Matt's 1970 Opel GT - Project Log

remy_martian said:

Solder cracks during temperature cycling and is not supposed to be used for mechanical strength...your fitting could go ballistic at hydraulic pressures.

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So, to be clear, I wasn't talking about, say, soldering two flat surfaces together. I was talking about threading two adapters together, where the female doesn't have a flare, and instead sealing the threads with solder.

I did a little digging about why copper is bad (again, I'm not using copper), and it said that brake lines are tested to 1100 Bar (not PSI... BAR!), but that copper lines fail around 300-500 Bar.

Shopped it around my car forums, some guys said don't use electronics solder, but A/C silver solder would be fine. One guy used solder on his 25,000 psi diesel injector lines and they've never had problems. Anecdotes being limited in value, but not worthless.

Progress:

Again, my goal:


This has a name, it's a "brake line union", however, no one in town had any 12mm metric, and I suspect they were all too short anyway. Couldn't find deep ones either, and it's so tedious to shop for online because nothing filters properly, it's 99% items that do no match the criteria. So, back to plan A of making a coupler.

So I bought a $1 7/16" coupler nut, (home depot doesn't have anything metric) which was long enough to fit both fittings. Smaller than 7/16" didn't leave any frame after the threads, bigger than 7/16" was already bigger than the 12mm threads:


Drilled out the threads to 25/64" or something, whatever weird drillbit size I happened to have:


Spent $14 buying a 12mm x 1.0 tap (even my big tap set with 3 12mm taps didn't have anything close to that fine of a thread pitch), and threaded the coupler. This is the nice end, the starting end had trouble grabbing and ended up a bit cone shaped, I'll be trimming it a bit:



And, when screwed together, ta da:


...

Challenges:

- The (long) residual valve seals with a crush washer, and the sealing lip for it is a lot thicker than what I've got for the coupler. I might have to weld up a little more width so that it crushes properly.

- Likewise on the 12mm --> 10mm adapter on the other side, since there's no female bubble flare on the coupler (there is one on the inside of the 12-10 adapter, which is where your actual brake fitting goes), if I wanted to try to use a crush washer there's not really any shoulder there to crush it against.

- The part I want to solder, is the 12mm-10mm adapater into the coupler nut. Note that there are 10 threads of engagement, so, the solder isn't mechanically required, it's only required for sealing the threads.

- Considering "soldering" the two together using Zamak instead of solder. Zamak (96% zinc, 4% aluminum) just barely melts on a stovetop, around 700'F. And I have lots of zamak shavings laying around. Any reason zamak wouldn't work? (Other than, now I've got steel [iron/carbon], brass [copper/zinc], and zamak [zinc/aluminum] all together in the same joint).

remy_martian said:

Just order the right 12mm part, even if it's from the EU.

Click to expand...

If I could've seen one, I would've bought one.

I've found 12mm unions, but they're all like 10mm too short to actually screw that long residual valve in. Plus, they still have the same mating issues (it's not a bubble flare on the valve, it's just a rounded bottom, the seal is the crush washer). So either way it was going to need modification.

You have lots of other stuff to work on while the man in the rowboat gets it to you.

Click to expand...

Y'know, sometimes yeah, but other times, I get so bogged down hunting for specific parts and meanwhile have the enthusiasm to work on something TONIGHT, so, even if I waste a bunch of effort and it fails or I don't like how it turns out (i.e. my adapter plate), it's still better to give it a try.

One of the mistakes I've made over the last 4 years on this "summer project" is that every time I get roadblocked, or slowed down, or am waiting on something to arrive, I jump ship to a new task to stay active. That had me spread across an entire 2 car garage and almost every system apart. I'm trying to stick to only 1 or 2 things at a time now, since I can reach out and easily touch opposite walls on my new "shop". And I don't want to get ahead of myself (i.e. making brake lines, now that I've decided to move the brakes 3 times, glad I didn't).

Also I do just enjoy making stuff.

If you knew how things were going on the other system I'm working on when not working on the brakes, you'd be more incensed.

