Every 5 turns of the cranks in 3rd gear ( minimal/least tension on the cable) my sturmey archer CS RK3 hub was crunching.
This has progressed to a full on unridable slip every 5 turns of the cranks.... but only in the 3rd gear.
anyone been inside these are they just like the old 3speed single gear hubs - remove left cone , remove lock ring , remove drive unit - disassemble from the right cone ? probably not as i think its a copy of the sachs/sram hub .... and they sucked.
Likely culprit ? - i suspect a clutch pawl or spring may have gone.
Sorry, cant help. The mere mention of the name "Sturmey Archer" brings me out in a cold sweat. Crushed my clackers twice on the top tube due to these things slipping. At the age of 10 I vowed I'd never own another :o)
😀 ^ that is also my childhood memory of Sturmey Archer gears.
yeah mostly they slipped due to bad adjustment -
this is adjusted correctly and is fine in the tensioned gears - its the non tensioned gear thats giving me issues.
Our 1970's era 3 speeds mainly slipped due to the design (being fractionally out of adjustment let you find the gaps between gears).
The newer hubs like t_r's are "NIG" (no in-between gear) where they have supposedly removed the possibility of gaps / slippage from the design. A description of how these hubs differ to the old style is shown below. Does that give any clues as to how yours comes apart? I presume it is similar, just with a longer splined cassette body in place of the normal single sprocket mounting (my newish 3 speed has a very short single sprocket HG / Shimano cassette spline rather than the old 3 lug sprockets).
There are some links to technical stuff on the SA history pages which I think Alan Clarke collated before he retired (was a very helpful guy when I once swapped some emails).
Interesting video
Not worked on NIG sturmey before
Even more clueless about what is going to greet me when I crack it open.
Theoretically what I’m experiencing shouldn’t be possible going by that video should only drop into second gear.
But that is assuming of course that this does have a sturmey NIG insides. . Who knows
When I spoke to Alan (10 years ago mind) I'm pretty sure he said that everything was now the new design, so yours should be..... 🙂
I'd try opening it like the one in the video and see what you find. Any exploded tech docs on the Internet? Might be worth an email to SA (think it was a .nl email address).
I'm building enthusiasm to look in my neglected Alfine commuter hub.
What if you have a broken tooth on something? That would sound a candidate for a regular / periodic slip. Need some more braincells to work out which bit missing a tooth would equate to x rotations of the hub......
I have an incline that is the case given its seen over 1200watts a few times it's not out side the realms.
Will fire the hope big UN back on and take it into the shed for surgery.
I expect grey metallic sludge.
One of the main drive pawls that drives the hub body appears to be lazy.
Only seems to give slippage at max beans in top gear.....wondering if the single fully working pawl can't cope
Oh and one of the 3 pins that engage with the clutch was lazy too but sorted that.
Everything else seems to be fully intact
Looking a t photos perhaps gonna add tension to my spring see if it makes the pawls a bit more active mines seems to be stretched compared to most photos
Will reassemble and see.
Time to drop an e-assist loaded cargo Wattbomb and see what happens 🙂
Well at 1200watts peak there still a crunch.
But it's no longer hitting an unrideable kind of neutral.
Think I'll order a new circlip and pawls I think mines lost its *spring* and the cam shape of the Pawl looks worn.on the inner lobe compared to its opposite so the spring doesn't kick it out.
Significantly less evil inside than I expected. No bits or grit or grey paste evidence of metal being ground away.....
After all it's not rated for the loads I'm putting through it haha