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Gearbox - what years are interchangeable ?

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Hi, there is a listing on ebay for an item titled CRF 450R gear box 05-08.

The bike I want this for is a 08 CRF 450 R (5th gear won't stay put). The bike the dealer got the gear box from is a 06.

Now I checked the Honda micro-fiches and noticed that the part numbers for the gears and even the shafts have changed across those years. I contacted the seller and he informed me that to the best of his knowledge the engines have stayed the same and so I should have no problem.

So now I don't know what to do. Should I go ahead and buy the gear box or should I wait for 08 to appear on ebay ? I don't want to through money away but on the other hand parts for 08 are unlikely to come up on ebay any time soon

Help please ?

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From what i understood 02-08 should be interchangeable BUT you have to use the shafts that come with the gear set because some are different size from what i have heard, though i have no personal conformation on this , but it should still fit in the case , though i am not positive if the case bearings are the same ID and may have to be swapped as well , but i have not heard of this needing to be done either , the ones i have had apart LOOK the same to me but i never measured or compared year to year , i do know that a Wide Ratio Tranny Gear Set is available for the 450R and it is supposed to fit 02-08 , so i would think as long as you got everything that goes with it , and its swapped as a unit , you should be alright ! , a X tranny will not fit because the cases themselves are different as are the width of the gears making the X gears to wide to fit the R case , and 09-12 are different as well as obviously the cases are narrower than the older style 02-08 models

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You'd probably be better off just inspecting the trans you have and replacing the gears you need. When they jump out of gear like that its not always just the gears. Id replace the shift fork and the gears with the rounded off side dogs.

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Thanks for the replies.

I won't bother opening up the cases because I know for a fact that the gear box is busted.

The full story is that some six months ago a piece of metal broke loose from the kickstart mechanism and was subsequently pulverized in the gear box. The owner (this is a friend's bike) did not realize anything was amiss aside, that is, from the kick start making a constant annoying noise, and so he continued using the bike. When I finally opened up his bike to see what was wrong with the kickstart I found out that the oil was a sparkling silver substance and there were metal fillings everywhere !

So this might be the first issue with the gear box but I am sure that everything in there must be pretty worn out and other issues will come up in the future. This is why I am looking for a complete replacement in e-bay.

So I take it that if I were to replace the complete gear box (both shafts and all the gears) as 450XJimDirt suggests there will be no issues ?

edited to add: Shawn_Mc, it goes without saying that I am looking for auctions that offer all the gears the forks and the shift drum.

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ahhh...now we get the whole story...

All the transmission from 02-08 will fit, but the early gear sets had oiling issues and 5th would seize on the shaft from time to time.

You want an 05 or later (05-08) gear set with the shafts.

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As an aside, I still can't get over the fact that the bike is still working.

What is the point in worrying about frequent oil changes and the type of oil we use if these bikes can survive this kind of abuse ? If it took six months of constant use for this bike to brake then a bike that is barely ever maintained will last forever.

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