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Learning how to build Lotus Seven replicas...together!
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PostPosted: Sat Nov 27, 2010 4:41 pm 
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Location: Halifax, Nova Scotia
I've been putting this build log off, because I'm rather embarrassed at my slow progress, but I notice that I've posted about 140 times to the forum. You must be thinking, is this guy really working on a Locost, or is he just a poseur?

I have actually been maintaining a build log on my computer, although it mainly records good intentions. I will transfer (some) stuff from there over the next day or two. I'll keep the good intentions to myself.

Thanks to those who have already provided advice, mainly in the suspension and drivetrain sections, but also in tools.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


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PostPosted: Sat Nov 27, 2010 4:51 pm 
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I have always wanted to build a car, but before now never badly enough to actually get started. The starting point for this build was a 1989 Isuzu Pickup. It is unconventional but circumstantial. The truck was mine, thought of well, and since I’d always wanted to build a car I held onto the Isuzu when I bought a new truck. The Isuzu engine is a 2.6l in-line four, single over-head cam and fuel injected, and is connected to a five-speed manual gearbox. The rear axle is fitted with disc brakes. The Isuzu was stripped of almost all but the fuel tank, starting me off on a single-donor build.

The Isuzu was originally to be the starting point for a Speedway Motors 32 Ford ‘Loboy’ roadster, but the expense of the necessary hot rod bits (tall radiator, straight front axle, etc., etc.) kept the project in limbo. A friend introduced me to the LOCOST 7, through his interest in building a Birkin. By moving to a LOCOST platform I could use more of my suspension bits, and possibly even my radiator (a radiator suitable for the 32 Loboy was one of the killer costs for the hot rod project). The switch was rational, but I admit that I think a LOCOST is nowhere near as attractive as a 32 Ford Loboy.

Building a frame would have made this project genuinely low cost but ‘forever-delayed’ and so I bought a nearly complete non-standard frame from COLD: +4 wide and +1 deep frame with some ‘Aussie mods.’ The extra depth was desirable to accommodate the tall Isuzu engine, and the width the wide Isuzu gearbox and bell housing. The near-complete frame also recognized that the automobile engineer used by Nova Scotia for approvals of one-offs and hot rods was reputed to frown upon chassis welding done by unlicensed hobby welders (or maybe just bad welding – my own dealings with him have always been quite positive). The frame was sent without suspension brackets, in view of my non-standard suspension. The rear end of the frame turned out to be built for a deDion rear end and the front end is reminiscent of the Collins design. (Summer 2008: not a good time to be shipping things with fuel surcharges driving shipping costs from BC to Nova Scotia to around $750!)

Before I made much assembly progress (well, before any progress really) my ‘Birkin friend’ discovered that his JDM Nissan S-15 SR20DE Autech engine and six speed gearbox wouldn’t fit in his Birkin, so my single donor strategy became diluted by a Nissan engine/gearbox. There are two advantages and one disadvantage: a 60,000km Nissan vs. a 195,000km Isuzu and about 4 inches less height for the Nissan, against the need to Megasquirt the Nissan, since it came without an ECU. I would have had to have made a new, lower intake manifold for the Isuzu had I stayed with that engine, but would have had a completely plug and play electrical system, assuming that 20-year old electronics would still work.

Specification• ‘+4 wide, +1 deep’ LOCOST 7 chassis from COLD (This is actually a third-party build, completed by COLD)
o Roll bar from Kinetic Vehicles after COLD forgot to ship mine with the frame, and then went quiet
• 94 ¼ in. wheelbase
• 1989 Isuzu pickup donor
o 2.6l 4 cyl., fuel-injected engine, 120 HP (together with donor wiring loom), subsequently replaced (2010) by a JDM SR20DE Autech engine from a Nissan Sylvia
o 5 speed manual gearbox with Isuzu/6 speed with SR20DE
o Live rear axle on (leaf-spring donor to be converted to three-link coil-over suspension with WOBLink)
 4.11:1 ratio open differential. An after market LSD is available, but I have not been able to find a numerically lower ring-gear set.
o 4 wheel disc brakes (on Isuzu uprights and rear axle)
o Steering wheel/column (possibly to be replaced by tilting column)
• Special order manual steering rack, tbd (originally to be Maval Gear, MII-based, but as of Dec 2010, likely to be MGB rack)
• After-market pedal box and master cylinders (w/o power assist), probably Wilwood hanging pedals with balance bar, unless Isuzu hanging pedal box found to be suitable
• 205R65x15 V-rated Continentals on 15x7 aluminum rims. The tire size was driven by the desire to maintain the Isuzu rolling radius before the engine switch (I wanted to reuse the Isuzu instrument cluster and mechanical speedometer). Sixteen inch rims in the same style, which would have allowed 60 profile tires, weighed 22 lbs vs. 17lbs for the 15 inch rims – still not light, but not offensive – but they are little lighter than the original 14 x 5 1/5 inch steel wheels which weighed 19 lbs. The principal challenge of the Isuzu pickup donor was its 6 x 5 ½ inch bolt circle hubs. Wheel selection was not great. I actually tried to get Minilites, because there was a Mitsubishi SUV with 16 inch wheels with the same bolt circle on Minilite’s web site, but the company was apparently disinterested in the business. As a fallback, I also considered some Isuzu SUV wheels but the California-based car breaker refused to ship to Canada, even by UPS. I had no interest in used, salt-pitted aluminum wheels from local breakers. I ended up with Chinese wheels from TireRack (also available from Summit Racing as ‘T50/51’) with +1/4inch offset. I bought the new wheels and tires in Spring 2008, before delivery of the frame, to reduce assumptions during suspension and chassis set-up. I could have waited a lot longer! Indeed, had I waited and bought something with lower rolling radius my suspension geometry design would have been easier. [Edit: Dec 2010: Due to issues noted elsewhere in log replaced tires with 205/50R15 Dunlop Direzas, and will resell the Continentals]


