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2016 Kx450f transmission went at 43 hours.

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I have a 2016 kx450f i bought new. Im a c vet mx track rider not racer.  43 hours track time. 4th gear started slipping in and out of gear and wont shift to 5th gear.  Im looking to see if anyone else had problems with the 2016-2018 trans.  Drained out oil and found one of the trans shims in pieces. They are on both sides of 4th gear.  Pulling motor and doing job myself. I am very surprise a bike 3 years old would break like that. I maintain my bikes well.  So i wasnt lack of maintenance and i run the castrol power1 racing full synthetic oil like manual recommends. Im thinking maybe i bent a shift fork and that caused the shim breakage.I would definitely like to hear from u if this happened to your 2016-2018 kx450f

Edited by CrobarGreg

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We are running two 2017s, ones at 28hrs and the others at 50. So far were ok but will let you know if anything happens. We do notice that they don't like to shift under load

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We are running two 2017s, ones at 28hrs and the others at 50. So far were ok but will let you know if anything happens. We do notice that they don't like to shift under load
Thanks. I forgot to tell everyone i am running a rekluse torque drive manual clutch with stiff springs. Talk to a kawasaki team mechanic and he said rekluse clutch is hard on trans. Took it apart heres the damage. Fork is not bent. Wear is from gear popping out and pushing on fork. 3rd to 4 th gear 20181027_191502.jpeg20181027_191526.jpeg20181027_191511.jpeg20181027_192101.jpeg

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We are running two 2017s, ones at 28hrs and the others at 50. So far were ok but will let you know if anything happens. We do notice that they don't like to shift under load
You can see the broken trans shims in the oil in this photo down by oil pump screen. 2nd photo minor case damage. Will use a die grinder and clean that up. 20181027_185303.jpegScreenshot_2018-10-29-17-26-03.jpeg

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It would be easy to imagine the fork bending due to the stiff shifting, but I don't see how that would directly effect the shim. But from your photo the shim literally machined itself into chips. I'd wondering whether something happened prior to the shim coming appart like that. Did the shift forks check out?

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It would be easy to imagine the fork bending due to the stiff shifting, but I don't see how that would directly effect the shim. But from your photo the shim literally machined itself into chips. I'd wondering whether something happened prior to the shim coming appart like that. Did the shift forks check out?
The shift fork is straight i measured it with a digital caliper on a flat surface and compared it to the new 1 i bought. The shim broke because 4th gear hammered on it when it slipped out of gear under a load. The gears dogs are worn and ramped so they would push out under power and put pressure on the fork wearing it uneven. The gears was slipping in and out and hammering left to right. The shim washers are on both sides of 4 th gear. The clip that was on shaft between shim washer and gear was all bent up. But didnt let go. There were some large pieces of shim. I believe some fell between the gear teeth and were shredded.
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i missed you writing about the forks checking out. the doggs on input gear three that engage into input gear four are definitely worn. gear four looks "salvagable" from the pic. I can understand that the clutch is mounted to the input shaft, where you had the problem occur, i just cant understand why it would affecting the tranny in that way. even with a stiffer clutch, the brunt of the axial thrust should be taken by the main clutch bearing and not the shims. are the metal filings blueish "look burned"? that would indicate rubbing.

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i missed you writing about the forks checking out. the doggs on input gear three that engage into input gear four are definitely worn. gear four looks "salvagable" from the pic. I can understand that the clutch is mounted to the input shaft, where you had the problem occur, i just cant understand why it would affecting the tranny in that way. even with a stiffer clutch, the brunt of the axial thrust should be taken by the main clutch bearing and not the shims. are the metal filings blueish "look burned"? that would indicate rubbing.
I will take a look at the metal shavings this weekend and get back to you on that when im at my work shop. I am replacing all the mating gears on the input shaft.

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What you wrote above makes sense. If the filings are blueish there could have been an issue that led up to the problem. But if they are simply shredded with little discoloring than more likely they burst under the side pressure from "popping" out of gear. In all honesty though 3rd and 4th input gears are the ones that need replacing provided nothing happened to the gear sets on the output shaft. I would also be curiouser how much axial play there is in the fourth input gear after installing the new washers.

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What you wrote above makes sense. If the filings are blueish there could have been an issue that led up to the problem. But if they are simply shredded with little discoloring than more likely they burst under the side pressure from "popping" out of gear. In all honesty though 3rd and 4th input gears are the ones that need replacing provided nothing happened to the gear sets on the output shaft. I would also be curiouser how much axial play there is in the fourth input gear after installing the new washers.
Shim 92200a. The bushing on 4th gear is okay. Screenshot_2018-10-31-20-34-13.jpegScreenshot_2018-10-31-20-34-02.jpeg

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I'm also looking at the microfiche. That washer looked like it simply came appart most likely due to the pressure of popping out of gear as you said before. Well I havent really added anything to what you already know. I wonder about the axial play because that determines how much of the gear dogs surface is actually engaged. Even a small increase in engagment area would result in a more durable gear. If it's very loose maybe consider a machined to thickness washer.

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I'm also looking at the microfiche. That washer looked like it simply came appart most likely due to the pressure of popping out of gear as you said before. Well I havent really added anything to what you already know. I wonder about the axial play because that determines how much of the gear dogs surface is actually engaged. Even a small increase in engagment area would result in a more durable gear. If it's very loose maybe consider a machined to thickness washer.
Thanks for the info. Hope this doesnt happen to you.

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What you wrote above makes sense. If the filings are blueish there could have been an issue that led up to the problem. But if they are simply shredded with little discoloring than more likely they burst under the side pressure from "popping" out of gear. In all honesty though 3rd and 4th input gears are the ones that need replacing provided nothing happened to the gear sets on the output shaft. I would also be curiouser how much axial play there is in the fourth input gear after installing the new washers.
I just did some research part numbers changed on 3rd and 5 th input for 2017-2018. The ones that are bad. Probably updated the part. Im ordering 2017 gears. May have a problem the secretly updated following year. Maybe the hardening process??

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Tough to say. Visually they look identical so I can imaging if the issue was prevalent in 2016 the quickest/easiest thing to do is change something at the supplier level. Usually these are just Band aids though. If it's something to do with hardening I'd bring down the hardness of the spacer/washer so it would bend and not shatter when the gear slams In to it.

 

 

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Spacers/washers are same part number. From 2016-2017. Im thinking there was a durability issue with 3rd gear . Also the 3rd gear part number changed for output shaft. I will order 2017 parts. Hopefully they were upgraded and will last longer. 43 hours is not a lot of time on a trans.

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