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#1
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Shimano Nexus roller clutch failing to engage in 5th gear
I have a SG-8R31 hub that has a problem with the roller clutch failing to catch
when I start to pedal in 5th gear. It does not always happen, and when it does the hub will engage after a half turn of the crank. The other gears do not have this problem. Once the roller clutch is engaged it will not slip as long as it is under load, but sometimes it will disengage between pedal strokes. This has been an issue since I got the hub, but it seems to be getting worse. In search of a simple solution, I have replaced the twist shifter with a trigger shifter, replaced the CJ-8S40 cassette joint with a CJ-8S20, replaced the stock cable housing and cable with jagwire ones, tried both types of AR washers that will work with the dropout, and adjusted the cone tension. The cable housing is free from kinks and sharp bends and is heavily lubricated with WD-40. It moves quite freely when pulled back and forth by hand. The return spring has more than enough force. One possible symptom is that when I shift up from 1 into 4 I get a different reading from the cassette joint marks than when I shift down from 8 into 4. This had been constant with both CJs, shifters, and cable housing set ups. I have tried dialing the hub in going off of both readings and the problem remains the same. Does anyone know if shimano has a standard on which reading you are supposed to use? The lubrication history is as follows: When I first got the hub I soaked it in phil's tenacious oil and used phil's grease on the inside of the hub shell and the bearings. Six months later I did the same thing. One year later I soaked the hub is mobile ATF and greased the hub shell and bearings with phil's again. From looking at this Shimano document: http://tinyurl.com/a7bldon http://www.shimano.com/publish/conte...08%20Speed.pdf It appears that 5th gear connects to the hub shell via the 3rd roller clutch, the small one next to the non-drive axle. Is this correct? I suspect that I either have a damaged roller clutch (has anyone ever seen that?) or that the large amount of grease I use on the brake side bearings has somehow contaminated the roller clutch and caused it to slip rather than engage. The problem with this theory is that the hub also uses the 3rd roller clutch in 1st gear and 1st gear does not have this issue. Anyone have any idea if this is possible? |
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#2
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Shimano Nexus roller clutch failing to engage in 5th gear
On 21/11/2012 8:38 AM, Frank White wrote:
I have a SG-8R31 hub that has a problem with the roller clutch failing to catch when I start to pedal in 5th gear. It does not always happen, and when it does the hub will engage after a half turn of the crank. The other gears do not have this problem. Once the roller clutch is engaged it will not slip as long as it is under load, but sometimes it will disengage between pedal strokes. This has been an issue since I got the hub, but it seems to be getting worse. In search of a simple solution, I have replaced the twist shifter with a trigger shifter, replaced the CJ-8S40 cassette joint with a CJ-8S20, replaced the stock cable housing and cable with jagwire ones, tried both types of AR washers that will work with the dropout, and adjusted the cone tension. The cable housing is free from kinks and sharp bends and is heavily lubricated with WD-40. It moves quite freely when pulled back and forth by hand. The return spring has more than enough force. One possible symptom is that when I shift up from 1 into 4 I get a different reading from the cassette joint marks than when I shift down from 8 into 4. This had been constant with both CJs, shifters, and cable housing set ups. I have tried dialing the hub in going off of both readings and the problem remains the same. Does anyone know if shimano has a standard on which reading you are supposed to use? The lubrication history is as follows: When I first got the hub I soaked it in phil's tenacious oil and used phil's grease on the inside of the hub shell and the bearings. Six months later I did the same thing. One year later I soaked the hub is mobile ATF and greased the hub shell and bearings with phil's again. From looking at this Shimano document: http://tinyurl.com/a7bldon http://www.shimano.com/publish/conte...08%20Speed.pdf It appears that 5th gear connects to the hub shell via the 3rd roller clutch, the small one next to the non-drive axle. Is this correct? I suspect that I either have a damaged roller clutch (has anyone ever seen that?) or that the large amount of grease I use on the brake side bearings has somehow contaminated the roller clutch and caused it to slip rather than engage. The problem with this theory is that the hub also uses the 3rd roller clutch in 1st gear and 1st gear does not have this issue. Anyone have any idea if this is possible? My guess is that 1st gear doesn't slip because there is more torque applied compared to 5th, to cause the clutch to grab. In 5th you say it sometimes disengages between pedal strokes. I guess because you momentarily apply so little torque that the clutch slips a bit. As the clutch relies on friction, manufacturers tend to recommend not using lubricants with EP additives. Maybe try a different lube? -- JS. |
#3
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Shimano Nexus roller clutch failing to engage in 5th gear
On 21/11/2012 9:01 AM, James wrote:
