250R Aluminum Swingarm Extension Project (finished)

[Red Rider]

I've been wanting a Calfab aluminum swingarm for my '86 250R for quite some time now, and I've all but given up on ever finding one, so I decided to make my own. I bought an '88-89 TRX250R aluminum swingarm on ebay as the donor patient. Since the TRX swingarm is 1" shorter than my stock ATC swingarm, I knew I'd need to lengthen it.

I guess I could have gotten a late model TRX450R cast aluminum swingarm, because from what I understand, they are identical in length to my stock swingarm, but I figure, if I'm changing swingarms, I might as well change to a longer one. And since I'd need to lengthen it, regardless of which one I went with, I decided to go with the TRX250R unit, as it has less cast aluminum in it, which should make for better/stronger welds.

Pics #1 & #2 show the unmolested swingarm.

Pic #3 shows the inside of the front half of the swingarm. While cutting it in half was easy, I had a hard time cutting up a perfectly good swingarm, especially since I had no idea what the inside would look like. Basically, I needed to destroy a good swingarm to figure out if I could actually complete this project.

Pic #4 shows the inside of the rear carrier. I guess I chose the perfect point to cut it in half. If I had made the cut about 1/16" more to the rear, I would have been cutting through the rear cast aluminum plate, which is solid from top to bottom. It's better to be lucky than good!

Pic #5 shows the swingarm pieces layed into the jig that will keep everything straight & true (fingers crossed) while being welded.

[Red Rider]

I want the lengthened swingarm to be +2" longer than my stocker, so I'm lengthening the TRX unit by +3".

Pics #1 & #2 show the front half of the swingarm, which was split up the middle in order to keep the sides of the swingarm one continuous straight line. This method was inspired by Mr. Sandman's swingarm lengthening project.

Pics #3 & #4 show the rear carrier with slots cut in it to accept the new extensions.

Pics #5 & #6 show the swingarm extensions, which were made by welding 2 pieces of 25x25x3mm square tubing inside the 60x30x3mm rectangular tubing.

[Red Rider]

All jigged up & nowhere to go!

Pic #1 shows all the major pieces.

Pics #2-4 show everything clamped in place in the jig and waiting to be welded tomorrow morning, which is now today. I better get to bed! More to come in a week or so.

[jeffatc250r]

Nice jig setup you have there, since you split the swingarm did you have to relocate the linkage mout ears on the swingarm? I have a spare 450r swinger that ive been procrastinating on doing the same to, only instead i want to do a +5 since the 8 over is kind of too much on my 500

[Red Rider]

...since you split the swingarm did you have to relocate the linkage mout ears on the swingarm?

I won't need to relocate them, but I will need to make some plates to put in between them to fill the extra gap that was created when I spread the swingarm apart.

[jeffatc250r]

Cool, cant wait to see the finished product.

[tecat-z]

Very nice project you have going on. Never thought of splitting the swingarm to keep the outside straight. Gotta love ingenuity. Keep us posted on progress.

[Red Rider]

The first stage of welding is finally complete.

Pic #1 shows where I ground away the original factory welds from the cast swingarm pivot/box section tubing, so I could spread the sides of the swingarm apart.

Pics #2-4 show the results of the first trip to the welder.

[Red Rider]

A lot more progress today & I'm now ready for the second stage of welding.

Pic #1 shows the wedge, which will fill in the gap that was created after splitting the swingarm down the middle & spreading it apart. Also in the first pic is a plate that will return some strength, to the area below the shock linkage mounts, that was lost when the rear carrier was cut off.

Pic #2 shows the wedge & plate installed before welding.

[Billy Golightly]

This is turning out really well, great work

[Kilborg]

Nice looking welds, looks like you probably do it for a living like I do...


What are you using as far as welding equipment goes? Iv been wanting to get a welder for the house, but have yet to decide what to do...As of now I use the welders at my shop. Not to hijack..

[Red Rider]

Nice looking welds, looks like you probably do it for a living like I do...

What are you using as far as welding equipment goes? Iv been wanting to get a welder for the house, but have yet to decide what to do...As of now I use the welders at my shop. Not to hijack..

I only wish I could weld like that! I take my stuff to Dave @ Precision Welding of Rialto to be welded. While he was doing some more welding on the swingarm today, I glanced at the name on his TIG welder, and now I can't remember what brand it was. I'll try and remember to make a note of it next time I'm there, which will be in a few weeks.

[Red Rider]

After about a month of not working on this project, I finally made some more progress on it. I got the center section welded back together and have already ground & smoothed the welds in that area. I also cut out the top & bottom plates that will enclose the open box section at the rear of the swingarm. I've also cut out the spacer plates that will be welded onto the insides of the "dogears" (where the shock linkage bolts to the swingarm). If all goes well, 1 more trip to the welder tomorrow morning, and I'll have a finished product to show off!

Kilborg, Dave uses an ESAB Heliarc 252 welder. I'm no welder, but I have a hunch it's the man operating the welder that makes such nice welds, rather than the welder itself.

[Red Rider]

As planned, I got the rest of the welding on the swingarm done today, as well as the 2 new engine motor mount tabs that were added to the frame. After several months of work, I've finally got an aluminum swingarm for my machine!

[BigGreenMachine]

Very nice! I mean wow, another great addition to your sweet R.

cheers