Chopping a swingarm

Chat about choppers here. Any posts considered by forum administrators to be used by businesses as unpaid advertising will be promptly removed...

Moderator: Prof

Post Reply
Stray
Posts: 139
Joined: Sat Apr 11, 2009 12:55 am

Chopping a swingarm

Post by Stray » Tue Aug 30, 2011 1:06 pm

I've a question. Have been thinking of ways of getting the back wheel a few inches back. I know people stretch the frame, and that counts as a frame mod and needs engineering for rego. Yet has anyone stretched the swingarm like 3 or 4 inches and inserted a bung for reinforcement? This would move the wheel back, and would require lengthening of all the brake lines and such, but would that still count as a frame mod? To my mind that would give the stretch, and using the same mounting points for the springs it would lower the bum enough to look decent. Allowing space for the seat and rear fender to be customised appropriately.

Any holes in my theory? Shoot me down if it is just ridiculous.
every man needs a shed, to put his stuff and clear his head and work out what the hell she said.

Aussiehard
Posts: 669
Joined: Fri Mar 04, 2011 5:31 pm
Location: Melbourne S.E.
Contact:

Re: Chopping a swingarm

Post by Aussiehard » Tue Aug 30, 2011 1:30 pm

Depends on what bike you have but some bikes you can swap in a longer swingarm from a compatible doner bike.

Cromag
Posts: 2563
Joined: Tue Nov 15, 2005 10:58 am
Location: NSW

Re: Chopping a swingarm

Post by Cromag » Tue Aug 30, 2011 7:22 pm

Yeah, thats right, things like cb 750 frame will accept a gs750 swingarm, (ya just got to bore the swingarm pivot holes out a touch) or even a cb900 (requires you to grind off the sides of the pivot point/ i dont like this one) .....if you cut one, make sure you do it on the parrallell part or your swingarm gets wider and you need to make appropriate spacers for the wheel.

I'd say its counted as a frame mod......but unless your in the Convict state (NSW) where you have to do a blue slip, i wouldnt worry about it....if you are.....best have a spare on hand, just to slip back in.

both the swingarm mods above only give about 3".....you could do the same by relocating the mounting position of the bottom shock mount.......

ive got 3 spare swingarms iam keeping to complete a similiar job....i like the look of the extra length when the drop rakes it out too.
Does not work or play well with others
Loud pipes save lives
"These are not the Droids you're looking for"

Prof
Founder, Choppers Australia
Posts: 5902
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
Contact:

Re: Chopping a swingarm

Post by Prof » Tue Aug 30, 2011 10:05 pm

I did a couple of articles on extending swingarms in January's Chops'nBobber mag .

You can lengthen swingarms by extending the legs, but need some tweeking and spacers as they end up wider at the axle plates. A stronger, better looking way is to attach the pivot section of one swingarm to the front of the other one. Gives plenty of weld area and can be finished off very neatly.

I think it is a good way of dropping your back end as street bikes are too high anyway... choppers are all about cruising and sweeping through the corners not playing boy racer. If you are replacing an 18x4.50 wheel/tyre with a 16x5 set up you loose about an inch in ciameter and gear your bike down accordingly unless you use a 10 profile tyre which is available in older style tread patterns. Extra length adds to stability, smoothness over undulations and is much safer in a slide.

I would imagine you would be unlucky to be defected on a longer swing arm if it was from a donor bike of similar capacity.
Chopit'nrideit... Prof

dg6oo2
Posts: 433
Joined: Sun Sep 12, 2010 1:36 pm
Location: victoria-pilbara

Re: Chopping a swingarm

Post by dg6oo2 » Wed Aug 31, 2011 4:49 pm

If the job was done good enough you could say it was factory and plead ignorance.
friends welcome family by appiontment only.

Happosai
Posts: 367
Joined: Tue Dec 09, 2008 1:07 pm
Location: Melbourne

Re: Chopping a swingarm

Post by Happosai » Wed Aug 31, 2011 6:25 pm

dg6oo2 wrote:If the job was done good enough you could say it was factory and plead ignorance.
If its done well enough nobody would know, unless they messured the wheelbase.

Hap
I used to be Vague...................Now I'm not so sure

Stray
Posts: 139
Joined: Sat Apr 11, 2009 12:55 am

Re: Chopping a swingarm

Post by Stray » Wed Aug 31, 2011 10:23 pm

Ah yeah, thanks for the replies. I kinda thought it was possible.

Do you have a link to the articles Prof? Would not mind reading on it. And the idea of extending the pivot point is something i did not consider at all.

When i get around to actually mapping things out i will do some schematics first for sure.
every man needs a shed, to put his stuff and clear his head and work out what the hell she said.

Bacca

Re: Chopping a swingarm

Post by Bacca » Thu Sep 01, 2011 10:16 am

When doing mine I cut a peace of pipe that fitted between the axle plates & put axle back in, tightened so plates stayed same distance apart
Image
Some thought the inside slugs should have been longer but in all the k's I did on it including a lot on ruff gravel roads as lived on a farm then it never looked like cracking. Not saying this is right way, just it worked for me.

Cromag
Posts: 2563
Joined: Tue Nov 15, 2005 10:58 am
Location: NSW

Re: Chopping a swingarm

Post by Cromag » Thu Sep 01, 2011 5:43 pm

Use to live in a country town, only 2-3 blue slip blokes availble......2 of the 3 measured bikes i tried to get through blue slip inspection, never got to the third one and never had it done since..... i suspect they were both unfamiliar with bikes.
Does not work or play well with others
Loud pipes save lives
"These are not the Droids you're looking for"

Bacca

Re: Chopping a swingarm

Post by Bacca » Thu Sep 01, 2011 8:09 pm

I lived in a small town that when you saw the 1 cop down the street ya said g'day Ray,
he never said a thing about the chopper but I used to stick to the local area pritty much.
Once we moved to Stawell with heaps of cops I let the rego run out :D
Amen will have to go through engineering for rego so won't be a worry!!!

Post Reply

Return to “Chopper Chat (includes how to post photos)”