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Author: Subject: The Gecko Project
TheGecko

posted on 29/1/12 at 12:43 PM Reply With Quote
Have had a couple of bursts of productivity over the last few weeks.

Mocked up the position of the inner toe-link mounts at the rear. Used the engine hoist to run the suspension up and down through full travel while checking bump steer. Waiting on some LH female rod ends to arrive now. Will add some pics of the final bracket and adjuster once they're done.




Today was rack positioning. After some faffing about, took the 9" grinder to a pair of diagonal tubes that were in the way Made things much easier after that. Stuck some temporary rails under the rack and fiddled with various packing pieces until the right position was established. With a small laser pointer strapped to the stub axle (pointing out to the side) total bump steer (all toe-in) was 5mm measured at 3.6m away. That'll do alright Next step is to mount the column again and find the correct rack angle, then make permanent mounts.





Dominic

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TheGecko

posted on 11/2/12 at 09:50 AM Reply With Quote
A few quick updates:

- made some rack mounts from bent 20x3mm with 1.6mm sheet stiffening webs



Looks like Gemini (Chevette) and Escort racks share basically identical mounting dimensions so quick-rack upgrades should be a relative doddle

- today, cleaned up the remains of the cut-off diagonal tubes, fitted the two 20mm cross rails, and made a stiffening web to tie the two rack brackets together. Dry fitted for now, will post another shot without the rack once it's all welded up.






Dominic

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John Bonnett

posted on 11/2/12 at 03:26 PM Reply With Quote
Hi Dominic,

Good to see your progress and work of the highest quality. I've been fairly quiet on this Forum for a while as I am restoring a Triumph GT6 but I keep an avid eye open for news of your project. Please keep the pics coming. Your thread is a fascinating read.

Best regards

John

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TheGecko

posted on 17/3/12 at 02:05 PM Reply With Quote
Haven't posted an update for a while, so.....

Finished welding up the rack mount in the bench and spent a fair bit of time getting it properly positioned in the chassis before welding it in. Some finish welding to do once the chasis is flipped into a more accessible position. End result is stiff and light.



Progress has slowed because the semester has started and work pressures ramped up accordingly. Still, have managed to twiddle around with engine mounts and got to this point....



That's it sitting/hanging on the four tacked in mounts Everything was put together with the drivetrain centred (i.e. equal length driveshafts). Now that it's in, it's readily apparent that it can/should go left quite a bit. So, this weekend I'll pull the engine, knock off the tacked mounts and shift everything left a few inches. Will make for a much happier level of access around the accessory end of the motor. If I don't do it, it'll just wee me off forever more

More as it happens...

Dominic

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TheGecko

posted on 18/3/12 at 09:35 AM Reply With Quote
OK, knocked all the mounts off the chassis, shifted the front and rear ones to the left by ~70mm, remade the left and right mounts to suit. Done.



Pedals are next....

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TheGecko

posted on 7/5/12 at 08:39 AM Reply With Quote
Realised I hadn't posted some recent updates here.

Fuel tanks are made by my friendly fabricator. Here they are side by side with the CAD (Cardboard Aided Design ) prototype.



This is the two inner ends showing the various balance, feed, vapour etc lines top and bottom.



And here they are in the chassis:



Also, finally got the firewall panels welded in. I originally thought about full seam welding but they're probably just going to get a bead of Sikaflex/seam-sealer both sides and then painted over. Second photo shows them from the front and a little of the arm-rest/sill fill panels taht are also welded in now.






Pretty much ready for the chassis torsional strength tests now Bit of a make or break moment that!

More as it happens.

Dominic

[Edited on 7/5/2012 by TheGecko]

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andyd

posted on 10/5/12 at 08:48 AM Reply With Quote
Nice stuff Dominic.

Q.
How do you intend to test the torsional strength?
Clamp three "corners" and jack up the fourth with a strain gauge attached?
If so, what figure would you be looking for and how did you decide on that figure?

I'm just curious as to what you believe is good (or good enough) and how you'd go about finding out.

