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Chassis Stiffness


Guest Wragie

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Guest Wragie
Here you go dave

 

Some lightweight reading for you

 

 

http://grahamsgarage.webs.com/alltheinfo.htm

 

 

Thanks Ian but thats not what I'm looking for. Or I managed to miss it on Grahams site the last few times

I've looked there.

 

I'm not looking at or for general stiffness mods but the actual beam test or stiffness per degree measurement

of the chassis. The guys from Oz end up doing this as most 7's don't meet thier standard for stiffness.

 

Dave

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hi dave

as far as i am aware this has not been done , pm scottmac in the states , he is a lot more tech than me .

there is as i remember some further speculation on the lightweight section from another guy in the states re the

actual quality of the ally used .

sorry cant be more help .

 

graham

 

there is a pic in the rhsc brochure of a lightweight on what looked like a test bed ?

i dont have one handy at the mo .

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Guest Wragie

Hi Graham

 

I hadn't heard anyone mention doing it either so thought I'd ask.

 

I know the pic you are talking about. I just saw that

one the other day. Bare frame on a steel bed with a few

hydraulic cylinders. It's prbably what got me wondering

what the numbers actually arre.

 

Just talking to Scott about the material type the other day.

I still think its a 3000 series alum.

 

Cheers

 

Dave

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hi dave

re the literature thing , mayby speak to gbs , they may have some info re the test bed .

i rember that there was some results re the test cos the question has i think been asked before .

graham

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Guest ScotMac

In terms of the chassis stiffness, i think what Dave is looking for is the results for the BASE RH chassis. Obviously the numerous chassis w/ strengthening are going to run the gamut, in terms of differing stiffness...depending on what strengthening was done and how effective it is.

 

So, maybe GBS would have the info, or the original Tricky Dick...

 

Scot

Edited by ScotMac
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Guest Wragie
In terms of the chassis stiffness, i think what Dave is looking for is the results for the BASE RH chassis. Obviously the numerous chassis w/ strengthening are going to run the gamut, in terms of differing stiffness...depending on what strengthening was done and how effective it is.

 

So, maybe GBS would have the info, or the original Tricky Dick...

 

Scot

 

You pretty much have it Scot. The reason I mentioned the Oz ADR beaming test is that test is designed for the builder/car owner to do.

Had hoped someone was curious enough to try it ;-]

 

The basic idea is to simulate what happens when one front tire hits a big bump and hits the stops. And they measure

how much force is required per degree of body twist. It's a non destructive test btw in case anyone wants to try :rolleyes:

A Lotus S3/Locost has about 1400 newton meters per degree, the Oz spec is above 2000, the Oz mod'd locost is about 2400.

A full race 7 with cage etc is about 8500m, good monocoque sedan car is about 9000 and something with say carbon fibre

chassis would top 10000.

 

 

I've got 2 pics of it being done on a conventional steel tube 7. Other than borrowing a lot a dial gauges the actual test

looks pretty simple to do.

 

post-1707-1236321258_thumb.jpg

post-1707-1236321273_thumb.jpg

 

Dave

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  • 3 months later...

hi dave the techy bit passes me by im affraid

i can only report that mine has been on the road for over 2.5 years and has been over very big pot holes

no probs as far as that is concirned .

my prob is the power i now have and its trying to escape ?

dans has been on the road and has been driven to every major show for over 2 years and is still in one piece

with a bit of extra strenghening arround the diff .

so re the testing not sure as i dont know the figures required to pass .

but the lightweight will continue here at least for now . wheather it be mine or dans .

 

graham

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  • 2 years later...

Hi folks,

I was rather hoping that there may have been an answer to this question - especially as I se it was first launched in 2009.

 

I am in Oz and facing the test on my wide body Zero kit. Eddy, the guy in Orange NSW I bought the kit through has a conventional body Zero and has tsted his to 3300nm, however I am reading the current ADR's and they are suggesting 4000nm as a pass figure! They do qualify this figure with a statement that it can be less than 4000 if the manufacturer of the chassis can prove that it was engineered to a lower stiffness. I have not had an answer to the question from GBS yet, but I live in hope...

 

BTW, it can be done by the builder (although here the testing engineer has to record the data), but it is not cheap ( Eddy helped his engineer build the equipment used in the test and it cost over $1,500 - £975) that's a lot in he scheme of things for a piece of test equipment. It also costs about $1,500 for the engineer to do the test - if he provides the equipment.

 

If any one has done the test over there or in the U.S I would really like to hear the results.

 

Cheers

Geoff

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Hi Geoff,

 

just to clarify the thread started for the Robinhood Lightweight which is an all alu monocoque that was produced for a couple of years but is no longer made.

 

The Zero is a more traditional square tube frame that as you say has only been produced recently by GBS.

 

They will have quite different figure i would imagine. just wanted to make sure there was no confusion as to which car type people are talking about

 

 

as an aside it would also be interesting to see what the 2b specs were like as well. that way we could see monocoque, square tube and round tube differences.

 

hth

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Thanks agent-zed,

That the thread refered to a different type of construction did get past me, and I thank you for pointing it out.

 

I am getting hold of the tsting equipment in the next couple of weeks and will post the results her when I have done my initial tests (prior to the engineer's official test). Can't help with the lightweight I am afraid.

 

Cheers

Geoff

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  • 8 months later...

i´ve seen that some people are using galvanized bolts on the moncoque. in combination with the alloy (+water) this will form a "nice" galvanic-element, which fianally ruults in alloy corrosion.

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