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Learning how to build Lotus Seven replicas...together!
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PostPosted: September 17, 2015, 7:41 pm 
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So, after far more Real Life Drama(tm) than I wanted, I'm able to resume work on my wife's mid engine build.

Most of the design remains the same:

1x1 tubing chassis
general "Lotus 7" appearance
full cage
15 inch wheels with 195/50-15 tires
De Dion rear axle
1-liter Suzuki/Geo FWD engine and driveline
inboard rocker arm front suspension
rear mounted radiator

Over the last few weeks I've been turning my scribbled sketches into dimensioned scribbled sketches. This involved making decisions on various parts, then purchasing them.

This has, of course, not been without its adventures. I know what the space between the hub flanges is on the donor; to determine the width of the chassis, I needed to know the backspace of the wheels.

An early decision was to use Honda 15x6, 4-on-114.3 steel wheels. In my previous experience, steel wheels often weigh the same or less than the same size of aluminum wheel, a very similar wheel is used on some base Caterhams, and the local U-Pull place wants $6 for a steel wheel.

Except, of course, they didn't actually have any 15" Honda steel wheels. I noticed that some of the Honda aluminum wheels were decent-looking, particularly the "5 thick spoke" style.

Honda being Honda, they have more than a dozen wheel styles, most of them in 4-on-100 instead of 4-on-114.3mm bolt pattern. I wanted to stay with the 114.3 since that's that the Geo hubs use. The local U-Pull wants $14 each for OEM aluminum wheels. Hey, that's cheap enough. Except... they didn't have any of those either. So I hit the local "auto dismantler", who claimed to have a set... nope, it they'd entered the wrong code, all they had were some of the "Ronco Vege-Matic" style. No way am I going to use those. They found some of the proper wheels out of state, for $50 + a charge to remove the tire + shipping, coming to over $80 per wheel. I checked Craigslist and eBay and the usual suspects, but the going rate to my door from anywhere looked like $70-$90 each. Too much for a used wheel, in my opinion.

After a few weeks I punted and started looking at new wheels. I sort of wanted some spun aluminum Center Lines; I've run them before and they're very light. But Center Line doesn't make spun aluminum wheels any more. In fact, almost nobody makes spun aluminum wheels now. Even three-piece wheels aren't very common. On the other hand, cast wheels are way cheaper than they used to be. I wound up with a set of Motegi 15x7s that supposedly weigh 13 pounds each. They cost $95/each to my door. Considerably more than the $6 I started off expecting, but way cheaper than an equivalent wheel was, not that long ago.

Luckily, this ain't my first rodeo, and such things were to be expected...

After iterating around various configurations, I decided to weld up the front uprights from a spindle and sheet metal. It turns out Honda had some neat cartridge bearing hubs that fit on a spindle. Some cars used them on the rear. I picked up a pair for a 2000 Accord for $14 each, then a pair of new brake rotors for the same price. The rotors go between the hub and wheel, so I had get some to find out how thick they were.

The 2011 plan called for using a rear-steer Geo rack and pinion. This evolved into using a VW steering box with a relay rod and idler arm; much easier to deal with bump steer and easy to play with Ackermann. However, the fuel tank had migrated from behind the seats to between the front wheels, and the steering box, fuel tank, and inboard springs and shocks wound up trying to share the same space.

I eventually decided to go for a center-steer GM rack with two idler arms. This isn't quite as demented as it sounds; two short rods from the rack to the idler arms will replace the relay rod. I managed to snag one off eBay delivered to my door for less than the local U-Pull place wants. As an extra bonus, it's the non-variable ratio version.

The rack will sit high on top of the footbox, ahead of the brake and clutch pivots, and over the top of the fuel tank. Since I'm welding the uprights from scratch, the tierods will be in line with the upper control arm pivots to simplify bump steer geometry.

The rack is *just* narrow enough to fit inside a Book chassis. The Jaz fuel tank will fit. The springs and shocks will be offset ahead of the fuel tank. The idler arms will be above the fuel tank and to the sides, so there shouldn't be a problem there.

Various bushings have arrived; I'll be using Spitfire rubber bushings on the upper A-arms, Audi TT lower arm bushings on the lower arms, plus the four link in back. The Audi bushings sound exotic, but most of the VAG cars made in the last quarter century appear to use the same bushing; the "Audi" ones were just the most common and cheapest.

A trailing-arm Beetle upper ball joint is designed to take spring load. I ordered one to measure.