I'm still in virtual land with my design but I'm always looking to learn





Andy

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Fred W B

posted on 10/5/12 at 09:49 AM Reply With Quote
I have the below list of several figures, obtained from various sources on the internet, particularly contributors to www.locostbuilders.co.uk

Ultima - 3300 ftlb/Deg (coupe) and 2500 ftlb/Deg (spyder)mass 135 kg,
Lotus 23 - 1500 ftlbs/Deg, 45 kg
Lotus 7 replica, "locost book" spec - 1200 ftlbs/Deg, 82 kg
Lotus 7 replica, uprated "cymtriks" spec - 2540 ftlbs/Deg, 78 kg
Lotus Elise - 7350 ftlbs/Deg,
Lamborghini Countach - 1900 fp/degree.
Ferrari 360 spider - 6250 fp/degree.
Lotus Elan: 5,000 - lb-ft/deg
Porsche 959 - 9,500 lbs-ft/deg
Lotus Esprit SE Turbo - 4,300 lbs-ft/deg
GTD Lola T70 replica - 3300 ft/lbs per degree.

Cheers

Fred W B





You can do it quickly. You can do it cheap. You can do it right. Pick any two.

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TheGecko

posted on 11/5/12 at 02:34 AM Reply With Quote
Andy,

Because the test is a required part of the engineering certification there is a formalised test process. This involves restraining the rear end of the car (through the hubs) and applying torsional stress through a beam attached through the front hubs. Obviously, all shocks & springs are replaced with rigid spacers for the test. Here's a photo of someone elses frame on a torsion jig:



The beam is loaded up with weights, either steel or concrete blocks (what our North American friends would call "cinder blocks" but always known by the trade name "Besser block" in Australia), and displacements measured at the dial guages down the side. Allowance is made for deformation of suspension bushes etc by measuring the deflection at the rear axle line (theoretically nil) and subtracting that from the other values.

In terms of actual values, local registration requirements mean I need to get at least 3600 Nm/degree (from memory) which is about 2650 ft-lb/degree. As Fred's numbers show, a "stock" Locost chassis doesn't even get close . A recent test by a local builder of a modified chassis returned around 8000 Nm Video of the test being performed can be seen here and here.

A beaming strength test is also required, where each seating position is loded with 160kgs and the beam deflection of the chassis measured. Maximum is 1.25mm.


Thanks for the interest. I'll certainly be posting pics of the test process and my results once it's done.

Dominic

[Edited on 11/5/2012 by TheGecko]

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andyd

posted on 13/5/12 at 09:29 AM Reply With Quote
Thanks Fred & Dominic for the info.

It looks like a good idea to stop people from just welding up a few bits of steel and driving off down the road

Not sure the UK officialdom would be able to cope with this being something that we'd have to do to pass our approval tests but as most of the builders would value a good stiff chassis it would make sense for people to carry out the tests themselves even just for self satisfaction.

As my goal is a Lotus Elise'a'like, thanks to Fred's research, it looks like my chassis would have to go some to get close to the real Elise numbers!

Good luck with the test Dominic. It'll be good to hear/see how you get on.





Andy

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TheGecko

posted on 26/7/12 at 10:54 AM Reply With Quote
So, after a variety of delays, the fateful day arrived today









That's 285kg of concrete blocks and scrap steel loaded onto the beam for the torsion test and 140kg per seating position for the beaming strength test.

I don't have the engineers report back yet but, based on the trial runs I did the night before, I believe it exceeds the required 3800Nm/degree by quite a margin (possibly as much as 50% )

Can go to work on the tail end now with the various non-structural support tubes for the rear bodywork.

Dominic

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iank

posted on 26/7/12 at 05:32 PM Reply With Quote
Well done on getting through that, it looks even more nerve jangling than standing next to a rolling road while the operator gives your new engine 7500rpm!





