Other than time issues, are there any considerably difficulities building an aluminum monocoque using sheel aluminum with rivets for joints unseen and epoxy or spot welds for the remaining?

Anyone know why more chassis like this are not made (other than cost) in the kit car markets?

Thanks

its probably easier to design a well handling space frame chassis. im only guessing there tho.

cheers

My opinion is that it is very costly and time consuming to build with Aluminium.

As discussed elsewhere on this site, rivets are not as strong as they could be unless you go the Aviation route. This puts up the cost considerably.

Would you really be comfortable bonding panels together structuraly?
I think you would need to be really confident that you were using the correct materials under the right conditions.

Finally, welding aluminium is a specialist job. I'd give it a go and I am quite comfortable welding steel, but would not do it on any area that was structural.

That is why there are not many aluminium cars about, even production models.
These are just my opinions though! Somebody prove me wrong please!

Terry

Hi Terry, I think you have correctly mentioned the main issues.

Another big one...design.
There are a lot of spaceframe cars out there for us to go "hmm, yes 1" x 16g should be good here"....but very few monocoques. Spaceframes are easier to analyse, they can be done on paper (and were done that way for many years) but sheetmetal structures are much harder to analyse without FEA...(read Roark's classic works to see why)

So, that alone would put me off (even though I've designed machines and structures for 20 years)....and then as you say the cost and time come into it..

I read a book by Allan Staniforth (the suspension guru) on how to design and build racing cars, but cant for the life of me remember what it was called (Probably How to Design and Build a Racing Car...) In this book he explains various methods and materials available for the home builder utilising aluminium honeycomb panels for to make a monocoque tub. May be of use if you can find the book.....

Stu, it is called.....Race and Rally car sourcebook....yes good book, but I don't know if you'd be a monocoque guru after reading it though

You would definitely have a much better understanding of the issues and techniques that is for certain.

Worth getting, it's a useful reference. It was a follow up to "High Speed Low Cost" which is another "must have" book....if you can find a copy

quote:

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Originally posted by Alan B
Worth getting, it's a useful reference. It was a follow up to "High Speed Low Cost" which is another "must have" book....if you can find a copy

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Liam,

There are some repeated diagrams etc., but more than enough extra stuff fo it to be worth having both.

Basically, "High speed low cost" is the story of the Terrapin mini based racing/hillclimb/sprint car...the world's cheapest 140 mph car

It covers chassis design concepts, theory and practice. Material selection. Suspension design including the legendary "string computer". The full story and build up details of the car and much, much more

IMO it is a far more significant book than the "book"...

Most of the princples and techniques can be applied to road cars too. It was the first book that said to me"Hey, you CAN build your own car..."

If you can find one..get it...you won't be disappointed.

The Highspeed lowcost is very good reading and even though it is old it gave me some ideas on how to get around the suspensions adjustable and such. It also shows a good pic of a string computer and rear susp and upright. The terrapin is about 60-75% of a locost weight so do have to beef up somewhat.

The thing I am looking at here is essentially designing a tub out of card paper, then transfering that onto aluminum ect.

However, price isn't really a big deal for aluminum here. As I live in Canada, the metal prices are VERY cheap and aluminum sheet for a chassis wouldn't be all that much in excess of the total steel to do a chassis.

Likely, I will use steel, but I was wondering what the feasability was for a monocoque.

I had also looked at going the aluminum honeycomb route, but I currently have not located a manufacturer anywhere close to me.

Something like this:




This is just a mockup that I threw together using some 3d software I own.

[Edited on 13/12/02 by MattWatson]

Matt, it is probably worthwhile joining the locost north America and locost theory lists on Yahoo if you aren't already. Both good resources as well as here.

I hope I don't seem negative about the monocoque idea, but just to bring to your attention what's involved

It is certainly feasible, just not very practical unless someone has exsisting monocoque design experience...IMO

I would be the last person on here to discourage taking the less troden path.....


My build is hardly conventional for a locost

http://www.desicodesign.com/meerkat/

I am most likely going for a steel space frame, but thought it might be cool to try something different.

Thanks for the advice!

