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Matt's 1970 Opel GT - Project Log

36524 Views 164 Replies 15 Participants Last post by  MattsAwesomeStuff
I've decided to convert a 1970 Opel GT to electric.

As usual with my builds, this is a budget build not just for low cost, but trying to use as much unwanted/recycled/garbage/repurposed items as possible. It's not a performance build.

I'll try to update this front post to act as a table of contents for the progress on the thread.

To be updated, but, rough project specs:

- 1970 Opel GT ($200, but, $700, and up as I go).
- AC Forklift motor (free, from a scrapyard).
- Prius Controller (probably, haven't bought yet), with Damian's prototype brain for it. This might also be the charger.
- Recycled 18650 batteries from tool packs (already have).
- 70mph (110 km/hr) or so top speed (highway speed)
- At least 60 mile (100km) range, 120 mile (200km) would be better, I think I have enough cells.
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Matt I think you are doing great things, and yes as much having fun and learning and doing it your way. Take others' comments with a pinch of salt. If they can't be supportive or at least courteous they should mind their own business.

I'm impressed with your approach and pragmatism to your build and hope you make it to the finish line. I'm sure you will and it'll be a better build for it too!

PS the casting is looking promising. Better too much material and you can dress it back than not enough. I'd be tempted to use a blueing technique using permanent marker against the motor spline to get the fit just right, once you have successfully poured your coupler.

Cheers
Tyler
 

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Discussion Starter · #122 ·
I may be way off base, and I confess my only knowledge on the subject comes from what I read on wikipedia.
Hmm. "Pot metal" is just a derogatory term for "throw in anything that's left over and melt it". So it varies.


Zamak on the other hand is a controlled mixture, is nearly as strong as cast iron and is self-lubricating.


If I add a little bit of copper (1%) and a little more aluminum (a couple %) it's becomes even stronger and harder.

Is the idea to machine down an end of your casting to mount the flywheel?
Nope. Join motor shaft to transmission output shaft.



That's just the little tail housing on the transmission, it's about the size of Coke bottle.

I'd be tempted to use a blueing technique using permanent marker against the motor spline to get the fit just right, once you have successfully poured your coupler.
I might do that if I have to machine it manually. Not worth a lot of extra effort in the mold making stage to get it perfect.

It's not that much effort to just adjust the shape afterwards. There are 25 splines, there are 4 faces on each spline (peak, valley, left and right sides), I might have to remove 0.003" from each face. A little bit of filing with a key file or a piece of sandpaper wrapped around a hacksaw blade. Just go around in a circle until it's done. Same thing they do with dentistry.

Considering the motor shaft is hardened steel and the coupler might be aluminum or zinc... if I could support the ass end of it and not be hammering on bearings, I'd just squirt some cutting fluid on it, use the shaft itself as a perfect broach and hammer the coupler on and off until it was clear. We're talking chips thinner than a sheet of aluminum foil.
 

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Discussion Starter · #123 ·
No news like bad news...

Took a close look and noticed some funny coloring on the driver's side.


Trouble is... in the area I know to be bad, I can't visually identify it with the scope. So for all I know, most of it is that bad.

I only lightly chain-whipped the outer rocker, pretty hard to get any kind of movement with a narrow triangular cross section, but, maybe better than nothing. Looks like lots of debris knocked loose, but, I didn't chain-whip the inner and it looks exactly the same so maybe not.

Looks like I'll need to patch significant portions of both wheel panels on both sides in the rear, and probably the rearward portion of the front wheelwells too. I expected a couple small patches, looks like I'm in for 6 medium sized patches, and I get to discover how applicable my trigger time welding up the interior is going to be on the exterior where it'll be visible. I predict.... not well. Have a feeling I'm coming on a turning point of a project I can finish, to one I never will.

