Just about to lengthen the swing-arm on my bantam project, anyone know how much I should lengthen it by?

It’s a wider type sports cub swing-arm

Edited June 13, 201214 yr by suzuki250

Can anyone help me, I was thinking about extending them 3/4" ???

Your best bet is to go to a trial and measure up what is sucessful. Why do you want to extend them anyway? A short wheelbase is one of the few advantages that a Bantam has so depending on how much you have steepened the head angle i wouldnt go too long on the swing arm.

It’s now done, (cut and extended the tubes)

I’ve extended it so the wheel has some clearance from the front of the swing-arm

Edited June 15, 201214 yr by suzuki250

yes, they do run very close as standard....and there's no room for the mud to 'escape'

OK makes sense now. Never had much to do with Bantams so didnt realise. I knew they would suffer from the same width restrictions as cubs.

Progress of swing-arm One side finished, other sidw still needs filing down

I think I’ll have a go at making some alloy Cub Hubs next

(Can’t make up my mind if I’m going to turn them from billets or cast them, If I cast I will make a few sets )

Edited June 17, 201214 yr by suzuki250

I’m now in the process of making my hubs and yokes, yokes are nearly finished just need to make the spindle and bar risers

It’s taking a little longer than planed as don’t seem to have a lot of time at the moment (wifes just had a baby!)

I will post some pics of the hubs soon

Edited March 23, 201313 yr by suzuki250

nice work.

Hi Guys.

Hi Suzuki.

Bad Engineering practice extending the arm like that, now you have two welds to break?

Do your homework on the hubs , it is far cheaper to buy some than to make your own. And you know the ones that are already tested work, been there as they say, Give Alan a ring.

Regards Charlie.

Hi Guys.

Hi Suzuki.

Bad Engineering practice extending the arm like that, now you have two welds to break?

Do your homework on the hubs , it is far cheaper to buy some than to make your own. And you know the ones that are already tested work, been there as they say, Give Alan a ring.

Regards Charlie.

I would disagree on the welding, I have inserted a bush into the swing-arm (see pic) even if they were butt welded I would be surprised if it did fail as most of the stress is transmitted though the shocks the swing arm acts more like a control arm than on a modern mono-shock bike (but I’m not the best welder!)

I have worked many years as an Automotive prototype engineer / quality engineer, after serving a technical engineering apprenticeship so I would hope my work would be satisfactory

But I would agree its not worth the time making parts, if you don’t have a CNC machine. But I’m in the process of buying one

I’m sure you would agree most of the fun is making your own parts, I find it very satisfying

Edited January 28, 201313 yr by suzuki250

the reply regarding bad enginnering practice is outrageous you trained in prototype enginnering the same as myself and with 40 years in the game i see nothing wrong with that work at all.my bantam swinging arm has been extended by one inch by cutting the 5/16 flat plate where the spindle sits and welding one inch in no probs in five years.any time served welder would just laugh at that comment.you may need to heat and straighten the arm after welding though.one thing to be aware of is that a lot of people like to mig weld vertical to get a neat finish but you risk getting cold overlap doing that which will introduce a weak point.

Hi Suzuki

Progress of swing-arm One side finished, other sidw still needs filing down

I think I’ll have a go at making some alloy Cub Hubs next

(Can’t make up my mind if I’m going to turn them from billets or cast them, If I cast I will make a few sets )

Hi Suzuki 250

What width and length did you lengthen the swing arm by because i am thinking of getting my swing arm altered?

Cheers Sam

3/4" to 1" seems to give just the right amount

make sure you have the wide type arm to start with

I lengthened mine by 1.5" and it still turns great. I used to feel it wheelied too easily up steel hills and it seems to grip better with the longer arm. Used a scarf cut for strength and inserted a tube for strength - used for 2 years and lots of drop offs/rocky sections and no problems.

Stu