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Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 9:56am
by breakwellmz
Hi

Back in the day,when people would convert 4 speed hubs to 5,what was used for a control?

Cheers

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 11:05am
by robc02
Two controls are needed:

A three speed trigger, or one of the current alternatives, on the right.

On the left, either a derailleur friction control or a trigger. The trigger is adjusted so that two positions are used. Mine is set so that when the middle gear position is engaged the cable is just tight.

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 11:14am
by breakwellmz
Hi

I had a twin cable 5 speed set up like that at one time.

I didn`t realise that a 4 to 5 conversion added a cable,i had visions of people having to make/adapt their own triggers.

Cheers

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 11:38am
by Brucey
^ yup, that is right for a 'left side push' conversion.

A left side push conversion is preferable to a left-side pull conversion (i.e. to S5-2 spec) IMHO. It is simpler, more reliable, and requires fewer conversion parts.

There are several ways of doing the left side pushrod itself;

1) The Jack Lauterwasser method (as depicted in Tony Hadland's book, first done in ~1950 or something mad like that :shock: :shock: )
2) a bell crank (difficult to source these days)
3) the Brucey-style 'L' shaped pull-to-push rod. (although I was not the first to do this...)

I have used the L shaped pushrod quite happily for many years now, on several machines. The only annoying flaw is that the left cable runs slack in the middle three gears; if too slack, the fittings on the cable can rattle around somewhat.

cheers

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 1:57pm
by robc02
A left side push conversion is preferable to a left-side pull conversion (i.e. to S5-2 spec) IMHO. It is simpler, more reliable, and requires fewer conversion parts.


It is worth noting that if you start with an S5/2 there was an upgrade in 1988. It used a different axle and one or two other parts, but is much less likely to slip in bottom gear than the pre 88 ones. The S5/2 was meant to cure the slipping of the S5/1 but wasn't wholly successful. My '86 hub slipped, albeit under extreme pressure, in bottom gear - the '88 mod fixed it. Clearly it is best to get the later model.

It seems a pity they didn't persevere with the early "push" model. I suppose they thought the pull method simpler for the user. I gather the SA bellcranks left something to be desired, hence the alternative DIY approaches.

Brucey, have you got a picture of your 'L' shaped pull to push arrangement?

I might be teaching granny to suck eggs now, but the primary sun pinion (the one that engages with the axle in bottom and top on a 5 speed) needs to have square dogs. I think the later 4 speed ones have ramped dogs to make it easier to engage low gear, but cause it to jump out of top (doesn't matter on a 4). I don't know when this change was made.

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 2:26pm
by Brucey
robc02 wrote: Brucey, have you got a picture of your 'L' shaped pull to push arrangement?


I have indeed, and I'll post it shortly. Watch this space.

{edit; as promised;
PullPushrod1v2.jpg
}

I might be teaching granny to suck eggs now, but the primary sun pinion (the one that engages with the axle in bottom and top on a 5 speed) needs to have square dogs. I think the later 4 speed ones have ramped dogs to make it easier to engage low gear, but cause it to jump out of top (doesn't matter on a 4). I don't know when this change was made.


I have heard this before; it says so in Tony Hadland's book, too. However all the FW and FG suns I have seen have had the chamfered dogs. My earliest FG hub is (IIRC) 1949 or something, has the diamond shaped logo on the hubshell, and appears to have original internals, with a screw threaded clutch driver etc.

So I'm confused; I don't suppose that Jack Lauterwasser would have bothered with a conversion attempt unless he had square dogs on an FW, (although he might have on an FM ?). If there were square dogged FG/FW four speeds, it is a surprise that I've never seen one either in the flesh or in pictures; I've personally worked on at least two dozen FGs and FWs from 1955 or earlier.

BTW re S5/2 sun gear slipping. With use, the dogs wear. Simply because of how they move in and out of engagement (let alone how they might have been made, or how axle might flex in use etc) it is likely that they will sooner or later wear to become 'a rejection ramp' of some kind. If a spring is holding this gear in, it is a question of how much force the spring exerts, vs how much is required to resist the gear popping out. Although much improved, most of the long term users of S5/2s (even with the modified springs etc) report that sooner or later they are liable to start to give trouble in this regard.

A friction shift on the LH side is OK for a push control on a hub that is in good condition, but a trigger shift on the LH side is much to be preferred if there is any doubt about the condition of the sun dogs; a considerable force can be exerted to preserve sun engagement.

By contrast the engagement of the smaller sun pinion rarely gives any concern, and does not seem to deteriorate in the same way with wear. Spring engagement for this sun seems very reliable.

There is a very nice chap that lives not far away from me (who I met quite recently); it turns out that he used S5/2 hubs extensively in the 1980s, and was driven scatty by the problem to the extent that he converted all his hubs to a left side push. Because he and others couldn't source them at the time, he even had a batch of bellcranks custom-made (at some expense) for this purpose. When I showed him my L shaped rod recently, I suspect that he wondered why he'd bothered.

cheers

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 2:50pm
by breakwellmz
I remember,some years ago catching up with an old chap on the high road to Bath from B on A.
We had a chat,amongst other thing,about his SA FM4/deraileur setup as we cycled along.

You`ve guessed,it was Jack Lauterwasser :)

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 2:54pm
by Brucey
breakwellmz wrote:I remember,some years ago catching up with an old chap on the high road to Bath from B on A.
We had a chat,amongst other thing,about his SA FM4/deraileur setup as we cycled along.