Rockers on the passenger side don't look as suspicious as the driver's, but, I'll give them the probing too. Not sure what to do about those. Maybe plug the ports with hot glue and fill them with another gallon of evaporust. I suspect the paint is structural in many places, I'll leave a plastic sheet underneath so I don't waste all my evaporust when it escapes. And then, who knows what's left in there.

Rather demoralizing, especially for my first day back working on it after several months, and having wasted all the daylight hours of the summer on other people's vehicles. Back to working under bulb light. Probably has to be fixed to pass out-of-province safety too.
 

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Matt - there comes a time in every project

I think you need to either get the whole shell blasted and start again

Or simply start again

Have you looked at the "Locost" ?
It would probably be quicker and easier to make a Locost chassis to take the Opel running gear
 

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Have you looked at the "Locost" ?
It would probably be quicker and easier to make a Locost chassis to take the Opel running gear
Perhaps, but it would make little sense to use the Opel running gear without the Opel GT body - the body is the point of this vehicle selection. If building a tube frame special, there are many more suitable donors of suspension parts.
 

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Discussion Starter · #126 ·
the body is the point of this vehicle selection.
Indeed.

Back to square 1 if it doesn't look like a GT. Heck the suspensions are on my list of things to eventually replace. My car selection process was pretty much "Is it small and light? Does it look cool and would I want to drive it?"

The rust isn't murderously bad, and I knew I'd be doing work ahead and behind the wheelwells, just not this much work. It probably changes nothing except how much more work I have to do, which hurts my odds of ever getting it done, especially if it's a "must be fixed to pass roadworthy inspection" kind of thing.
 

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Discussion Starter · #127 ·
Well, did some more digging into the rust. Two weeks ago. Trying to stay motivated.

For those that enjoy sped-up rust pokin' 'n proddin':




Few notes:

- Driver's Rocker isn't in great shape, but appears to be worst just in a diagonal line. My guess is that it was parked outside, with the tail lights removed, on a driveway or hill, until dust settled. Annual Arizona rain rusted a single line through the metal there. The interior rocker has holes at the back but otherwise isn't too bad. I see a line of paint bubbles that seemed solid when I poked them but I'm thinking have to be where the rust bled through to a pinprick. Maybe best to just replace an extra 6" down that line.

- I don't know what those white goopy knobs are inside the driver's side rearmost fender, but, I'd suspected this car was rear ended at some point, lightly. Looks like those might be the scabs from dent pulling? Isn't obvious to me from the outside.

- Passenger side isn't nearly as bad, half the damage. Doesn't really matter, a slightly smaller or larger circumference doesn't add too much time, and the damage is mostly in a single plane so no complex curves, low enough that the wheel flares haven't sprouted form the side yet.

- Passenger rocker has no holes at all that I found. Rust spot is from the outside where paint wore off. Camera scope picks up a couple rusty patches inside, but otherwise looks great.

- Front wheelwells and fenders seem intact, couldn't poke a hole anywhere. So damage is confined to the ass end and the driver's rocker.

I'm not even sure where to buy sheet metal from affordably. Had an idea to just take a sawzall to the junkyard and cut the roof off a minivan or something equally sheet-esque. Then I wondered if the metal on a new car is more likely to be paper thin compared the GT. Maybe should try the side of a truck box instead. Maybe older is better? Will have to do that soon, summer is over, fall is here, snow arrives soon.
 

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Matt
I have been there - you need to handle rust as a zero or 100% - you are going to do a ton of work - and then nothing

Rust is horrible

Either blast it down to bare metal and paint it immediately - as in within the hour - or it will do a zombie and come back at you

I have a horrible prediction that you will make a half decent car and it will then fall apart in front of you
 

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Discussion Starter · #130 ·
Finally made a go at casting with Zamak, after my first attempt struggled to maintain high enough temperature with aluminum.


Stunning partial success:

- This is a great way of turning $300 of conduit couplers into $3 of zinc.