Kinetic uses a particular Moog tierod end as a ball joint. I ordered one of those to use as the bottom ball joint. Jack uses it on top, but it shouldn't make any difference. There won't be any spring load on it.

Camber adjustment will be by screwing the lower ball joint in and out. I'm not making any provision to adjust caster. If there's a problem I'll weld up another set of control arms. Same with the trailing arms in back.

All of the tierod ends are VW Beetle, left and right hand. This left me with 12x1.5mm LH and RH for the tierod ends and 16x1.5mm for the ball joints. Metric jam nuts in those threads were not available locally; some are coming via Amazon.

I had to order three different metric taps, which have arrived.

The lower ball joint is supposed to have a 7 degree taper. Nobody online seemed to agree about what taper the VW bits have. I bought a piece of O-1 drill rod to make a D reamer from. After I measure the tierod ends I'll make a reamer to match.

All suspension joints are ball joints or rubber bushings; no rod ends.

I picked 125#, 10x2.5" front springs to start with. I had to have something to measure and build around; if I need 100 or 150# springs I'll get them later. Compared to what I'm used to, the 125# springs look like they're for a toy. The wire is pencil-sized. Theoretically the rockers will run them at 1:1 with the wheel; the chassis width, front taper, and fuel tank location may require shorter rockers and a less favorable ratio.

Miscellaneous bolts, bits, and bobs have arrived, including a complete MGB triple wiper setup for $45. I won't need that for a long time yet, but the price looked right.

I still need more parts before I can firm up the front end layout, but at least I have some bits to work with now.


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PostPosted: September 18, 2015, 10:32 am 
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TRX, good to hear that you're underway. Don't forget; PICS AS YOU PROGRESS! Just out of curiosity, is the MGB triple wiper gear still the 'oscillating-cable-and-wheelboxes' setup from Lucas?

Best of luck to ya'!

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PostPosted: September 18, 2015, 1:45 pm 
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Yes, that's it. I got everything except the wiper arms and the switch. It's supposed to be from a '78 model. The wiring diagram and an appropriate switch are on my to-do list, along with disassembly and clean-up.

Also today, a box showed up with the coilover spring mounts. The price on those has gone way up since I last bought any. I wound up with four threaded mounts, nuts, jam nuts, urethane (top) and rubber (bottom) spring isolators, and four mystery springs for $44.95 to my door. The package was intended to convert a Honda Civic to coilovers. Neither the ad nor the package has any indication of what the spring rates are, but they're impressively stout. When I get some time I'll measure them, calculate the spring rate, and pass them on to someone who might be able to use them.


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PostPosted: October 8, 2015, 6:11 pm 
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Okay, the wheels are here, and all four appear to be the same size and color. The "Ultra Black" looks sort of silvery-black to me, but it should do nicely. The Motegi hub bores appear to be substantially larger than the Honda hubs, so I'll have to make centering rings for the front as well as the back, no biggie.

Also snagged some 1-piece CV boots for the Geo axles, and the little metric screws that hold Honda brake rotors to their hubs. The wheels were an unexpected expense that pretty well hammered this months Discretionary Spending Allowance.


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PostPosted: October 8, 2015, 6:46 pm 
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:cheers:
I need a drink, so today you're my excuse.

I also sympathize with the starting with the $6 wheel concept and then after reality bites a couple times landing up with something else that works, but is mysteriously much more expensive. Then you come back and read our forum and someone else scored an entirely useable car for $150, which unfortunately slows down their locost car project for a week because the cheap car came with enough spare parts to make another car to send a kid to college with... :rofl:

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PostPosted: October 9, 2015, 8:56 am 
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<grin> Ain't it the truth...

By the way, I was looking for an MGB windshield wiper wiring diagram last night and found that there are are three different wiper motors: single speed, two speed, and two speed with "flick", where the wiper will move once across the windshield and park. The "flick" was only on the last few years of MGB, and it turned out that the wiper assembly I bought last month is a '78 and should support it. So I wandered off to eBay last night and found the correct switch assembly.

Various cars using the Lucas wiper system had a pull knob, a twist knob, a toggle switch, or a stalk on the right side of the column. The "flick" MGBs all used the stalk, which is fine with me. My old Capris had a floor switch that would swipe the wipers one (1) time across the windshield and park; everything I've had since does it twice, which usually makes a nasty judder on the second sweep.

