Lachlan's 1972 Datsun 1200 Sedan

[datsunfreak]

On 7/28/2024 at 8:29 AM, Lachlan said:

As part of rebuilding the steering components, I set the tie rods identically to factory spec and installed them. The steering wheel has always been off (too far right) and I want to fix this as the indicators when turning left don't self-cancel. I took the horn pad off and the steering nut. Turns out the wheel isn't the problem as the dots line up. 

 

What do you guys recommend?

 

Take the steering wheel off and move it. 😁

 

Getting that pitman arm off is a herculian task. I do not recommend it unless absolutely necessary. 

 

If you have enough steering angle with it as is, just rotate the steering wheel. Two mintue fix beats cussing and pulling you hair out on the pitman arm removal. 

[Stoffregen Motorsports]

I would not "re-center" the steering wheel or the pitman arm. The steering box has built in stops and if you move the wheel or the pitman arm, the car will turn more in one direction than the other.

 

Why can't you get the tie rods to be the same length?

[Lachlan]

On 7/30/2024 at 6:07 AM, datsunfreak said:

Take the steering wheel off and move it. 😁

 

Getting that pitman arm off is a herculian task. I do not recommend it unless absolutely necessary.

 

13 hours ago, Stoffregen Motorsports said:

I would not "re-center" the steering wheel or the pitman arm. The steering box has built in stops and if you move the wheel or the pitman arm, the car will turn more in one direction than the other.

 

Why can't you get the tie rods to be the same length?

 

Thanks for the replies! I'll try to clarify what the problem is as I may have explained it poorly.

 

When I was rebuilding the steering system, I regularly checked the service manual to make sure I did this properly because it's a critical part of the car. I've taken screenshots of the relevant sections and put a box around the important parts. I know you've both done this many times before, but this is my first rodeo so I kept to the book.

 

 

Steering System Intro

 

 

 

Linkage Installation

 

 

 

Before installing, I set the both the tie-rods to the same length of 296-ish millimeters as I was using a tape measure. When stood on their ends and a spirit / bubble level placed on top, they were identical in length. This was only meant to get me to the alignment shop so it could be done properly.

 

Here's where the problem is.

 

With the tie-rods set to identical lengths and the front wheels pointed straight, the steering wheel is not at 12 o'clock. I thought under the previous ownership the steering wheel may have been removed and replaced on the spindle out of alignment. When I removed the horn pad, I could clearly see the mark on the steering wheel aligned with the mark on the steering column. The nut showed no signs of ever being removed, so I'm confident I was the first.

 

Given this is a steering box connected to a centre link and held in place by a pitman/idler arm setup, there are really only three points of adjustment to change the steering wheel and driving wheel orientation to one another:

 

1. Tie-rod length

2. Steering wheel to steering column

3. Pitman arm to steering box

 

The tie-rods must be the same length, and they are.

The steering wheel must be aligned to the steering box as @Stoffregen Motorsports suggested, and it is.

That leaves the pitman arm and it's alignment to the steering box, but I cannot see any alignment marks when I've looked previously.

 

Edit: I just thought of another, and that's the steering column connection to the steering box itself. Theoretically, if that had ever been separated then that could also be out of alignment. I think this is an unlikely scenario though.

 

Hopefully that's clearer. All I want is for the wheels to be pointing straight while the steering wheel is at 12 o'clock without having any issues with unequal tie-rods or hitting steering box stops.

Edited August 3, 2024 by Lachlan

[Stoffregen Motorsports]

Maybe someone removed the steering shaft from the box at some point and did not reinstall it in the same orientation. Doubtful, since it is not easy to disassemble one of those.

 

One way to know for sure if the box and pitman arm are centered is to put the pitman arm where it looks to be centered and then turn each direction until it stops aand then count the rotations of the steering wheel. Ypu might find that the pitman arm has been removed and reinstalled incorrectly.

[Lachlan]

Bit of an odds and ends update.

