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85 250trx fourtrax transmission bench test

2308 Views 10 Replies 4 Participants Last post by  wheelsquad
first - some background on the 250trx fourtrax gears order. R, N, SL, 1, 2, 3, 4
- also shaft driven

When the quad was put in SL, it would just click and not move. I tore the tranny apart expecting to find something broken, but all i found was a washer laying in the bottom of the case missing from the top of the countershaft. Everything else looked good with only light wear.

i put all the gears back together and put the case back together and wanted to bench test it by shifting through the gears and watching the output drive rotate. i am having all kinds of issues with this. It feels like the drum is binding sometimes and it is very hard to shift or many times i cannot rotate the gears (they lock up). i am beyond frustrated at this point. i've had it apart and together more times than i can count and cannot figure out what is wrong.

I am certain i have everything together correctly and in order.
1. i took video of every piece coming out and laid each piece in order
2. i have the schematic to match against
3. i can tell by "wear" marks that everything is back correctly

has anyone had experience bench testing a tranny? should it shift through the gears easily (understanding that i have to keep the shaft rotating to line up the dogs)

I have the drum groves lined up to each fork and the forks in the correct order and facing correctly up. Nothing appears bent. the shift drum pin is lined up with the hole on the drum and the drum shifter is back on correctly as well.

Biggest problem is i cannot test it with the case off laying how it sits in the bike or everything will fall out. with the case together, i cannot see half of the gears to see what is going on inside. I was told it really has to be sitting like it sits in the bike or gravity makes it difficult with the forks.

Any insight would be appreciated. I'm desperate at this point.

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On the 85's 250A's they were marked SL,1,2,3,4.

Still a 5 speed and the "SL" gear was the same tooth count as first gear was on the later 250A's. They just called it "SL"

As far as the transmission is concerned, are you sure you have ever thrust washer in place, that all of the gears are correctly oriented? I've caught hell a couple of times when one gear was on backwards (I think that was on a 420 IIRC) and the only difference in one side and the other was very slight offset of the center of the gear.

I usually set the engine is a Radio Flyer wagon I have at a very slight angle to keep the gears from going everywhere, and then rotate and turn the shift drum, making sure everything spins freely. Make sure you have oil on the forks and drum too.
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I just use 250A when referring to the 80's vintage 2wd 250's.

250ES is the Big Red 3 wheeler.

And then you have the later 250 Recons, so I use 250A to make sure there isn't any confusion as to which model is being discussed.
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