Scrambler250

I was towing a camper this weekend, and on my way, I got off the interstate on an exit ramp. As I was decelerating down the ramp, 5th gear, I started hearing a slow knock coming from the transmission. The knock was steady, but at a completely different RPM than everything else. It almost sounded like something was around the driveshaft, hitting the body, but it was slower than the driveshaft would have been turning. The noise only came when decelerating, and in all gears except 4th. After 10 miles or so, it started making the same noise on acceleration too, but still not in 4th. The noise also seemed to get louder the further I went. I get no noise when in neutral, or when the clutch is in. The noise does seem to speed up with higher RPM's. Any idea what this could be, and why it's not happening in 4th?

Number47

4th is direct drive but i dont have anything else for ya without hearing the knock

johnyb59

I could possibly be a broken gear tooth

dozer12216

Nut on fifth gear has worked loose. There is a upgrade kit with locking device to hold better. you should replace fifth gear as it moves on splines. New will be tighter(trust me), along with jamb kit. It can be repaired without pulling tranny, by a knowledgable person. A FSM helps a bunch. Do not run in OD below 57.8 MPH in future. You are lugging engine / tranny.

Scrambler250

Broken gear tooth was correct. Input gear had a broken tooth, reverse idler had some broken teeth, and forward most countershaft gear had a bunch of broken teeth. Fifth gear looked fine/tight. I'm now weighing the cost of the gears, and tools to rebuild it, vs. buying a reman. Any suggestions?

towpather

I went the rebuild route with a new input shaft,mainshaft,syncros,bearings. Nothing on the countershaft. If i had to do it again i think i would swap it with a reman.

RickCJ

Blumenthals rebuild for $1600

MikeR

With that much screwed up, I'd go the reman route.