Need help on '85 250SX - drive shaft/trans problem?

[Tantrix]

As the title says, my '85 250SX has an issue.



When riding, I can feel a slight bit of what feels like what I can only describe as "slack" in my drive-train. For example, I'm cruising slowly in 2nd gear and then let off the throttle abruptly (like maybe to avoid a pothole or something) then get on the throttle again, there's a slight "jerk" when the trike begins to move forward again. The differential checks out ok, no strange noises. It feels like there's a bit of slack in my drive-shaft or something (like maybe in the joint). Anyone ever have this problem?







Thanks in advance. :TrikesOwn

[Dirtcrasher]

Could be the u joint in the drive shaft. You'll probably have to tear it apart to find the issue but at least you can get it all freshened up.

That left fork being stripped is not good. It may feel solid but now nothing is really tying the 2 forks together and they could come apart if the front end takes an impact. That should be a cheap easy fix, so many guys change over to 200X forks and have the old SX legs kicking around....

[Tantrix]

Could be the u joint in the drive shaft. You'll probably have to tear it apart to find the issue but at least you can get it all freshened up.

That left fork being stripped is not good. It may feel solid but now nothing is really tying the 2 forks together and they could come apart if the front end takes an impact. That should be a cheap easy fix, so many guys change over to 200X forks and have the old SX legs kicking around....



Update...

This morning I got up and located a spare '87 250SX frame I had and replaced the left fork and used the axle from it too. It's good as new.


You might be on to something about the joint in the drive-shaft being loose...that's exactly what it feels like. While getting that fork this morning, I also pulled the drive-shaft from the '87 frame so if that's what it ends up being, I have the part already. Crossing my fingers that it's nothing major.

[Dirtcrasher]

Good deal :D

I hope my post helped but don't go entirely be me........

Apparently I am useless 80% of the time according to SAUL.

Maybe put up a post and see what he has to offer :beer:

[Tantrix]

Well...upon further inspection, the drive-shaft I pulled from the '87 SX happens to have....


wait for it...





wait for it...





A busted u-joint. :lol:




However...I do have an '85 250ES with a blown engine that has a drive shaft I can yank if needed. There may be hope for this thing yet...





Oh, and here's a pic of her...she ain't all original, she ain't mint, and she ain't perfect, but she's mine.


Oh, and the rack isn't a 250SX one (as if it isn't obvious...lol) It's actually the rear rack I took it off of a Yamaha Timberwolf quad and slid underneath the Maier plastics. The back of the rack rested on the grab-bar, but I needed a way to secure it to the frame so I used tie-wire in about 8 different spots along the frame. Yeah I know, it's a pretty ghetto idea, but the wife and son ride with me a lot so I had to do something. It's working for the time being. :lol:

http://i201.photobucket.com/albums/aa193/glockthirty/IMG_02611.jpg

[Dirtcrasher]

I'm not sure if the ES shaft can be used. It may be solid and I think the SX is spring loaded so to speak.....

Good thing you caught it before you destroyed the diff or something :beer

[Tantrix]

I'm not sure if the ES shaft can be used. It may be solid and I think the SX is spring loaded so to speak.....

Good thing you caught it before you destroyed the diff or something :beer


Yep, I looked at the '87 SX shaft and it's got the spring on it. :cry:

[rooster67]

Hey guys. I am experiencing slack in my drive line as well. 85 SX. Same symptoms as described above "cruising slowly in 2nd gear and then let off the throttle abruptly (like maybe to avoid a pothole or something) then get on the throttle again, there's a slight "jerk" when the trike begins to move forward again." However, I just recently rebuilt the rear end (all new diff bearings and outer axle shaft bearings as well. The drive shaft (propeller shaft) ujoint is good and tight and so is the play at the ring and pinion. I noticed when I had the swinger off that if you had the bike in gear and turn the splines on the output shaft that THIS IS WHERE THE PLAY IS. YOu can twist the spline shaft back and forth with the play increasing the higher gear you are in. Also when the bike is turned off and in gear, you can push/pull the bike forward and back and feel the slack that way as well.So at this point i am wondering is it the output shaft? Or is it play in all of the tranny gears over the course of 28 years of wear and tear?? ANY ideas would be greatly appreciated.

Garrett

[ps2fixer]

I picked up a 250sx with a similar issue (more extreme though) for $200. Ended up being the splines on the ring gear / rear axle were worn out. I replaced the axle, axle spacer, and complete diff with 85 250es parts I got for $100 :). Just another thing to look at. Personally never seen the transmissions in the 250es/sx engines get slop like that.

Good news for the old sx rear end / axle, I hope to make a shaft drive dune buggie some day, and it would give me a perfect cheap start for the rear end (independant suspension, so the axle would be cut down anyway). Plan would be to carefully weld the ring gear to the axle. I wouldn't suggest this on a 3 wheeler since everything is housed in the tubing.