Slipping SA 3 Speed

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Rhodrich
Posts: 180
Joined: 10 Jul 2012, 11:17am
Location: Thames Ditton, Surrey

Slipping SA 3 Speed

Post by Rhodrich »

Now that the spring is here, I really want to bring out my pre-war Hobbs tandem for some family outings. However, it's been sitting in the garage for a while due to having severe slippage on its gears, which on a tandem can be downright dangerous.

I believe it's a standard AW code 3 speed SA (though I might have to check the code when I get home), and is currently operated by the stoker. I've tried adjusting the indicator spindle, but to no avail - you can be cycling along as normal, and then suddenly lose all drive. I've also given it a fresh dose of oil to see if that will fix it, but it hasn't.

My concern is that with it being over 70 years old, and having been fitted to a tandem, it could well be severely worn inside. Whilst I'm happy playing about with derailleur gears, internal hub gears worry me greatly, and I don't have the confidence to rebuild it myself.

Does anyone have an ideas for anything I may have missed, or else does anyone know anyone who's good with these things? I live in Thames Ditton, near Esher in Surrey.

Many thanks.
Brucey
Posts: 44515
Joined: 4 Jan 2012, 6:25pm

Re: Slipping SA 3 Speed

Post by Brucey »

if it is an AW it is most likely to slip in gear 2 or gear 3. Which gears does your hub slip in? Are you certain that the chain is not jumping on worn cogs?

Hub slippage can occur through wear, internal stickiness, bad adjustment, a draggy control cable, or all four.

If the control cable is draggy, then gear 3 won't be selected properly; the spring in the hub needs to be able to pull the cable back until the cable is completely slack in gear 3.

Similarly in gear 1 the cable should be within 1mm of being fully taut, i.e. such that you can't pull the control rod out any further.

In gear 2, moving the gear selector slowly towards gear 3 should put the hub into neutral after 3-4mm of movement. If it is less than that when a neutral appears it is most likely that the adjustment is wrong. [NB the advice re looking at the control rod shoulder on the axle end in gear 2 is OK but it is reliant on the correct control rod being fitted.... this isn't always the case...]

Internally, pawls etc often become sticky during storage. I would suggest that the hub should be given a goodly dose of oil and then is spun up on the workstand, so that the oil works its way around the hub everywhere. Ordinary motor oil is fine for this purpose. If the hub is very sticky inside it may take several days to free off completely. Running the hub through the gears on the workstand each day will help. Expect surplus oil to leak out of the hub.

If the adjustment is good, the control cable moves freely, the hub is well lubricated, and it still slips, then there is an internal fault. If the hub slips in some gears and not others you may be able to infer which parts are faulty.

If it is an earlier hub and not an AW then everything is different.

In any event, slippage under load is to be avoided at all costs; the hub will be damaged by such slippage.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Rhodrich
Posts: 180
Joined: 10 Jul 2012, 11:17am
Location: Thames Ditton, Surrey

Re: Slipping SA 3 Speed

Post by Rhodrich »

Many thanks - that gives me quite a lot to go on! I had been looking at the length of the indicator rod - as you say, the incorrect one may be fitted. I'll have another look and play, and report back. I don't think it's the chain that's slipping. I'll take it for a ride to check, and to be sure what gear it's slipping in.

Otherwise, I could consider moving to something a bit more modern, but given the old wheel size (26 x 1 1/4), and the need for a 40H hub, as it's a tandem, I would have to get someone to lace something up for me, and I doubt it would be economical.
Last edited by Rhodrich on 8 Apr 2014, 10:49am, edited 1 time in total.
Brucey
Posts: 44515
Joined: 4 Jan 2012, 6:25pm

Re: Slipping SA 3 Speed

Post by Brucey »

whatever you do it is likely to be more economical than a new tandem!

If it is an AW the simplest solution is a replacement internal in the old hubshell, if the wheel is OK.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Hein
Posts: 31
Joined: 25 Jan 2014, 10:43pm

Re: Slipping SA 3 Speed

Post by Hein »

Another option: If the RH side bearing's cone has come loose (or is not adjusted correctly), the correct alignment of the indicator rod leads to maladjustment of the hub and slipping in gear 2. It's not that hard to adjust correctly, you'll find the service manual on the SA-heritage site. (There is an error diagnostics table in the manual, too)

Basically it's:
-loosen the LH counternut & cone
-loosen the RH counternut
-screw the RH cone all the way in
-loosen the RH cone 1/4-1/2 turn until the washer that keeps it from turning fits over the square top of the cone
-fasten the RH counternut
-adjust the LH bearing correctly
goatwarden
Posts: 701
Joined: 20 Nov 2009, 12:03pm
Location: Bristol

Re: Slipping SA 3 Speed

Post by goatwarden »

This is not advice on why you're losing drive but don't be afraid of taking the AW apart. If you are happy adjusting the bearings on a conventional hub then there is nothing in the AW which should prove worrying; they are really simple mechanisms and explosion diagrams, manuals, etc are readily available to download. Also most parts are readily available.
I had not looked at one until a couple of months ago but have worked on several recently and am fairly confident I could rebuild one without looking much (to do it blindfold would be too dangerous.)
Brucey
Posts: 44515
Joined: 4 Jan 2012, 6:25pm

Re: Slipping SA 3 Speed

Post by Brucey »

I agree about the RH bearing adjustment, but this is unlikely to move by itself on an older hub, simply because they used to fit tabbed washers on the RHS to prevent loosening (come to think of it I have taken a fair number of older three-speed hubs apart that had a tabbed washer both sides...)

