Chassis stiffness...

[Roark_John]

Fran, do you have any numbers for torsional stiffness on the SL-C chassis?

Given the way that it hooks up on the track, and the relative shortness (overhanging length) of the SLA suspension, it seems to be pretty damned rigid!

I came across something that "may" be of interest to you, possibly for an all-out track car, or those guys who want a little something extra...

http://allterrainresearch.net/store...pID=43&zenid=34c175b18dae137383b028af739666bd

Think of it as Viagra for your chassis (Not saying that you need it, but you & others may WANT it...not trying to be a cook in your kitchen, just thought I might share with you of one of my many performance related discoveries)

These extrusions are meant to slip inside of 1.5" x 4" tubing, so I wasn't sure if these would fit inside the main rails of your chassis.

Anyways, I was showing an acquaintance of mine several bits of footage of your cars on-track, as he had enquired about the car I was going on about...he was quite impressed to say the least, as he has several very nice cars in his stable...among them a Ford GT, Ferrari 360, Corvette ZR1, Corvette Z06, Audi R8, Hennessey Camaro with LS9, etc.

That's what prompted the question of chassis stiffness, in relation to other aluminum chassis' cars he is familiar with both on-road and on-track.

 

[Fran Hall RCR]

Thanks...pretty cool...looks pretty heavy though..

We know for a fact that the standard street base chassis without cage is over three times stiffer than the I quote "worlds fastest car"...and thats not taking into account that the SL-C race car has a very substantial cage and will rival most anything else out there...racing or otherwise.

We actually do run tubes inside of tubes on the SLC chassis to increase strength in critical areas, creating a multilevel extrusion without the need to make custom tooling...

 

[Ray]

That's the spine that I installed in my Can Am Renegade800x quad, the frame is the weak link on Bombardier 4 wheelers.
Cheers Ray

 

[James]

I read somewhere on these forums that an Austriailan team with the racing cage had something like 24000 ft/lbs/deg.

I am guessing by Fran's quote that the SLC in street form is around 10,000 ft/lbs/deg

 

[Fran Hall RCR]

James there is no Australian SLC with a race cage.....only the two here in the USA with race cages...so far....

The 01 car with the race cage has shown over 35,000 in FEA analysis...this is without any drivetrain components being installed...(engine plate or engine)..which would obviously increase the test figures shown.

 

[James]

I reread the post I saw. I must have misread it, I thought it was with a cage, however it was just with just fitted with anti-intrusion bars.

The post said the following

* ADR test documentation for chassis, body, suspension etc. Standard street chassis has torsional stiffness of 25500 Nm/deg/M. Suspension strength exceeds ADR requirements by more than 10 times.

That's 18,800 ft/lbs/deg,, which is pretty impressive

 

[Fran Hall RCR]

She is a strong one....now add the race cage (which has 20 points of attachment to the chassis) and you have a very safe...which is the primary goal IMHO...strong and capable chassis...

The ontrack proshop at VIR was kind enough to allow us use of their scales at the 13 hr...I am hoping to get the picture they took of the scales and the accuracy of our set up...without pictures you guys will not believe me....trust me it was awesome.

 

[Ben Whittle]

She is a strong one....now add the race cage (which has 20 points of attachment to the chassis) and you have a very safe...which is the primary goal IMHO...strong and capable chassis...

The ontrack proshop at VIR was kind enough to allow us use of their scales at the 13 hr...I am hoping to get the picture they took of the scales and the accuracy of our set up...without pictures you guys will not believe me....trust me it was awesome.

Go on, you can always back it up with pics later

Out of curiosity, how much does the bare chassis weigh? I think the Ultima is supposidly 120kg and isn't the new Maclaren like, 80kg or something?

I'm not entirely sure why it matters enough for them to quote these figures since I'd only be concerned with overal weight and unsprung weight.

Regardless, that is some impressive chassis stiffness....

 

[Fran Hall RCR]

As soon as the picture arrives from Vic. I will post it....

The SL-C is not as light as the Ultima in overall vehicle weight by about 100lbs but it all depends upon drivetrain too....many SL-C have Ricardo boxes which are hefty compared to the G50's too.

 

[Dave]

The SL-C is not as light as the Ultima in overall vehicle weight by about 100lbs but it all depends upon drivetrain too....many SL-C have Ricardo boxes which are hefty compared to the G50's too.

They aren't nearly as rigid either.

 

[Ben Whittle]

Ever get that pic of the weight?

 

[Fran Hall RCR]

I asked again the other day....so not yet but what it read was that the car scaled with only a 1lb discrepency

 

[Henry]

Hey Fran, do you have any pictures of the race cage without the body on. I am curious to see the various mounting points.

 

[Fran Hall RCR]

Yes and we make our own cages and dont want anyone attempting to replicate them...they would not be certified as FIA legal if we dont make them in house...to our certified prints and specs...its a serious cage ..and as safe as it gets..

 

[Henry]

Wow, thanks. Thats a work of art. I was just wanting to see the difference between the standard and the race cage. I am trying to decide if I want to add more roll/crash protection but still be able to conceal the bars in the interior for the most part. Is there a way to get a modified race cage leaving a select few bars out? Mostly looking at the one that runs down the middle of the windshild and the center of the cabin. Does the front cross bar run under the dash?

Thanks for the pics Fran

 

[Fran Hall RCR]

We offer a trackday cage...The standard 6 point is completly concealed inside the interior kit.
We then have bolt in side protection for the more serious trackday guy....these can be removed in a few minutes without really impacting the usability of the car on a daily basis.

The race cage is a race cage ..pure and simple.

 

[Henry]

what are the diferences between the trackday cage and the standard 6 point? I like the idea of the removable side bars and I realy like the overhead protection of the race cage. Thanks for the help, I am just trying to picture this all in my head why I plan this thing out. I will be running track events but not full on races.

 

[Fran Hall RCR]

The race cage upper structure is very intrusive to a street car and not recommended without wearing a helmet ...ALL the time...

The standard cage has twin bars and is safer than most and is completely hidden and has removeable side bars as mentioned as a track day option....

 

[Henry]

Got it, thanks for clearing that up for me.

 

[Troy]

Sorry for the thread drift, but in other pics I've seen of the race car, it's fitted with a different seat? (I think?) Are the seats in the racer made in-house?