Attachments:
File comment: My Isuzu donor, my Soling, ‘Piaf’, and my 22 x 30 ft. boat barn
cum workshop which is now shared in winter by ‘Piaf’ and
my Locost 7 build (photo 2001, the year before my new truck) [I don't know why it happens, but my new computer & software seems to be stretching all my photos horizontally - the Isuzu was never that long and low, and the barn should be taller. Bill Gates strikes again.]

Piaf_trailer_barn.JPG
Piaf_trailer_barn.JPG [ 33.61 KiB | Viewed 6903 times ]

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Last edited by Warren Nethercote on Mon Dec 27, 2010 8:40 pm, edited 2 times in total.
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PostPosted: Sat Nov 27, 2010 4:54 pm 
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Location: Halifax, Nova Scotia
I wanted an assembly table to save my back during mock-up and assembly, but wanted to minimize space conflict, and allow for future use. I have a 22x30ft heated workshop, but share it with my boat, among other things. As a result, my ‘table’ is two tapered box-beams riding on plywood horses. The whole thing is made of ¾” plywood, and if one of the box beams is flipped end-for-end, you end up with a 2x8ft table, for some long-distant day when I’m doing other projects slowly. (Christmas 2008).

You can just see the Kinetic roll bar loose in the cockpit in the assembly table photo. The centre of the ‘C’ tube has not yet been cut out for the bell housing. The engine brace ‘R’ will also have to be added after the engine installation is finalized. My new wheels and tires are under the table and the Isuzu engine and transmission haven’t yet gone to the scrap yard.


Attachments:
set up on build table.jpg
set up on build table.jpg [ 42.75 KiB | Viewed 6903 times ]

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601
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PostPosted: Sat Nov 27, 2010 5:00 pm 
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The assembly table’s horses are sized and located to carry the wheels, or brackets to locate the hubs at ride height and track width, and the box-beam thickness (plus appropriate spacers) allows for ride-height to be set. I started with the goal of a 5 3/4 inch chassis ride height with the Isuzu engine oil pan hanging down 1 ½ inches. I live on a gravel road and so ‘low-riding’ is not for me. I considered, but rejected increasing chassis ride height to 6 ¼ inches to avoid having the rear fenders too high on the chassis sides because of my 24 ½ inch rolling radius tires. The chassis upper side tubes in way of the rear fenders are round, so I wanted to locate the fender inboard flanges below them, on the flat chassis sides, to avoid having to remanufacture the inner flanges of the COLD rear fenders. In any event, I will have to organize some sort of filler where the rear-most part of the fender profile goes beyond the flat sides onto the round corner of the rear panel.

Edit, Dec 2010: to my horror, I’ve discovered a dyslexic moment when construction the build table. The tire radius for 205/65R15s in 25.4, NOT 24.5! The build table is ‘off’ and I carried the error into my early suspension work with a string computer. I’ve decided to bite the bullet and replace the 65 ratio tires with 205/50R15s, as shown below. There are now spacers under the tire, chassis ride height is reduced, my rear fenders will sit a little lower, and there will be a place to attach snap buttons for a top.


