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Chassis, floor specifically...
stevio73 - 31/8/13 at 03:13 PM

Hmmm, I'm nearly at that time to start plating and so forth but need some advice.

I was thinking about aluminium chequer plate for the floor, reasoning was the general in' and out's by feet and shoes
Will scratch any flat Ali plate and start looking as such quite quickly, chequer plate not so much. But then I got to thinking
How thick? 1.5mm or 2mm? I'm looking to run a ZZR1100 in it so don't need massive weight.
The next quandary is fixing it to the chassis.... Do I opt for zillions of rivits or go with captive nuts in the rails and countersunk
Allen bolts from underneath, or weld on tags inside the frame to bolt from underneath and have a nut above. Or indeed a combination
of all of these methods?

This is my first time building a roadster type car. Previous stuff I've done all had shells etc (escorts and the likes) so never encountered
Such a predicament.

sebastiaan - 31/8/13 at 03:26 PM

2mm thickness, you do NOT want anything to come up through the floor and bang you in the nads... As for fixing: sikaflex and lotsa rivets is the way to go, but I'd think twice about the checkerplate as you will not be able to fit it snugly up against the chassis and it will end up looking naff. I fitted carpets to mine, the kind of rot-resistant stuff that you can get to upholster car boots. Lasted well, looked nice and weighs next to nothing. probably lighter than the checkers on the checkerplate...

Slimy38 - 31/8/13 at 04:40 PM

I currently have my eye on a bit of chequerplate that I'm planning to use on the floor, but your point about it not fitting flush is something I'd not considered. I wonder whether it would be possible to flatten the chequer just where it sits under the tubes (before it gets bonded and riveted)? Aluminium isn't that rigid, and it would only be an inch wide strip?

[Edited on 31/8/13 by Slimy38]

jacko - 31/8/13 at 05:13 PM

quote:
Originally posted by Slimy38
I currently have my eye on a bit of chequerplate that I'm planning to use on the floor, but your point about it not fitting flush is something I'd not considered. I wonder whether it would be possible to flatten the chequer just where it sits under the tubes (before it gets bonded and riveted)? Aluminium isn't that rigid, and it would only be an inch wide strip?

[Edited on 31/8/13 by Slimy38]



If you do decide to remove the bar's don't use a grinder the alloy gets stuck in the grinding wheel very dangerous
I think its best to use flat sheet because as its easier to clean all the stones and rubbish out the car and you dont see that much of the floor
Only my opinion
Jacko

Peteff - 31/8/13 at 05:25 PM

Use a fibre disc in the angle grinder with WD40 to take the chequer off, it works well.

Talon Motorsport - 31/8/13 at 05:28 PM

The out side ridges can be removed with a flap disk in a grinder (use a dust mask!) the inner bits if your doing it in one piece can be done with finger linisher,air file,25mm finger belt sander what ever you want to call it.

stevio73 - 31/8/13 at 05:41 PM

Yeah good points all round. I had already thought about the removal of the cheque where it meets the chassis.

Rivits and sticky it is then. But thickness still up for debate.... Years ago I raced a 250cc Kart with a plastic floor tray. Never had any issues with floor penetrations. Okay, clearance was next to zero which to my mind would increase penetration likelihood.
Originally I considered 1.2mm, Thoughts?

jps - 31/8/13 at 05:57 PM

quote:
Originally posted by stevio73
clearance was next to zero which to my mind would increase penetration likelihood


or, it meant the front acted like a broom, catching anything that might penetrate and stopping it from getting under the floor
in the first place?
I'm using 3mm ally on the floor, but only because it was free!

stevio73 - 31/8/13 at 06:11 PM

I realise the concerns, but surely your not going to willingly 'run over' something that looks spikey without slamming on the anchors?

Even if you went for steel of, say 22gauge, the same penetration risk is there? I'm not about to use tissue paper but, the whole idea is to get performance from small engine, so weight is the issue.


Bit of an addition to the original question, what's everyone using for the sides? And do you plate inside too?

Peteff - 31/8/13 at 09:54 PM

You may as well use two layers of cooking foil as 22g. 16g or thicker aluminium if you are going to need to stand on it to get in and out of the car. 18g for the sides at least or they will ripple every time you touch them.

stevio73 - 31/8/13 at 10:32 PM

Good point. Was maybe being extreme with 22g.

Another consideration is how much rigidity the panels add to the chassis? I had heard that the Elise Ali tub is glued and riveted extrusion but the strength of the glue renders the rivits extra to the deal just a belt and braces kinda deal. How rigid does a chassis need to be?

jps - 1/9/13 at 08:03 AM

quote:
Originally posted by stevio73How rigid does a chassis need to be?


have a bit of a dabble with the search function for stuff on chassis ridigity - ive seen a couple of threads over the last few months that cover this to a level that lost me very quickly!

steve m - 1/9/13 at 10:29 AM

"In my younger days I had a Lotus 2+2, that had a fiberglass body, including floor, that was "plonked" over a double Y chassis, real Kit Car !!

On my way to work, I saw somthing in the road ahead , and decieded it safer to drive over it , than swerve, into the oncoming lane,

If my wife or any other passenger was sitting next to me, they would have been killed !!!!!!!!!
the 2 X 4piece of wood about 24-30 " long, came thru the floor with such a force it took the seat cover off the passenger seat and went thru the headlining
It left a hole in the floor about 4" square, that was so neat , you would have said it had beed drilled !. and all this happened at about 60 mph
and when I say seat cover, iI do mean a original fitted, Lotus spec seat cover,not a halfwits thing !!

