Replacing old freewheel
 

Hello everyone,

I'm trying to recondition an old Mongoose mountain bike as cheaply as possible for a friend who would like a bike just for getting around. I don't know the exact year, but it is an early 90s (probably 91' or 92') Mongoose Maneuver with a solid Cro-Mo frame that is in fine shape. It does have a couple of problems after sitting around for so long, however, and I need a bit of advice.

The main problem is that, if I pedal and then stop, the chain sags (on top) and bunches up; while it isn't totally seized up or anything, my guess is that the freewheel is not so "free" anymore. The sprockets themselves are pretty rusty, too.

The other problem is that the shifters are very, very stiff. I may be able to recondition them if I open them up, clean them out and re-lube them. At least one of them moves well enough for me to test the front derailleur, which seems to work fine.

With that bit of background, my concern is thus: The bike came with SunTour gear -- SunTour XCT AccuShift Plus with X-Press shifters, to be precise. Even assuming that I can re-condition the shifters, is there any chance that I can find a new freewheel / cassette that will be compatible with the old shifters? Do I have to be concerned whether the old SunTour stuff is usable with any newer Shimano / SRAM / whatever gears, or will any old derailleur work with most freewheels? I also should point out that don't know if it is a freewheel or freehub setup or something else proprietary.

Any help or insight would be very much appreciated. Thanks!

if nothing else works you could go with friction thumb shifters... simple, cheap and work great, especially with newer ramped cogs

Need pictures ? blind guessing is ..... a shot in the dark


sun tour made 2 and 4 prong freeweel removal tools , but unless you are the original owner
and so know the whole history
an earlier owner could have replaced the freewheel . with something else.

FWIW .. (+1) friction shifting allows a lot of parts mixing ...

The SunTour index systems of that era did use different cog c-c dimensions and different lever/der movement ratios then Shimano. Chains and cables will interchange. I have done a few system conversions to Shimano, a bunch more with friction thumb levers and a lot with just cleaning and tuning with a fresh chain. Andy.

Thanks for the quick responses!
I am the original owner of the bike. I can say confidently that whatever freewheel is on it, it had when it was new. However, I haven't ever tried to remove the freewheel before since there had never been a problem with it before now, so I don't know what type of tool it requires. It has been so long since the bike was put in storage, the chances of me having the old tool are pretty much zero, sadly.

The pointer about friction shifters is very nice to know; I'm glad I should be able to make it work without investing a bunch in buying completely new running gear. So am I to understand that a replacement freewheel would probably be incompatible with the SunTour shifting equipment, then?

BTW, sorry for not providing images.
I'm unsure what would be most helpful, but I hope these are informative :)
http://bikeforums.net/attachment.php...hmentid=367184http://bikeforums.net/attachment.php...hmentid=367185http://bikeforums.net/attachment.php...hmentid=367186http://bikeforums.net/attachment.php...hmentid=367187http://bikeforums.net/attachment.php...hmentid=367188

Ah thanks for the info. So unless I can get it to work just by cleaning it all thoroughly, if I need to change the freewheel / cassette then I will need to buy some friction shifters unless I want to do a whole conversion to Shimano or whatever. At least friction shifters are cheap :)

interesting reading, even the well-aged responses. :)

i never knew there were such freewheels, they make amphibians look like regular animals or like discovering that these little guys really existed!

http://users.stargate.net/~mnovak/ja...ics/lope18.gif

Boone & Crockett material, no doubt. :)

So, I tripped over this info: http://sheldonbrown.com/cribsheet-spacing.html
Looking over the info, it appears that I probably have either a Sun Tour "Ultra" 7 speed, or a Sun Tour "Microdrive" (the only 7-speed Sun Tour freewheels).

While the Microdrive appears to be fairly unique in its specs, the Ultra 7 seems like it has nearly identical cog spacing to the Shimano HG, and differs only in overall width. If I do indeed have the Ultra 7, can I assume that a Shimano HG freewheel would be compatible with the old shifters? Or would the extra width cause an issue?