Attachments:
File comment: Reduced ride height with smaller rolling diameter tires (Dec 2010). Fender is shown with a full 3 inch clearance from tire at ride height, which may prove unnecessary
rear fndr w 50 ratio tire.jpg
rear fndr w 50 ratio tire.jpg [ 48.26 KiB | Viewed 6428 times ]
File comment: Original 205/65R15 tire with fender
Rear fender 3qtr view.jpg
Rear fender 3qtr view.jpg [ 43.45 KiB | Viewed 6900 times ]

_________________
Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Last edited by Warren Nethercote on Mon Dec 27, 2010 8:49 pm, edited 1 time in total.
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PostPosted: Sat Nov 27, 2010 5:12 pm 
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As noted earlier I diluted my single-donor Isuzu build with a Nissan engine, as described below by the seller:

Quote:
It is an SR20DE Non-turbo Autech engine out of an S15 Sylvia. There tends to be a bit of misinformation regarding the Autech engine as they are pretty rare. Autech also produced a similar engine for the front wheel drive cars but it was substantially less power. This one is 200 BHP at 7800 RPM. The engine mods by the factory included the 6 speed transmission, the stainless exhaust header, VVT, sodium valves, lightweight flywheel, high performance clutch and high lift cams. The ecu is non standard since this is one of the few high performance non turbo engines. I was not successful in locating an ECU and if it was a standard one it would need to be modified anyway to allow more fuel to flow and to control the VVT There was a good article about this engine being used in a Datsun 510 in California. One of the nice things about the car is that since it is fitted with a distributor and coil the Megasquirt only needs to control the fuel and VVT (just an on/ off solenoid on the engine). I think all of the Turbo engines require the ecu to control spark and that is where a lot of difficulty comes from.


The SR20DE/six-speed combo fit well, although getting it in was not without its struggles (October 2010). Ultimately, it required the C tube and some of the fully-plated bottom of the transmission tunnel to be cut away to allow the oil pan to rest an inch below the chassis bottom. The Q tube had to be cut out as well – there was no way to install the engine and gearbox as a unit otherwise. (The required Q ‘substitute’ has yet to be designed, let alone installed.)

The first ‘natural’ longitudinal position for the engine/gearbox positions the gearshift lever in a sweet spot, free of any interference with structure (just aft of the top horizontal N tube ‘loop’, which had been designed to be just aft of the original Isuzu shift lever). This position also gives access to the clutch slave cylinder from the engine bay, but presents problems for the factory SR20DE Autech exhaust header. The header ‘fits’, but the exhaust pipe flange is too close to the firewall to allow attachment of anything but a 90 degree ‘log’ connection (see photo). Two solutions exist: one is to move the engine/gearbox forward, at the expense of gear lever location; the other is to replace the manifold exit pipe with a tight 90 degree mandrel bend, so that the header flange would point athwartships rather than aft and down. I will play with that soon, but am engaged in front suspension geometry at the moment (end November 2010).


Attachments:
File comment: The factory SR20DE Autech header: a thing of beauty!
Factory Header Outlet.jpg
Factory Header Outlet.jpg [ 67.32 KiB | Viewed 6898 times ]

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601
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PostPosted: Sat Nov 27, 2010 6:18 pm 
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Hopefully the inspector has issues only with welds that look bad (which may be fine) versus the credentials of the welder.

You could fab a removal brace to replace the tube removed above the bell.

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My reverse commuter trike build log: viewtopic.php?t=11384
Fitting glass and weatherstripping: viewtopic.php?f=23&t=6451
Growing various fruit trees, berry bushes, and wine grapes in zone 7b.


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PostPosted: Sat Nov 27, 2010 7:22 pm 
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Stories from local hot-rodders say that the inspector wants evidence of use of a certified welder, and a former colleague asked the question explicitly: "Can I weld my own sports car frame?" The inspector reportedly said, "No, I want a certified welder."

I am going to tack or mechanically position my various brackets and bits and pay someone with some sort of ticket to weld them. It may well be the local stock car/hot rod builder who the inspector has dealt with before.

I too hope that welds that look like Jack's duck doo-doo cause him to raise his eyebrows, regardless of any evidence of a ticketed welder.

But I believe that the ticketed welder is an expediency on the inspector's part, based on a discussion with him. He is not a mechanic, but rather an automotive engineer engaged by the NS Department of Transportation to certify the suitability of one-offs for the road. His report to the NS DOT is a letter, with the PE's professional stamp, certifying the suitability of the vehicle for licensing. His inspection does not replace the province's periodic 'motor vehicle inspection' which examines things like brake shoes, ball joints and light bulbs. The inspector told me that he tries to keep his fees reasonable, and I imagine his insistance on certified welders improves the quality of structure presented to him 'on average', resulting in fewer failed inspections. Since he has a flat-rate fee for 'an inspection' (I forget what his fee is, but from the perspective of a professional enginneer, I recall it being surprisingly low - he clearly is supportive of the car-building hobbiest) a failed inspection results in the need for another visit and another bill.

I don't know if I support this approach or not, but it's the world I've got. Certainly, hobbiest welders are more in line with the Locost philosophy, but with the province using a PE for inspection, things might get expensive. I do wonder though, about home-built aircraft, where home-builders do build. But aircraft-building is a federally-regulated activity in both Canada and the US, unlike car building which is administered by provinces and states, where everyone gets his own process, good or bad.

