1986 250SX swingarm question

[200XCSR]

alright i remember a while back people where putting honda 250 fourtrax swingers under honda 250sx's so here my question what all do you need to do it?i got the swinger in an had to get the center tube between differential and other side of swingarm becauce the 250sx's was to short so i need the axle it self out of a fourtrax also i guess? thanks kyle

[Flossyb20]

You'll need the whole rear-end set-up, and then you'll have to fabricate a rear shock mount to use the 250sx shock (the trx shock would require modding your frame)...you gain about 3.5 inches of stretch...but remeber that the trx came with 25 in tires, so the gear ratio is a bit different...best to use your sx rear diff and maintain the proper ratio.

[stillhunter]

When I was researching putting 25's on my sx, I believe it was suggested to do that complete rear swap and that because of the fourtrax gearing it would not strain the sx engine and driveline. Sorry can't link I'm on my phone.

[200XCSR]

the fourwheeler i got the swing arm and center tube from was already missing the diff and the left axle tube but that what im getting at i used my diff and the left axle tube and my axle is about a inch to narrow so im assuming that the fourtrax axle is wider or the left axle tube is shorter on the fourtrax?

[Name Brand]

200xcsr - Are you asking if you could bolt on an '86 SX rear diff to the '86 - '87 TRX swingarm? I think that can be done if you use the complete SX rear axle setup (axle, diff, brake, bearings and tubes) rather than trying to combine the SX and TRX rears. The TRX swinger is three inches longer than the SX; are you just trying to get a longer wheelbase? The '85 SX swinger and rear axle are built as one assembly and wouldn't work with the TRX swingarm. Because the '86-'87 SX rear axle unbolts from the swinger as the TRX does both swingarms should swap with eachother. Everything at the frame is the same. You will have to fab up a lower shock mount and I do recommend going with the TRX rear brake cable.

I wanted to run 25's on my SX and knew I needed to lower the gear ratio to keep the engine from being overworked. I wanted the longer swingarm for tire clearance. I briefly ran some short 22's; lots of hill-climbing torque but was very slow in fifth gear. 25's with the TRX diff and stock 250SX engine has been a great setup.

Follow the SX link below the picture in my signature to see and read in more detail what I did.