Re a stripdown, I agree, it isn't especially difficult to do, but it isn't for everyone, plus the first one is never the easiest. Only slight wear on some parts can cause slippage under load in some gears (e.g. Jobst Brandt ranted about how his SA gear would slip and blamed the design, but he still took several goes before he had actually replaced all the worn parts....even then he may not have caught all of them)

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
ambodach
Posts: 1023
Joined: 15 Mar 2011, 6:45pm

Re: Slipping SA 3 Speed

Post by ambodach »

I had similar probs with a couple of SA 3 spd. I was advised to fill the hub as far as possible with WD40 and spin daily on the bench for at least a week. Drain off the WD40 and relub with car engine oil or similar. Do not use 3 in 1. Worked for me . Worth a try as the easiest first option.
Rhodrich
Posts: 180
Joined: 10 Jul 2012, 11:17am
Location: Thames Ditton, Surrey

Re: Slipping SA 3 Speed

Post by Rhodrich »

Well I got the tandem out at the weekend, and turned my attentions to the hub. It is indeed an AW hub, with the date code 66, so is a great deal younger than the rest of the bike.

I unscrewed the chain from the indicator rod, screwed it back in with the cable slack in gear 3, and took it for a ride on my own. Try as I might, I couldn't get it to slip in any gear! Either this means that the problem is fixed (it has been sitting over the winter full of 3 in 1 slowly dripping out, so it could have loosened itself up by itself), or it'll only start slipping with two of us on the bike. Need to get a couple of us on it to see.....

It was then that I came across the next problem: the bike is fitted with Dunlop Special Lightweight rims in 26 x 1 1/4 size (597mm). The tyres on there are Dunlop Special Tandem Tyres that look almost as old as the bike (and I'm told that Dunlop ceased making bicycle tyres in the 60's). The only tyres I seem to be able to find that would fit are Schwalbe HS130 ones, which have a max pressure of 85psi, and aren't rated for Tandems. Do you think they'll be alright. I guess they'll be better than the ones that are already on there?

Thanks for all your help. The sooner I get this bike back on the road, the better. Hoping to get a small child seat for the front for my 18 month old son, and to put the attachment on to tow my 4 year old on her tow along bike - we'll then be able to get the whole family on it for some summertime fun!
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s1965c
Posts: 257
Joined: 24 Sep 2009, 3:41pm
Location: Devon

Re: Slipping SA 3 Speed

Post by s1965c »

Those Schwalbe HS130s are about the best quality / highest pressure tyres available in 597 and the situation isn't going to be getting any better longer term.

Would I trust putting the entire family on them? Dunno. I'd be very upset with myself if they got injured due to a tyre problem.

FWIW, I'd happily run them on a solo (105Kg).
_________
LEJoG slug
Brucey
Posts: 44515
Joined: 4 Jan 2012, 6:25pm

Re: Slipping SA 3 Speed

Post by Brucey »

I would not choose 40 or 50-year old dunlops over new schwalbes, no....

Bu tyres are going to be a problem around that size. I guess you could rebuild the wheels to 590 or 584; more choice of tyres there.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Hein
Posts: 31
Joined: 25 Jan 2014, 10:43pm

Re: Slipping SA 3 Speed

Post by Hein »

Depending on tire clearance on the frame and tire width even ubiquitous 622 could be possible. It's just a difference of 1,25cm.
Rhodrich
Posts: 180
Joined: 10 Jul 2012, 11:17am
Location: Thames Ditton, Surrey

Re: Slipping SA 3 Speed

Post by Rhodrich »

The bike has a type of cantilever style brakes that clamp onto the front forks/ rear seat stays, and these can be moved up and down, so it may be possible to fit different sized wheels.

Pics of the bike (before I owned it) are here: http://freespace.virgin.net/hobbs_of.ba ... _fr_3.html , though I'm not sure that those are the wheels that are currently fitted to it. They're definitely not the current tyres, which are amber wall. I may have to do some measuring....
Brucey
Posts: 44515
Joined: 4 Jan 2012, 6:25pm

Re: Slipping SA 3 Speed

Post by Brucey »

it sounds like you have a classic machine there; they might well be relison (edit; I meant 'Resilion' but my ten clumsy thumbs and three brain cells couldn't manage that, it seems.... :roll: ) cantilver brakes which are (if in good condition) collector's items and quite sought after. They are not necessarily terribly good brakes, but only you can judge if they are good enough or not. BTW If they are old, I would be at least as worried about the brakes as I would about 597 tyres. IIRC there are very many soldered nipples in the cables, the failure of which disables the brake entirely.

With a vintage machine you always have the dilemma whether to upgrade or keep it period correct.

If it were mine and I wanted to use it a lot I'd probably convert it to another wheel size for which would fit and for which I could buy tyres. 622 (if they fit) or 584 (which has long been a favoured tandem size) would be at the top of the list. I'd also think about getting wheels with hub brakes; SA do 90mm hub brakes and these are good enough for lightly laden tandems without doubt.

cheers
Last edited by Brucey on 9 Apr 2014, 9:29pm, edited 1 time in total.
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Hein
Posts: 31
Joined: 25 Jan 2014, 10:43pm

Re: Slipping SA 3 Speed

Post by Hein »

Bruce is right, those old brakes may fail and may be insufficient. If it was my bike, I'd probably fit some more or less period correct drum brakes (in the 30's there were 110mm ones made for tandems, but I'd stick with the 90mm which are way more common) in addition to the cantis. I wouldn't remove the cantis, I'd give the control over the front drum brake and the rear canti (or the other way around) to the stoker. And I would give the cantis a complete overhaul to prevent them from failing.
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