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Pincushion

cases split... which gears are shot? (w/ pics) 00' 426

15 posts in this topic

My motor ingested something bad a while ago. It did some trans damage, totally destroyed the oil pump and did my cylinder real bad. I've finally got the cases split and took some pics of my gears. Please look at these and advise which ones are damaged or reusable (if any). The shift forks had minimal wear, but were not damaged or bent so there seems to be no misalignment of the trans. They are getting replaced so I didnt post pics.

Starting with the drive axle side:

#1 - 1st gear, meshes with 5th

#2 - 5th gear, meshes with 1st

#3 - 5th gear, meshes with 3rd

#4 - 3rd gear, meshes with 5th

#5 - 4th gear. No bueno'

#6 - 2nd gear, meshes with 4th

Now to the main axle side....

#7 - 5th gear, meshes with 3rd

#8 - 3rd gear, meshes with 4th

#9 - 3rd gear dogs

#10 - 4th gear damage

I know both sides of 4th are shot due to the teeth damage, but how about the rest? 1st gear is showing some rounding where the dogs engage, is it too much?

When replacing shift forks is it mandatory to replace the 2 adjoining gears as the manual states?

Thanks for looking at my long post.

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I would like to see photo # 7 & 8 retaken with pics on both sides, but all remaining gears need to be replaced. Replace any gear if it has any wear marks.

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Ask this question, to any competent enginer builder on this site. RHC comes to mind.

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In my opinion:

Change: #1 - 1st gear, meshes with 5th

Reusable: #2 - 5th gear, meshes with 1st

Change: #3 - 5th gear, meshes with 3rd

Reusable: #4 - 3rd gear, meshes with 5th

Reusable #6 - 2nd gear, meshes with 4th

The rest look ok from the pictures its hard to tell with the shaft still assembled. I wouldnt change all the gears. How many of them actually gave you trouble? Remember that if one gear shows slight wear on the clutching and you mate a brand new gear with it, there should be no issues with it popping out of gear. Take a good look at the shift drum and look at the shift forks and make sure none of them are worn or bent. Usually when the fork is bent there will be rubbing marks from the collar on the surface of the fork. Change the rest of the gears that have the holes. If money is not an issue then you could always change all gears with any wear just for piece of mind, but its not always nescessary. Hope this helps......James

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Good advice so far I think.

Both my 426's ('00 & '01) had 4th primaries that ended up looking like yours. What is up w/ that?

Any wheels w/ worn or even slightly damaged dogs, like 1st & 3rd, I would replace. Slight damage to recesses I would worry less about. Make sure the splines are damage-free.

At this point I would consider replacing all 3 forks regardless (after all, how did all those dogs get marred like that?).

My two cents.

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In my opinion:

Change: #1 - 1st gear, meshes with 5th

Reusable: #2 - 5th gear, meshes with 1st

Change: #3 - 5th gear, meshes with 3rd

Reusable: #4 - 3rd gear, meshes with 5th

Reusable #6 - 2nd gear, meshes with 4th

I agree except for the 2nd one.

#2 - 5th gear, meshes with 1st...Replace it just to be safe.

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I agree except for the 2nd one.

#2 - 5th gear, meshes with 1st...Replace it just to be safe.

Change: #1 - 1st gear, meshes with 5th

Reusable: #2 - 5th gear, meshes with 1st

I still think #2 is fine.... as long as you change the gear that mates with it #1

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Change: #1 - 1st gear, meshes with 5th

Reusable: #2 - 5th gear, meshes with 1st

I still think #2 is fine.... as long as you change the gear that mates with it #1

True, but I was kinda tired when I read it so I thought he was already replacing the other one.

Man, just get a whole new tranny, lol

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How many of them actually gave you trouble?

If money is not an issue then you could always change all gears with any wear just for piece of mind, but its not always nescessary.

None of them were giving me trouble (yet...). Something got ingested into my cylinder so I went into the cases looking for the culprit and thats how I found this damage.

Money is a definite issue and I cant really afford to replace my entire trans :)

I've been riding for 20+ yrs and am not hard on the trans. I'm thinking the damage came from the previous owner.

So far I'm replacing all of the drive axle gears (#2 can't be reused cause the other side of it has damaged dogs) and 4th gear on the main side. This is gonna be expensive.....

Hick,

are you serious about 5th gear on both your bikes? I thought that damage was from a foreign particle getting in there and damaging the teeth. Strange you've had it happen on 2 different bikes.

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Hick,

are you serious about 5th gear on both your bikes? I thought that damage was from a foreign particle getting in there and damaging the teeth. Strange you've had it happen on 2 different bikes.

Yeah, this is not an uncommon thing. It was fourth primary BTW on both bikes.

On my '00 fourth gear chunked off a few teeth, these somehow got caught in 3rd gear dogs. 3rd gear grenaded. This caused the shift fork that rides on 3rd gear to get spit into the crank, wedging between crank and cases, and breaking the slot in the case where the fork shaft sat. Nasty. I needed cases, crank, rod, cylinder, gears, bearings...

On my '01 I installed a magnetic drain plug the day I bought it. After about 100 hours I was changing the oil and there was a gear tooth stuck on the magnet. At this point I didn't consider splitting the cases to be that big of a deal, so out they came and 4th primary was also losing teeth, the load-bearing faces were pitted (just like in your pic), looked like bad metallurgy or something. Same as my '00, just not quite as bad. I think the outcome could have been identical but the magnetic drain plug saved me.

I used to have some pics of the gears, I can't seem to find them, but my 4th gear and yours looked about the same....

Ty Davis used to glue magnets at various places inside his gearbox. I wonder why?

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My 01 426 did the same thing. Bad metallurgy is also my opinion. Where the gear tooth was broken it looked like the metal was porous. I would replace all shift forks and all gears that show wear or eventually you'll end up splitting the cases again to replace what you didn't replace the first time. The second time is much easier but why do it if you don't need to?

KC

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Thanks everyone for the advice.

I ordered all 5 drive axle gears and 4th gear from the main. All others on the main looked good.

both of my 4th gears have damage to the teeth. I think my damage was caused by something foreign in my case..... but both you and Hick have seen the same thing. Weird!?!?!?!?!?!

This rebuild is about up to $1k now. Guess I should've bought new.

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I think my damage was caused by something foreign in my case..... but both you and Hick have seen the same thing.

My guess would be that what caused it was a chunk of 4th gear, just like on my '00.

This rebuild is about up to $1k now. Guess I should've bought new.

It does seem that the 450's four speed, w/ their wider gears, has avoided this problem, so maybe you would have been better off.

My '00 upchucked 4th gear w/ less than 30 hours on it. I also went to an overbore since my cylinder was gouged, and counting the boring/plating, piston, crank/rod, cases, gears, gaskets and bearings I spent about $1,300.

So it could've been worse, but I feel your pain man.

Again I'll advise you to make sure the splines on both shafts are not nicked and that all splined gears slide effortlessly along them. You can mock up the assembly in the left half and spin the shift cam manually to ensure glitch-free operation before you button it all up.

Also, clean the inside of your mag, you may have some metallic debris stuck there.

Good luck.

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