Boy, that was a long answer to a short comment!

PS: Yes, I intend to fabricate a bolt-in brace above the bell housing.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


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PostPosted: Sun Nov 28, 2010 7:43 am 
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Thats true, but repair of aircraft structure by welding in the States does not require a certificated welder unless it is a Lightsport Aircraft built to a consensus standard versus 14 CFR 43.

Since you have a welder, practice and take the test or take a Certified Welder class where the test is the last step. Either way the cost should be under $400 to be certified in something. No one cert covers all the welding required to build a chassis. The single most applicable AWS code is 5RF GMAW for fixed horizontal tube (5), restricted position (R), fillet weld (F), and Mig welding (GMAW).

www.aws.org
www.api.org
www.asme.org

_________________
My reverse commuter trike build log: viewtopic.php?t=11384
Fitting glass and weatherstripping: viewtopic.php?f=23&t=6451
Growing various fruit trees, berry bushes, and wine grapes in zone 7b.


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PostPosted: Sun Nov 28, 2010 2:03 pm 
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From the pic that header should work fine.


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PostPosted: Sun Nov 28, 2010 6:34 pm 
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Miatav8,

Thank you for the advice on welding training. I will investigate locally.

Warren


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PostPosted: Fri Dec 10, 2010 9:17 am 
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MiataV8,

Going back to our earlier discussion, my own interpretation of the engineer's view was incorrect: your 'hope' is more accurate. I recently sent him my first build progress report, and re replied with the following comment:

Quote:
Looks good so far, I was interested in your comment on the "certified welder". As you are aware, the actual welding is the critical item, not the welder. If the host materials are identified and the appropriate filler materials, amperages, and weld type and size are used, we are less concerned with the welder.

We have seen some excellent backyard welding and terrible "professional qualified welder's" workmanship. Although certified shops should be expected to produce proper welds, this isn't always the case, and it becomes critical for dynamically loaded structures such as vehicle frames and cages.


I guess I misconstrued his views in discussions with him. Comments from the local hotrodders must have been a result of refusal of some of their own work.

(My next update to this build on LocostUSA will be around front suspension geometry)

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


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PostPosted: Fri Dec 10, 2010 9:20 am 
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Thanks for the clarification.

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My reverse commuter trike build log: viewtopic.php?t=11384
Fitting glass and weatherstripping: viewtopic.php?f=23&t=6451
Growing various fruit trees, berry bushes, and wine grapes in zone 7b.


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PostPosted: Fri Dec 10, 2010 9:31 pm 
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That is much better news.

Does your welder have a placard with amperage and speed settings versus wire diameter and material thickness somewhere?

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PostPosted: Wed Dec 29, 2010 4:32 pm 
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First, to Andrew: yes, my welder has this information. The engineer's response has encouraged me to to do some practicing and I 've also looked into some courses. The best one (for me) seems to be a three-day intensive at the Nova Scotia Agricultural College in February (about a 2 hour drive away). There are closer ones at the local Nova Scotia Community college, but they are more expensive and spread over two month's of saturday mornings.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


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PostPosted: Wed Dec 29, 2010 4:46 pm 
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Recapping, my Isuzu donor is supplying major suspension components for my car. The rear end is already fitted with disc brakes, but (per the norm) has been relieved of its leaf springs in favour of trailing links and coil-overs. My inclination is towards a three link rather than a four link system and I plan to use either a WOBLink or a Mumford link to get better roll centre location than would be possible with a Panhard bar.

The front uses Isuzu uprights. The uprights and rotors were cleaned up, as were the hubs. Disc rotors were replaced (at $25 a pop for new ones it was not worth trying to have the old ones machined). They are not the lightest things around:

Item Weights
Kg Lbs
Spindle (clean and painted) 4.0 8.8
Hub (clean) 3.75 8.3
Rotor (new) 4.90 10.8
Caliper (loaded with pads, but dirty) 5.60 12.3
Sub-total 18.25 40.2
Dust Shield (dirty) 0.40 0.8
Grand Total 18.65 41.0

(Grrrr: I wish I could figure out how to format tables here)

Kingpin inclination is 10.9 degrees.


Attachments:
File comment: The Isuzu rear end, all 194 lbs. of it!
Rear Axle 1.jpg
Rear Axle 1.jpg [ 65.44 KiB | Viewed 6419 times ]
File comment: Isuzu upright initially set up (in error) for a 24.5” diameter tire, neither the correct 25.4” diameter 65 ratio tire nor the final 23.1” diameter 205/50R15 tire
Upright hub 3qtr flash (Large).jpg
Upright hub 3qtr flash (Large).jpg [ 52.83 KiB | Viewed 6419 times ]

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601
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