Possible Suspension Arm Failure, Racing - Tornado GT40

[Jim Cowden]

Re: This happens to a Tornado if you really race it

What is the wall thickness and OD of the lower arm.
If I had one fail I would have run it threw the bandsaw.??????.But thats just me.

You can clearly see the shock is to far in,maybe they are trying to chase shock ratio or there is component clash on turn
Has anyone made a shock bracket that fits onto the lower ball joint mounting bolts or do they wait till it breaks then put the same part back on.
It may require a longer shock and a change in spring rate due to ratio change.

Jim

 

[Mark]

The picture posted by Frank earlier shows a much better lower shock mount position. As Jim say above, what is the material thickness of the tubing used in the standard lower arm?

@ Trevor, a replacement lower arm would not be overly expensive to have made up to spec. I know people who made mine (they manufacture parts for Williams F1), were not expensive at all.

@ Andy (Tornado), you mention upgraded items as being available and including rose-joints. Is the material used in these items stronger/higher grade thatn the standard items or are they essentially the same, just imcorporating the rose joints? It's not a dig BTW

Although a Tornado owner could easily out-source the fabrication of custom lower arms to a stronger spec, it sounds as though Frank Catt and Mick Sollis have already done this, so why re-invent the wheel, IF Tornado do not have a suitable upgrade?

Threads like this are GOLD. No need for anyone to assume a defensive posture.

 

[Tom]

With this as a potential fault, it seems like an easy fix with some 1/8" sheet steel, a band saw and a welder - turn the bend-load bearing tube into a truss with the deepest point directly under the shock mount. Maybe not optimized for lightness etc, but it would maintain geometry (so springs/dampers don't need to be re-figured).

I'd think the arms could be suitably modified with a few hours work.

 

[René]

that looks indeed better, the schock as close as possible to the point/wheel of the lower arm, so the stress comes there and not 'half-way" the arm so that every load works like a lever on that point were it can bend the lower arm...

maybe they choose that "wrong" point for fixing the shock because of this option?>>

that way it looks like the shock has to go more away from the ideal point see>>
it looks like a separate lever for the steering-arm...

sorry that I took some pictures out as example from this thread>>

http://www.gt40s.com/forum/gt40-build-logs/29836-tornado-build-www-gt40builder-com-25.html

maybe that system is "wrong" takes to much room? and makes the stress point go to the "weak" point of the arm, instead of mounting the shock as close as possible to the outer point of the arm, the shock is mounted almost half way and so much stress on that point (lever arm acting manner, wheel to shock point) Hope you understand my limited way of explaining what I see in English

also, Tornado uses the other wheel things, and then you see that the shock could be replaced more to the wheel if you want...(remake those) their is some room left to get the shocks closer to the wheel/point.

 

[Dylan]

Putting the lower coilover mount so close to the center of the A-Arm is like supporting a 2x4 on each end and piling a ton of bricks onto the middle of the board and expecting it not to break. This is exacerbated by the gusset plate only extending back a tiny bit from the lower mount location. It creates a hinge point- pretty much a predefined fault line- at which all of these A-Arms are bending/breaking. This is adequate design for a custom street/show car, but very poor design for a car driven every day on bumpy roads, let alone a track car.

Unless you are very knowledgeable in both welding and suspension work, and know what the A-Arm is made out of, I would caution against welding ANYTHING to it. You'll be pumping a bunch of heat into the arm to graft a piece of material on that probably will not come close to matching the metallurgic properties of the existing arm, and you will have no idea how soft you've made the metal afterwards.

It is very clear that these arms are still inadequate after the redesign, unless wall thickness was tripled and the material was changed to moly or something much more suitable for this type of component. I would not be looking to Andy for news on which type of A-Arm they have- I'd be waiting for a new design from him, or fabricating a jig to make my own. You can't expect everything on such an affordable kit to also be designed to the nines.

 

[Darrin]

FWIW, my builder offers lower wishbones for the Tornado and they are fairly inexpensive. Looks like they put the shock mount point a bit toward the center as well but the material appears much beefier and the webbing extends further back as well. May check into this to see if there is any reason that mounting point needs to be so far inboard...although again given the thickness and webbing it appears better able to handle extra load.

That said, I am sure as long as Tornado has been around they will do right by their customers and at least offer an upgrade/retrofit of sorts. Andy has always been pretty good about answering emails as I recall and has a pretty good track record.

 

[Mark Littlewood]

Interesting problem,it looks very much like the steel used is clearly not up to the job ( from the bend in the steel) and using a rod end replacement is useless unless the steel used is of a certain quality, so if the standard part used poly bushes and was of T45 or 4130 it would still provide a reliable all purpose wishbone. The surface corrosion mentioned quite frankly is nothing!

 

[Cliff Beer]

Carlos, don't feel so bad, suspension stuff is always breaking and bending on race cars....particularly when run hard for extended periods.... The original GT40s had many documented cases of suspension failure too....and they had whole teams of smart people to do the engineering and maintenance.