 

On 8/3/2024 at 3:59 PM, Lachlan said:

Upon reassembling, I let the car run for a while to get up to operating temp. When it did, I noticed two things:

 

1. The idle had risen from 700RPM to 1000RPM and I couldn't get it back down with the throttle set screw.

2. An annoying squeal had begun and it was definitely coming from the carb.

 

Carb Squeal

 

I had a hunch the problem would be found in the top of the carb after taking a close look down the bores. Turns out the new carb top gasket couldn't handle the raw power of the A12 and deformed itself. Nothing a newly cut gasket couldn't fix. I'm fairly competent now with all the practice I've had taking this Hitachi apart. Speaking of which ...

 

Power Valve Piston

 

I'd read over on the Datsun 1200 Tech Wiki and also posts by @ggzilla on Ratsun that the power valve piston could be causing some vacuum leak issues. I'd often wondered how this thing worked and more importantly how to test it. Mine didn't appear to hold vacuum or the piston in the down position when I tried the suck test. As mine had been through numerous carb cleaning baths, it moved fairly freely. That said, I think it meant the power valve was always engaged so that might have also contributed to an overly rich mixture at idle and cruising.

 

I tried sourcing another but they seem to be made of unobtanium. There was scant info available online about repairing them, except from an esoteric corner of the car world called Binder Planet focused on International Harvesters. Kind of like Ratsun, but less unhinged. The basic fix centres around placing a shaved down o-ring in the groove of the piston so it can respond to vacuum once again. I didn't have a fresh one on hand and tore the old one I did have, so that didn't help.

 

However, it did get me thinking. If the reason it failed was due to wear on both the bore and the piston itself resulting in too great a tolerance between the two, I just had to work out a way to decrease it again. I had come across this problem before. When I was zinc plating all the bolts during the steering system refresh, I accidentally over-plated one of the strut to knuckle bolts to the point where it no longer fit in the old hole. I didn't know this was possible. Using this experience, I set about to plate the piston many times to see if I could close the gap with the bore.

 

I dipped it in short plating baths lasting 4 minutes about 10 times over, giving it a #0000 steel wool polish each time and repeating the vacuum test. I also polished the bore by rolling a wad of steel wool into the bore and spinning it with the electric drill. Came up a treat. I gave it a thorough spray with carb cleaner, a second dip in the ultrasonic cleaner and even went at it with cotton tips and methylated spirits (denatured alcohol). Eventually, after much perseverance my plan worked. I got the piston to hold vacuum once again.

 

Annual Safety Inspection

 

With the bogging issue largely resolved, I looked at getting another safety inspection. I say another because the first one a few weeks back was a non-starter. I'd handed the keys over barely 5 minutes earlier when they called me over to say they couldn't find the car in the system and that they'd have to do it the manual way via the book. That is, if they could find the book, which they could not. The 1200 was also too narrow for their alignment rack. I did chuckle at that.

 

I booked in again and after someone senior there managed to find it in the system and we're good to go for another year.

 

Cars & Coffee

 

It's been almost a year since I last headed along to a local meet in any car for that matter not just the 1200. In some ways, I wanted to head along as a celebration of the steering system being finished and it being back on the road. Compared with last year, this was a small turn out but the feel had a good vibe. The usual muscle cars were there like Mustangs, Impalas and Aussie favourites like Toranas and Commodores, but also a few more uncommon ones. I got chatting with the owner of a South African built Mazda Capella in fairly good original condition. There was also a Suzuki Mighty Boy and a 70s F-250. The local supercar owners had commandeered another part of the carpark for their meet so I had a good ogle at their cars too. All in all a great morning!

 

 

Running Temperature

 

As this was the first drive with a working temperature gauge having recently replaced the temperature sensor, I noticed that the car takes a long time to warm up and stays stubbornly below normal operating temp. It gets closer to the midway mark while doing sustained high speed driving on the freeway, but as soon as you tootle around town again it drops to about 1/4 to 1/3 on the gauge. I know Datsuns can operate on a fairly wide range, but I would've thought that the thermostat's one job is to keep the temp stable so the needle stays around the halfway mark consistently. Keep in mind, we're in winter down here so I don't know what effect the cool air temp was having. I'm thinking the thermostat is stuck open or stays mainly open at too wide a temp range which is stopping the car from getting to and maintaining an optimum temperature. As soon as it got close to normal temp, it was a lot more responsive and smoother. I did give the whole system incl. radiator and block a thorough flushing and replaced the coolant only a few months ago.

