one off failure but at the end of the day its a failure none the less.
once the car is back on the road I will let rally design have the broken part to further their investigation. I don't want to point any fingers
as it could just be that the design wasn't suitable for my application. the haynes wishbones are a different geometry to the gts bones so there
could be a hidden issue there.
the purpose of this thread wasn't to start a man hunt on the manufacture it was to warn people to check their adjusters.
as said rally desgn have sold a lot of these adjusters and this is the first one to fail. its not constructive to point fingers and try and blame
people. if i did something wrong then fine as hopefully it will educate people how to do it correctly. if the design has a flaw then im sure the
supplier will look into correcting it.
at the end of the day nobody got hurt and that's all that matters
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Exocet (Finished & Sold)
New Project (Started)
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eddie99
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| posted on 20/3/10 at 04:17 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by ghostrain
They showed me a simple test rig they had organised with Darryn where they mounted a wishbone with an adjuster and transit drag link mounted in a
vice,I was offered the opportunity to try to break the adjuster using 18" long pipe wrench. Despite using all my strength I could not break the
adjuster,a crude but impressive test
That gives you some idea of ultimate strength, but it does not replicate the fatigue cycles which are nearly always the cause of failure of stressed
light alloy parts...
I agree with your opinion of Rally Design however, they are always extremely helpful and I've received nothing but good service from them.
However I do think that if they have a problem with this thread they should either make a post themselves, or at least contact the forum owner or
moderators rather than going through a third party.
Hang on a second, Fatigue doesn't affect materials which are under constant pressure does it?
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