If a car is seeing a lot of track time then the suspension should be regularly disassembled and checked for cracks and flaws. It's just about impossible to build a race car suspension that will go for years without a failure.

Thankfully it was just a bend, not the whole lower A-arm letting go at high speed (which happens too). As others have said, moving the lower attachment point closer to the ball joint will help a lot.

 

[(C)arlos]

Cliff thx for the kind words.
I agree to a certain extend if the car had seen track days and hard pushing on bad roads, I would agree, but it only has been driven on F1 circuits so far, flat smooth no bumps and no curbs ( not hunting for 1/1000 of a second)
I have driven it perhaps 98% on the road so no abuse.
However as somebody else said, the ring is raced by 1000 of cars per month and they don't break ...And I would expect the same from this car.
However, I am just the messenger her ( because of language difficulties the current owner has) but if it would still be my car, I exactly know what I would had to do....

Carlos, don't feel so bad, suspension stuff is always breaking and bending on race cars....particularly when run hard for extended periods.... The original GT40s had many documented cases of suspension failure too....and they had whole teams of smart people to do the engineering and maintenance.

If a car is seeing a lot of track time then the suspension should be regularly disassembled and checked for cracks and flaws. It's just about impossible to build a race car suspension that will go for years without a failure.

Thankfully it was just a bend, not the whole lower A-arm letting go at high speed (which happens too). As others have said, moving the lower attachment point closer to the ball joint will help a lot.

 

[(C)arlos]

If you buy a kit and have to outsource important parts to 3rd party manufactures or even competitors that would leave a very bitter taste...

Although a Tornado owner could easily out-source the fabrication of custom lower arms to a stronger spec, it sounds as though Frank Catt and Mick Sollis have already done this, so why re-invent the wheel, IF Tornado do not have a suitable upgrade?

 

[Keith]

Carlos, please don't be disingenuous. The 'Ring' may be "driven by 1,000's of cars" per month they are mostly production cars, fully manufacturer tested to destruction and designed for 100,000 miles + of abuse with manufacturers liability and warranty and fully compliant suspension - nothing much critical about their set ups, i.e. not stressed.

I think it an unfair comparison with a kit car, perhaps built by someone without knowledge (not yourself obviously) and now driven by a "racing driver".

What I'm trying to get across, is not defending any manufacturer with their parts or design that's between them and their buyers, but I'm trying to alert people to the fact that the 'kit cars' are just that, kits with, in some cases, unproven pedigree in engineering terms. Really, the buyer, assembler & user becomes the testing regime.

If you buy a kit, I believe it is the owners responsibility to ensure it is fit for your purpose, and not just to assume it is a "high performance car" when the supplier has no idea of your skills of engineering and assembly or even usage.

These kits are extremely affordable but if parts have to be manufactured to the nth degree, then they will certainly not be. It also is right that heavy duty parts are also made available for those who want to push the envelope. However, if there are limitations with standard parts, then that too should be flagged up, i.e. "road use only" - leave the track bit out, as that can be interpreted in many different ways.

It is precisely because I am NOT a skilled engineer is why I would always resort to a qualified person at the building stage, as I wouldn't trust myself to know what's good and what ain't.

Perhaps I'm not explaining myself very well, but in 'component car' terms, I believe the buyer/builder must accept some responsibility for the car's construction and use which totally different to a standard production road car mindset.

 

[Jac Mac]

Carlo's, can you put up a photo of RF shock/spring assy as removed from the car?

 

[Mark]

If you buy a kit and have to outsource important parts to 3rd party manufactures or even competitors that would leave a very bitter taste...

To be fair Carlos, many a car, kit or mainstream, will require many upgrades to make safe enough or strong enough for the track. I sense you are beginning to attack a manufacturer now, rather than simply raising awareness to a shortcoming in a particular kit?
I am simply pointing out that should a tornado owner wish to upgrade a part that has been found to be lacking in regards to track use, they need not re invent the wheel, when the work has already been done by someone else.
Should Tornado offer a better explanation and more complete statement regarding their upgraded items? Yes! But let's not make this a witch hunt.

 

[(C)arlos]

Will do so, might takes a day or two...

Carlo's, can you put up a photo of RF shock/spring assy as removed from the car?

 

[(C)arlos]

Pls read above what I have written about your concerns already.

Awareness has been raised I guess, but the tornado is not reacting on this and explaining what they want to do to solve this.

Somebody else already said, is it worth to make extra $$$ here and sell an "upgrade" ( not having seen any pics yet ) to a potential false designed part of a kit ( beside this I like the tornado kit ...once again ) since years instead of improving the overall product quality and design and let this go into the main production process ?
Many of us here have kids and wife's, are you going to be the messenger in case and tell them somebody wont come home no more ?


Andy should step in here and give advise and solutions for the problem.

But saying nothing and waiting for the end of the storm is not O.K. and of course this is not inline with how he wants his company to be recognised (longest in business, most kits, ....)