 

Still to do

 

- Replace the thermostat, hoses and water pump

- Move the pitman arm over a notch or two

- Drain and refill the diff oil

- Regrease the rear wheel bearings

- Repaint the wheels and body repairs

- Gently restore the paint

- Drive, drive, drive

Edited August 5, 2024 by Lachlan

[Lachlan]

On 1/2/2024 at 11:14 AM, Lachlan said:

I also discovered that the best way to cold start is:

 

... not quite the way I described in my earlier post.

 

I found an Owners Manual PDF that actually included the proper way of using a manual choke. Turns out you don't pump the accelerator at all, just let the choke do the work and only give it a little press on the gas when starting.

 

 

Hopefully this can help someone else with a manual choke as most of the info is around the automatic choke equipped versions.

[datsunfreak]

7 hours ago, Lachlan said:

 I know Datsuns can operate on a fairly wide range, but I would've thought that the thermostat's one job is to keep the temp stable so the needle stays around the halfway mark consistently. 

 

It is indeed. 

 

7 hours ago, Lachlan said:

Keep in mind, we're in winter down here so I don't know what effect the cool air temp was having. I'm thinking the thermostat is stuck open or stays mainly open at too wide a temp range which is stopping the car from getting to and maintaining an optimum temperature. As soon as it got close to normal temp, it was a lot more responsive and smoother.

 

Even is cooler temps, it should still be up to operating temp within 5-8 minutes of driving and stay there. It definitely sounds like the thermostat is either malfunctioning, or is stuck open.

 

A-series engines like to run pretty warm, and are way more efficient and powerful running at 190F/88C or higher. Most original Nissan thermostats are 194F/90C, but aftermarket ones are usually 180F/82C. If your cooling system is up to snuff (and it sounds like it is), the hotter thermostat is always better. 

 

Normally I put in a 160F or 180F when first getting a car going, then step up to the 194F once I know the cooling system is sorted. 

 

A good way to "test" the theory is to purposely heat soak it. Drive it around on the highway, pull off and shut it down for 5-10 minutes (let it build up some heat), then start it up and go again. If the temp immediately comes back down (and the car runs better when "hot"), you need a hotter thermostat. 

[Lachlan]

Short update.

 

The 1200 is running great! Between replacing the accelerator pump, a new top gasket and fixing the power valve piston, it’s the best it’s ever been. Previously I’d had issues with the air fuel mix being stubbornly rich and fouling the plugs. Finally this has been resolved. After a long drive a couple weeks back I checked them to find a great light tan colouring. First time under my ownership! Some slight signs of oil on the middle two plugs but I know about that.

 

I’ve been looking for excuses to drive it every weekend and it’s performed flawlessly. And good timing as one of my other cars needs some intensive maintenance done which will take me weeks.

 

Something else to add to the list is the transmission kick down. Definitely not operational. Thankfully the shift points are well tuned now so it’s not a big issue, but the click at full accelerator pedal travel does nothing. Any tests or things to check?

[slowlearner]

Nice! Those seats are Nana spec. LOL. I reckon they're more comfy than the terrible thrashed seats in the front of my datto. I should hurry up and put those Subaru seats in.

[datsunfreak]

On 8/30/2024 at 10:49 PM, Lachlan said:

Something else to add to the list is the transmission kick down. Definitely not operational. Thankfully the shift points are well tuned now so it’s not a big issue, but the click at full accelerator pedal travel does nothing. Any tests or things to check?

 

Are these cable operated or vacuum operated? It should either have a cable from the carb down to the trans to tell it to kick down a gear at WFO, or a vacuum modulator on the trans that uses intake vacuum to kick it down a gear. 

 

Pretty sure that click is not connected, but I can't be 100% sure...

[Stoffregen Motorsports]

Some autos use electronic solenoids to kick down. TH400 is one of them. The click on the pedal is the switch that sends the signal to the electric solenoid.

[datsunfreak]

1 hour ago, Stoffregen Motorsports said:

Some autos use electronic solenoids to kick down. TH400 is one of them. The click on the pedal is the switch that sends the signal to the electric solenoid.