- Best cheap source of Zamak I found was in old 2-hole punches. Just had to rip them apart and remove the steel punches and springs. They were a pound and a half each. Towel racks, cheap chromed drawer knobs, banister supports, and a CVT pulley from an old treadmill were all also Zamak.

- Zamak weighs 2.5 x as much as Aluminum. My previous attempt that got the giant airpocket frozen into it was 404g. If that was filled solid it would probably be 40% heavier. All told, I'd need at least 2500g (actually, bad math I notice now, I calculated as if missing 60%, not 40%, oh well). Turns out I had around 4kg of the stuff, so, should have been plenty even after the excessive dross of melting it in a frying pan.

- A heavy duty stainless steel frying pan is not strong enough to lift 10 lbs of zinc. Had to use pliers on the far side to help

- Missed the sprue, sloshed over into the main pour.

- Zamak is 2.5x the weight of aluminum. Buoyancy on that plaster form is now 2.5x as strong. Up it pops like a cork. Nothing to do but finish the pour and spend 2 hours melting it down again. In retrospect, this is like filling a bathtub and expecting the tennis ball to stay at the bottom.

- Form seemed relatively undamaged by the pour, so for shits and giggles, I stuffed it back in the topside, just guessing at where the center was and the correct angle.

- I hit pretty close to center. I hit pretty close to square to the surface of the pour too... except that the mold wasn't square.

- I probably destroyed the motor bearings, but I lightly hammered the coupler onto the motor, and then pried it back off a half-dozen times. The hardened motor shaft is taking just the slightest shavings off of the surface on a half-dozen splines. It's already 2/3 of the way on, I won't press it further until I have a slide hammer or some way of getting it off, it's too deep into the recess to pry it out if I go deeper.

- Surface of the splines seems as good as they ever were in plaster. Zamak is famed for being a zero-machining process, you can capture the surface of a coin accurately if you want, so all imperfections were silicone/plaster based. It's good enough.

- All the excess chunks I cut off showed solid metal all the way through, no porosity.

- The coupler being off-kilter isn't a big deal. It doesn't have to be a 1/2" thick, and certainly won't be at the transmission end.

Overall, Zamak was beautiful to cast with. Stayed glassy smooth for several minutes (off camera) after the pour. I'll have to keep an eye out at the junkyards for old bathroom fixtures and such.

Plan now is to get the motor spinning, and use it with a grinder as a lathe to make the coupler centered on the motor shaft. Then drill it out for the transmission shaft (a drillbit on a rotating workpiece is self-centering... supposedly).

Also, there's an air cavity at the bottom of the splined area, probably from gas escaping from the plaster. It's not critical, and once I have the hole drilled for the transmission tail shaft, I can gouge the sides and repour some zamak just to give it a helping hand and fill the gap, even if it doesn't add much for strength.

.
 

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"Pot metal" is just a derogatory term for "throw in anything that's left over and melt it". So it varies.


Zamak on the other hand is a controlled mixture, is nearly as strong as cast iron and is self-lubricating.
Finally made a go at casting with Zamak, after my first attempt struggled to maintain high enough temperature with aluminum.

...
- Best cheap source of Zamak I found was in old 2-hole punches. Just had to rip them apart and remove the steel punches and springs. They were a pound and a half each. Towel racks, cheap chromed drawer knobs, banister supports, and a CVT pulley from an old treadmill were all also Zamak.
How do you know that any of these salvage pieces are Zamak, rather than another random pot metal alloy of similar density? How do you know which Zamak alloy they are, or that they're the same as each other?
 

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Discussion Starter · #132 ·
How do you know that any of these salvage pieces are Zamak,
In short, other than reasonable guesses, I don't.

Rather than another random pot metal alloy of similar density?
Similar density and melting point? Zamak is heavy and melts on a stove. Not much else will do that.

I took samples of each and put them on a burner first to make sure they melt in isolation, not dissolve into the alloy (which can happen at a much lower temperature).