Whelp, a health dose of failure this week on the brake coupler:

• Tried using silver solder to join the 12mm brass to the steel hex nut. Flux wouldn't take, solder wouldn't bond. Tried at different temperatures, didn't work. Maybe need to get some more aggressive flux.
• Tried Borox as a flux, didn't work, I think borox is more for liquid metals and 1000+'F temperature ranges.
• Tried using zinc shavings as solder, since they melt at these temps. Nope, didn't bond, just sat on the surface.
• Tried pushing solder down the inside, seems to have bonded somewhat to the brass, but not to the steel, and didn't wick at all into the threads, I could still unthread the M12 brass after I was done.

I'm considering welding the brass to the steel... if I weld the edge of the steel, won't that, in effect, liquify the brass and and end up being a braze? I don't think I have a torch hot enough to do actual brazing.

But, steady progress on the motor coupler:

My botched casting where the plaster spline popped up like a cork in the liquid zinc and I tried to rescue it by just holding it down flush. Ended up off angle:


Mounted the coupler to the motor and spun it up, used a sharpie to find center and see how much meat I would have to work with:


Also, a great success, holding a drill bit against the center had it self-center the hole. I later deformed it a bit by hammering on it (and maybe it aligned better when farther onto the motor splines), but, no reason I can't do the same thing to fix it again. It's only 1/2", will need to be bigger later.

Against most advice, I used a circular saw to roughly shape the coupler, cut off the excess from the botched casting. The motor splines are 1.6" diameter which is ridiculous, so, it's fat at that end and tapers towards to the transmission tail shaft (has to, because of the crooked form). I found that treating it like wood turning and shaping it with a chisel seemed to be the easiest method:


I had 1/2" to remove from the high spots, it was a lot of material to hog down...


Here's my using the circuilar saw, while the motor was spinning, to knock off those high spots. I used a demolition blade in a "polish plane" technique, because it was 1/3 the price of a metal cutting blade (1/3 the carbides). There was so much material to hog down I had the motor off when I did most of it. Just lightly slid it back and forth to shave it down. Covered the whole garage in chips, ear-piercing chatter.


Did a little facing yesterday, and it's not bad. I also spun it up to 100hz, which is ~200km/h, without any detectable vibration from the motor (despite still being unbalanced from the untrimmed motor side):


So, that's what I'm left with. I've now got to decide on a diameter to drill the coupler out to, and grind down the transmission output shaft to match that (and maybe trim it a bit for length).

Anyone have some rules of thumb for ideal wall thickness?

I could heat it up and do a smooth interference fit, but, maybe I'd like to be able to take it apart some day, so, I think I'll put a slit in it and do a taper lock instead, like this (but just one end, the other end will be motor splines). That's what I see most people doing with EV conversions:

...

And then I just have to decide what kind of housing I'm going to build to separate the two and leave room for the coupler:


...

I also figured out my math was way off, somehow I thought I was needing 400hz to go highway speed, I actually only need 48hz, which is what the motor is rated for, so, all good there (and I've spun it up to 100hz now, it was steady and vibration-free).

Success!

- Bought some flux that wasn't solder paste, is just flux.

- Maybe part of the problem was zinc plating on the coupler? Let's see... apparently vinegar removes that in about a day or two. But hydrochloric acid removes it in minutes. It's 2am and I can probably buy opium easier than HCl at this hour. But, motivation is now so, apparently you can make HCl by bubbling the gaseous output of sulfuric acid (batterey acid) and table salt through water. I also have no battery acid, but I do have some dried out lead acid batteries. Add water, shake-shake-shake, dump into bottle with vinegar and salt. Is it acetic acid, sulfuric acid, or hydrochloric acid at this point? All three? Who cares. Nuclear option. Tossed the parts in, threw them in the microwave until boiling hot, shook it around while I cleaned up the shop.

- Drowned the parts in flux, both sides. As if they needed more etching.




- Screwed together, threw it back on the stove, soaked up silver bearing solder merrily. Burned some of the flux, oh well, solution is more flux.

- Did the inside too and got a nice little torus of solder. Hopefully it wetted all the way deep in the threads, but if not, at least both ends are sealed now.

- Wirewheeled the schmoo off the outside.

- Drowned it in brake cleaner on the inside to try to get rid of burnt flux residue. Chased threads with a bottoming tap.

- How to clean left over flux? Hmm, isopropanol apparently. Tossed it in a bottle of hand sanitizer overnight. Ta da.


I think that's my first non-electronics soldering job.

Now, if I hadn't lost my crush washer and my 10-pack of 10mm invertered flare nuts some time in the last year, I could be connecting this up tonight.