 

Yes sir, I was just assuming an old ass Borg Warner or Jatco from the 60s did not do it that way. 😁

[datzenmike]

The in house made in Japan 3N71b was introduced in April '71 in the 510. I think this was the end of reliance on the BW35

[datsunfreak]

17 hours ago, datzenmike said:

The in house made in Japan 3N71b was introduced in April '71 in the 510. I think this was the end of reliance on the BW35

 

I think this mostly applies to North America and Japan. They seem to have done things a bit differently down under. 😁

[Lachlan]

On 9/1/2024 at 10:13 PM, slowlearner said:

I should hurry up and put those Subaru seats in.

 

Absolutely! Replacing the seats it came with which didn't fit (they were from a 180B / 200B) with the slim MX5 Miata NC seats was one of the best changes I've done so far.

 

On 9/5/2024 at 3:12 AM, datsunfreak said:

Are these cable operated or vacuum operated? It should either have a cable from the carb down to the trans to tell it to kick down a gear at WFO, or a vacuum modulator on the trans that uses intake vacuum to kick it down a gear.

 

Vacuum operated for normal shifting. When I replaced the vacuum modulator, I got an adjustable one that allows fine tuning of the shift point. It works really well now.

 

On 9/5/2024 at 3:17 AM, Stoffregen Motorsports said:

Some autos use electronic solenoids to kick down. TH400 is one of them. The click on the pedal is the switch that sends the signal to the electric solenoid.

 

This transmission also has the electronic solenoid to kick down and still has the audible click at full pedal travel. When I was under the car last time, I did give the solenoid and connections a good look over but I couldn't see any broken or loose wires.

 

On 9/5/2024 at 5:18 AM, datzenmike said:

The in house made in Japan 3N71b was introduced in April '71 in the 510.

 

This 1200 also has the 3-speed Jatco 3N71B transmission which I understand is a great unit. No complaints from me so far.

 

On 9/5/2024 at 10:32 PM, datsunfreak said:

They seem to have done things a bit differently down under. 😁

 

They certainly did. Our 1200s had different brake systems (PBR), ignition systems (Lucas), rear axles (BorgWarner), heaters (Smiths) and interiors (I think made locally in the Melbourne assembly plant). Other parts like the engine, transmission and body were unchanged.

 

For those interested, I've included a summary below on the context of the Australian vehicle industry from 1965 to 1975 that explains the rationale behind the part substitutions. In short, the Government wanted the build the local vehicle industry and protected it from imports by applying a sliding scale tariff according to the amount of local content e.g. higher local content meant lower tariffs on foreign manufacturers and lower prices for consumers. In principle, at least.

 

The other way around these laws were for foreign manufacturers to ship complete knock down (CKD) cars to Australia and have them completely assembled here, bypassing the tariff entirely. This has been covered in much greater detail on the Datsun 1200 Tech Wiki.

 

--

 

Throughout the 1960s and early 1970s the major aim of Government automotive industry policy was to increase the level of local content in vehicles assembled or produced in Australia. The Government’s stated policy was to:

 

... maintain a viable industry producing at high levels of local content and ensuring consumers access to reliable, economical and reasonably priced
vehicles. (House of Representatives 1976, p. 1130)

 

In 1965, the Government introduced the first of a series of Motor Vehicle Manufacturing Plans to promote higher levels of local content. Local content
provisions under the plan provided vehicle producers with tariff concessions on imported components if the vehicles they produced consisted of at least
95 per cent local content. The first plan included separate local content provisions for small volume producers which varied according to production
volume, the specified level of local content and the tariff concessions provided. The competitive position of the industry steadily declined in the late 1960s. The Government responded by increasing the tariff rate of PMVs from 35 per cent to 45 per cent in 1966.
By the mid 1970s the Government recognised that there was a potential conflict between its policy objectives:

 

High costs of production in Australia, resulting mainly from the smallness of the domestic market and the short productions runs, means that the higher the level of Australian content in vehicles the less competitive they become against imports and to the extent that higher protection is provided the greater is the price to consumers. (House of Representatives 1976, pp. 1128–29)

 

Source: The Automotive Industry: Volume II Appendices

Edited September 7, 2024 by Lachlan

[Stoffregen Motorsports]

6 minutes ago, Lachlan said:

This transmission also has the electronic solenoid to kick down and still has the audible click at full pedal travel. When I was under the car last time, I did give the solenoid and connections a good look over but I couldn't see any broken or loose wires.