--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous

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TheGecko

posted on 27/7/12 at 06:06 AM Reply With Quote
Got a phone call from the engineer, who obviously knew I was sitting like an expectant father waiting for results 5828 Nm/degree will do OK His remark? "You could put a V8 in that if you wanted!"

Happy as a dog with two tails right now.

Dominic


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Benonymous

posted on 13/8/12 at 12:20 PM Reply With Quote
Well done Dominic! Isn't it a pain what we have to go through to build our own car. Makes me very sad how shiny bums in the "public service" sit around all day with nothing to do but dream up more laws to restrict peoples creativity and inventiveness.

I'm all for safety but what could be an accessible way to build something we really want has accumulated all this extra cost when the number of individually constructed vehicles is minute in this country.
As a matter of interest, what do you think the ballpark cost of the engineering and approval will run you?

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Doug68

posted on 14/8/12 at 10:40 AM Reply With Quote
Yep, well done indeed!





Doug. 1TG
Sports Car Builders WA

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TheGecko

posted on 14/8/12 at 02:13 PM Reply With Quote
quote:
Originally posted by Benonymous
Well done Dominic! Isn't it a pain what we have to go through to build our own car. Makes me very sad how shiny bums in the "public service" sit around all day with nothing to do but dream up more laws to restrict peoples creativity and inventiveness.

I'm all for safety but what could be an accessible way to build something we really want has accumulated all this extra cost when the number of individually constructed vehicles is minute in this country.
As a matter of interest, what do you think the ballpark cost of the engineering and approval will run you?


Ben,

I'm kind of torn about the engineering requirements. In one way they're somewhat of a pain to meet but on the flip side they do help do ensure the end result of my "back-of-the-envelope" doodling isn't a complete death trap

Re: costs - I still have a couple of tests to do once the car is driveable. Lane change stability and brake performance (both of which can no longer be done on public roads so add in a track hire cost as well); drive by noise tests; and the final engineering submission to the Transport Department for approval. All up I'll be surprised to have much change out of $1500-$2000 in engineering and associated costs.

Oh well, it's only money

Dominic

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Benonymous

posted on 15/8/12 at 12:30 AM Reply With Quote
Thanks Dominic, that's very interesting. I know that state-by-state the laws change quite significantly in Aus and an ICV (Individually Constructed Vehicle) that is registered in one state may not be eligible to be registered in another. I'm surprised at the relatively low cost you've quoted, a bloke in NSW was telling me that he is expecting to fork out nearly $50K to get his ICV engineered, approved and registered! I didn't know about the stability check either. I think the shiny bums are just going to keep inventing tests and adding costs until everyone just gives up and buys a Holden.

Bastards.

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TheGecko

posted on 13/10/12 at 10:17 AM Reply With Quote
Despite the absence of updates I have been busy on the car since the B&T. Here's a few updates....

Started fitting the various non-structural tubes that will support the rear bodywork.




Round corner pieces were "rescued" from a chair frame I saw in a skip at work. Seemed a shame to let those nice mandrel bent 25mm tubes go to the tip A bit of a trim and a join to add a straight piece in the middle, plus a folded 1mm steel gusset plate in each corner.

Then added some bits to define the edges for the wheel arches and support the first of two mid-level tubes across the back.





Don't worry, there's a plan for what the rear will look like

Didn't really like the bits of 25mm angle I'd used for the wheel arch supports so I made a hammerform from various bits of timber....



..and formed up a 1-piece sheet metal part instead. This has folded edges both ways for stiffness.



Meanwhile, a pair of standard rear guards have been trimmed to fit over the side-shape of the bodywork. That trimming lost all of the flat mounting flanges at the back so I need to glass in a new flange. To do that, I need a smooth form, the same profile as the final side shape of the car. Some wood profile blocks plus a spare piece of cosmetically scruffy 1.6 ali plus some time with the 1200mm folder equals....



Still some tidying up to do on that one before glassing. Was hoping to get that finished this weeked but time has beaten me.

More in the next post....