On 21/11/2012 8:38 AM, Frank White wrote: I have a SG-8R31 hub that has a problem with the roller clutch failing to catch when I start to pedal in 5th gear. It does not always happen, and when it does the hub will engage after a half turn of the crank. The other gears do not have this problem. Once the roller clutch is engaged it will not slip as long as it is under load, but sometimes it will disengage between pedal strokes. This has been an issue since I got the hub, but it seems to be getting worse. In search of a simple solution, I have replaced the twist shifter with a trigger shifter, replaced the CJ-8S40 cassette joint with a CJ-8S20, replaced the stock cable housing and cable with jagwire ones, tried both types of AR washers that will work with the dropout, and adjusted the cone tension. The cable housing is free from kinks and sharp bends and is heavily lubricated with WD-40. It moves quite freely when pulled back and forth by hand. The return spring has more than enough force. One possible symptom is that when I shift up from 1 into 4 I get a different reading from the cassette joint marks than when I shift down from 8 into 4. This had been constant with both CJs, shifters, and cable housing set ups. I have tried dialing the hub in going off of both readings and the problem remains the same. Does anyone know if shimano has a standard on which reading you are supposed to use? The lubrication history is as follows: When I first got the hub I soaked it in phil's tenacious oil and used phil's grease on the inside of the hub shell and the bearings. Six months later I did the same thing. One year later I soaked the hub is mobile ATF and greased the hub shell and bearings with phil's again. From looking at this Shimano document: http://tinyurl.com/a7bldon http://www.shimano.com/publish/conte...08%20Speed.pdf It appears that 5th gear connects to the hub shell via the 3rd roller clutch, the small one next to the non-drive axle. Is this correct? I suspect that I either have a damaged roller clutch (has anyone ever seen that?) or that the large amount of grease I use on the brake side bearings has somehow contaminated the roller clutch and caused it to slip rather than engage. The problem with this theory is that the hub also uses the 3rd roller clutch in 1st gear and 1st gear does not have this issue. Anyone have any idea if this is possible? My guess is that 1st gear doesn't slip because there is more torque applied compared to 5th, to cause the clutch to grab. In 5th you say it sometimes disengages between pedal strokes. I guess because you momentarily apply so little torque that the clutch slips a bit. As the clutch relies on friction, manufacturers tend to recommend not using lubricants with EP additives. Maybe try a different lube? Also, try to apply more even torque. Try to pull back as the crank goes through 6 o'clock, and push forward through 12 o'clock. You might be a bouncy rider, which could make the clutch slippage more of a problem. -- JS. |
#4
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Shimano Nexus roller clutch failing to engage in 5th gear
1. I don't know the system but I'd try backpedaling to setup the shift to 5th
2. could be a problem with the installation wixh would produce consistant error or anomalic readings. |
#5
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Shimano Nexus roller clutch failing to engage in 5th gear
On Tuesday, November 20, 2012 2:06:49 PM UTC-8, James wrote:
Also, try to apply more even torque. Try to pull back as the crank goes through 6 o'clock, and push forward through 12 o'clock. You might be a bouncy rider, which could make the clutch slippage more of a problem. Me personally, I'd throw the hub away before I required myself to adapt to its shortcomings. Slipping is one of the more unpleasant malfunctions to be subjected to, although at least this hub isn't doing the slip-under-heavy-load thing. Tom Ace |
#6
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Shimano Nexus roller clutch failing to engage in 5th gear
Frank White wrote:
:I have a SG-8R31 hub that has a problem with the roller clutch failing to catch :when I start to pedal in 5th gear. :It does not always happen, and when it does the hub will engage after a half :turn of the crank. The other gears do not have this problem. :Once the roller clutch is engaged it will not slip as long as it is under load, :but sometimes it will disengage between pedal strokes. :This has been an issue since I got the hub, but it seems to be getting worse. Your hub is defective, and you should have had it replaced. You're probably **** out of luck, since you've used something other than shimano's snot in it, though. -- sig 118 |
#7
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Shimano Nexus roller clutch failing to engage in 5th gear
On Nov 21, 8:32 am, Tom Ace wrote:
On Tuesday, November 20, 2012 2:06:49 PM UTC-8, James wrote: Also, try to apply more even torque. Try to pull back as the crank goes through 6 o'clock, and push forward through 12 o'clock. You might be a bouncy rider, which could make the clutch slippage more of a problem. Me personally, I'd throw the hub away before I required myself to adapt to its shortcomings. Slipping is one of the more unpleasant malfunctions to be subjected to, although at least this hub isn't doing the slip-under-heavy-load thing. Hallelujah, brother - even small aggravations are not worth accepting (and more costly in terms of well being than people realize) when you don't have to. |
#8
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Shimano Nexus roller clutch failing to engage in 5th gear
Hi, I have exactly the same problem with my SG-8r35. I'd like to know if you have finally found the solution.
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