You`ve guessed,it was Jack Lauterwasser :)


I'm a little bit jealous; I would have considered it a great privilege to have met the man, and even more to have ridden even a few miles with him.

cheers

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 4:07pm
by robc02
Brucey, have you got a picture of your 'L' shaped pull to push arrangement?


I have indeed, and I'll post it shortly. Watch this space.


Thanks for the photo. Did you need to dress the hole in the forkend to prevent the toggle chain from tending to jam in it?

I have heard this before; it says so in Tony Hadland's book, too. However all the FW and FG suns I have seen have had the chamfered dogs.


Are you saying that you have converted hubs with chamfered dogs and managed to prevent slippage? If so did you use a trigger shifter or just a very tight friction shifter? This would make converting a four speed to five quite a bit more appealing!


BTW re S5/2 sun gear slipping. With use, the dogs wear. Simply because of how they move in and out of engagement (let alone how they might have been made, or how axle might flex in use etc) it is likely that they will sooner or later wear to become 'a rejection ramp' of some kind. If a spring is holding this gear in, it is a question of how much force the spring exerts, vs how much is required to resist the gear popping out. Although much improved, most of the long term users of S5/2s (even with the modified springs etc) report that sooner or later they are liable to start to give trouble in this regard.


I'm quite prepared to believe this. There is much more torque transmitted in the lowest gear so, all else being equal, it seems sensible for the cogs to be positively held in position rather than relying on spring pressure. In my case, I don't often use bottom (though I use top quite a lot) so perhaps it won't suffer too badly in the short term.

Re: Sturmey Archer 4 conversion

Posted: 25 Jan 2013, 4:20pm
by Brucey
robc02 wrote: Thanks for the photo. Did you need to dress the hole in the forkend to prevent the toggle chain from tending to jam in it?
A little bit; but it has also kind of 'dressed itself' over time.... :roll: I do plan to make stainless steel fittings that would allow this to be done to a bike that lacks such a dropout, BTW.

I have heard this before; it says so in Tony Hadland's book, too. However all the FW and FG suns I have seen have had the chamfered dogs.


Are you saying that you have converted hubs with chamfered dogs and managed to prevent slippage?


Goodness me no! In fairness some chamfered suns do have a short unchamfered section; maybe you would be able to pedal gently in 'top' gear. But no, I've not done this with standard parts. I've converted to five speed using a replacement square dog 5speed sun pinion in about a half a dozen hubs now; they all worked fine.

cheers

Re: Sturmey Archer 4 conversion

Posted: 27 Jul 2019, 3:32pm
by steve browne
Hi Brucey,
Is the ā€œLā€ shaped pull/push rod made from a standard SA toggle chain? I have an FG hub I want to upgrade to 5 speed and the only axle I have is a pre 1988 version with the weak springs.
Thank you
Steve

Re: Sturmey Archer 4 conversion

Posted: 9 Aug 2019, 9:27am
by steve browne
Hopeful thread bump!

Re: Sturmey Archer 4 conversion

Posted: 9 Aug 2019, 9:36am
by Brucey
you need a piece of ~3/16" steel rod (the first time I made a rod I used an old nail.... :shock: ) and you need to be able to rivet (or weld) the chain and threaded piece from an SA indicator rod to the end of the L shaped rod.

If converting an FG or an FW, you can (with great care, using a Dremel tool) reshape the sloping dogs on the larger sun pinion so that they will bear load in gear 5. Fortunately the load is usually small in this gear, and the new flats don't have to extend the full width of the dogs to be effective.

If converting a pull-chain 5s hub to a LH pushrod, you need to omit the LH spring from the axle assy.

In either case the spring in the hub is strong enough to change/hold the gear mechanism inside the hub but it isn't always strong enough to pull an even slightly draggy cable. It is not a bad idea to fit an external helper spring that pulls the cable; amongst other things this keeps the cable from rattling around when it would otherwise be completely slack in gears 2,3(usually),4.

cheers

Re: Sturmey Archer 4 conversion

Posted: 9 Aug 2019, 12:16pm
by rjb
I've seen a similar arrangement to Bruceys using a normal gear cable threaded through the drop out like the photo and run over a nail with a slot filed in the end and the cable end then secured on the drop out. Operating the cable with a gear lever then pushed the nail control rod into the hub. Hope this makes sense I searched the internet for a photo but no luck. :wink:

Re: Sturmey Archer 4 conversion

Posted: 9 Aug 2019, 7:57pm
by Brucey
the arrangement you describe is very similar to Jack Lauterwasser's (yes he of Olympic and handlebar fame) conversion for the 4s hub (circa 1950). It is said that these details were even published in the CTC magazine around this time although I have not been able to verify this. Raleigh/SA asked Jack to keep schtum about this and he subsequently obliged, being a Raleigh employee at the time.

IIRC there is a photo of this arrangement in Tony Hadland's SA book, but I can't find it on the web just now.

Folk who have used this setup tell me it works reliably enough but I would expect the cable to object to this treatment after a relatively low number of cycles; this may still give an acceptable life, given that this control isn't used anywhere near so often as the RH control is.

There is a short biography/obituary of Lauterwasser here

https://www.bikebiz.com/jack-lauterwasser-bike-pioneer-and-racer-dies-age-98/

cheers