Dunk anything you can into evaporust. It is amazing what that stuff can do. Leave it sit for 12-15 hours, scrub gently with a toothbrush and put back in for awhile.

Yeah saw that on a lot of videos. Unfortunately it seems to be hard to get over here so I settled for vinegar since I was worried about affecting the structural integrity of the alloys with local chemicals. Having some evaporust shipped from Amazon for some future builds.

Having used all of the suggested materials, evaporust is the only one I don’t worry about anything I chuck in there. Anodized, brake shoes, hub parts, plastic bits.

It actually softens up old brake shoes a bit. Weird side effect.

It's impressive you're willing to take on such a project for your first restoration - but a Nakagawa is surely more than deserving that distinction! Lot's of help will be forthcoming on how to treat that rust; others here have dealt with stuff at least that bad, and some even worse.

Looking forward to your separate thread and updates as you massage this from ugly duckling to swan

DD

Get the tool.

When you say "cassette", I've a hunch that you mean "freewheel". But I'm not sure. If you too aren't sure, see Freewheel or cassette? For freewheel removal, see this. Yes, you need a Suntour tool -- but only in the sense that it's for Suntour; it doesn't have to be made by Suntour (Maeda). If there are holes for two prongs, get the Park FR-2; if for four, the Park FR-3. If (like me) you lack a vise for clamping it, you'll need a one-inch box wrench (as long a wrench as you have or can borrow).

++ For EvapoRust! The stuff is amazing! I’ve found tho, that 12-15 hours might not be enough for anything more than light surface rust. Many (if not all) of the ferrous components in the OP’s pics are pretty severely rusted and while the EvapoRust will remove the rust, the pitting will still remain. This restoration is going to truly be a labor intensive and IMHO a fairly spendy endeavor! I do hope that the frame (internally) hasn’t suffered the degree if rust that the external components are showing. Before throwing too much cash into the project, I’d definitely have a close look at the inside of those tubes. The seat tube and head tube will be easy but I’d consider borrowing or renting an automotive bore scope for the rest.
Best of luck to the OP! I’ll be interested to see how this project progresses.

I have been thinking about getting one of the bore scopes that hook up to your phone, relatively cheap, but I have no idea how good they are.

LeSexyFishorse I think those rims will be difficult to save. They look like alloy with riveted steel eyelets. Those eyelets are in bad shape from the rust and sandpaper really will not work there. Your spoke nipples are probably fused to the spokes and trying to true the wheel will probably start snapping spokes. Before you start on the rear wheel you could take it to a bike shop to remove the freewheel. It has to come off to fix the spokes and is very difficult to remove if the hub is removed prior.
I think your derailleurs will clean up fairly easily, the brakes will take more work.
As has been suggested, Evaporust is really needed for a bike like this.
Your chainrings should be fairly easy to find at 130BCD. I do wonder if you really need more than 53 outer. 38 on the inner would make hills a bit easier.
Good luck!

I don't know what bike shops are like wherever it is that LeSexyFishorse lives, but in my part of the world I wouldn't assume that a bike shop, even a good one, has the right tool for a decades-old Suntour freewheel.

The Park product doesn't cost much, it's easy to find, and of course it can be reused later.

I’d be pretty unimpressed with ANY bike shop, especially one in Japan, that didn’t have the tools required to remove Japanese freewheels .

I (in Tokyo) wouldn't assume that it wouldn't have the tool. I just don't know. I do know that the man who runs (well, who is) my favourite LBS didn't/doesn't have a wrench needed for one stage of the installation/removal of a mid-80s Suntour BB. He was very apologetic about this, and recommended that I go to a larger, longer-established and reputable rival a few hundred metres away, which would be likely to have it. It then occurred to me that I might have the tool myself, went home, looked for it, found it, and took it to the shop, where he took out the disintegrating old BB and replaced it with one made by Shimano.

Another problem is that some (otherwise hospitable) shops here politely refuse to handle old bikes (other than for humdrum matters such as changing tyres). (Yet other shops are happy to do so.)

Yes I have experienced this so this is also what I have decided to do. I have ordered the tool and taken it to a shop to have them do the removal and I watch and ask questions so I learn how. I also encounter the same problem here where approaching a weekend or during regular hours that some bike shops wont take small jobs because of the backlog of work they have for upcoming weekend rides from larger groups (there are quite a few in the area). So what happens is if they do take it I have to wait for 1 1/2 weeks for a wheel to get trued. Not being able to ride for a week and a half has inspired me to learn to do it myself and to get a 2nd bicycle .

Quick update:
Wheelset - purchased this Dura Ace wheelset with 7 speed cogs to temporarily replace my suntour one while I look for replacement rims for it. I went on the basis that 7 speed should work with the RD be it suntour or shimano cogs. Rear spacing was listed as 126mm which is the same as I measured on my bike. Rear cogs are 13-21 7 speed, velobase says sprint 9000 wont take more than 23 for indexing so it should work indexed (the click from the indexed is quite satisfying to use ) I have read something about shifts not being crisp for the last 2 upper gears due to spacing issues between suntour vs shimano cogs. Do you guys see any potential compatibility issues?



Brakes
So I read that single pivot brakes are not that good compared to modern dual pivots. So I decided to get some more modern brakes and ended up finding these Ultegra BR 6800's (which have yet to arrive) and some ultegra 6700s (because they were super cheap). Decided to stage the brakes by replacing my existing ones on my SS to see any potential issues. This is what I found:
Suntour issue: Ultegra 6700 issue:
For the suntour, what happens is that when I depress the brake lever for the suntour brakes, the opposite of the cable side pushes into the rim only. The cable side does not seem to want to compress towards the rim. The rotating attachments have all been lubricated with teflon grease and they move fine when I depress them by hand. All the screws have been tightened. I did notice that the brake cable covers do not come in contact with the barrel adjuster. Can this be causing the issue? The cable seems to be pulling the whole assembly upward instead of in a clamping motion.

For the Ultegra 6700, I noticed that the off cable side (non-drive side) pushes into the rim hard ever so slightly. This causes the rim to move towards the drive side. What this is doing is causing the front fork to violently vibrate under braking even at low speeds (as low as 5km/h) probably because the rim is repeatedly getting pushed out of alignment and fighting back? I can minimize the pressure for a while but it eventually comes back. All bolts are tightened as well on this and the spring tension/return does not feel abnormal (compared to my existing ultegra 5500's). Anyone know what could be causing this?

Aside from these issues, cranks have been polished to mirror shine (pics later when buffed with a buffing wheel (going to a local shop for this since I don't have a wheel). Working on RD/FD next. My goal is to try to get this bike up and running this month and use if while I service my SS. Once my SS is back up I will have her repainted and the final touches put done (fingers crossed).

The outer cable must be fully seated in the brake adjuster and have enough slack to flex with the brake arm action. Probably need new cables.

PS, Your updates should probably go into your "Nakagawa: Ugly Duckling to Swan Project" thread.