Bafang SWXK bolt problem

[jonathan75]

I don't know if it's clear from the photographs, but on the left-hand side of the motor, the oval-shaped part of the bolt which comes out, i.e. the bit which goes into a torque arm, only extends 2mm from the motor. On the right-hand side it extends only 4mm. This seems to mean that on the right side the torque arm must go inside rather than outside the fork, if that's possible; and on the left side, there can be no torque arm. The small pile of two nuts and a few washers which the seller sent, seem to indicate this. Have I got this about right?

Thanks

 

[jonathan75]

Scratch that, that's impossible: the Cycleezee torque arm can't go up the inside of the fork because it would be flush against the motor with nowhere for its bolts to go. So this SWXK motor seems incapable of having a torque arm of any kind. Is that about right? Unless I use one or two 15mm spanners attached to the nuts in picture two.

 

[shemozzle999]

Did they not supply a torque washer like one of these?

Can you show a picture of the other side of the motor?

http://www.ebay.co.uk/itm/like/111481480211?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108

 

[jonathan75]

No they didn't. The bolt in the below picture is fully rounded right up to 4-5mm before where it meets the motor unfortunately.

 

[Cyclezee]

Scratch that, that's impossible: the Cycleezee torque arm can't go up the inside of the fork because it would be flush against the motor with nowhere for its bolts to go. So this SWXK motor seems incapable of having a torque arm of any kind. Is that about right? Unless I use one or two 15mm spanners attached to the nuts in picture two.

Hi Jonathan,

Our torque arms wouldn't work in this instance, they are intended for use on axles where the threaded section has 10mm flats.

 

[jonathan75]

Hi Jonathan,

Our torque arms wouldn't work in this instance, they are intended for use on axles where the threaded section has 10mm flats.

Got it, thank you. Would you know if there is a solution available for this please, for example what people ordinarily do to secure motors with this particular type of layout? I have a long-single-arm type torque arm which could go up the inside of the fork, or I could do a spanner/jubilee clip/forks arrangement attaching to the 15mm nuts which go on the wheelbolts. I can't imagine that anyone rides these without some sort of torque arm arrangement.

 

[Cyclezee]

Hi again Jonathan,

An anti rotation washer isn't going to help as they would still allow the axle to rotate.

If you have good quality forks with adequate 'lawyer's lips', the washers and nuts that you already have should be OK if tightened adequately, then you could use a modified ring spanner secured to the forks by Jubilee clips to prevent the axle nuts from working lose.

 

[jonathan75]

Hi John,

Thanks for the advice, I appreciate it. I've attached a photo - do these forks look adequate? They're aluminium.

 

[Cyclezee]

Are you sure that they are Aluminium forks?
This is where I "chicken out", to be perfectly honest Jonathan, they look like they have had a fair bit of wear and tear already, so I would be hesitant to try it myself.

This is what can happen if it goes wrong​

 

[Deleted member 4366]

You're missing the anti-rotation washers that are specifically needed for that motor. They're the standard Bafang anti-rotation washers. The motor is pretty well useless without them, so you need to contact the supplier and ask where they are.

You cannot fit a torque arm on the motor unless you make something special.

 

[jonathan75]

Thanks d8veh. Oh wow I can see exactly why John is advising me against. The mechanism for the anti-rotation washer seems to put all of the stress on the lips of the fork. That's crazy. That treats the fork as a consumable part more or less, to be replaced as and when it breaks. No idea what Bafang were thinking. Definitely getting shot of this front wheel kit.

Incidentally the motor wheel was so badly laced up that some of the spokes actually rattle. Nobody should ever get a laced up wheel sent from China. The extra postage alone would pay for two or more professional lacings in the UK, which one will typically have to fork out for all over again anyway with wheels built like this one.

 

[jonathan75]

You're missing the anti-rotation washers that are specifically needed for that motor. They're the standard Bafang anti-rotation washers. The motor is pretty well useless without them, so you need to contact the supplier and ask where they are.

You cannot fit a torque arm on the motor unless you make something special.

P.S. Do you know if there are instructions for fitting rear wheels anywhere please, the order of nuts and washers etc etc? I'm finding the Woosh guide useful but not comprehensive, it assumes some basic bike knowledge which I lack.

 

[Deleted member 4366]

There's no exact way to do it. There's lots of ifs and buts; however, it's not difficult.

Your front motor would be OK in steel forks. What are yours made of? If they're aluminium, it wouldn't take much or cost much to change them.

