I don't know what this would be a part of, the hub, the cassette, something else?
Trying to get this apart so I can more easily put in grease and bearings. As you can see, it's been hit a little too hard by something, probably PO using a chisel and hammer instead of the right tool. I have the correct tool to remove it, it just keeps slipping because one side is well rounded. Any other ways outside of welding a nut on to get it out? Any tricks? I can hit it with the impact gun but unsure if the Park tool would survive and if it would just round this off more. Luckily, my fingers are small enough that I can regrease the bearings without having to get this off, but would like to be able to take it apart one day.
Can't wait to find a new job so I can just get a new wheel set lol.

That is the freewheel. Two tricks to share. 1. Use your skewer to hold the tool tighly into the slots on the freewheel when you put the wrench to it. Once you bust it loose, remove the skewer amd remove the freewheel. 2. If you have access to a vise, use the skewer method above but put the tool in the vise and use the wheel/rim to unscrew the freewheel. This is the best method as you can put downward pressure on the wheel when you turn it to keep it from slipping out of the slots.

First of all this is a freewheel, not a cassette, and the tool used is a freewheel remover.

The key to successful removal is to use the hub's QR (or axle nut) to lock the remover firmly to the freewheel so it cannot cam or climb out. Then it takes a decent amount of torque to break the freewheel free. (the forward thread tightens when you ride, so freewheels can be super tight on bikes you use for climbing steep hills).

My preferred way to remove freewheels, is to place the properly locked-on remover in a vice, channel the spirit of Ralph Cramden and tak the bus into a hard left turn.

IMPORTANT--- once the freewheel breaks loose (1/10th turn or less) immediately loosen the QR so the skewer isn't stretched as the freewheel backs off.

BTW- put the axle back since it needs to be there to stabilize the skewer.

Just stop beating on it soak the thing in modern 40 weight oil for a couple hours you will get the same results clean up and put back on. To take apart a older Suntour it takes several specific tools some skill and usually a torch to do so. The good thing is this is not needed better Suntours almost never fail even after 30 years. Just soak it in oil drain and it might go another 20.

+1 once you have it off, there's no reason to "service" it. A long soaking bath in solvent, followed by draining and running some oil in and it'll go forever. I've ridden freewheels or 45 years in all kinds of weather, never ever bothered servicing them, and I've never had a freewheel body fail before the sprockets wore out.

I tried the quick release trick. It's been so worn that it still won't stay in the slots and just bends the QR, which is luckily easily straightened. This thing is done like dinner, not even going to bother. Now when you guys say soak in oil... what part? Around the cassette? Because I don't see anywhere inside that oil would go, just grease for the bearings.
I should've left it alone and just rode it until it seized lol. Gonna squeeze some grease in and put it back together and call it a restorations At least I got all the grease off the drive train. Who greases a chain? Honestly!

Put the axle back in, with the spacers on the right side just as if you're going to ride it. Then try removing again. The axle's spacers stabilize everything and it should come off if you do it properly. In the normal sequence, freewheels are always removed before axles.

Once the freewheel is off, you can service the hub properly if you want, and soak and lube the freewheel without getting anything else dirty.

+1 put the axle back in! (there are however some freewheels, usually with internal spines, that require you remove the axle; but yours is not one of them) I had the same problem and helped it with dremel carbide bit like these https://www.widgetsupply.com/category...ylinder-1.html Just remove the ramp of metal on the left side notch and try to use the tool again, this time with the axle installed. Again use a skewer and check that the tool stays centered.

Boy do I feel sheepish . Thanks guys, put the axle in, put the tool in, and jumped on the wrench and it came right off! Maybe I can still be riding this weekend. Cheers!

Biggest downside to these freewheels was the two notch removal, Suntour also used a 4 notch which is only marginally better and in every case the tool must be secured to the freewheel so that it does not slip and ruin the freewheel and the tool.

A Shimano freewheel will shift more smoothly because of it's improved cog design and removal is so much easier because of the better design of the splines and tool but internally, the Suntour was a much better freewheel.

It is much rarer to find an older Suntour that still does not work smoothly while Shimano freewheels tend to have a much higher rate of failures... I rebuild Suntour freewheels with fresh cogs as the freewheel bodies never seem to wear out. This is another difference between them as for a time Suntour provided cog boards for customization and rebuilding (like many other companies) while Shimano adopted a more disposable approach when it came to building freewheels.

I had a 6 spd. Suntour freewheel come apart while riding. The only explaination I can think of is that the lockring (the kind you need a pin spanner for) must have been loose. The small parts inside were strewn all over the place and not worth the trouble to find. The result was a long walk. So while these may last forever, it's not a bad idea to check the lockring every now and then. I didn't think to.

Fortunately someone bought the remaining large parts on eBay for $10. The sprockets were in good shape, and I hate to see useful things discarded. It's pretty cool that these freewheels can be taken apart and serviced.

The ONLY freewheels I've ever seen come apart in use are those that have been user serviced (disassembled and reassembled). The factory does a good job setting them rock tight and they don't move. If you do opt to check the lockring for tightness be sure to remember that it's reverse threaded, so you don't loosen it in your effort to check that it's tight.

IME the soak,flush and oil method works well for service, and the only reason to ever open a freewheel (other than curiosity) is to remove a shim and take up some wear. OTOH, most bodies outlast the sprockets, and a complete freewheel is often less than the cost of replacement sprockets bought separately.

From a maintenance standpoint freewheels are one of those items where less is often more.

in the 80s they had the last of the cog boards in the shops. .but that is just not done any more..

the hyperglide tooth is now the norm , on whole freewheels..
no more pick your cogs for your riding needs ..

I don't doubt that, but I had never taken it apart myself. It may have been taken apart by a previous owner. I know I didn't take it apart because I didn't have the tool to before this event. I may have flushed it with lube.

Anyway, it was a nice opportunity to upgrade to a 7-speed, no modification required. I was amazed at how much some of these freewheels were selling for on eBay - sone nearly $100 if NOS.