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TheGecko

posted on 13/10/12 at 10:23 AM Reply With Quote
Amazing how much time can be spent on what seem like simple things. Because the car is in someone else's shed, across town, I have half-finished bits of plans floating in my head all day that I then try to turn into actual parts in the workshop. At that point, the physical reality of the car intercedes and stuffs up my plan A few nights ago I made one little(ish) bracket but made it three times (four, if you count the initial cardboard template!). Managed to bend the first one on the wrong fold line (working on the back with incomplete marking), marked and cut the second one wrong and didn't realise until the last two folds wouldn't work, finally got the third one right. Took a photo after Mr H helpfully labelled the three versions for me



Then added one our my/our standard flanged lightening/stiffening holes, welded up all the internal corners, and gave it a test fit in its final home. Now I just need to make a mirror image one for the left (which I have a 50:50 chance of screwing up ) and weld them in.





And even then, it's still not obvious to anyone what they're actually for Was also hoping to get enough done this weekend to make it more apparent what's going on - will see how tomorrow goes.

Dominic

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TheGecko

posted on 13/10/12 at 10:24 AM Reply With Quote
Teaser pic....


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John Bonnett

posted on 13/10/12 at 12:20 PM Reply With Quote
Some really nice work there Dominic; very impressive. The hoops you have to jump through to get your on the road make our SVA/IVA seem trivial. As you say, having the seal of approval from the structural engineers must give a lot of confidence in the integrity of your design.

The thread is inspirational.

U2U sent.

John

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Benonymous

posted on 14/10/12 at 10:55 PM Reply With Quote
Glad to see you're still soldiering on with the project Dom. I love the "at fkn last" label on that part, there would be many people on this forum who could relate to that!!
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TheGecko

posted on 23/12/12 at 02:59 PM Reply With Quote
Hmmm, not so much with the updates for a while. Been busy, busy with work, plus off to Sydney for the Tasman Revival and then full of the flu since I got back So, here's some updates from before all of that, that I hadn't got around to posting yet

New flange glassed inside the cut rear guards:


and how they look in their final position:


The flanges are actually a little "wonky" because my temporary form was a bit more flexible than I allowed for so I need to glass some more inside them in a few spots and then grind them flat. Nothing major, just grubby, annoying work (I hate fibreglassing).

A little CAD (Cardboard Aided Design) for the rear light support. The rest of this horizontal space will be filled with horizontal black grille slats - both sides of the lights and in between.




A bit of rework necessary there - the box part is a little tall and pushes the wedge part out of angle. That's what CAD prototypes are for

These bits should get made in ali before the New Year and, if I really get busy, the grille slats too. Then the whole lot could go off for black anodising.

More soon (I hope).

Dominic

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TheGecko

posted on 8/1/13 at 01:06 PM Reply With Quote
Took the video camera with me on my last visit to the workshop. Here's a quick walk around of the car as it currently sits which may give a better sense of scale/proportions for the interested few .....



[Edited on 8/1/2013 by TheGecko]

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TheGecko

posted on 13/1/13 at 11:26 AM Reply With Quote
Following on from the Cardboard Aided Design posting a little while back.

Today, despite high heat AND humidity in Brisbane, I had a very productive day in the workshop. Marked, cut, and trimmed the ali pieces for the taillight/ rear vent infill panel and the floor panel for the bottom tail section. Still need to make the "boxes" that the lights will actually mount to. That will be Tuesday night's job hopefully.

The infill is made in two halves because it's 1350mm wide and wouldn't fit in the 1200mm bender in one piece Plus, it was more effective use of material than cutting a strip way down the side of a whole 1200x2400 sheet. It'll get TIG welded together in the middle before the final trim of the ends. Then holes can be marked and drilled and Rivnuts set into the rails top and bottom for mounting. There's more ventilation holes to come in this part which will be done once I finalise some of the exhaust details and the grille pieces.





Access hole on each side to get at the back of the lights once everything's together.



The bottom cover panel with diffuser vanes - for added wank value, not because I expect them to make any real difference





Felt good to have some really visible progress at the end of a bloody hot day.

Dominic

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