 

[jonathan75]

Hi again Jonathan,

An anti rotation washer isn't going to help as they would still allow the axle to rotate.

If you have good quality forks with adequate 'lawyer's lips', the washers and nuts that you already have should be OK if tightened adequately, then you could use a modified ring spanner secured to the forks by Jubilee clips to prevent the axle nuts from working lose.

What sort of modification would be required to the ring spanner, is it a case just of it being flat enough? I've seen some non-ring-types for cheap which are flat, but obviously there's a higher chance that the nut will secured a part-turn off the optimum. Which could mean lessened tension.

There's no exact way to do it. There's lots of ifs and buts; however, it's not difficult.

Your front motor would be OK in steel forks. What are yours made of? If they're aluminium, it wouldn't take much or cost much to change them.

It turns out they are steel after all. And I found some torque washers which fit (from the CST set, the same sort it seems). My only concern is that it is the lip alone of the steel fork (and the tightness of the bolts) seem to be the only things stopping the rotation of the entire setup. Photos in a minute.

 

[jonathan75]

This is before the bolt has been tightened (don't yet have the right tools to do that). As you can see in the first photo, there is only a tiny gap between the rotating part of the hub, and the 'ankle' of the fork, even before everything has been tightened up. I have two thin washers on the first photo, and one thick washer 'ring' thing on the second, only. Is this an appropriate setup? Are these 'crush' washers which require (for this setup in particular) being tightened and then never re-used, in order to maintain friction?

 

[jonathan75]

Are you sure that they are Aluminium forks?
This is where I "chicken out", to be perfectly honest Jonathan, they look like they have had a fair bit of wear and tear already, so I would be hesitant to try it myself.

This is what can happen if it goes wrong​

View attachment 11088

Thankfully they're steel, you were right to ask, thank you. I've had the bike myself from new, it hasn't even had a hundred miles, it just looks rougher than it is!

 

[Deleted member 4366]

There should be a plain washer in the dimple before the spring washer. Make sure it fits in the dimple. You might need to file the drop-out a bit deeper to centralise the axle. Alternatively, you can file the washer until it fits.

 

[jonathan75]

Thank you. Is there a certain amount of torque I need to apply - should I be buying a torque wrench and long sockets for this job? Or should I be investing in a long adjustible wrench? £3 from Wilko for 200mm, £11 from Amazon for 300mm .

I don't own any spanners but suspect the Poundland set isn't sufficient to create enough bolt tension. Is that true, or if I use a hammer gently to increase torque with a £1 spanner, could it damage things (apart from the risk of chipping paint etc)?

What if rather than hammering, if I were to attach my breaker bar to the £1 spanner with jubilee clips? At what point should I stop turning the nut?

 

[shemozzle999]

Hi jonathan,

The SWXK5 motor shaft you have there is the same as the SWXU, it has an old type thread 3/8" British Standard Cycle thread which has a fine thread so I would not advise over tightening it.

http://britishfasteners.com/threads/bsc.html

You need to measure the distance across two opposite flats on the nut mine measure 14.85mm so a 15mm A/F (across flats) spanner may be too loose unless you use a ring spanner.

Spanners are purposely designed with varying lengths and the theory is you apply the same hand pressure no matter what the size of the nut and what that pressure is comes with experience.

I use a short adjustable spanner from Poundland and have not been able to over tighten it - it is also handy to keep in my repair kit.

Also looking at your forks you might be able to fit one of these which will stop the nut from getting loose after you have tightened it:

http://www.pedelecs.co.uk/forum/threads/torq-lock-locking-torque-arm-for-ebikes.20358/

 

[Cyclezee]

Thank you. Is there a certain amount of torque I need to apply - should I be buying a torque wrench and long sockets for this job? Or should I be investing in a long adjustible wrench? £3 from Wilko for 200mm, £11 from Amazon for 300mm .

I don't own any spanners but suspect the Poundland set isn't sufficient to create enough bolt tension. Is that true, or if I use a hammer gently to increase torque with a £1 spanner, could it damage things (apart from the risk of chipping paint etc)?

What if rather than hammering, if I were to attach my breaker bar to the £1 spanner with jubilee clips? At what point should I stop turning the nut?

Hi Jonathan,

Follow D8veh's advice about the washer before before the spring washer and as you have steel forks you should be OK.

A chepo flat ring spanner of the correct size for the axle nut with the 'C' cut off and strapped to the fork with a Jubilee clip to prevent the nut rotating would be a belt and braces solution.

​