It's certainly cool to try something different (can I tempt you with 4WD?) and I reckon doing a monocoque tub is *just* within the capabilities of the average amateur home builder - construction wise. I considered it myself initially - a tub with removable steel tube sub-frames for front and rear transmission/suspension. But unless you know *exactly* what you're doing designwise, it's rather daunting territory and you could easily end up with something dangerous. What kind of background do you have?

I decided I didn't have enough knowledge to do a tub and didn't want to spend ages acquiring it (not for my first ever build anyway), so I'm sticking with good old steel tubes. I'm keeping my head aching with 4WD and an engine that looks twice as big as my engine bay - I knew that 'Tardis Design' module at uni would come in handy.

Cool - you're in Canada. You must know my cousins Aeron and Byron Pope - they live in Canada too.

Liam

I am wondering what a mono tub actually does for you?

If its weight, to be as radical as making a composite tub to save a few lbs, you would need to be as radical everywhere else to make it worthwhile.

Just pick up a wheel and hub/upright. Heavy. You have four on the car. I would guess that one or two would weigh more than the basic space frame.

Lets say a normal 'frame with a alu floor, but without panels weighs 140lb as a guess, and you reduce it to 70lb - a 50% reduction. In a car that typically weighs 550kg (1200lb) thats not a ballistic saving.

You would need to think radical all through the design.

The problem with being radical, is that its seldom possible to get everything right first time. If you screw up on a one off car and something fails on the road, the consequences could be bad. There isnt a lot of scope for testing.

Hence Alans theory of if you have seen it on other cars, its more likely to be 'ok'.

My car isnt exactly standard, but I havnt taken what I think are 'out on my own' risks.

If the alu is to save cost as its cheap locally - it wont. The cost of the chassis and panneling can easily be outstripped by a decent set of shocks and alloys!

Building the spaceframe is one of the cheaper parts of the car to build.

atb

Steve



[Edited on 13/12/02 by stephen_gusterson]

quote:

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Originally posted by Alan B


...(read Roark's classic works to see why)

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quote:

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Originally posted by Alan B


...(read Roark's classic works to see why)

---

Alan,

Do you know of any good online bookshops that might have the "High speed, low cost" book?
Other than Amazon, I keep forgetting to bookmark them.

I have "The Rally Source book", so is "Competition car suspension" worth getting as well?

Cheers
Terry

quote:

---

Originally posted by Bull
Alan,

Do you know of any good online bookshops that might have the "High speed, low cost" book?
Other than Amazon, I keep forgetting to bookmark them.

I have "The Rally Source book", so is "Competition car suspension" worth getting as well?

Cheers
Terry

---

I use these these people,and have so far managed to get every single motoring book i've wanted.

http://www.chaters.co.uk



Doh!! except this one,site says its out of print but you can back order and its £25.
New ISDN 0 85059 037-X
Published by Patrick Stevens

[Edited on 14/12/02 by bob]

if u really want to try a monocoque why not try a 50/50 approch first look into to build a chassis with a backbone lotus elan style (i think)

then use a tub for the cockpit

Dont be afraid of using adhesives, I work in a VAG approved bodyshop and we repair A8's and A2's on a regular basis. They use a combination of bonding and rivets in their construction. The rivets are not the pop variety, but compression and need a special tool to apply, but could be done with a hammer and dolly if you have a practiced swing!
The adhesive is 3M structural bond and was used to 'glue' together the 6R4 body shell amongst others as it does not stress fracture like a spot weld would.
I think the Elise uses the same stuff for the side rails, with a single rivet at either end of the adhesive fillet to prevent shearing.
The strength of this stuff has to be seem to be believed, because the bonded are is greater than a row of spots, it is much stronger, and I think it may be stronger than a seam weld in mild steel because there will be no HAZ (heat affected zone) which is the weak part between the weld and the base material.
The only problem is the cost, its about £30 a pair of tubes and needs a special mixing applicator (£100), but it is BLOODY GOOD!

mark

seen as you work at vag how the hell do u get a interior door panel of a '96 A4


(guess wat i was at 2nite)