Sunrace Freewheel - Mega Drive

[simonrogers]

I have a Sunrace Freewheel on my GT Aggressor Sport and there seems to be a problem with it. On the 3/4 cogs when pedalling there is a clunking noise. The freewheel seems to be slightly loose with some play in the hub. I have tried to remove/inspect the freewheel but I cannot work out what tool is required to undo the lock ring?

I have the spline tool to remove the freewheel from the hub, but this does not work. Am I correct in thinking the outer locking ring has to be removed first before the freewheel can be removed from the hub? The part which says Sunrace R2 on it? If so what tool is required? I have searched all over the internet and can find no explanation of this. I've contacted Sunrace but had nothing back from them. Any idea why the freewheel has this play in it?

Would really appreciate some help as this has been driving me mad!

Thanks

SIMON

[Mick F]

Welcome to the forum!

Last week, or was it the week before, I was checking out a mate's bike.
It had a freewheel cluster much like yours, and when I took it for a test-ride, the clunking was driving me mad!
The freewheel had a touch of sideways play, and under load it was clunking side to side.

Pedalled back home and sorted it.

There's a ring further in. Your second picture shows it.
It's a left-hand thread, and you have to tap it round with a small hammer and punch clockwise. I used a small screwdriver and tapped the handle.
Loosen it a bit.

Then insert your splined tool into the splines with the QR completely out. Then refit your QR to hold the tool in place.
You then need a vice.

Place the wheel in the vice horizontally with the tool held tight.
Turn the wheel anticlockwise and the freewheel should shift.
Lift it out, remove the QR, and turn the tool by hand anticlockwise to remove the freewheel.

As the ring has been loosened, lay the freewheel down and undo the ring CAREFULLY. Be careful to catch any of the small ballbearings that my be stuck to the ring.
There's some thin circular shims in there near the ballbearings. Remove one of them, and replace the ring and the freewheel and any ballbearings that came out.
Tap the ring tight anticlockwise, and refit the freewheel to the wheel.
Tighten the freewheel by hand.
Check for sideways play and freedom of rotation.
If there's still play, repeat the above.

It's all very well me saying all this, but I've done this job countless times over the years.
It's easy, but you have to be delicate and catch anything that drops out.

[simonrogers]

You sir, are a hero!

Thanks so much for the advice. I will be out in the garage soon to give it a try. I will report back!

[Mick F]

Just be careful.

The tiny bits will go everywhere if you're not.
I do mine on a tray and have a magnet nearby.
Any bits that fall out will remain on the tray and you can get them all back again.
Use dabs of grease to hold the bits in as you reassemble.

Hopefully you won't disassemble so no bits should come out.
Just don't let it all fall apart.

[Brucey]

Mick's instructions are correct apart from two (important) details

1) It isn't necessary to remove the freewheel from the wheel in order to adjust the shims; at best it is redundant effort. At worst it actively hampers the work since you can't so easily tighten/loosen the lockring in order to determine whether or not you have succeeded. [FWIW I have gone to the trouble of building a tool which holds the freewheel body properly when it is off a wheel, but if the freewheel is firmly attached to a wheel, I just leave it there; it certainly serves no useful purpose to remove it and indeed it is most usually counterproductive].

2) You won't get access to the freewheel body lockring without first removing the sprocket lockring (marked 'R2') in this particular model of freewheel.



You need a four-dog remover and a (long/strong) chain whip. You may be able to improvise the tool somehow (indeed you may have to, I don't recall seeing this for sale); if the hub axle is removed this is made easier (but again leave the freewheel on the wheel because this stabilises it when a chain whip and another tool is being used). I think the sprocket locking is on a RH thread in this model freewheel. Only once that is removed can you access the freewheel body lockring (LH thread) and perform the adjustment you require.

If you are worried about losing parts then I suggest you carry out the work over an old sheet or something like that.

cheers

[Mick F]

I bow to your knowledge about that particular model, but I do not agree that the whole thing should not be taken off the wheel.

If the ring comes off and bits fall out and the freewheel unit comes away from the fixed inner, it's a difficult job to reassemble.
Best to take it right off the wheel after loosening the ring, and then laying it down in a tray to catch any bits. It's difficult enough to tweak out the shim(s) without disturbing and moving some of the outer balls.

