WR450F 2004 gearbox Question

hey all, how are we.

Mates WR450 has blown its gearbox for a 2nd time now and done quite a bit of damage this time, unlike last time only 1 gear got stuffed, this time 3 got stuffed and a nice tear mark in his case etc etc

Ok so my question is, the INPUT shaft got some slight damage to it where the 5TH Pinion Gear sits, now it NEEDS re facing so i have had it done by a qualified engineer and i have been informed that since this has been done the gearbox may seize up as the coating has been taken off the shaft from the refacing, is this true ?? if so, anyone know any wreckers that i could contact to get hold of one, as the poor blokes just spent near a grand on it in repairs/parts hence im doing labour for free and id hate to ring him up and tell him his up for another 500 bucks or so haha

Cheers Guys.



I looked up that shaft your talking about . This seems to be it

Part Number: 5TJ-17411-10-00

Description AXLE, MAIN

Price $47.40

Thats from a USA parts store . I know here they double it and add 200% . But with the time it takes to strip out the engine and the cost of gaskets. I would be replacing the input shaft. Even if you order it from the states.

The shaft from new has case harding on it. The 5th gear will pick up on the shaft. I'd rather spend a little bit more than have to do it again. Like you said he's saving 1000 in labour with you doing it. So help him out and replace the shaft. You should replace that mating gear too. Sorry to be the bearer of bad news.

Na your right mate, i appreciate the response.

yeah pretty much the hole box has been replaced in means of gears, i have been informed its road use that does it to them but i find that strange being that it is an endurance bike. I'm trying to convince him to sell it after this haha.

ill contact port yamaha on monday about getting one as my suppliers cant get genuine yamaha parts and they dont make an aftermarket input shaft.

thanks for the help/info, very much appreciated :crazy:.


Don't try to fix axle or gears, just change them. It is by far easier and cheaper in long run. I do everything exept boring and changing rod on crank by myself and I'm not an engineer or mechanic. It only needs patience and reading instruction.

Timo McKeown

yeah true, im no mechanic either, i work as a 2nd year fitter/machinest haha.

bikes are pretty basic though, grown up with them all my life, but cars, they go to a mechanics for me hahaha

i dont know why his having so much trouble with it, ive had a CRF450 02 since NEW and not one single issue with it, except the yearly rebuild/recondition but i wouldnt consider that a problem, just maintenance.

Cheers. Rodney

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