Iride01 

This thing is or was working correctly wasn't it? Why not just call it a day, put it back together and ride it until you either have a problem or finally find some more information about it.

Otherwise, your inquisitiveness might just require you to buy another.

For certain it's not helping with your cycling at the moment. <grin>

Crankycrank

Axles can sometimes get a little stuck in tight fitting cartridge bearing I.D.'s and as Iride01 suggested a light hit with a mallet may knock it loose. "Light hit" being the key.

trenzterra

Thanks, it certainly isn't helping with my cycling

Actually I have two set of wheels, purportedly identical (same brand and model and purportedly original) and one seemed to have a little bit more friction than the other (the rear wheel wouldn't spin as freely). So I wanted to open both up to figure what causes the difference.

At the same time, given my freehub body is made of aluminium and the cassette has already made some 'nicks' into the freehub body, I wanted to see if I could replace the freehub body easily in future.

1. First freehub - I was able to get the drive side nut off at first, but on subsequent attempts I could only get the non-drive side out. "Solution" was to put a bit of threadlocker to get the non-drive side out.
2. Second freehub - I was able to get the non-drive side nut off at first, on subsequent attempts I could only get the drive side out. And then after tightening some things up I could now only get the non-drive side nut to open.... I have not tried the threadlocker trick.

In any case, after inspecting both freehub bodies, I realised that despite being the "same" wheel, the internal mechanisms are slightly different. Freehub body 1 (which spins less smoothly than Freehub body 2) has 6 pawls and Freehub body 2 has only 4 pawls. The inner tooth dimensions are also slightly different such that I cannot swap Freehub body 1 into Freehub 2 and vice versa. So the theory about being able to replace the freehub body down the road goes out the window...

I am visiting a home-based bike mechanic tomorrow who specialises in wheel servicing. Will see if he has any tips and tricks to get both locknuts open at the same time.

The wheels in question are inexpensive... so maybe the freehubs are not meant to be opened up and serviced although it can be done. But they are pretty much the most common/ popular 451 wheels where I live (in Singapore) as they come standard on many folding bikes here. The thing is, I'm sure many people have opened up their freehubs before (I have read posts on a Facebook group where people mention things about greasing the bearings inside or even changing it out), but somehow there is no sharing culture over here and people basically refuse to share the information as to how to open it up. Most bike shops over here do not service wheels as well -- it is just not lucrative business for the amount of effort required when they could spend less effort selling you a new set of wheels instead.

For me, maybe it's just a combination of me wanting to get to the bottom of things/ knowing how things work, and a bit of OCD.

Iride01 

Thread locker "trick" ? I wouldn't. If you use permanent thread locker then you will have to use heat to get the nut off you put thread locker on. If you use non-permanent thread locker, then maybe you will and maybe you won't get the other nut off. And if it does work, your nut will now be stuck on the non drive side and you will still have to use heat to get it loose. Which I wouldn't put heat to any of my bike parts other than an old steel frame that might need brazing. You'll ruin any tempering or annealing that was done to them.

As for one hub being stiffer to turn, that might just be that one has more grease packed in it and it hasn't gotten pushed out of the way of the bearings yet. Particularly if it is a new hub being compared to a hub that is been used a while.

trenzterra

I brought it to the mechanic and he was able to remove both sides by using a vise grip wrapped around a towel.

Welp, learnt something new today!