Again, we are all human, we all make mistakes ( man I made a lot of them in my life) but we all should take responsibility for them ... And this is what I am missing here.

To be fair Carlos, many a car, kit or mainstream, will require many upgrades to make safe enough or strong enough for the track. I sense you are beginning to attack a manufacturer now, rather than simply raising awareness to a shortcoming in a particular kit?
I am simply pointing out that should a tornado owner wish to upgrade a part that has been found to be lacking in regards to track use, they need not re invent the wheel, when the work has already been done by someone else.
Should Tornado offer a better explanation and more complete statement regarding their upgraded items? Yes! But let's not make this a witch hunt.

 

[Jim Cowden]

Re: This happens to a Tornado if you really race it

You will see in the attached picture that the alternative lower wishbone unit ( not a Tornado product ) carries the weight of the car as close as is physically possible to the outer upright swivel joint, which prevents any bending moments or stress in the wishbone arms, Frank

Carlos

There is your sollution post # 32, ring Frank.

 

[Martin]

Interesting read.

My opinion would be this for what its worth.

Tornado cars are built to go fast, otherwise they wouldn't be supplying them with V8 engines as an option. The difference between a Tornado and say a modern Mustang is that it is a replica of an old race car. Therefore, unless it is expressly stated in the sales literature, on the website and on all forums etc that the car is NOT suitable for track use, it is likely that the assumption is that it would be. That is because it's sold as a 'REPLICA'. We don't like to be tarnished by the 'Kit Car' label and like our cars to be known as replicas. If that is going to be the case, then the old 'kit car' mind set has to change as well. If Tornado isn't suitable for the track without major component changes, it needs to be explicit about that, not just reactive to criticism.
I wasn't aware that Tornados had issues about track use when I was in the market for a replica GT40 and would have appreciated knowing as it is a decision to be made when we purchase. Will we or won't we use it on the track ? I didn't go for a Tornado in the end but I was looking at them as a serious option at the time.
Not everyone who buys these cars is a techno wizard either and can't always make determinations themselves about what should and should not be upgraded before taking their car to the track. The manufacturers have a duty of care to inform about the limitations of their cars.
To me it is obvious that a good proportion of these cars may well see track time or at least be driven spiritedly on the road.

My second point would be that the design of the suspension arm is obviously flawed and under engineered for the type of car it has been designed for. I don't accept the argument that the price of the kit would sky rocket if it were made to take more load. The current design is just bad. A serious weak point has been found and at least that component should be upgraded. In my mind on all cars, not just a track specific mod.


Martin

 

[Glenn M]

Jim, and others who have asked, the bent OEM Tornado arms that I have seen were made using 16swg ERW seamed tubing.

Glenn

 

[Randy V]

Jim, and others who have asked, the bent OEM Tornado arms that I have seen were made using 16swg ERW seamed tubing.

Glenn

Are you absolutely certain that ERW tubing was being used?

While I've yet to see the case where that weldment has broken, the largest issue with ERW seems to stem from the inconsistent wall thickesses observed within the circumference of the tube itself.
I believe that ERW tubing has been banned by most motorsports sanctioning bodies for use in rollcages due to this very thing.

This is unfortunate for certain, but track use, particularly that part of the track where curbs and rumbles (gators) are encountered, can be extremely demanding on all components of a car...

 

[Andy Sheldon]

I thought I would wait until all of the background noise had died down before making a subsequent post to my original post No 19.

Quite why some have posted here I am not sure and they obviously have hidden agendas.
Or maybe they are not so hidden.

Regular visitors to the forum will know exactly who these posters are.

The correct way to handle such a complaint would have been for the OWNER to contact the factory directly. This has not been done.

A bend in the rear leg of the front lower wishbone is usually caused by fitting the wrong shock absorber, spring or incorrect adjustment. There is a warning about this on page 30 of the build manual.

The shock and spring combination controls the suspension travel. If the spring becomes coil bound the shock load will go to infinity and something will bend. In this case the wishbone.

The wishbone can easily be replaced but the chassis is more difficult to repair.

Looking at picture 5 in the original post the bottom platform on the shock absorber looks to have been wound right up which will cause the spring to become coil bound during suspension travel.

The platform should only be 1 or 2 threads from the bottom of the shock.

I have seen mentioned that moving the lower shock mounting outboard removes the bending load. This is not true and would only reduce the bending load by approx 10%.

Moving this mounting outboard will soften the spring rate and more easily cause a coil bound situation to occur. If the wishbone is manufactured in gas pipe like some I have seen it will damage the top shock chassis mounting. Those who have fitted them be warned!

Our wishbones have never been manufactured in 16 gauge ERW and to say so is Liable.

They were manufactured in 14 Gauge sometime ago.

We have always offered an upgraded suspension package for regular competition use.

If any customers have any further concerns or would like to upgrade please contact me directly at [email protected] or call me on 01562 820372.

Thanks

Andy.