El Choppo
Thread Starter
|
Ultimate HDF Member
Joined: Nov 2008
Posts: 6,682
Likes: 12
El Choppo
Anyone here have any experience chopping a frame? I'm considering trying to build a bike from the ground up. I was thinking about finding a frame to start a winter project but I've never cut a frame. Can someone here tell me how you maintain the rake while adding or taking out of the backbone or downtubes? I've wanted to build a bike for a long time and I worked in an Indy shop for a while but I've gotta say, I think building from the ground up is going to be a whole new animal. Any pointers or advice?
Club Member
Joined: Mar 2009
Posts: 66,125
Likes: 51,441
From: Niles Canyon Ca.
Frame kinda depends on what look , style motor , drive train and how fat in azz you want it be . If your going shovel the frames are well suited for modification with lots of info to found on the net . Softtail bikes can be fairly strait forward also , the stamped steel box frames on late 80's and up I'd stay away from at a beginners level .
I'd do some research online to get a feel for what 's involved if you haven't done anything similar before for starters . I've seen some good stuff showing frames being worked . You still want an insight after PM me or an email I've done mild to wild in a proper shop and the back yard poor broke biker method .
I'd do some research online to get a feel for what 's involved if you haven't done anything similar before for starters . I've seen some good stuff showing frames being worked . You still want an insight after PM me or an email I've done mild to wild in a proper shop and the back yard poor broke biker method .
Last edited by TwiZted Biker; Aug 24, 2010 at 01:05 AM.
Outstanding HDF Member
Joined: Apr 2008
Posts: 3,140
Likes: 17
From: Wisconsin
I built a chopper a long time ago, took the frame in to have it stretched and raked. I took it in because my buddy had screwed his up trying to do what I wanted. The place I took it to had a frame jig to line everything up for welding. Since then I have seen this done numerous times in different shops, always with a frame jig for alignment. So, my guess is you need to aquire or build a jig that will work for you .....
Extreme HDF Member
Joined: Aug 2007
Posts: 17,625
Likes: 1,665
From: Blairsville GA
I AM NOT RECOMMENDING THIS TECHNIQUE TO ANYONE!!!!!
However, the one frame I "chopped" was in the mid '70s, and it was done like this:
1) Cut through 90% of the neck from right behind the stem, up through the casting. Leave about 1/2" of the casting intact.
2) Heat the casting in the area of the cut red hot with a torch.
3) Using something like a Gandy stuck down through the neck bend it out to the desired angle. Pay particular attention to not twisting it left or right. Use a protractor to check for the desired angle.
4) Fill the cut as well as you can with weld. I heard of people cutting a small piece of iron to fit the notch, but I didn't do it that way.
5) Weld gussets made from 1/8" to 3/16" stock to each side. Make sure you get a full circumference weld.
As I said, from the vantage point of 40 years this seems like a suicidal way to modify a frame. but it worked for me. Assuming you're going to use a rigid, you can buy a custom frame with any dimensions you want much cheaper than buying any stock HD rigid frame.
However, the one frame I "chopped" was in the mid '70s, and it was done like this:
1) Cut through 90% of the neck from right behind the stem, up through the casting. Leave about 1/2" of the casting intact.
2) Heat the casting in the area of the cut red hot with a torch.
3) Using something like a Gandy stuck down through the neck bend it out to the desired angle. Pay particular attention to not twisting it left or right. Use a protractor to check for the desired angle.
4) Fill the cut as well as you can with weld. I heard of people cutting a small piece of iron to fit the notch, but I didn't do it that way.
5) Weld gussets made from 1/8" to 3/16" stock to each side. Make sure you get a full circumference weld.
As I said, from the vantage point of 40 years this seems like a suicidal way to modify a frame. but it worked for me. Assuming you're going to use a rigid, you can buy a custom frame with any dimensions you want much cheaper than buying any stock HD rigid frame.