Done loads of these things.
I know the best way.

[Trigger]

Unless you remove the outer sprocket lock ring with a 4 dog tool first, you won't have clear access to the freewheel lock ring to punch it around so it has to come off anyway does it not?

https://www.ebay.co.uk/itm/Park-Tool-FR ... Swiv5dmHFi

[Brucey]

I know the best way.

I expect I have done about ten or a hundred time more of these things.

IME when the freewheel is off the wheel you can't fully tighten the lockring unless it is held using a jig of some kind. If you cannot tighten the lockring fully you cannot correctly assess the free play in the bearing.

With many models of freewheel the centre isn't flush with the back, which means it needs to be held on a pedestal of some kind if it is not to be half-way apart when you are trying to remove shims (which might explain the difficulty you experience doing it). The wheel serves this purpose perfectly.

So by all means take the freewheel off the wheel if you want to spend longer than is necessary doing a worse job, with more difficulty.

cheers

[Brucey]

Unless you remove the outer sprocket lock ring with a 4 dog tool first, you won't have clear access to the freewheel lock ring to punch it around so it has to come off anyway does it not?

yes that is what I said above.

https://www.ebay.co.uk/itm/Park-Tool-FR ... Swiv5dmHFi

that remover is meant for older sun tour freewheels. I'm not sure it is the correct size for the sprocket lockring on this freewheel.

cheers

[Trigger]

What about a BMX single speed tool

https://www.tredz.co.uk/.Birzman-BMX-Fr ... zAQAvD_BwE

Sunrace have this on their site but I don't see one for sale

http://www.sunrace.com/en/products/detail/tlef1

[Mick F]

IME when the freewheel is off the wheel you can't fully tighten the lockring unless it is held using a jig of some kind. If you cannot tighten the lockring fully you cannot correctly assess the free play in the bearing.

When you've removed a shim, put the lockring back as tight as you can. Easy done to get it tight enough for checking.
Then on screw on the freewheel by hand and check for play.
If there's still play - probably not - take it off again and undo the lockring and remove another shim .......... and repeat.

Simple, but you have to be careful not to loose any bits.
Best to do it off the wheel and in a tray.

[Brucey]

What about a BMX single speed tool

https://www.tredz.co.uk/.Birzman-BMX-Fr ... zAQAvD_BwE

Sunrace have this on their site but I don't see one for sale

http://www.sunrace.com/en/products/detail/tlef1

I think a BMX freewheel tool is too large, but having said that I have not tried one either so I can't say for sure (the eyeball said 'no' firmly enough that I didn't bother trying). The tool you linked to looks like another BMX freewheel tool but without dimensions it is impossible to say.

I've improvised a tool in the past.

cheers

[Brucey]

IME when the freewheel is off the wheel you can't fully tighten the lockring unless it is held using a jig of some kind. If you cannot tighten the lockring fully you cannot correctly assess the free play in the bearing.

When you've removed a shim, put the lockring back as tight as you can. Easy done to get it tight enough for checking.
Then on screw on the freewheel by hand and check for play.
If there's still play - probably not - take it off again and undo the lockring and remove another shim .......... and repeat.

needlessly awkward to get the shims in and out of a loose freewheel, not good enough for accurate work (you need the lockring fully tight to assess the play properly), and needlessly slow; completely pointless taking the freewheel off and on every time you change a shim .

The possibility of losing bits is easily mitigated in other ways.

More than one way of skinning a cat and all that, but some ways are slower and more awkward than others. As I mentioned already, working with a loose freewheel is so needlessly slow and awkward that I went to the trouble of building a tool to hold it properly; it is a good tool but it is still quicker and easier to service the freewheel when it is firmly attached to a wheel.

cheers

[Brucey]

I found a similar freewheel in my collection of old rubbish

'Golden Sun' 7s freewheel; (never heard of it before)

the sprocket lockring is RH threaded and (quite sensibly) uses a UN-type BB tool to fit it (employing every other tooth rather than the full set).

With the sun race freewheel I'd use an improvised tool to remove the sprocket lockring, and then perhaps modify it to suit the UN type tool if I thought I'd ever want to remove it again.

cheers