Topic: Did I get the wrong bearing from yamiya750?

[persson-johan@hotmail.com]

Hello!

I ordered all the bearings for the gearbox in my cb750 from yamiya750 this summer. I have installed 8 out of 9 now and noticed something strange with it. The bearing im describing is the one pressed into the lower case, not the one in the holder by the shifter mechanism.

The one i took out was a NTN 6204, didnt say anything about the clearance. The one i got from yamiya is also a 6204 but with crazy much clearance, it says c10 and i can feel a big difference between the new and the older. The new one has significant more play.

So is this ok or have yamiya750 sent me the wrong bearing? They generally have good stuff i think. I havent read that this bearing should be any special with more clearance..

This is the one i bought and i have the same art.nr on the box:
http://www.yamiya750.com/index.php?main_page=product_info&cPath=246_21_250_52&products_id=102

Hope someone can help with this!

Regards
Johan

[disco]

Hi Joper,
I'm just about to install the same bearing & also bought my bearings from Yamiya. I've had nothing but positive experiences with Yamiya. However, your post made me check that bearing before installing.

It does appear to have a little more clearance straight out of the packaging. Give it a shot of engine oil & it will immediately feel more normal. I'm going ahead with the install.

[Swoop]

Measure them.

[disco]

How do you measure the play in a ball race bearing?? It's entirely a feel thing.

[RAFster122s]

You could measure the distance with the race secured and the thickness between the inner race when it is clamped 180 degrees perpendicular to the bottom surface and measure that top distance between inner and outer race. Then pressing it down to the surface measure the same point again. It will give you a crude measurement of the play.

Contact Yamiya about it...
It is likely when it is oiled up the clearances will be different as it will have the film of oil and it will change the perception of movement in the bearing.  To a small degree it could actually change the measurement, but we are talking very small measurements.
David

[PeWe]

I changed this bearing earlier this year. Same bearing from Yamiya750. The old one was marked NSK 6204. I did not noticed any difference, but I did not check the play either. I used a heat gun to remove the old that had a big bolt hanging in it and out it came. Heated case and the new just fell in place without any additional hammering.

I checked my stock of new parts. The other Yamiya750 6204 I have are exactly the same as here C15-10. I have not heard any bad sound from transmission, all gears worked well too.
I have bearings for 1 or 2 more CB750 engine builds...Shop as long as they are available...

[persson-johan@hotmail.com]

Thanks for the answer!
I googled around for a while and checked with original Honda parts nr and pictures and it seems to be all good. I went ahead and installed them and put the engine back together today

I've read a bit about the transmission bearings here on the forum and a lot of recommendations about buying all bearings except one in standard clearance differs from what Honda delivers.  There are one C7, one C5 and one C10. Hasn't heard any concerns about it tho so probably not a problem

[strynboen]

c 3 is a standart for most universal use
 .(..c5 c7 c10 is krazy heigh numbers(have never seen one),,must be for only gear box use..vho need to tolerate some Flex in the shafts.
..i have used c3 ..think sticking gear is a problem even vith orginal bearings..so it are prob not a problem/or make anything vorse,or better

[PeWe]

Really sure that the 15C-10 here is clearance? Not preload?
I have not find the spec on NTN homepage. NSK has C10 as a symbol for preload....
http://www.nskamericas.com/cps/rde/dtr/mx_es/na_literature_bearing/E1254e_Super_Precision_Bearings_Catalog.pdf

NTN has some about bearing loads for different applications
http://www.ntnamericas.com/en/website/documents/brochures-and-literature/catalogs/ntn_2202-ixe.pdf

[disco]

Yeah I agree with PeWe. I don't think that 15C-10 refers to the bearing clearance.
I checked the NTN website and their extra clearance bearings only go up to C5.
I think it's just an ordinary 6204. The fact it was not lubed up from the factory, made it feel it had a little more clearance.
Wheel bearings etc, come supplied sealed & grease filled which makes them feel tighter.