Club Member
Joined: Mar 2009
Posts: 66,125
Likes: 51,441
From: Niles Canyon Ca.
I AM NOT RECOMMENDING THIS TECHNIQUE TO ANYONE!!!!!
However, the one frame I "chopped" was in the mid '70s, and it was done like this:
1) Cut through 90% of the neck from right behind the stem, up through the casting. Leave about 1/2" of the casting intact.
2) Heat the casting in the area of the cut red hot with a torch.
3) Using something like a Gandy stuck down through the neck bend it out to the desired angle. Pay particular attention to not twisting it left or right. Use a protractor to check for the desired angle.
4) Fill the cut as well as you can with weld. I heard of people cutting a small piece of iron to fit the notch, but I didn't do it that way.
5) Weld gussets made from 1/8" to 3/16" stock to each side. Make sure you get a full circumference weld.
As I said, from the vantage point of 40 years this seems like a suicidal way to modify a frame. but it worked for me. Assuming you're going to use a rigid, you can buy a custom frame with any dimensions you want much cheaper than buying any stock HD rigid frame.
However, the one frame I "chopped" was in the mid '70s, and it was done like this:
1) Cut through 90% of the neck from right behind the stem, up through the casting. Leave about 1/2" of the casting intact.
2) Heat the casting in the area of the cut red hot with a torch.
3) Using something like a Gandy stuck down through the neck bend it out to the desired angle. Pay particular attention to not twisting it left or right. Use a protractor to check for the desired angle.
4) Fill the cut as well as you can with weld. I heard of people cutting a small piece of iron to fit the notch, but I didn't do it that way.
5) Weld gussets made from 1/8" to 3/16" stock to each side. Make sure you get a full circumference weld.
As I said, from the vantage point of 40 years this seems like a suicidal way to modify a frame. but it worked for me. Assuming you're going to use a rigid, you can buy a custom frame with any dimensions you want much cheaper than buying any stock HD rigid frame.
With a few tricks added for proper alignment and square that's pretty much the " Backyard Poor Broke Biker " method . Frame jigs are the way to go if available but with a decent table , clamps and couple of round bars of the proper size you can do good clean job and keep it straight . It's all in the lay out & welding work . There's some math involved and knowing how to center line and square steel , basic Millwright / fabricator skills . You need good welding skills also to keep things square . Most guys start running long beads on one side at a time , big no no doing it this way a neck will pull itself 1/4" + off and you won't see it till done .
" Fill the cut as well as you can with weld " works for a small gap , 1/8" max , anything wider fit solid gussets in and weld up . Filling a big gap with welds heats up the area WAY too much cast steel will warp and the base metal actually weaken badly . Ever seen a piece of cheap angle iron break after being welded ? same thing .
Not knocking any body's advice here . It's part of what I do for a living I can't help it , too many clueless apprentices over the yrs .
Every body has heard of Paughco frames ? Old name in the parts world . I had to return a frame had a tweaked neck off the truck, went their plant in Carson City Nv . No joking or fudging their frame manufacturing plant is a wooden pole barn add on , dirt floored and the frame jigs were 2" tubing welded to old truck rims with 3/4" water pipe gubber on & visegrips to hold parts . And we pay money for stuff that is built using this , Scary isn't it ...
Sorry if it's a bit long but this isn't something simple to explain . The bike in the second pic was done 28 yrs ago in the garage with real basic tools ( hacksaw
& buzz box monkey wards welder ) add on hardtail section & some neck work
Last edited by TwiZted Biker; Aug 18, 2010 at 12:14 AM.
Trending Topics
Elite HDF Member
Joined: Dec 2009
Posts: 4,598
Likes: 14
From: navarre ohio
buy a cheap/junk jap bike and practise.. mabye you could get a pretty cool 750 chopper in the process.. it could offset the cost if you sell it..
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Club Member
Joined: Mar 2009
Posts: 66,125
Likes: 51,441
From: Niles Canyon Ca.