I'm pretty happy with the wipers so far. Next step is to bench-test the wiring and make sure everything works as expected. I found a huge amount of Lucas wiring stuff on the 'net; enough to make me suspect that there's more than one way that works, and that there might be differences between different versions of the wiper motor. So I want to make sure of things before I build the harness...

Not that I plan on driving in the rain other than by bad luck, but it's nice to have all the fancy bits working as intended.


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PostPosted: October 10, 2015, 8:36 am 
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...and this morning I picked up a new Audi turn signal switch from eBay for $12. That, with the MGB wiper switch, will let me figure out the shroud for the steering column. And where all the wires go...

Since this is a no-donor project and I'm saving ounces where possible, I'm making my own steering column. 3/4" tubing for the shaft, weld-in GM spline fitting on the rack end, some Teflon bushings and some 1-1/8x.055 tubing for the housing. Though the column will be very short (the rack will be over my feet) I need to provide for a collapsible section; I'm still looking at the various ways to do that.

While older cars usually had compact switches that fit within the diameter of a 2-1/2 or 3" housing (the part of the column that sticks out from the dash), modern switches are much larger and expect a big rectangular box, which I'd like to avoid. The VW and MG switches are compact, and I hope to fit them inside 3" or 4" PVC pipe. The PVC is easy to work with and I have some on hand.

Both stalks have Z-bends offsetting the switch further behind the steering wheel, which should make things more interesting. I'm planning to use a quick-release steering wheel coupler, but that will be outside the shroud and exposed to the world; for now, all I need is for the steering shaft to stick out the shroud and I'll deal with the coupler later.

The left stalk will handle turn, horn, and high beam. The right stalk will handle the wipers. The headlight switch will go on the dash; I don't much care what kind of switch, so my wife will make her executive decision as to pull knob, toggle, or rocker, and where to put it. (hey, you have to make *some* concessions when it's technically her car...)

All the VAG turn signal switches I looked at have rows of pins sticking out the back; I haven't been able to find the mating connectors anywhere yet. If it comes down to it I can get a connector from a junkyard. It's sort of odd since the connectors for American cars seem to be a common item.


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 Post subject: Transmission Error
PostPosted: October 11, 2015, 10:39 am 
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So, waiting on electrical bits, I turned my attention to the transmission.

Back when this project started, my wife wanted to use her 1991 Geo Metro as the donor. That was a 1 liter 3 cylinder with automatic transmission. Not long after Real Life(tm) stalled the project, the transmission in the car died. Upon disassembly it seened to be worn clutches, but when cleaning I found several of the internal ball bearings had balls that weren't particularly round any more. Those ball bearings are unobtainium; Suzuki and Chevrolet don't stock them as replacements, nor does Toyota, who used that transmission for a while. So I called the official US NSK importer and talked to their tech people, who got hold of the main office in Japan, who said those were a custom run for Aisin and not a catalog item, and they had no leftovers in stock. Aisin USA said basically the same thing; if they had any leftover bits when they stopped making those transmissions they scrapped them long ago.

Well.

Ya gotta do what ya gotta do... I found some off-the-shelf bearings with a larger ID, smaller OD, and narrower width. Probably 3/4 of the load-carrying capacity of the originals, but I could make some bits on the lathe and press it all back together and hopefully have an operational transmission. And if the bearings eventually failed, well, they're only ten bucks (and a ton of work...) to replace...

A bunch more Real Life(tm) occurred at that time and we wound up scrapping the car and she bought a nice PT Cruiser to drive. The Aisin transmission got bagged up and boxed along with a pile of custom-made tools (most of it is pressed together) and put up on a shelf.

I have another Geo automatic on hand - for various reasons, I have a bunch of Geo bits "in inventory" - but it came out of a non-running car, and it turns out the little Aisin boxes have a bad rep among transmission rebuilders. They work amazingly well, particularly considering they're primitive non-lockup three speed designs, but not known for reliability. So I've been vaguely planning on using one of the five speed transmissions.

The problem is, my wife has had knee surgery and walks with a cane, and working a clutch is painful for her now. Enough that she will only drive my 5-speed Geo in an emergency. I don't blame her; I've had my left knee cut on too, and driving a stick can be downright miserable in traffic.