The sagging chain is due to freewheel friction. Rinse it out with solvent then lube with a fairly heavy oil, letting it drain before reinstalling on the wheel.

I hope I can do so since that would make everything much easier and cheaper, but it's not entirely clear how I'd rinse it out. People generally seem to advise not taking apart freewheels since it is so difficult to get the bearings back in, and I don't see any obvious way to get a solvent (or oil) inside the freewheel mechanism. It's a 4-prong SunTour freewheel, if that makes any difference.

if water and air can get in and rust and dry them out, light oil can get in too. have faith :). just soak it in a bowl of oil, then let it drain, as recommended above.

story,

i disassembled my first freewheel in the back yard when about 10 years old. i desperately wanted to get that spoke protector off and thought i might have a chance if i disassembled it (i didn't know about freewheel removers then). all those (about 50?) bearings poured out onto the lawn.:eek:

i had just gotten the 5 speed Schwinn Collegiate and had removed the fenders against my father's advice, so was already halfway in the doghouse, and now i figured i had ruined the freewheel. my dad, who would be one very unhappy camper when he saw what i had done, was due to be home in about an hour. so i got some grease, rounded up as many bearings as i could find in the grass, figured out, through trial and error, that the grease would hold the bearings on the race and if i was careful, very careful, i could slowly rotate the cluster and bearings and pawls would engage the teeth and the whole thing would slip in. which it did, after about 20 attemps. i made it with about five minutes to spare. i still don't know how many ball bearings i lost, but years later, when doing some maintenance i removed the freewheel the proper way and that spoke protector just fell off. imagine that! :lol:

thanks for letting me reminisce...

It's unclear from your photos whether you have a freewheel or a cassette. A side photo of the cluster taken with the wheel and quick release removed should answer the freewheel/cassette question.

It makes a big difference whether replacement would be a cheap strategy.

Just to confirm what's already been said... Like Andrew pointed out, the cog spacing varies on SunTour AccuShift indexed setups, so it's not a straight swap for other 7-speed freewheels. Not if you want it to index well, at least. Not too long ago, I had a 7-speed AccuShift freewheel (on a '91 MTB like yours) that was just plain worn out and after searching in vain for a replacement, I wound up replacing the whole drivetrain with recent Shimano parts.

Here's a video about cleaning a freewheel to give you some idea. http://www.youtube.com/watch?feature...=eDdSpIPt5qkru

I actually don't think the process he uses is the most efficient and effective, though. I would dunk the freewheel in solvent for some time and then brush off the entire outside first (gloves are a good idea). Then lower back into the solvent and back out repeatedly, spinning (carefully) to help flush out debris and old grease. Then feed in oil at the small gap between the center and the moving portions, spinning again until it is quieter and the oil comes out the other side. I prefer putting the oil in from the front of the freewheel, as the rear gap is larger and therefore allows debris to flow out easier. Use a fairly heavy oil so that it stays in better. DO NOT use any type of grease, including spray grease.

Pffft! I used to see jackalopes all the time while traveling in New Mexico.!

I took the rear wheel off and it appears to be a freewheel that takes the 4-prong SunTour tool.
This isn't mine, but it my freewheel looks essentially like this -- just a lot dirtier, lol. What would the difference be? I figured that in either case I'd be buying new gears, a hub, and shifters, just that the gears and hub would be a single piece in the freewheel scenario. Clearly my knowledge is incomplete, though.

Also, I am assuming in all these scenarios that my derailleurs will work fine with new components. My understanding is that the derailleurs simply move however the shifter cable tells them, and that as long as they are capable of sufficient range of motion that they can be tuned with cable adjustments and whatnot. Once again, however, I am assuming that my knowledge is incomplete.

BTW, thanks so much for all the great information, everyone! I am definitely going to attempt to clean (and maybe even take apart depending on how the cleaning goes) my old freewheel before I replace it, and if I do replace it I have a much better idea what my options are.
Such a helpful bunch :)

1. No - the freewheel is removed and another screwed onto the threads with no need to replace the hub. that's why there's a remover for the freewheel. A freehub can be replaced as well, but the cog assembly is separate.