... but wait a minute, did I see that the GT MC actually had 3 connections? It has a built-in splitter for the front brakes? Ugh. The CRV booster does not. So... need to buy a T. Or, practice my soldering and make one, since I have all these extra M12-M10 adapters (or steal the T from my spare rear axle?)

I guess next up, figure out the mounting system for the booster.

Well if you're going to bitch about that, it gets worse...

More brake work:

- Went through almost everything I own looking for my brake nuts, gave up, ordered 15 steel ones from NAPA.

- Spent 6 hours to drill 4 holes, apparently:

- To mount iBooster where GT booster used to be, need new mounting holes. Worst case for annoyingly close, about a 1/2 bolt diameter away, so I can't just drill new holes, drillbit will want to skip into old holes.

- No problem, this calls for a template to help force the bit straight. 3/4" particle board should be fine. Oops, I notice the iBooster bolts have a bit of a locating shoulder past the threads, past the shank. This is only as thick as the first bit of sheet metal (the radiator wall), so, those need to be bigger, (21/64"), but the ones to the GT pushrod brace are plain 3/8". No matter, rotate 45 degrees, drill a new set of holes. I want it to look nice and be located precisely (foreshadowing...):

- Stupid particleboard doesn't help keep the drillbits straight, they still wander, and now holes are in the wrong place and need to be reamed.

- Don't just use a larger drillbit, oh no, use the round file, use the dremel and shatter two grinding cones, use the drillbit at an angle, use the drillbit with sideways force on the shaft, use a rotary burr.

- Let's move onto the pushrod brace, at least off the car I can mount this and the jig in vice and do much better, right? Wrong.

- Ream and ream and ream again. Test fit, test fit, test fit, test fit. Hmm, what was that about precise, and looking nice?:


- Precise doesn't actually matter much, since those bolt shoulder don't do much locating, the locating is much more nitpicky on the giant hole in the middle (which, I didn't modify... is that standard? A 1969 booster exactly fits the same hole as a 2017 booster?).


- Ha ha, bonus reaming, because even if the bolts fit, that center hole is really, really picky (not 1mm clearance), so, go ahead and just ream the 4 bolt holes out even more until all 5 holes fit.

- She fits!


- Except for the firewall bolts, one needs chasing with tap and die.

- Done, except... the central holes between the firewall, and the pushrod brace are off by like, 1/4" vertically. There's no way I got that wrong, or that it should be reversed (the face is sloped), it's just that bad from factory?

(It's not parallax angle, it's as bad as it looks).

- Ever wonder what your brake pedal sees?


- Bolted the CRV master cylinder on without issue (stupid 2-page reservoir I complained about is a blessing in disguise, there's no room for anything bigger there). And the hood hinge even has a couple mm of space when bottomed out.


- Wait, back up a minute, why does the booster look so crooked? I swore it was off by like 5 degrees in person, but, only now in graphics, adding this yellow line makes me a bit relieved:




- I notice my original front brake lines are still there, and both seem undamaged. Foolish to re-use?

- Time to test fit it all up, let me just grab that coupler I spent 2 days making for the residual valve... and... it's not here, I've lost it.

More brakework:

- Found the coupler I soldered, it fell out in a friend's yard.

- Went to where I'm keeping my second rear assembly to steal the brake line T-connector for me to use on the front brakes (CRV MC only has 2 brake ports, not 3). Umm, oops, forgot to bring any tools and didn't want to haul the whole axle home. I did have a vice nearby though. Wow did that ever work well despite 50 years of dirt and rust. They should make portable, grippable versions of these vice things.


- This little thing is my favorite component on the car. It's brass, it's moderately complex, and it has tiny little Opel logo on it. Of all the things Opel needed to manufacture themselves, you would've thought a brake T-fitting would certainly not have been on that list. But, it was.


- Alright, so here's the challenge, join the original pushrod, to the iBooster. Considered re-using the large coupling nut, but it appears to be staked onto the booster shaft, not screwed on.


