chagzuki

Forum members might remember some trouble I had with my X-RF5 hub a while back involving a rattling noise whilst free wheeling/coasting. The problem was cured after I took my hub apart, though I never discovered any specific cause.

Recently I've been riding a Brompton with a 3 speed SA hub and the same problem exists only this time I've serviced the hub and it's not been cured. Searching the web has revealed that some people seem to think that this issue is endemic to SA hubs.

For instance here:
https://www.foldsoc.co.uk/bromptont6.html

"Compared with the 12 year old T5, the new T6 felt more free running and stiffer - less flex in the handlebar stem. The 3-speed Sachs hub seemed to make a louder ticking sound both in drive and coasting, but of course without the rattling that accompanies coasting with an old Sturmey-Archer hub."


This thread appears to be about exactly the same problem, though it's clear from the responses that the cause isn't identified:

https://www.bikeforums.net/showthread...oisy-or-silent



Here's another:

https://www.bikeforums.net/showthread...cher-AW-rattle

"has anyone cured an AW rattle ? I took it apart last night and put
it back together and though the cones are now more snug on the drive
side the rattle hasn't changed. it never rattles under power, just coasting
and when hitting bumps"



If every SA hub rattled when coasting then (besides the fact that no-one would use them) it would be stated as a known issue on forums. But it seems that only some hubs suffer from it and adjustment of some kind affects it.

So I'm wondering, is it a specific part of the hub that's rattling or are there several parts that are loose enough to rattle (when not under pedaling load)?

What's different from one hub to another such that some rattle and others don't?

Could it be to do with the quarter or half-turn loosening off of the bearing cone? I.e. is that difference of tension enough to affect the way the internals mesh together?

I'm trying to picture the situation in my head (not easy):
One potential culprit would be the driver vibrating against the planet pinions. In 3rd gear (on a 3-speed) the driver is engaging the pinions pins when pedaling, so when you stop pedaling the driver is next to the pins and free to rattle against them.
If you're in gear 1 or 2 there's more likely to be space between driver and pinions as they wouldn't have been meshed during pedaling. In those gears the clutch drives the gear ring, so when not under pedaling load those two parts would be free to vibrate against each other. . . presumably.

At this point my head is exploding.

The driver could be rattling against the clutch if there's a bit of play in the fit.

I guess one has to establish how the rattle changes depending on the gear one's in to get a clearer picture of what parts are causing it. But having done that what's the solution? Perhaps it's merely a question of making sure there's loads of grease in that drive-area of the hub (if grease is the solution then older oil-based hubs would always rattle).
Could the exact tightness of the drive-side bearing cone (i.e. half-turn/quarter-turn) make any difference?

I've forgotten the driver-type configuration on my X-RF5, I know it's quite different to an AW. . . yet a similar rattling problem arose.

Carcinogent

There is an article in A to B magazine. Look up "Brompton mystey rattle solved" or something like that basically he tin can metal thing that covers the extra set of pawls on the driver rattles get it tight ebough so it can rotate without binding. My personal experience though; Pinions rattle agains the ball ring/planet cage. Especially in the AM hub they are quite meaty. Hence it does not rattle in gear 1 and 3 (ie when pinions are in drive) when pedalling but does rattle when coasting. 2nd gear rattles all the time. Solution in my case: liquid (NLGI 0 grade) grease. Apply liberally and it does quiet things for some time. After a while it does start to be noisy again. I guess once it spreads around from all the spinning parts. I am still trying to figure out how much and where to put the grease but overall that seems to be on the right track.

-Carcinogent

tcs

The actuator (HSA470) rattles in some NIG hubs. It's no big deal. You can pull 'em out and tweek 'em a bit if it bothers you.

chagzuki

The actuator wasn't responsible for the rattling in my 5 speed AFAIK.
Riding some more the AW hub has a rattle that seems consistent accross all gears. I haven't read the A to B article yet, I'll get round to that soon.

chagzuki

Ah, yes, that article, I had read that before after all. I've never had problems with the 'actuator' component.

chagzuki

I just dismantled, examined and rebuilt my AW hub (again). There's a lot of play amongst parts on the drive-side which I've attempted to mitigate with even more SA grease, thick grease on the bearings, and by very careful tightening of the bearing cone/nut. I've probably backed off slightly less than a quarter turn after finger-tightening. A half-turn would allow a ridiculous degree of play.
I'll see how this goes.

chagzuki

It appears the clank is gone but not the rattle. I don't see that there's anything else to be done other than use thicker grease than the official SA stuff, which probably isn't a good idea. The noise is within a tolerable threshold now but not nearly as quiet as my X-RF5 hub, which makes me wonder whether the newer hub designs are a bit better or if it's to do with manufacturing tolerances at the time the specific hub was made.

Carcinogent

Small wheels+high pressure tyres amplify the problem a lot. All the parts need to be loose in order to run freely. Dunno what kind of noises you have exactly though. Grease gets rid of all noise for me. I am yet to try Phil's tenacious oil. That stuff is raher thick and supposedly sticks to metal very well (tenaciously).

-Carcinogent