2. No again. If the derailleur is bent, corroded, the wrong capacity for the gearing, not compatible with the cassette/freewheel spacing, etc. etc. it will not function properly.

I would suggest in-person help at this point. Where are you located? There may be resources nearby.

For friction shifting, that's often the case, but not necessarily for indexed shifting.

With indexed shifting, each click of the shifter pulls a predetermined, non-adjustable amount of cable, which needs to move the derailleur the exact distance from one gear to the next. Because of this, shifters and derailleurs used together need to be designed for the same "pull ratio" -- the amount of cable the shifter pulls to move the derailleur a given distance. Within a given manufacturer's product range, pull ratios are often (but not always) consistent, which is why (for example) you can generally use Shimano 7/8/9 speed derailleurs interchangeably.

I'm pretty sure your SunTour components use a different pull ratio than Shimano or any other readily available replacement components, which leaves you with at least three different options:

1) Find a compatible SunTour AccuShift freewheel. (Good luck!)

2) Replace your freewheel with a Shimano or other non-AccuShift model, keep your derailleur, and use friction shifting.

3) Replace your freewheel with a Shimano or other non-AccuShift model and install compatible indexed shifter and derailleur.

1. Ah I see -- I thought that you could replace just the splined freewheel mechanism of a freehub without replacing the whole hub/axle thing. Is that not the case? Anyway, it's academic since my bike does have a freewheel.

2. The derailleur is in good shape, the gears spin freely, the hinges are smooth, and I'd be keeping the same # of gears. I didn't realize that it had to be compatible with the gear spacing, though; I thought the shifters took care of that. I had read elsewhere that derailleurs were mostly "dumb" pieces of equipment that were largely cross-compatible Thanks for the correction!

And yes, I have an LBS pretty near me and I will consult them. I just always feel better when I have an understanding of how things work and what my likely options are before I go into a store. :)


Thanks a ton, I very much appreciate the specific mechanical breakdown.
I always like to have a "working model" in my head; it helps a lot in understanding what is or isn't likely to work and why.
I'll probably end up going with option 1a (cleaning) or option 2 if that doesn't work.
Option 3 is for if my friend feels like paying for extra parts :)

That's definitely a freewheel. That means a cheap strategy is possible and equivalent replacement parts are available.

The bad news is that the freewheel/hub threads are probably worse than the rest of the bike. Taking the freewheel off will be a big headache. Your best bet may be to have a shop do it. The shop will earn every cent of a nominal $5-$10 charge.

The worse news is that every moving part on the bike should be inspected, based on its general condition in the photo. My guess is that all will need cleaning and greasing. Your derailleur and brake cables probably need to be replaced. This is mostly labor but requires specialized tools, which you probably do not have. You can keep your costs down, if there's a bike coop near you. Otherwise, between buying the tools or having a shop do it - you may not have a cheap option.

Whelp, on the advice in this thread I attempted to rehab my old freewheel and it actually went swimmingly. The rust-coated gears make it look a lot worse than it actually was; once I used some WD40 to clean off the oily grime in the middle of the freewheel it was squeaky clean and in very good shape. Thirty seconds later it was spinning free and bathing in some 3-in-1 oil. The shifters were actually exceptionally clean once I took the covers off; after cleaning and lubing them they worked well.

With the wheel back on I gave everything a test run, and with the rehabbed shifters the derailleurs worked smooth and nearly flawlessly, with the exception of the rear derailleur sometimes missing the second to largest sprocket. A minor inconvenience, but the important part is that the drive-train is in working order even with no replacement parts. As for the brake/derailleur cables, they obviously aren't in brand new condition, but they aren't rusted either and they all appear to be working fine.

I'll still take it by a shop to have it checked out, but it looks like the only thing it absolutely requires to be ridden now is a seat and some tires/tubes.
Thanks everyone! :)