My car (point left ) has a 3mm welded steel floor, and I for one would not even think about going fiberglass,
The only saving grace in a seven, is that the floor is only 4-6 " from the ground , so in theory nothing would have the leaverage to spin/dart upwards

The 2+2 was sold within 2 weeks with a fiberglass patch. and the carpet glued over the hole

shame really, as it was my 3rd favorite car of all time

Fav no 1 E- Type
Fav no 2 DB5 Aston
Fav no 3 Elan


Fav no 326 "7""


and the thread it came from


http://www.locostbuilders.co.uk/viewthread.php?tid=55719

PhillipM - 1/9/13 at 11:00 PM

quote:
Originally posted by stevio73 How rigid does a chassis need to be?


A rough rule of thumb for bare minimum - 10x as stiff as the difference in front and rear roll stiffness for decent, linear handling.
For durability, ride comfort and 95th+ percentile suspension performance, 10x stiffer than the maximum spring loading on one corner including the damper force required to compress it at that speed if it results in a higher force at some point in the travel. (which you can work out from the weight of the car and the force needed to get the time, giving damper velocity and hence rough force level).

That way the chassis also accounts for assymetrical loadings, shock loads, potholes, jumps, etc, etc, rather than just pure cornering stiffness on a perfectly smooth track.

dhutch - 2/9/13 at 06:29 AM

quote:
Originally posted by Slimy38 I wonder whether it would be possible to flatten the chequer just where it sits under the tubes (before it gets bonded and riveted)? Aluminium isn't that rigid, and it would only be an inch wide strip?
I dont thing you would manage that, not with a hammer anyway. Flap disk would work, as would machining it off, but the later might be overkill!

That said, I would go with flat. Resolves the above issue, lighter, cheaper, better with carpet, and I have not had an issue with mine being slippy or looking naff. You get a very purposeful looking 'random brushed' dull grey effect which I think like very nice actually.

As said, assuming it doesn't need to be removable, I would bond it on with sikaflex (or other brand of PU) with a fairly small number of pop rivets, to hold it while the PU cures, and in case of the highly unlikely PU failure. I expect every 100mm is enough to hold it alone, else you could got far lower if you also clamped it while the PU cured. Bar the minor and controllable issue of sliding, you could probably do worse than bonding it on using clamps, and adding the pop rivets afterwards!
Depending on what you think your paints like, I would be very temped to remove the majority of it on the bonding surface, but leaving enough to ensure small overlap between the PU and paint.

In terms of thickness, while Ive not measured it, mine (standard westfeild oem from 91, as far as i know) is around the 2mm mark, which enough nothing else, if just about thick enough to mount the seats too (four point harness keeps me/seats in, so its just stopping it sliding and or, me falling onto the road) and I am fairly happy with that.

In the advent of something coming up under the car, jamming between the road, my floor, and forward progress, im confident it would get through, in fact with the right object, there's enough energy there to get to anything suggested. At which point I agree that the main saving grace is that the floor in question is low, and smooth (bat my seat mounting bolts...) so the chance of something getting in the right place is slim. Karts work in the principle, that and the fact on a track the're in a fairly controlled environment compared to the open road.


Slight aside:

I have, in a tintop however, driven over a 8ft length of somewhat bend scaffold bar at about 50mph, so anything can happen. Made one hell of a bang, and put a fair dent in the bottom edge of the front 'chassis member' narrowly missing aircon, sump, and main wiring harness (pug306) before flirting into the fast lane. Really did sh it me up, pulled over 50yrds later at slipway exit shaking like a stick, to inspect what I was assuming was going to be a fair mess. Lucky.
I was following a truck, and a not un reasonable distance, on a two lane dual carrageway, when said bend scaf bar came out from under the wheels of the truck, from where I will never know, jumped into the air about head height, as I slam on the anchors, with it landing just about as I went over it, having scrubbed 65mph or so down to maybe 40/50.



Daniel

TheGiantTribble - 2/9/13 at 08:15 AM

Why not got with the flat steel/aluminium and then add the checker plate on a roll stuff you can stick on
like this.... http://www.cbsonline.co.uk/product/Chequerplate_Effect__Floor_Mat_CHEQU

stevio73 - 2/9/13 at 05:00 PM

Thanks for all the advice, I am still undecided on the chequer or not. Whichever way I go its gonna be 2mm and stuck and riveted.

Hit a bit of a mile stone today. Got all the legs on it and on the ground as a roller! Feeling really good about that. Had some goodridge hoses arrive for the brake flexis. Fronts are a little short though meaning I'm going to be playing with bracketry and maybe exposing a bit of copper or even.... (I'm getting ideas even ask I type this) dished bulges on the sides. It might look a little hamster like but fairly sure it'll work.

hughpinder - 23/9/13 at 02:01 PM

I remember a program on the telly 15 or 20 years back called something like 'extreme survivors'. One of the episodes featured a guy in a volvo who had driven into a bridge where the side rail was a scaffold pole supported alonfg the side of the bridge. The poles end had been left sticking out horizontally. Anyway the guy drives off the road at about 60 - 70 mph. The pole penetrated srtaight through the length of the iron engine block and through his chest/1 lung pinning him in the car. The description of the resulting cutting of the pole to get him out of the car, and removal of it in hospital is quite gory/horrific. Anyway, if you want to avoid all chance of penetration of your floor, don't drive above 50mph unless your floor is stronger than a volvo engine! 3" high tensile steel should do it.
I'm using 2mm 5000 seriesd aly bonded and rivetted for my floor.
Regards
Hugh

[Edited on 23/9/13 by hughpinder]

[Edited on 23/9/13 by hughpinder]