what year of fourtrax swingarm for 250sx?

[edizzle89]

I have an 86 250sx and I am looking at getting the swingarm from a Honda fourtrax 250 to gain some extra length. I have seen one thread that they used an 86 fourtrax swingarm but are there other years that can be used? I think i saw somewhere that the 85 swingarm isnt desired since something about the axle tubes are welded to the diff or something like that? So what model year fourtrax's have the good swingarm? is it any of them from 86-89?

also is the 250 engine in the fourtrax the same as the 250sx? i though if i could find a runner for cheap enough it would be good to have an extra engine as backup/spare parts.

and if anyone has a fourtrax 250 swing arm with the driveshaft let me know and i will buy it from you :beer

[edizzle89]

Nobody has any info they can share on this? I could really use the help as I am looking to buy ASAP so i can get it done over winter and have it ready for next year

[TheRealFatShady]

1986 fourtrax 250 and I think it ran for a few years after that. The only other trx 250 from that time period is the 250x which is chain drive and closer to a 350x engine.

You can also have the driveshaft and swingarm extended to get a stetch and allow for a lift. The issue with using just the swingarm and the driveshaft from the TRX and not the entire rear diff and axle/axle housing is the four bolts that mount the swingarm to the axle tube. On the 85 250es/250sx, it was one piece but on all the TRX and the 86/87 ATC, it bolts on with 4 bolts.

You can use an old 85 rear end, just got to cut off the old welds and add a plate to match the four bolts from the TRX swingarm to the ATC rear axle tube. May sound kind of complex, but I've bought plates pre-made for like $20-$25.
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Notice the four bolts, not at the differential? the locating spot on the 250 atc models and the trx are off, so you either make an adapter or you have to use the full trx250 swingarm/axle/driveshaft/axle tube/hubs.

[edizzle89]

thanks for the help! I have an 86 250sx so it does have the bolt on axle tubes.

Also i was planning on basically just using everything on the TRX swingarm including the TRX axle tubes and diff and maybe just get some bigger rear tires to offset the different gear ratio's between the SX and TRX. that is if i can find a complete rear end, if not i can bolt my SX parts to the TRX swingarm like you said.

[Name Brand]

It should be just the 86/87 TRX250.

For the 250cc machines (ES, SX, TRX) the rear diffs had different gear ratios and I do believe the transmission ratios had some differences.

It sounds like you want to build a machine like mine. I know mine works fantastic with the gears and tires it has. You will have to make a rear shock mount for the swing arm. Follow the link here; http://www.3wheelerworld.com/showthread.php/61999-250sx-12-2-update-broken-and-fixed!

[edizzle89]

yea your build is what made me want to do it haha

do you know what is different about the 88-89's that make them not work?

[TheRealFatShady]

Also some people make lifts and cut/sleeve the driveshaft to add length if you're willing to consider that.

[edizzle89]

Also some people make lifts and cut/sleeve the driveshaft to add length if you're willing to consider that.

i have seen that as well. Sleeving the driveshaft is the part that kind of would make me worry. It would be something i would consider if there wasnt a bolt in option from the TRX but since there is it seems like the easy button

[conbon]

I'm not sure if there's any differences between the 85-87 fourtrax 250's, a quick google search showed a bunch of swingarms that look the same. You could go online to a parts fiche and look up numbers and compare it between years.

Your best off to just use the whole fourtrax rear end, axle, tubes, brake, etc instead of trying to mix and match SX parts from the SX axle onto the fourtrax swinger, make it easy to buy replacement parts in the future when there's not custom stuff.

Fourtrax diff has 3.88 gears, same as 250es, fw300, and fw350. I always forget, SX is either 3.80 or 3.60, its not geared all that much higher.

I wouldn't be scared about building a stretched swinger and driveshaft either, there's a couple big reds out there and many, many 300's running like 6" stretch with a sleeved driveshaft and 28-32" tires. You'll blow diff's up before driveshafts as long as its done correctly.

-Connor