Morning all, apologies in advance if this has been covered but afraid I can't find the info so here goes...
On my SA rear drum there is enough, let's call it float, in the actuator arm that it actually fouls the spoke heads at one point in its travel. It appears that the float is deliberately designed in, but seems excessive. I can't see any obvious way to adjust or shim it out.
Am I missing something or is just worn? I don't know it's full history but doesn't appear to have done a million miles...
Thanks in advance!
I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.
Sturmey Archer drum brake actuator arm slop
-
elPedro666
- Posts: 1554
- Joined: 9 Oct 2014, 7:38am
- Contact:
Re: Sturmey Archer drum brake actuator arm slop
Is the brake shoe cover disc thingy (Brucey will know its name or I'll look it up later) loose on the axle? I think that can be tightened and it probably should be.
I don't remember either of my drums having much sideways float on the actuator arm - worn bolts or are they rivets? I'll go look.
I don't remember either of my drums having much sideways float on the actuator arm - worn bolts or are they rivets? I'll go look.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.
-
elPedro666
- Posts: 1554
- Joined: 9 Oct 2014, 7:38am
- Contact:
Re: Sturmey Archer drum brake actuator arm slop
Appreciate that - a comparison with one in good condition would be ideal! Disc thingies are tight, the play is in the arm itself.mjr wrote:Is the brake shoe cover disc thingy (Brucey will know its name or I'll look it up later) loose on the axle? I think that can be tightened and it probably should be.
I don't remember either of my drums having much sideways float on the actuator arm - worn bolts or are they rivets? I'll go look.
Good news I'll be outta work in good time so hopefully pull it apart this afternoon...
I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.
Re: Sturmey Archer drum brake actuator arm slop
if the brake plate is snug and the lever arm (= 'brake lever" in SA speak) is flapping around there are two or three possible causes.
1. that the 1/4" BSF nut that secures the arm to the cam is loose; (simply retightening the nut (with a little threadlock) should fix it)
2. that the cam is loose where it passes through the brake plate. Possible causes for this include wear, wrong parts fitted, parts missing.
3. That the 'brake lever' part is the wrong one. The correct arm for a rear brake is HSB 406 or HSB 205 or HSB 220. [The correct lever arm for the front is HSB 408; front and rear parts are a mirror image of one another]
HSB 205
If someone has fitted the wrong arm it will foul on something. If an attempt is made to deform the arm 'in situ' to improve the clearance then this may damage the assembly such that the bushing will not work properly. If the lever arm sees a knock accidentally then the same thing can happen.
The bushing itself is meant to be captive in the brake plate, and the cam is meant to rotate within it. This may need a tiny amount of lubricant from time to time. If this seizes, and the bushing starts to rotate within the brake plate instead, it will soon wear to be a slack fit in the brake plate. In this instance it may be possible to make a repair by bonding the bushing into the brake plate using epoxy resin. However if the brake plate ever gets really hot (think going down an alp) then the adhesive will soften and the repair will fail.
cheers
1. that the 1/4" BSF nut that secures the arm to the cam is loose; (simply retightening the nut (with a little threadlock) should fix it)
2. that the cam is loose where it passes through the brake plate. Possible causes for this include wear, wrong parts fitted, parts missing.
3. That the 'brake lever' part is the wrong one. The correct arm for a rear brake is HSB 406 or HSB 205 or HSB 220. [The correct lever arm for the front is HSB 408; front and rear parts are a mirror image of one another]
HSB 205
If someone has fitted the wrong arm it will foul on something. If an attempt is made to deform the arm 'in situ' to improve the clearance then this may damage the assembly such that the bushing will not work properly. If the lever arm sees a knock accidentally then the same thing can happen.
The bushing itself is meant to be captive in the brake plate, and the cam is meant to rotate within it. This may need a tiny amount of lubricant from time to time. If this seizes, and the bushing starts to rotate within the brake plate instead, it will soon wear to be a slack fit in the brake plate. In this instance it may be possible to make a repair by bonding the bushing into the brake plate using epoxy resin. However if the brake plate ever gets really hot (think going down an alp) then the adhesive will soften and the repair will fail.
cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
-
elPedro666
- Posts: 1554
- Joined: 9 Oct 2014, 7:38am
- Contact:
Re: Sturmey Archer drum brake actuator arm slop
No.2 takes the prize, top notch as ever Brucey!
When I really got into it there's a lot more going on as well though, Bad Things have befallen this poor old hub in the past...
The disc itself is bent out from the hubshell at the point where the brake lever connects, the bush was loose in the disc, one shoe was twisted and cracked and the star retaining washer is missing. I would surmise that the brake lever has got caught/dropped on something at some time, bending and disc, and the subsequent misalignment has caused the twisting and wear on everything else.
For the time being I've straightened it as best I can (don't ask, it wasn't pretty!), deburred the hole for the bush, filed down the bush so that it's slightly thinner and added some large washers between the disc and the lever. Clearly this is not A Good Solution as the washers will scrub against the disc, but it has minimised and contained the play enough that it'll be alright for tomorrow's ride.
[IMG ]//uploads.tapatalk-cdn.com/20180224/f86a230ca449ec4ba377fdf29da1ca8c.jpg[/IMG]
Note the shiny face of the thinned bush bush.
The really good news is that I've found complete new assemblies on eBay for twenty quid, so with a little luck it'll be spick and span sometime next week.
Thanks again for your help, much appreciated as always [emoji41]
I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.
When I really got into it there's a lot more going on as well though, Bad Things have befallen this poor old hub in the past...
The disc itself is bent out from the hubshell at the point where the brake lever connects, the bush was loose in the disc, one shoe was twisted and cracked and the star retaining washer is missing. I would surmise that the brake lever has got caught/dropped on something at some time, bending and disc, and the subsequent misalignment has caused the twisting and wear on everything else.
For the time being I've straightened it as best I can (don't ask, it wasn't pretty!), deburred the hole for the bush, filed down the bush so that it's slightly thinner and added some large washers between the disc and the lever. Clearly this is not A Good Solution as the washers will scrub against the disc, but it has minimised and contained the play enough that it'll be alright for tomorrow's ride.
[IMG ]//uploads.tapatalk-cdn.com/20180224/f86a230ca449ec4ba377fdf29da1ca8c.jpg[/IMG]
Note the shiny face of the thinned bush bush.
The really good news is that I've found complete new assemblies on eBay for twenty quid, so with a little luck it'll be spick and span sometime next week.
Thanks again for your help, much appreciated as always [emoji41]
I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.