caber
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 posted on 28/1/06 at 11:55 PM |
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Stiffness . . .
I have been looking at Cymtricks paper on the Locost chassis and see what is proposed. In terms of practicality welding the transmission tunnel up so
you can't get at the gearbox tail and diff nose could make life tricky. I was wondering if the front and back top panels could be replaced by a
frame with a diagonal or possibly panels with access hatches.
I have also been looking at venting the rad at the back of the nosecone rather than letting it flow through the engine compartment. this would allow
for a plate that could stiffen the area behind FU1 and FU2.
Anyone any suggestions or thoughts about this?
Also, apart from welding, how can you attach panels to a chassis to transfer loads effectively?
Caber 
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iank
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| posted on 29/1/06 at 12:13 AM |
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I guess it depends how often you need to get access to that end of the gearbox from above. In a book locost Ron does fit it with self tappers  or
rivinuts. So putting in an access hatch couldn't be any worse.
What about venting upwards through a slot in the bodywork? Though with 7 aero it wouldn't make a lot of difference either way 
As for fitting panels Brazing/Bronze welding would work nicely I'd have thought (assuming you are worried about warping), and I'm sure
there are unbelievably strong adhesives that are up to the job.
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caber
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| posted on 29/1/06 at 12:39 AM |
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I was hoping to find a removable method preferably mechanical
Caber 
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C10CoryM
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| posted on 29/1/06 at 02:48 AM |
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Ive thought of this as well and have decided to use tube to triangulate the holes that I need access to. Shifter hole specifically. Then the
sheetmetal is just a cover and only needs to be held on by a few fasteners. To correctly triangulate something using stressed skin the sheetmetal
needs to be supported the whole way around. Usually closely spaced rivet and/or bonding agents. Otherwise the sheetmetal will just wrinkle or
flex which ruins the whole idea.
Regarding the radiator exhaust check out this post
http://locostbuilders.co.uk/viewthread.php?tid=37839
You will find that most people like that idea
Cheers.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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niceperson709
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| posted on 29/1/06 at 06:32 AM |
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I have made a pannel that directs the hot air from the radiator out either side of the car as you sugest not that hard to do just use some cardboard
to work out the right shape i have folds running from the inside bottom of Fu1 & 2 to a point above where the diagonal braces meet in the centre
of the frame . I will have some pictures at my build blog in a couple of days .I di think of making this in
steel and welding it but ended up using ally and fixing with self tappers )
Best wishes IAIN
life is not the rehearsal , it's the show so don't sit there thinking about it DO IT NOW
http://iainseven.wordpress.com/
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907
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| posted on 29/1/06 at 08:35 AM |
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quote:
Originally posted by caber
I have been looking at Cymtricks paper on the Locost chassis and see what is proposed. In terms of practicality welding the transmission tunnel up so
you can't get at the gearbox tail and diff nose could make life tricky. I was wondering if the front and back top panels could be replaced by a
frame with a diagonal or possibly panels with access hatches
Caber
Hi,
I've no idea what this does for the strength of the chassis, but what I did was to run the tunnel top rails
from the top of the dif mounts and brace them to match the chassis sides.
I have a one piece welded in floor with a vee cut in under the g/box, panels screwed in on the inside of
the tunnel for sides, and a recessed bits & bobs tray in the top, for fags, phone, sweets, tranquillizers etc.
All trimmed so the chassis shows. Access is by removing g/stick surround then top tray.
The whole thing acts as a sort of arm rest.
Paul G
 
Rescued attachment progress-aug-05-008s.jpg
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britishtrident
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| posted on 29/1/06 at 12:43 PM |
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Cymtricks mods are of great benefit to the chassis stiffness but they were to large extent forced by local regulations designed to clamp down on hot
rooders fitting oversized V8 into cars with inadequate chassis. To build a practical car you have to comprimise a bit, access is needed to the
gearbox to guide in the propshaft splines, connect the speedo drive and check the oil level, the solution is quite easy -- a large round hole
exactly as
Colin Chapman did on the original Lotus Elan. And use suitable large rubber bung from series Land-Rover to cover the hole.
A long time ago it was pointed out to be by an old hand that you only need sufficient chassis stifffness to allow control of the roll couple
distribution by spring rates and anti-roll bars. A Mini and an MG Midget aroughly the same weight and power but the Mini is about 3 or 4 times
stiffer than the Midget but both cars handle extremely well and if you put identical engines in both, all other things being equal they would turn
out very similar lap times. Of course if you were putting a much larger and heavier engine in the Midget you would want a lot more torsional
stiffness.
Adding a bulkhead panel at the front will severly limmit engine access and complicate engine removal/replacement.
To stiffen up the front of the chassis a digonal running from the corner LB-LC to LA-LD will stop lozenging of the front frame - a proven mod on real
Lotus Sevens
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blueshift
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| posted on 29/1/06 at 01:36 PM |
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Off-topic, but 907: haven't seen any pictures of your car for a while but that is looking really gorgeous. Not just the welding, but the
aesthetics of the colours, trim, dash.. well done.
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907
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| posted on 29/1/06 at 01:59 PM |
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quote:
Originally posted by blueshift
Off-topic, but 907: haven't seen any pictures of your car for a while but that is looking really gorgeous. Not just the welding, but the
aesthetics of the colours, trim, dash.. well done.
Thanks very much, but I just seem to go backwards.
I've started on the bodywork, ally wrapped round the back, and the top on.
Now doing the boot bin and lid. Sides are next, but that means the seats are
out (again) and the scuttle cover is off. Every time I look at the car there
seems less on it than the last time.
Is every ones build like this or do I do everything the wrong way round?
atb
Paul G
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MikeRJ
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| posted on 29/1/06 at 04:20 PM |
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That is a fantastic looking interior, probably one of the nicest I've seen in a 7.
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907
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| posted on 29/1/06 at 05:25 PM |
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quote:
Originally posted by MikeRJ
That is a fantastic looking interior, probably one of the nicest I've seen in a 7.
Thanks, but no no no, Zetec wears that crown.
Anyway, this thread is supposed to be about stiffer tranny tunnels.
Paul G
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Volvorsport
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| posted on 29/1/06 at 05:59 PM |
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mines completely kevlar/carbon . how much stiffer i couldnt say , the bigger and wider it is , the better it will be .
im not fussed about enclosing the prop in either - have you ever worked on a lotus elite with inboard drums etc .
do that stuff from underneath .
www.dbsmotorsport.co.uk
getting dirty under a bus
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mark chandler
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| posted on 29/1/06 at 11:36 PM |
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I had the same dilemma last week and have opted for a halfway house, only the top half of the frame to support Handbrake, gear change and next week
electric reverse.
I chose to angle the tunnel and start the jink from bulkhead angle to horizontal a couple of inches back under that basis that this would add more
strength. My tunnel although not shown in these pics has a taper.
[Edited on 29/1/06 by mark chandler]
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mark chandler
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| posted on 29/1/06 at 11:41 PM |
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Pic
 
Rescued attachment Transmission tunnel 29 Jan 2006.JPG
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