Gear Monkey
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| posted on 4/12/11 at 07:49 PM |
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20mm Box Section Used For Chassis
Hi Guys,
After building a Locost way back in the 90's to the original book using a 1600cc MkII Escort I decided to build another one, only this time a
whole lot lighter and faster. I started this project around 7 years ago and only got to the stage of a 75% finished chassis when other things meant
the project had to go on the back burner, but I've now got more time so the project is back on!
I have however gone down the route of using 20 mm 16 SWG box section as I had around 70 meters of the stuff in the workshop. As This material offers
less strength than the 25 mm I made a number of changes to the book adding a number of additional triangulation's which I believe will actually
give me a stiffer chassis than the standard without adding any additional weight. I'm not going to be able to test this with any accuracy but as
an engineer I'm happy this will produce a good car.
I intend to install a Fireblade engine but if anyone out there has done similar I'd like to know a few things.
1- Is it possible to retain the center section of the chassis cross beam C as there wont be a bell housing or gear box to locate? If this is possible
then this will add to the chassis overall strength.
2- Is it possible to reduce the size of the transmission tunnel to create for space to my feet when using a bike engine?
3- How far back does a blade engine sit in the chassis? If there's room I plan to create an X brace between FU1 & FU2 which will really
stiffen up the front end.
4- Would an MX 5 diff/rear end be any good with a bike engine?
5- Are there any weight distribution issues to deal with when using a bike engine? I imagine there is a lot of weight over the left front?
I'd really appreciate any help with these questions guys so many thanks in advance 
G Monkey
[Edited on 4/12/11 by Gear Monkey]
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austin man
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| posted on 4/12/11 at 08:21 PM |
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I would think that the tunnel can be widened as there is no bellhousing would say that 3 to 4" extra could be gained in each footwell
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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mark chandler
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| posted on 4/12/11 at 09:30 PM |
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I did the same thing, have a look in my archives.
I made a smaller handed transmission tunnel, more room for pedals for the driver and left the tubes top and bottom as only needed room for a
propshaft. To make as much room as possible I alligned the engine with the side rails, not straight down the middle.
This is an inverted pic before I added an ali floor
 
Inverted chassis 2 April 2006
I also shortened the passenger footwell so I could pull the engine back a bit more, thing to watch is exhaust (stopped me taking the engine back a bit
more, although in hindsite I could have planned around this and moved it back further), you will need to make your own and make sure the pipes do not
foul the diagonals, I added extra bracing around the rack and front suspension and created an enclosed in part Transmission tunnel.
I have also subsequently taken my exhaust back in by the diff and out the rear as the mechanical/induction noise of the engine puts the db meter over
the edge on track days for static as very close together.
The rear suspension on mine is a bit different on mine as well as I like diagonals so rather than make a box to hang the bones off of I ran diagonals
to the roll cage mounts.
If I was to make again I would shrink the whole thing by 15% all around if possible, use the short sierra rear drive shaft and cut down the long one
to take a few inches out the rear track, its just feels a bit big.
Diff, you need as low as possible really, I have a 3.14 with 185/60/13 tyres and run out of revs, look at a freelander diff maybe, my sierra one
built up with LSD came in around £300.
With me sat in the car, I weigh a tad over 13 stone on a good day, 13 stone 6lb when greedy the diagonal weights are pretty much equal, car is great
on the track with just me, add a passenger and it all goes to pot but the suspension is set for one.
In short, do what you want, just keep it triangular 
Regards Mark
[Edited on 4/12/11 by mark chandler]
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Gear Monkey
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| posted on 4/12/11 at 10:15 PM |
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Thanks for the advice Guys, I particularly like the idea of shortening the passenger foot well allowing to shift the motor forward, makes allot of
sense.
I looked at your chassis picture album Mark and can see you've done a first class job, I'm impressed!
Thanks again
GM
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