I was using mostly mass-produced cast items, not oddball junk, which gives me higher hope.
- Conduit fittings are pretty reliably Zamak. Fire hazard and industrial corrosion, I can't see them just being pot metal. They all came out of commercial facilities.
- The 2-hole punches are old, Canadian-made, and heavy duty
- The CVT pulley was US made.

Those were 98% of the mass of the melt, I'm reasonably confident they were proper Zamak die cast. More importantly, because they're all old already, I'm reasonably sure they don't have lead-inclusion leading eventually to "zinc pest" where the lead crumbles the zinc away because there no signs of that, and even then, that takes decades after a new melt. I might be dead before that happens.

The towel holders and knobs I'm less confident of other than their melting points. Probably should have excluded them since I was clearly over the minimum I needed and they might have had lead or cadmium or who knows what dissolved in them. Almost certainly chinese made, and cheap/thin. They went in last and because of the chrome plating, ended up being mostly dross that was removed anyway.

Also, economics. There's shortcuts to take in terms of not properly sorting scrap metal, but anything else thrown in deliberately is going to be more expensive than zinc.

Tin and Zinc weigh almost exactly the same, but tin is 8x the price so there's not point in using it. Lead is about 2x the price.

Nothing else would melt at that low of a temperature. Aluminum and copper would dissolve into the alloy I suppose, but again, each are more valuable on their own.

How do you know which Zamak alloy they are, or that they're the same as each other?
I don't, but it doesn't matter, they're all in the same ballpark and the alloy differences aren't magic. The more X you put in, the more you start to see properties associated with that alloy. If they're many different alloys, I'll have an averaged out performance of whatever was in the pot. I probably should have sprinkled in some more copper, tends to make it stronger, but, then I'm having to stir it to make sure it dissolves equally and then I have more dross and air dissolved so, meh.

For example, wiki says: "Zamak 5 has the same composition as zamak 3 with the addition of 1% copper in order to increase strength (by approximately 10%[17]), hardness and corrosive resistance, but reduces ductility.[31] It also has less dimensional accuracy".

So, if I mix 50% Z5 with 50% Z3, I'm at worst losing out on 10% strength gain, but most likely just gain 5% strength and hardness instead of 10%. If I accidentally add 3% copper, I've made Z2 which has 20% more strength increase, but becomes brittle over time. Z4 has less copper than normal, and it's to prevent the melt from sticking to the dies. Z7 has more magnesium so that it's thinner and fills small voids easier.

... none of this matters. If I mix a bit of each, I'm getting partial changes in the properties. And I'm casting a giant slug of it, not picking up delicate surface features.

It's almost certainly all Z3 anyway. Basic boring industrial stuff.

Perhaps most importantly... DIY EVers have typically made couplers out of aluminum, which is weak and brittle compared to zinc. I'm building a zinc coupler of comparable size, so, minute differences just won't matter.

Or... I'm wrong, and it falls apart after use. I guess we'll see.
 

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Discussion Starter · #134 ·
This car is a LOT of work!
I was going to have my first conversion be something simple and lame, like a '94 civic or something. Dead simple, easy to swap, be done with it. Then do a car I was more interested in driving.

But then I discovered what car I really wanted to convert, and one came up for purchase, cheap, almost immediately, so, I got thrown into the deep end a bit on car restoration. Without even having a shop to work on it.

Its been a while since there was an update. How is it going?
I haven't worked on it in 8 months. I was procrastinating on some other big things I needed to take care of, so I figured, I'll put the car on pause and stop avoiding one type of work by doing another type.

Fast forward 8 months, I haven't worked on my car, but I also haven't done any work on the other things that need doing.

Also, Covid put a bit of a wrench in the works, I needed a transmission from the local owners club, but, didn't want to take risks with any of them hauling it out of the parts barn, which was also snowed in.

