Space Frame Vs Monocoque

Hi All,
Having just recieved the deposit on my R500 I can now move on to the next project. I think the best looking GT IMHO (see I read the rules /ubbthreads/images/graemlins/cool.gif)is a MK1 with Gulf Flares to which I probably will need to add a Guerney Hump..My planned use is Track day's, Hillclimbs at Prescott, sprints, Brighton time trials and the odd cross channel blast to the Nurburgring,SPA & LeMans.

After searching all the posts I still have some questions.

I have narrowed down to 2 kits the deciding point is whether to have a space frame or Monocoque.

What are the pluses and minuses of the two designs? Weight? Stiffness etc.

My current Spec list looks like...
MK1, Flares Guerney Hump, Twin nostril,aircon,Stroked 302, injected, solid roller cam, alloy heads (spec?)Drysump,6 speed audi, Pin Drives, Tyres not decided.


I am keen to have a 6 point cage but wonder about the pro's and con's of this. The only GT40 I have been in did not have a cage. Since I am 6'I did nt have a lot of spare room to play with.

So your thoughts on all of this would be greatly appreciated.

Cheers David

 

[Hershal Byrd]

Dave,
Go with what makes you happy. They are both very good chassis.
If you do a search on this you will find a wealth of conversations on this very subject.

Hersh /ubbthreads/images/graemlins/smile.gif

 

[Bill D]

Both frames are very solid and will hold up under almost any track condition. The main difference lies in repairs. A monocoque is difficult and expensive to repair if you crunch the car. A space frame is relatively easy with just cutting out the damaged portion(s) and welding in new along with the replacement panels.

Bill D

 

[Trevor Booth]

IMHO-Go Monocoque route, lighter, stronger, neater, torsionally stiffer (if made correctly) You wont be disappointed

 

[Rune]

As a newbie can someone post pictures that show the diff?.
Rune

 

[Keith]

If money were no object (!) I would order 2 monocoque tubs (1 for spare)because there is no doubt they are superior and weight = HP. However, as has been said, you could bend a space frame and have it fixed for the following week for little money which would not be true of the mono. Actually, I would say that probably the only downside of a space frame is weight, as the average driver would not be able to exploit the advantage in setup gained from an extra stiff mono.

Just my 2 pennies worth. /ubbthreads/images/graemlins/crazy.gif

 

[Bill D]

Newbie-

Picture of a monocoque frame:

"]http://www.gt40s.com/ubbthreads/files/52584-davidbrown.jpg[/img][/url]

Here is a picture of Jim Dewar's RF GT40 with a space frame Hope you don't mind Jim. Yours is an excellent example of a space frame build.

Bill D

 

[Bill D]

The link in the previous reply didn't work, so check out this thread made earlier

link


Bill D

 

[Bill Hara]

Bill

The link you posted:
http://www.gt40s.com/ubbthreads/files/52584-davidbrown.jpg
It had some crud on the end of it, should work now.

Bill.

 

[Bill D]

It does. Thanks

 

Cheers Lads,

For my intended use I am leaning to the Space frame as it is reparable. You see that with the Caterhams, a lot of people get over excited, clip a tyre wall and tear off a corner. In fact Arch (L7 chassis makers) say that they replace a front section on average once a week during the season.

The main issue, outside of weight, I have heard with space frame is that with all the drilling for panneling there is a chance for corosion inside the tubes.

I also got to say thank you to Ron, Hirsch and the folks Hosting this list. What a great resource, I look forward to posting all kinds of silly detail questions over the choice, ordering & build of my kit.After of course searching the history to see the previous answers.

 

[Keith]

Corrosion? I reckon that'd be the least of your worries unless you intend to road drive it in the winter over here - salt is definitely the killer. Of course, you can drill the individual box sections and inject Waxoyl etc, that should do the trick. Personally, I wouldn't drive it in the wet/damp/cold anyway.

It must be a luuurve thang.... /ubbthreads/images/graemlins/crazy.gif

 

[Bill Musarra]

I too decided to go with the space frame version. Repairability is high on my list, or should be if you plan any track time. If you are a purist then go with the tub. Remember, the weight to H P ratio on these things is rediculous. Your body weight probably plays a greater role than the difference in the two cars. I think you should go on personal preference, rational, etc.. Your the one who has to be happy. Compromises should come in other areas, like H P, orF I vs carb, or how much money you have to spend!!!!!
Bill

 

Well said,
I have gotten a lesson in power to weight over the last 4 years of owning the caterham. 235HP 500 Kilos ready to race. That car has taught me more about set up and impacts of things like un-sprung weights, changes in roll bar thickness, spring rates etc. Even the impact of 2 PSI change in tyre pressure could be felt. I am still learning about driving a car fast and the 7 has given me the opportunity to expedite that learning curve. I don't expect the GT40 to match its abilities but am looking forward to the different experience and the learning process that will bring.

 

[Jim Rosenthal]

The space frame is lighter, cheaper, and easier to fix. The monocoque is more original, but more expensive, gives less room inside the car, and is hard to fix if damaged. The monocoque is probably more prone to rust, which is not an issue with zinc-coated steel and proper painting. The ideal one, if you ask me, would be an aluminum monocoque cut out on a CNC machine and jig welded together. Lighter, no rust, and easier to build.
That's my monocoque in the photo, by the way, I think. /ubbthreads/images/graemlins/grin.gif

 

[Fran Hall RCR]

NEW RCR ALUMINUM MONOCOQUE

Well Jim,
you have just described the new RCR monocoque chassis to a "T".....
The first batch of five will be ready for build up in a few weeks .....structural testing taking place at the moment on the prototype...and it is performing extremely well.

A few details to wet the appetite......
WATERJET cut panels
TIG welded
Jig built
CNC uprights
rod end suspension all round
complete as a roller for less than $30,000 complete with Mk1 or Mk2 body.....

More info to follow.....just a teaser /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/tongue.gif

I had wanted to keep this quiet for a little while longer but as it is a current topic ...why not. /ubbthreads/images/graemlins/grin.gif

 

NEW RCR ALUMINUM MONOCOQUE

That chassis is going to be a beauty, Fran...

Any estimates on the final weights of your Mk. I kit with a Ford 302?

 

Well after much deliberation and discussions with some fantastic people. I have placed my order! Still waiting for confirmation of shipping dates. but expect to have a very fun Christmas and New Year!

 

[John W]

Good news Dave.
Did you go with a Mono or a space frame, and who from ?

Cheers,
John.

 

[Fran Hall RCR]

Michael,
the mono is not aimed at being lighter than the tube frame but it is marginally so.
Our goals are to provide a stiffer/stronger chassis with an eye on original design details to appease the guy that wants a more original feel and it is also an easier build with no drilling or riveting etc etc etc

We have widened the interior by two inches and been able to extend the footbox...like my pal Jim Dunhams mono, to accept a longer legged individual without having to drop the floorpan. A 6'2" guy seems to fit nicely compared to the tube frame cars.

Cheers