Sturmey Archer aw 3 speed hub slipping in middle gear

rjb · Post by **rjb** » 13 Feb 2009, 12:28pm

The Sturmey Archer AW 3 speed hub on my 1976 Dawes Kingpin has suddenly started slipping in the middle gear only. It doesnt slip continuously just occasionally. I have been oiling it with EP90 gearbox oil as opposed to thinner oils. I have double checked the cable adjustment and it appears to be ok. Any thoughts before I resort to stripping it down to take a look. If I find a problem within are spare parts still available, may not even be economically viable to repair! Any suggestions much appreciated.

hubgearfreak · Post by **hubgearfreak** » 13 Feb 2009, 6:01pm

sheldon says

95 percent of shifting problems on 3-speeds are related to the control cable or the handlebar trigger unit.

and here are his tips to get the right tension in the chain, maybe it's worth another go?

http://www.sheldonbrown.com/english-3.html#sturmey

if you do strip it down and need spares, take a photo of the bits you have that are worn out next to a ruler, and i'll check to see if i have them, there's loads of bits in't shed'o'doom

good luck

Colin Stanley · Post by **Colin Stanley** » 13 Feb 2009, 8:09pm

When you say "I have double checked the cable adjustment and it appears to be ok." The thing is for a 3 speed hub is to ensure the indicating rod shoulder (that is pulled by the little chain thingy) is flush with the end of the hollow spindle when in second gear (normal). I take that you have done this by adjusting the cable tension?

Probably not relevant (and here I must apologise for not making a small link, but being very old, I have forgotten how to do this) is:

http://www.honestjohn.co.uk/forum/post/ ... tm?t=59535

this discusses the use of EP oils in classic car gearboxes thus:

Why should I choose non-EP straight oils for my classic car?

Depending on the age, make and model non-EP gear oils may be required for use in gearboxes and final drives. Certain designs contained a lot of phosphor-bronze (copper containing) components that are sensitive particularly to the sulphur extreme pressure (EP) additive. The sulphur attacks the copper and destroys the integrity of the meshing gear surfaces.

I have never stripped down an SA hub so don't know what material is used for the things inside.

julk · Post by **julk** » 13 Feb 2009, 9:05pm

In days of yore, when I rode a SA 3 speed, the cable adjustment was critical to avoid gearslip in middle.
I hope it is something simple like the cable stop slipping along the frame.

When all else fails here are about 200 different SA spares for sale.

rjb · Post by **rjb** » 13 Feb 2009, 9:14pm

Many thanks hubgear and colin,

I have looked at sheldons site and links and seen the comment that most problems are related to cable tension. I have checked that the indicator rod flat lines up with the spindle end, but even small adjustments either side of this point do not cure it. I think i will investigate the trigger mechanism and cable before i resort to stripping the hub. I started using EP90 after reading sheldons article about not using 3 in 1 and using automotive oils instead. Perhaps EP90 is a bit too thick and 20/50 may be a better alternative. I dont think this bike has seen more than 1000 miles in total so is relatively young despite the 1976 year of manufacture.

Will keep you posted

rogerzilla · Post by **rogerzilla** » 14 Feb 2009, 8:20am

If the oil was too thick, causing the pawls to stick, it would also slip in high gear which uses the same set of pawls.

You either have a severely worn clutch (normally causes high gear problems first) or it's not being pulled out far enough - is the indicator rod fully screwed in and then not unscrewed more than half a turn so that the cable can be connected? Is the cable kinked anywhere? Is it correctly attached at the shifter?

rjb · Post by **rjb** » 25 Feb 2009, 6:29pm

Thanks for the help guys. I have replaced the trigger shifter and all appears well now. The old trigger shifter does feel spongy in comparison so i assume it has developed a fault but i can't see anything obviously wrong with it.

hubgearfreak · Post by **hubgearfreak** » 25 Feb 2009, 7:05pm

i'm glad it's sorted. but whilst we're discussing it, i'd suggest topping it up with thinner oil. drip by drip it'll gradually replace the car gearbox oil you've been using (that's designed for high temperature use). if you can't find anything suitable locally, there's some available in the on-line shop linked below.

http://oldbiketrader.co.uk/display_Stur ... ions=books

rogerzilla · Post by **rogerzilla** » 25 Feb 2009, 10:16pm

EP90 is indeed a bit thick - roughly equivalent to SAE 40 motor oil, with SAE 30 being recommended for Sturmey hubs. You can do without the EP too ("extreme pressure" anti-wear additives) - non-EP stuff smells less sulphurous. The worst-smelling stuff is GL5 gear oil for hypoid back axles, which is a far more severe duty than the simple spur gears in a hub.

I use 75W90 gear oil; at typical bike temperatures it's closer to its SAE 75 rating than the 90.

Incidentally, the reason the SAE viscosity numbers are different for motor and gear oils is simply to prevent people confusing them. An SAE 80 gear oil is not twice as thick as an SAE 40 motor oil - it's actually thinner, because a different scale is being used. SAE numbers are not proportional to viscosity anyway; they're just numbers on an arbitrary scale.