So, only update is that last week I got a transmission and bell housing, and have to make some choices about just how much of it I want to keep.

Also, my tools got stole a month ago, along with my commuter vehicle, so, that didn't help. Still trying to find out what I'm missing.
 

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I was going to have my first conversion be something simple and lame, like a '94 civic or something. Dead simple, easy to swap, be done with it. Then do a car I was more interested in driving.

But then I discovered what car I really wanted to convert, and one came up for purchase, cheap, almost immediately, so, I got thrown into the deep end a bit on car restoration. Without even having a shop to work on it.
There's nothing especially complex about converting an Opel GT (compared to other models of cars, such as a Civic)... but starting from body which needs a massive amount of work just to be structurally sound makes any conversion difficult.

Also, my tools got stole a month ago, along with my commuter vehicle, so, that didn't help. Still trying to find out what I'm missing.
Sorry to hear about that.
 

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Discussion Starter · #136 ·
There's nothing especially complex about converting an Opel GT (compared to other models of cars, such as a Civic)... but starting from body which needs a massive amount of work just to be structurally sound makes any conversion difficult.
Yes, the constraint was budget- and effort-wise. I wanted something I didn't care much about for one car and then something I did for the other. On the GT I was pretty sure I was going to have to do a tradeoff of time:money to get something nicer. And, that it would be older and probably require more attention in general.

A nicer, needs-nothing GT with no bodywork required is $5,000-$10,000. Too much of a luxury for me to spend on for a hobby.
A nicer '94 Civic hatchback is $800.
Instead I bought a pair of $200 GTs. With less rust to repair than a $3500 GT, but more internal bodywork needed.

No regrets but got in a little over my head. Hardly any of my challenge has been "convert an EV cheap", almost all of it has been "restore classic car cheap". Only regret I suppose is that I was actually looking forward to taking the engine and such out, and mine came with it already pre-stripped.

Biggest surprise so far has been that there was nothing convenient to fit the forklift motor spines.
 

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Discussion Starter · #137 ·
First update in a while, before I catch up, a question:

I want to use an iBooster (electric brake booster). I found some Gen1s for sale.


( Full unit )


( Just the booster, no MC/reservoir. )

Lots of these are sold without the master cylinder. That's okay, I have a master cylinder for the GT, already rebuilt/refurbished.



What do I want?

Do I want to save myself an extra $100 by not using the Bosch iBooster's master cylinder, and somehow plumb my proper GT master cylinder to the electric brake booster? Since the MC is designed for the brake system on the GT (is it?)? Or, do I want to spend that extra $100 and get the MC that belongs to the iBooster, but does not belong to the GT?

I'm redoing the lines anyways, so that's not an issue.

I presume the connection to the MC can just be any hydraulic fitting? And maybe slap a bracket there so that it stays put? I don't have much knowledge about brake systems.
 

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Do I want to save myself an extra $100 by not using the Bosch iBooster's master cylinder, and somehow plumb my proper GT master cylinder to the electric brake booster?
The iBooster boost unit isn't "plumbed" to the master cylinder, because the booster is completely electromechanical, with no hydraulic component. As far as the plumbing is concerned, there would just be the stock master cylinder (maybe positioned differently). What the booster does (like a vacuum booster) is add push to the rod from the pedal.

... Since the MC is designed for the brake system on the GT (is it?)? Or, do I want to spend that extra $100 and get the MC that belongs to the iBooster, but does not belong to the GT?
It probably depends on how readily the GT's master cylinder will work with (mount on and connect mechanically to) the iBooster. The GT's master cylinder will have the right size of bore (at least for the stock car) and ports that work with fittings matching the size of brakes lines in the car.

I presume the connection to the MC can just be any hydraulic fitting?
No. There are many styles of hydraulic fittings, and you need to match the master cylinder ports. They are normally flare connections (line is flared and nut around line clamps flared end into port), but there are various sizes and styles of flares. With any luck the GT has common double flares, but it's likely a metric line size.
 