- No matter, I guess I'll fabricate one. For anyone's reference:
- GT pushrod threads are M12 x 1.75, and there's about 27mm of them.
- GT pushrod nuts are 19mm, which if you're cutting down from a bar, is around 22mm across the diagonals.
- iBooster threads are M10 x 1.5, and you can just unscrew the brake pedal mounting clip from the shaft.
- iBooster pushrod doesn't have a proper nut on it, just a pair of flats 10mm apart. You don't have enough access on it to use a wrench 180 degrees, so, it's for holding the shaft still only.
- iBooster has ~12mm of thread
- Total distance from back of each side's threads is around 76mm, and the gap between the two rods is 37mm. (37 + 12 + 27 = 76mm). This is with the pushrod pinned into the brake pedal, at what appears to be its resting place.
- You don't want the nut to be the full size, or it'll have no way to retract or adjust, but you've only got 27mm to play with on the pushrod threads, so, I chose 70mm.
- After a brief panic, no, you don't need left-hand threads or a turnbuckle. The pushrod into the iBooster spins freely.

So, my plan, take a chunk of steel, drill an 11/32" hole, thread at least 12mm of M10 x 1.5 in one side, enlarge the other end to 13/32" and thread at least 27mm of it to M12 x 1.75. Add some flats on the steel to get a wrench on it.

It's midnight on a holiday and I want to work on it right now. Where am I going to find some 19mm hex rod, or ~22mm round stock? Hmm, not like I ever max out the barbell anyways, 26mm diameter? Lots of room for mistakes. Your sacrifice will not be forgotten:


Blech, my drilling is awful, across like, 3 inches, coming out in a different zip code on the far end. I even used the vice and squared it first! Oh well, it's not a rotating shaft, no one will ever know.

- Just a couple flats to add, 7/8" seems nice, that's the same as 22mm and it means not a lot of grinding. I put a couple flats next to the iBooster. NOPE. Stupid GT pushrod brace is so wide there, you need more than just 2 flats. FINE. I cut all 6. Go to put it together... nope. The amount of wrench space there is so small (the brace goes diagonal and gets fatter), even with flipping the wrench each time, you can't get 60 degrees of rotation. Well I'm not making a 12-point. The other end of the coupler has a bit more room, the brace is skinny there. Argg, I should've just picked that side.

Whelp, the jam nuts there are 19mm, so, let's cut down on the amount of wrenches future-me needs. Came up with an easier method than eyeballing and checking with the wrench a hundred times. Jam onto the cylinder a nut profile you want to copy, and then just grind to match:


- Bit challenging order of operations. Boring, skip this, it's for future reference since I bumbled through every mistake there is to make:

• Put the 19mm jam nut onto the pushrod FIRST, the next time you take this apart, because it's currently not on there and you didn't want to start over to fix it.
• The GT pushrod can't be pinned to the pedal (that's it's final resting place, you can only get there once its threaded onto the pushrod coupler), and, since it ends in a hook jammed up next to the brake pedal, it can't actually rotate. So, you have to thread it onto the iBooster side first, fully, then try to shove the pushrod back far enough to insert (it doesn't want to, it's past the pedal), then when you do get it far enough back, it probably doesn't want to move forward again, and it wants to stick out sideways, so you have to hold it in place wth a clamp while you hammer on it until it contacts the threads.
• Then to get the pushrod started, unscrew the coupler from the iBooster (which allows it to move towards the pushrod), until you catch a couple threads.
• Then, don't hold the iBooser steady, but do continue to thread the coupler onto the pushrod a bunch more threads.
• Then unscrew the coupler from the pushrod while holding the iBooster steady (you've now made extra room that it won't fall off the pushrod), until it's bottomed out against there again.
• Then tighten the coupler the rest of the way on the pushrod side. Stop when the hook is at the hole in the brake lever.
• Pin the hook through the pedal (prybar to open a gap, pliers to twist it sideways).
• (Maybe, you can skip all this and just use a prybar to compress the iBooster far enough to get the GT pushrod into place when it's already pinned to the brake pedal, I only just thought of that now).
• Then, when it's all fitting nicely... back the coupler off a bit again. The iBooster needs to see "some" non-zero amount of force on its pushrod when it calibrates booting (car powers on), or it gets an "out of range" error and angrily shakes instead of braking. This might be an intentional failsafe to alert the driver that pushrod came loose, or just, never happens in the OEM vehicles. Either way, it's a bit picky (and does the same if you over-press the brake pedal too and it passes by the top end of its scale, normally not a problem but there's a known amount of push you're supposed to confine it to, adjustable by changing the pivot point of the pushrod on your brake lever (annoying). Notes for future me when actually setting it up.