So, I'm doodling on the sketchpad this morning thinking, "I wonder if one of those remote power brake boosters could be used for a clutch?" So I harnessed the Power of the Internet and looked up master and clutch cylinder strokes and found that, yes, it would probably work. Then I found that various automakers have been using vacuum-assist clutches for a while now, mostly foreign-market stuff, but some in the USA - Toyota, Isuzu, and Nissan in particular. But most of those expect to mount where an ordinary clutch master cylinder would go, which means it would collide with the steering rack or the hood. But some Japanese-market ones are designed to mount on the transmission; they take a hydraulic line from the clutch cylinder and the output of the servo pushes the clutch fork directly. Some are reasonably cheap on eBay. Unfortunately they all seem to be push-type servos, and the Geo box is set up for a cable. So now I need to see if I can re-clock the clutch arm (which twists a shaft sticking out of the top of the transmission) to use a push servo.

There's no data available on the amount of force multiplication; some vacuum servos appear to be ordinary 7" or so in diameter, others seem to use tiny 3" or so servos.

So, more data collection and contemplation, but in this case it looks like the problem is selecting the optimal configuration from a wealth of options. And that doesn't happen to me very often...


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PostPosted: October 15, 2015, 6:18 am 
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I just snagged a balance bar and adjuster cable assembly from eBay: http://www.ebay.com/itm/BRAKE-BIAS-BALA ... 63&vxp=mtr

I did some web searching and found that they're reasonably well known in Australia, with a handful of mentioned in the USA, and the exchange rate makes them substantially cheaper than a Coleman or Wilwood setup once you add the remote adjuster.

I probably don't *need* a remote brake balance adjuster, but I've never had the opportunity to play with one before, so why not?


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PostPosted: October 15, 2015, 7:47 am 
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Hey, thanks for posting this. I'll be in the market for one of these pretty soon for my Lola build or is it a Lalo? Anyway, thanks.


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PostPosted: October 15, 2015, 5:19 pm 
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You're welcome!

In other news, if anyone is using a fuel surge tank, check out AC-Delco TS-9, which is the fuel strainer/filter that snaps onto the end of the in-tank fuel pump of various '90s-oughts GM cars. It's a round, lens-shaped strainer instead of the usual rectangular shape. It's a hair over 3" in diameter, so you'd need at least a 3-1/4 ID tank, but that would still let you drop a surge tank down through the usual 3-1/2" or 4" fuel tank opening.

I've also been reading about tank setups that use a jet pump to keep an internal surge tank full, or to pump fuel from one side to the other of an inverted-U shaped tank. The jet pump is just two tubes, using flow through one to make suction on the other; steam engines used them to pump water into boilers, cheap AC vacuum pumps that use compressed air to make vacuum use that principle, and so do the water bed pumps that you hook to a garden hose to drain the water out.

They're simple, neat, no moving parts, and dirt cheap. But my fuel system requires a free return path back to the tank; without it, the fuel pressure regulator wouldn't work. The only automotive jet pump data I could find said some Subarus used a 2mm orifice. So, basically, the Subaru is using a "returnless" EFI system, and the orifice is just a small leak as far as the system is concerned.

It's probably possible to make a jet pump that wouldn't restrict the return flow too much, but then you'd have the problem that at higher throttle settings you'd be using more fuel, which would reduce return flow and pump efficiency just when you need it the most. I'm keeping an eye out for a normal-looking return fuel system that uses a jet pump, but so far it looks like I'm going with a separate lift pump.

I also wanted to use an off-the-shelf JAZ or RCI plastic fuel tank. Unfortunately, the only way I can think of to get baffles inside one of those is to make them in pieces small enough to fit through the filler hole and assemble them by feel inside the tank. Which is entirely doable, but at that point scratchbuilding a tank from steel starts looking attractive. I've never tried welding a fuel tank before, but I've conclusively proven I lack the ability to make an oil pan that will hold oil...


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 Post subject: let there be warmth
PostPosted: October 16, 2015, 8:38 am 
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A heater and demister have been part of the plan from the start. Our main intended use for the car is to do the same kind of touring we used to do on the bike; day trips in the spring and fall, mainly. We normally rolled out before dawn. Sometimes there's frost in the morning and 70s by noon, other times it's just damp.

The problems here are a combination of high humidity and dew; annoying on a bike, miserable back when I had a Triumph Spitfire. Both sides of the Spitfire's windshield would fog over, requiring wipers on high and a towel wiping the inside continually. Once the Spitfire's pathetic heater caught up it actually helped the fogging problem a bit, but it took a while.