Well, it is a switching valve that lives in a pretty harsh environment. I just had to replace one of the switches inside the auto trans on my Cummins powered Dodge, with only 125k miles.

[Lachlan]

2 minutes ago, Stoffregen Motorsports said:

Well, it is a switching valve that lives in a pretty harsh environment. I just had to replace one of the switches inside the auto trans on my Cummins powered Dodge, with only 125k miles.

 

Thanks for the info! I feared this might be the case. Did you do any tests on your Dodge to narrow down that the solenoid was the cause? I'm not sure how to test it.

[bananahamuck]

Bump for a 1200 actually being worked on . 
 

  My thread is just pictures of other peoples cars. 

[Stoffregen Motorsports]

18 hours ago, Lachlan said:

 

Thanks for the info! I feared this might be the case. Did you do any tests on your Dodge to narrow down that the solenoid was the cause? I'm not sure how to test it.

Not really, I did about an hour's worth of reading online and then found the part and bought it. It only took two hours to replace and luckily it was the problem.

[Lachlan]

On 9/8/2024 at 1:31 PM, bananahamuck said:

Bump for a 1200 actually being worked on .

 

Thanks for the bump! Hopefully it's been interesting to follow along.

 

1200s don't seem to pull a crowd quite like the Z-Cars and 510/1600s do, but they're plucky little things with a lot of heart. Everyone loves an underdog.

 

That said, it's still on my list to own one or both models above. Ideally paired with a manual, but I've grown to love bombing around in an auto.

[Lachlan]

Tonight I took the car out for a test run. The plan was to blueprint the distributor by running it up through the rev range and recording the amount of mechanical advance it adds to base/static timing. There are no existing curves online as I've got a different one to most 1200s and it's been orphaned (Lucas 29D). Ultimately, I wanted to know what the total advance was at 4800rpm from a base/static timing of 7 degrees. I'm aiming for 28-32 degrees as suggested for the A12 on the Datsun 1200 Tech Wiki.

 

After giving it a high-speed run to warm it up, I found a quiet cul-de-sac with a streetlight in the industrial area so I wouldn't annoy people at home. I connected the timing light and newly purchased vacuum gauge and set to it.

 

I discovered two things:

 

1. My timing light wasn't initially responding to different settings with only the 0 degree setting working. I got it working later.

2. Hitachi DCGs have ported vacuum on the carbs so they only register when the throttle plate is cracked open. I found out why after I'd finished and got home.

 

I managed to record the settings up to 2500rpm before pulling the plug on the exercise. I wasn't sure if this was entirely good for the engine just sitting still and holding revs. With the vacuum advance disconnected, here are the crankshaft readings I got:

 

RPM & Degrees

750 = 7

1000 = 7

1250 = 8

1500 = 10

1750 = 12

2000 = 13

2250 = 15

2500 = 17

 

Will it do any harm to the engine to continue this up to 4800rpm at which most 1200 distributors are all in? I was feeling a bit sketchy standing in front of the car holding the throttle open even through it was in Park with the handbrake on. At least I've found a good spot to do it that won't bother anyone.

 

After a quick Google-fu on tuning with a vacuum gauge, I learned I could commandeer one of the intake manifold ports for getting a good vacuum reading at idle. I pulled the transmission vac line off and was now getting a vacuum reading, but not one I was overly pleased with. The needle was pinging rapidly between about 15 and 21. It was more erratic a lower idle (high 500s) and narrowed slightly as the idle was lifted (low 800s) while it warmed up again on the manual choke fast idle.

 

There's always been a ticking / clicking / tapping noise at lower idle speeds and I've already adjusted the valves while hot.

 

Could this be an indication of worn rings? It smokes a little on the highway when I give it full throttle and there's small amounts of oil on the middle two cylinder's plugs. I'll pick up a compression tester when they're next on sale and confirm.

 

And the oil pan gasket is leaking. So that's now on the list.

