Dura Ace 7850 Freehub/7700 Cassette problems

[carlucci1106]

Have a set of C24 Dura Ace Clinchers with the Ti freehub that I got lightly used in an auction.

They spin really well but I heard/felt a whirring (almost a muted scraping) noise which also transfers feedback into the pedals. Thought it could be gritty bearings so I inspected the bearings and cone tension/ replaced grease yada yada. Still there. You only feel/hear the problem when coasting, so I have narrowed it down to the freehub. But the wheels have few miles on them, and look almost flawless.

It is also peculiar that there is play in the Dura Ace Cassette that I got new for the wheelset, even when the lockring is very tight. You can wiggle the carrier with the four largest cogs and see visible play. Now when I mount my 9 speed SRAM cassette the play is not there. But there is still the noise/feedback.

I read on a thread here that someone got a bad hub once on these, and sent back to Shimano for replacement. I have also heard that these Dura Ace hubs should be ultra-smooth. So could mine be a dud?

Is it worth it to take to an LBS to have them dissassemble the freehub? I can't figure out how to remove it, and even if I could I feel wary about doing it.

I have a nice set of Chris Kings for training, but this wheelset was an investment for a nice 1 lb. weight savings for racing/climbing. But the feeback is more than I can bear when I am used to the butter-smooth CK's.

Any ideas of what to do?

[rnhood]

I have two sets of the 7850 C24 wheels with thousands of miles and they remain quiet and smooth. I think the slight play in your cassette is because you need the 1mm spacer between the cassette and free hub body. Shimano gives clear instructions on this, and when it should be used.

My advice is to let a qualified mechanic look at the wheel. It should spin effortless and quiet. You can also call Shimano and get their opinion, and even return the wheel to them for service.

Buy new next time. Too much risk buying used parts at auction.

[oldpotatoe]

Have a set of C24 Dura Ace Clinchers with the Ti freehub that I got lightly used in an auction.

They spin really well but I heard/felt a whirring (almost a muted scraping) noise which also transfers feedback into the pedals. Thought it could be gritty bearings so I inspected the bearings and cone tension/ replaced grease yada yada. Still there. You only feel/hear the problem when coasting, so I have narrowed it down to the freehub. But the wheels have few miles on them, and look almost flawless.

It is also peculiar that there is play in the Dura Ace Cassette that I got new for the wheelset, even when the lockring is very tight. You can wiggle the carrier with the four largest cogs and see visible play. Now when I mount my 9 speed SRAM cassette the play is not there. But there is still the noise/feedback.

I read on a thread here that someone got a bad hub once on these, and sent back to Shimano for replacement. I have also heard that these Dura Ace hubs should be ultra-smooth. So could mine be a dud?

Is it worth it to take to an LBS to have them dissassemble the freehub? I can't figure out how to remove it, and even if I could I feel wary about doing it.

I have a nice set of Chris Kings for training, but this wheelset was an investment for a nice 1 lb. weight savings for racing/climbing. But the feeback is more than I can bear when I am used to the butter-smooth CK's.

Any ideas of what to do?

For a shimano 10s cogset, you need the wee, 1mm spacer on first, why the cogset is loose. Not needed for 9s or sram 10s.

For the noise, you may have a toasted race in the FH body. For 7850, it is ti FH body, but bolted onto the hub body ala 7700, not like 7800/7810.

[carlucci1106]

For a shimano 10s cogset, you need the wee, 1mm spacer on first, why the cogset is loose. Not needed for 9s or sram 10s.

For the noise, you may have a toasted race in the FH body. For 7850, it is ti FH body, but bolted onto the hub body ala 7700, not like 7800/7810.

The cassette is DA 9-Speed. I thought the 10sp was narrower than the 9sp and thus needed the spacer.

http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/WH/EV-WH-7850-CL-R-2716F_v1_m56577569830698499.pdf

Is the race part #11 in this schematic?

Thanks

[oldpotatoe]

The cassette is DA 9-Speed. I thought the 10sp was narrower than the 9sp and thus needed the spacer.

Where would the race be exactly?

Thanks

shimano has always needed the spacer with their 10s cogsets unless you are using a first gen 10s hubs with the aluminum FH body.

The race is interior to the FH body, take the axle out and see if the bearings and race there is toasted/rusted/pitted. There are replacement FH bodies available for these hubs but remember there are 3 generations of 78xx rear hubs and they all used a different FH body.

Lots of pix and blowups here

http://techdocs.shimano.com/techdocs/index.jsp

[zzy]

There should be absolutely no play on the cassette. If the lockring is properly tightened, add a 1mm spacer. However it is not likely your problem. Since it was used, you don't really how many miles it has seen. I would use an allen key and remove the freehub body, after removing the axle. Check/replace the bearings and regrease; reassemble.

[carlucci1106]

There should be absolutely no play on the cassette. If the lockring is properly tightened, add a 1mm spacer. However it is not likely your problem. Since it was used, you don't really how many miles it has seen. I would use an allen key and remove the freehub body, after removing the axle. Check/replace the bearings and regrease; reassemble.

Yeah I don't think it needs the spacer. The 10sp does. Funny is when I installed my SRAM 970, snug as a bug. Took that DA Cassette and put it on my Chris King hub. Snug as a bug. Weird. But I want my light cassette on my light wheels, Damnit!

I intend to remove the FHub as soon as I get a 14mm Allen. Seems like no matter how many tools I get, I always need more. I'm gonna go with Old P. and say it's that little washer in there scraping. I'm 95% that it isn't the bearings. It rolls forever.

Also, to clarify, there is no play in the FHub. So it has to be a cassette thing as to the play issue.

[zzy]

I intend to remove the FHub as soon as I get a 14mm Allen. Seems like no matter how many tools I get, I always need more. I'm gonna go with Old P. and say it's that little washer in there scraping. I'm 95% that it isn't the bearings. It rolls forever.

Also, to clarify, there is no play in the FHub. So it has to be a cassette thing as to the play issue.

You only need a 10mm allen for the freehub bolt. Sounds like the bearings could use an overhaul regardless. If you're going to all that trouble to disassemble it, may as well replace the bearings while you're at it, balls are cheap. 7850 freehubs were strange and shimano had just changed back from taller splines, so I wouldn't be surprised if that was a contributing factor.

[nicrump]

be sure you are using an actual 7700 lockring on that cassette when on that wheel. same goes for when using a 7900 cassette. i cannot explain why, but i have found on my own 7850's that when the lockring is swapped out(by accident) for the other variety, that rattle and play persists.

no, i am not stupid. no, i cannot figure out what the diff is. simple pragmatics is all i got on this one.

ps, dont touch that body or axle unless you know what you are doing. it is easy as sin to rat-phook that smooth running hub you got there.