Back when I first laid things out I intended to run water tubes up to the front and use a heater core and bilge blowers with plastic gate valves. I wanted a *righteous* defogger. But I wasn't all that happy with running heater lines forward.

From time to time I've looked at the South Wind gas heaters Stewart-Warner used to make. Those were popular add-ons for cars in the 1930s through the early 1950s, and they're not only cheap on eBay, but you can get nicely refurbed ones from southwindheater.com for $200 or so. Hmm.

I finally started researching them, and found out that variants were used in Army vehicles, military and civilian aircraft, factory options from VW. and even as space heaters. I had thought that they vented into the cabin - I breathe my shop heater exhaust, after all - but it turns out they're vented either outside or back to the intake manifold depending on the model.

The South Winds have a large metal Art Deco cover. They're just shaped entirely wrong for a 7, and there's no defroster hookup, so I had always turned away... but I noticed some of the VW ones *did* have defroster ports, and so did the aircraft ones. Some more checking and I found that they used a heat exchanger, and some of the old models did have a defroster port; they just weren't common. I finally found an exploded view; the cover hides the fan and motor mostly; the actual heater part is very small. Then I found some pictures of installed units, and they're much smaller than I had thought.

I was intrigued enough to spend $22 for a junker from eBay. I can take it apart, see how the parts might be rearranged and get an idea how it works, and then buy a working one later. Parts kits are more expensive than working heaters even if the junker is repairable. Rust never sleeps, you know. I'm pretty sure the whole unit will be lighter than a heater core and twelve or so feet of heater lines full of water. The scale will tell. And instead of long runs of water lines, I'll only need a couple of feet of AN-3 line to hook it up.

The part that finally pushed the "buy it now" button was that I figure there's a 50/50 chance it might fit under the dash of my Geo Metro. Most modern cars don't have an open space under the dash where you can fit an extra heater box. The Geo has a large space between the bottom of the dash and the center hump. The Geo has a very sophisticated heater system; it even has gaskets between the side of the dash and the doors, feeding vents at the side windows - but with all the fancy air ducting, it just doesn't put out much *heat*. If the heater will fit, even with some minor rearranging of components, I'm going to be warm this winter...


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PostPosted: October 16, 2015, 10:20 am 
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I had originally planned for one of those electric defrosters that get screwed to the dash and plug into the lighter socket. They are cheap but somewhat anemic. I never went any further than thinking about it. Have you thought about them? Instant heat and the electric load might warm up the engine a few milliseconds faster. I had one of those gas heaters in a Karman Ghia once. I ner had the cojones to try and power it up. :cheers:

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PostPosted: October 17, 2015, 5:04 am 
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I've seen the electric heaters, but I'd automatically classified them with the "electric superchargers" after seeing how a 12V "RV" hair dryer worked. (well, it blew air, anyway...) If anyone has any hands-on experience with the electric defrosters I'd be glad to listen!

Ford had electric booster heaters in the defroster ducts of some of the Lincolns back in the day; I think it was after they dropped the heated windshields, which I thought were pretty cool. The Lincolns used gold leaf in between the glass layers as the conductor. The Taurus was supposed to get a cheaper setup using some kind of semiconductor as the flexible liner. I'm not certain that actually made it into production; I used to read "Automotive Engineering" and some industry magazines, and they often talked about Nifty New Stuff that somehow never seemed to hit the market.

Oh, and for anyone else who might consider driving in "brisk!" weather - retrofit electric seat heaters are cheap! Way cheaper than electrically heated motorcycle gear...

edit: whoa-ho! A quick search on "electrically heated glass" shows that there are companies out there selling glass with a semiconductor heating element between the layers; they seem to be mostly aiming at the marine market. Now to see if any of it meets "safety glass" standards and if the price is within my budget limits.

edit 2: further searching indicates these are all "made to size" panes with bus bars molded in on the edges. They don't look like the they're something the local glass shop can cut. Also, "heated glass" appears to be a big thing in Britain, where they're selling heated windows as radiant heaters, replacing the old under-window water radiators that were common there.


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PostPosted: October 18, 2015, 8:20 am 
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Back in the eighties I bought (J.C. Whitney) electric defoggers for my Blakely Bearcat. They "attached" to the windshield with suction cups at the base of the windshield and plugged into the cigarette lighter socket. They did help to keep the glass fog free. Hard to determine just how effective they could be, cursed side curtains and all that, you know.

If your interested, I think I still have one at our old house.

Bill


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