Edited September 9, 2024 by Lachlan

[RyanC]

Love that the 1200 is mostly on the road mate good stuff!!  Always a little list with this age of car I think but your getting on top of the majority of it.  Did you just move / reseat the steering wheel and check for turns left or right? 

[datsunfreak]

On 9/9/2024 at 7:32 AM, Lachlan said:

I managed to record the settings up to 2500rpm before pulling the plug on the exercise. I wasn't sure if this was entirely good for the engine just sitting still and holding revs. 

 

Will it do any harm to the engine to continue this up to 4800rpm at which most 1200 distributors are all in? I was feeling a bit sketchy standing in front of the car holding the throttle open even through it was in Park with the handbrake on.

 

I can assure you, it will hold 6k rpm almost indefinitely. And higher, if you're bogan enough... 😋

On 9/9/2024 at 7:32 AM, Lachlan said:

Could this be an indication of worn rings? It smokes a little on the highway when I give it full throttle and there's small amounts of oil on the middle two cylinder's plugs. I'll pick up a compression tester when they're next on sale and confirm.

 

Could be worn rings (less likely) or worn valve stem seals/valve guides (more likely). A compression test will usually tell you which. Leaky vavle stem seals do not normally effect compression readings, while worn rings often do. 

 

Upside is, replacing worn valve stem seals on an A-series is as easy as that job gets. 

[Lachlan]

On 9/10/2024 at 11:45 AM, RyanC said:

Did you just move / reseat the steering wheel and check for turns left or right?

Not yet. I figured I’d drive it for a bit to discover what else needs doing that you only find after some seat time. The tyres scrub a bit when reversing so I’m guessing it still needs an alignment. That’s brought my focus back to the steering so I’ll tend to this shortly.

 

Good to read your 620 is closer!

[Lachlan]

Measured the alignment and had toe-out of about 10mm after rebuilding with the factory specs (length of tie rods). Not wildly off, but it now has the desired 5mm toe-in when comparing the distance between tyres on the front side compared with the rear side (taken at midway up the height of the tyre). Hard to explain but it's good enough. Tracks much straighter and the steering gained lightness.

 

I also tried once more to get the pitman arm off. What a bugger! It just won't budge. I have soaked it in my home-brew penetrant mix of ATF & acetone (50/50) dripped down the shaft from above and WD40 sprayed up from below for days and it won't move. I can't get two heavy hammers under there because of access. The pitman arm puller jaws are just too wide and so it starts to slip down the side of the arm when really snugged up. Lastly, the threads at the bottom of the shaft where the puller pushes a bolt into is starting to mushroom making removal of the pitman arm nut difficult. Was feeling super defeated by this. The steering wheel is still canted off and it bugs me every time I drive. Next step is to break down and buy a torch to heat it up and break the rust bonds. I'll consider doing this next year. Maybe. Probably never.

 

I discovered the reason the kick-down on the trans wasn't working was because a wire had detached on the pedal switch. A short soldering job later and the kick-down works again! Comes in hard and super handy for accessing the upper revs on hills.

 

The trans pan is leaking. I did the shadetree fix of snugging up the bolts which will probably make it worse. It likely won't fix things as I didn't ensure the pan was flat when I changed the filter and fluid.

 

It consumes a fair bit of oil. After only a few weekend outings, it's already down to halfway on the dipstick. I knew it burnt some as there is always that smell when idling and I can also see a little smoke when flat to the floor on the freeway at night (lights from the car behind makes it easy to see). I suspect there will be a valve seal and piston ring replacement job coming up.

 

I tried to change the diff oil but didn't have a spanner/wrench large enough to get on the fill bolt (28mm?) and no sockets could get access. I'm going to suck out the old fluid with a hand pump as there's no drain bolt and getting the diff cover off will likely destroy the gasket. Being some old odd-ball BW unit that's long forgotten, I think I'll play it safe and live with not getting all the debris out. "Good enough" is becoming my new mantra with this car.

 

And because it wanted part of the action, the carb float bowl gasket decided to start leaking. Yes, "Weber the world" and all that.

 

At least when I took it to Cars & Coffee this morning, it really appealed to the over 60s female demographic. I don't know whether to call that one a win.