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Ukaszs2

WR 450 bearing problem

6 posts in this topic

Hello to everyone, i'm new here.

I'm currently rebuilding gearbox on my '05 WR 450. I just got all gearbox bearings that i ordered from my local yamaha dealer (Poland). One of ordered bearings is not the same as original one.

Comparison2.jpg

Comparison1.jpg

Dealer said that this part was replaced by another. I did some research and found out that original bearing (KOYO 6004 SH) can resist 10 times longer in contaminated lubricant compared to standard bearing. All bearings for gearbox have SH mark. SH stand for special heat treatment.

SHmeaning.jpg

Dealer send me standard KOYO 6004 bearing with C3 internal clearance. I have request, can someone check for me this part number: 93306-00426 and get information if it is really replaced by 93306-00423 ? I think that something is wrong, if i use this standard bearing it can broke very soon.

Apologize for any mistakes in post.

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Yes, the SH stands for 'super hard' and the bearings are tougher than a std bearing, to resist wear due to contamination in the oil

get the SH bearing if you want it to last, if your selling it, just build it up as it will run and last, but not as long

The C3 clearance is normally just the crankshaft I believe, the gearbox uses std clearance bearings (but I may be wrong here) - has the original bearings got C3 clearance stamped on them

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I want to get the SH bearing but i don't know where i can buy it. I called several yamaha dealers in my country and they said that this part (93306-00426 KOYO 6004 SH) was replaced by this (93306-00423 KOYO 6004C3).

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Interesting! Cost cutting manuever? Short supply of the original? We will probably never know the answer!!

Maniac

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