c15 front axle wheel nut size

[shoal48]

Hi all, hopefully this is a simple question. the bike is bits and hasnt been complete for over 35yrs so im finding wrong parts, missing parts etc.
I rebuilt the front forks with new bushes and seals and refitted what I believe is the original front wheel. but there is an alignment issue. with the right hand wheel nut (brake plate side) hard up against the slider, the anti rotation boss is not fully engaged in the brake plate and there are a few mm of the axle sticking out beyond the left stanchion and the wheel is offset to the left (kerbside uk)by several mm. The nut retaining the brake plate is a full depth nut. Its listed as part 29-2023 in the parts list but I cant find any thickness dimensions for it.

If the nut were a half thickness one, as on the rear wheel then all the alignment issues would go away so I suspect the wrong nut has been fitted at some time but it would be helpful if someone could confirm whether the nut is a reduced thickness one before I order a replacement. dont really want to spend £10 and find it was the correct part all along  thanks

[rhyatt]

https://www.bsaunitsingles.com/item.wws?cpubcode=BSA&SKU=29-2023

both my C15 are 1/2 nuts although 1 is slightly thicker than the other bike

i think they may be the same as the drive side crankshaft nut - not sure
https://www.feked.com/crankshaft-alternator-nut-bsa-29-2023.html

[Tigerfeet]

The 29-2023 nut on mine is 0.344" thick. 

On close examination I have realised that I have a clear gap between the lug on the fork leg and the bottom of the rebate on the brake plate.

I was initially tempted to think that I need to reduce the thickness of the 29-2023 nut.  But exploration with a torch and some feeler gauges has revealed that the fork leg is being held off the nut by the spindle cap. I think my next move will be to explore whether either of the spindle caps, in either orientation, actually give a flush face with the bottom of the fork leg where it abuts the nut.

I have also realised that a perfect fit of the fork leg lug into the brake plate rebate will be dificult to achieve. It would be possible to go too far (e.g. by reducing the thickness of the nut) such that the lug is bottomed in the rebate and the brake plate is being distorted when the spindle nut is tightened.

[Tigerfeet]

Further update. My spindle caps have clearly been machined on a Friday afternoon. In both cases the spindle groove is at an angle to the outside faces. I have filed square the face of the spindle cap that abuts the spindle nut, and it is now possible to assemble the brake plate etc properly.

[shoal48]

https://www.bsaunitsingles.com/item.wws?cpubcode=BSA&SKU=29-2023

both my C15 are 1/2 nuts although 1 is slightly thicker than the other bike

i think they may be the same as the drive side crankshaft nut - not sure
https://www.feked.com/crankshaft-alternator-nut-bsa-29-2023.html

I believe you are right, they seem to be the same part number and the crankshaft nut screws onto the front spindle ok and the crankshaft nut is full width
I think there is a problem with some suppliers that list a 29-2023 nut (front spindle & alternator) but the nuts are not the correct thread. I bought a 29-2023 on ebay and the diameter is right but its the wrong thread. co-pilot says the nut is a 5/8" 20tpi whit thread which may be true , others say it is 5/8" CEI 20tpi. most confusing. add to that some sites say it is a half nut, others say its a full width nut. all I can say with certainty is that the external dimension of the thread on the front axle is 0.625" and the thread is 20tpi.

[shoal48]

Further update. My spindle caps have clearly been machined on a Friday afternoon. In both cases the spindle groove is at an angle to the outside faces. I have filed square the face of the spindle cap that abuts the spindle nut, and it is now possible to assemble the brake plate etc properly.

thats interesting. I have replaced the sliders as one of them was slightly bent but retained the original spindle caps. I did notice that the drillings are not central in either cap. They must have built a lot of bikes on a Friday . I swapped the caps to give the best fit but maybe my problem is offset caused by the cap. something  need to check.
Finally after 35 years, the bike is a rolling chassis again, despite a couple of life threatening illnesses on the way. Im currently fitting the tinware before I spray them to check for fit and still finding little problems like odd missing springs on brake pedal, the front wheel alignnment. brake light switches etc

[shoal48]

https://www.bsaunitsingles.com/item.wws?cpubcode=BSA&SKU=29-2023

both my C15 are 1/2 nuts although 1 is slightly thicker than the other bike

i think they may be the same as the drive side crankshaft nut - not sure
https://www.feked.com/crankshaft-alternator-nut-bsa-29-2023.html

thats really interesting, some AI's say the nut is a half nut ( which I think would solve my alignment problem) and some say its definitely a full width nut. I am sure you are right about 29-2023 being quoted as both alternator nut and front spindle but I suspect some suppliers see 5/8" x20  and dont look at the thread type, one AI says with confidence the thread is whitworth, another says its CEI.m I bought one from ebay seller and the overall size is correct but its the wrong thread as it tightens up after 1.5 turns . The alternator nut fits fine on the spindle so it seems that the same nut is used for both alternator and front spindle but alternator nut is full width..the nut on my front spindle is also full width and I was hoping the alignment problem was because it should have been a half nut but maybe I need to look deeper

[rhyatt]

Never rely on AI