Otherwise, Ta da:


- Joyously stomp the brake pedal over and over and revel in the glory of the whole system being connected finally.

- Run and find some sawdust to clean up all the brake fluid you squirted everywhere because you forgot that the master cylinder was never actually drained.

It's a short enough to-do list I'm making a list!:

• Find somewhere to mount the residual valve for the rear lines and mount it.
• Find somewhere to mount the T-splitter for the front lines and mount it.
• Make new front or rear brake lines, if you want to.
• Make the central brake line that goes to the diff.
• Actually put the brakes onto the wheels.
• Find a larger reservoir to connect the mini-reservoir to, and mount it.
• Decide if you want to swap the whole rear end for the (better, more modern) spare rear, after cleaning it up, now, or later.
• Fill with fluid, bleed.
• Figure out how drum brakes supposedly work and hate your life adjusting them.
• Test brakes manually.
• Connect up all wires, fuses, and see if the iBooster actually works or whether it's a dud.

Hmm, that list is twice as long as I thought it would be. Oh well, "home stretch" for brakes. All but 1 of those is like, normal car stuff.

Taking a break from brakes for a bit, back to the drivetrain.

I've already destroyed an amputated transmission (had input shaft salvaged) to gain it's output shaft and tail housing, but it is an earlier generation 4-speed with the stupid right-angle speedometer attachment (like one of those gearboxes that help you drill between wall studs, only miniature). This transmission didn't have the right-angle gearbox when I got it, the one scrapper on the continent wanted like $100 for a used one, no other options turned up (snowmobiles maybe), so, since the local parts Co-op has a surplus of 4-speeds, I just bought a newer one with the straight speedo pickup and tore into it.


Went pretty quick (always does when you don't have to care about putting the thing back together). Here's the tail housing off, and the blue speedo geer and white nylon output shaft gear it mates to.


Hoping I can maybe just take the gear off, use the new tail housing, and not have to hammer the bejesus out of the transmission shaft again to get all those press-fit gears off. Let's compare to the one I already have:


Nope. Old one has longer splines, a longer neck, and then right where the white nylon gear would have to go, it changes diameter. I guess I could JB-weld the old shaft to the right diameter for all the torque the speedo gear has on it, but, ugh.

If you were ever curious how that nylon gear is held on, there's just a divot in the shaft that a spring clip with a barb on it tucks into the gear:


Shaft disassembly... I probably spent a half hour on this stupid snap ring until I gave up and destroyed it to get it off (I don't need it). It eventually broke the nose on my snap ring pliers. Was close to getting out the grinder.


The next set of gears requires a special tool (basically just a shoulder to press against, I used two piece of angle iron 3 years ago when I last did this), but it was too late to be sledgehammering.

Back to brakes!:

- I bought another local GTer's brake calipers (he upgraded to big brakes), and paid another guy in the club to refurbish them for me (I'm cheap, but, it's boring classic car restoration stuff, and a whole new system to learn, and it's brakes, I didn't want to get it wrong. It was like $20 in labor for the pair). So they're quite nice.

- Before doing brakes, I guess I should pull the rotors off and lubricate the hubs. Grease there is pretty nasty. Ordinary grease to replace it? STAY ON TARGET, I'm rebuilding the front assembly later anyways, I'll do it then (sorry future Matt).


- Wirewheeled and thread-chased the caliper mounting bolts. Mounted the calipers.


I've owned this car 4 years now, and with newer components on it, it's obvious I've never even bothered to wash it. Hmm.

Time to hook up some hoses.

Uh oh...


I can't recall where all these came from. I think the 3 that aren't rusted are from another local GTer, maybe the other two were mine? Well, the left two (the ones in good condition) aren't Inverted flare fittings (cone comes outwards), they're bubble flare (cone goes inwards). They also don't fit the caliper bracket, they're 16mm instead of 15mm. So, looks like I'll be needing new flex hoses.

Also, I've never looked at an intact GT and the service manual was no help. I'm not sure where these flex hoses go. IIRC there's a hardline "J-tube" from the caliper to the flex, and a hardline into the wheelwell from the MC, but not sure what the other end of the flex and the hardline mount to. Must be a pair of brackets I'm missing, and, some place it bolts to. Waiting on the GT guys for advice.

And that puts an end to my progress for the night.