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Look at what brakeline fittings you need, in detail which includes ordering & testing them, before you decide anything.

Using the iBooster master may involve unobtainium brakeline adapters you'll need to custom make.

Using the Opel master also means custom design & machining of the mount and pushrod if you use the electric booster.

For my C5....vacuum pump. Good enough for production Caddy & Malibu, good enough for me. Got bigger fish to fry.
 

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Discussion Starter · #140 ·
What the booster does (like a vacuum booster) is add push to the rod from the pedal.
Ahh, I figured at some point there would be fluid pushing at the entrance to the MC. So that's just a rod you push on? Hmm. Well that doesn't sound overly challenging.

It probably depends on how readily the GT's master cylinder will work with (mount on and connect mechanically to) the iBooster. [...] With any luck the GT has common double flares, but it's likely a metric line size.
Ahh, yes. The Opel GT community pointed me in the right direction of the proper fittings and such, I ordered those 2 years ago.

Look at what brakeline fittings you need, in detail which includes ordering & testing them, before you decide anything. Using the iBooster master may involve unobtainium brakeline adapters you'll need to custom make.
Ahh, good to know.

Using the Opel master also means custom design & machining of the mount and pushrod if you use the electric booster.
I think that intimidates me less than:

A - Spending at least an extra $100 for the iBooster MC, and,
B - Changing the fittings over.

For my C5....vacuum pump. Good enough for production Caddy & Malibu, good enough for me. Got bigger fish to fry.
I do already have a beefy 12v vacuum pump.

But, either solution is going to require a fair amount of custom work. To archive this here instead of just my Salvage Thread...

The Opel GT brake booster sits on a weird 2 foot long extension at the front of the hood, to get it all the way past the entire engine, for space constraint reasons:




Hood Vehicle Motor vehicle Car Automotive lighting


And my brake booster is in questionable state of functioning (it holds pressure, but I'm skeptical, as I mistook a large hexagonal seal for a plastic bolt and spun it way too many times). And, my replacement brake booster isn't from a GT, it's from a Manta, which has a different pushrod:



I think I've mostly decided not to keep the booster in its original janky location.

So that means I'm likely to choose between relocating the brake booster, and switching over to the Manta one (with a vacuum pump), or, using the iBooster (with a fabricated master cylinder).

Relocated Manta:

1 - Make a bracket for Manta booster near the firewall.
2 - Make a bracket for 12v vac pump
3 - Wire it up.
4 - Build/buy a vac reservoir.
5 - Make a mount for the vac reservoir.
6 - Make vacuum fittings to the reservoir.
7 - But and mount a pressure switch so it knows when to turn off, and wire that up to.
8 - Fabricate a booster pushrod adapter (doesn't match the GT's original)
9 - Still deal with the noise.

// OR //

Using the iBooster and the GT Master cylinder:

1 - Make a bracket for the iBooster.
2 - Wire it up
3 - Make and mount a plate to hold the MC to the iBooster

...

Both solutions will need new lines anyways (lines were cut for previous owner's V8 attempt). So there's no savings there.

So, if I'm doing the lazy "just get it done" thing... which is actually the laziest? The 12v vac pump solution has very little problem solving (which is the real time sink), and probably no hard obstacles. The iBooster solution is definitely easier, unless I struggle mating the GT's MC to the iBooster, and then I'll probably regret it.

And, I'm cheap, and this is supposed to be a fairly extreme budget build from garbage and unwanted items, but I bet every time I hear that vacuum pump turn on I'm going to wish I could pay $1 to not listen to it, and that pays for the iBooster in a couple months.

I guess then, not having really seen what's involved, how stupid is it for someone with an angle grinder, drill, and tap & die set to attempt to mate those two components together? Like, "take your time and you should be okay"? Or, "Even being your most careful you're not going to pull that off"?
 
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