Bearings


8 replies to this topic
  • Overson

Posted December 11, 2015 - 11:38 PM

#1

Hi I'm looking to replace my bearings as two of them have started to give up.
Not sure what ones to get ?
Yamaha bearings come with a high cost.
I have all the numbers off of the bearings.
But if you put in the numbers on a bearing company you get more than one bearing under the same number.
A friend of mine says you can use any C3 bearing with the same number ? Is this right ? Or are bike engine/transmission bearing only available from bike shops/manufacture's

Thanks for any help

  • GuyGraham

Posted December 12, 2015 - 04:22 AM

#2

Which bearings?

 

C3 bearings have extra clearance to allow for expansion at high temp, typically used for crankshaft main bearings

WR main bearings are not std c3 bearings though, as they have a higher hardness to cope with the dirty oil which goes through them, hence the extortionate price from yamaha UK

 

Other transmission bearings tend to be std off the shelf stuff, so just get the numbers off them



  • Overson

Posted December 12, 2015 - 04:40 AM

#3

Hi I'm thanks for the reply,
I'm changing all of them,
So the transmission bearing will be ok as normal C3 from my local bearing shop ?
But the main crank bearings marked as koyo 83C072C have to come from Yamaha ?

  • wdswkr22

Posted December 12, 2015 - 04:54 AM

#4

I think bearings made in Japan or the USA tend to be the best quality.
I might use a Chinese bearing for chassis or wheel bearing applications. Even there I'd rather have US or Japanese made bearings. In those applications the seal quality has a lot to do with bearing life I think. I'd never knowingly use a cut rate brg in the engine or trans. NSK and Koyo in the past have seemed to be top quality.

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  • GuyGraham

Posted December 12, 2015 - 08:18 AM

#5

Don't think the transmission bearing are C3 clearance - I think they are std

C3 clearance is not 'normal' in that if you don't ask for it you won't get it

 

Same size bearings for the mains are available but I'm sure I've seen it on here that they are not std, there is an extra code them indicating they are harder than comercial bearings and have to come from Yamaha. someone like Grayracer will know

Sure,off the shelf bearings will fit and work, but may not last as long as Yam supplied bearings

 

Yes,transmission bearings will be fine from bearing supplier

Stick with known good make - Koyo, NSK, SKF NTN. Avoid unbranded 'cheap' bearings

 

 

Read this

http://www.thumperta...-shaft-bearing/

seems to imply the Mains are C4 clearance not C3

Also, describes the meaning of the SH after the code on the bearing, which I seem to remember (rightly or wrongly) stood for Super Hard

Off the shelf bearings from a bearing supplier will not have the SH code on them, and prob won't be able to get them either


Edited by GuyGraham, December 12, 2015 - 08:41 AM.


  • Overson

Posted December 13, 2015 - 02:45 AM

#6

Hi thanks for advice, I've ordered prox crank bearings as they where recommended to me and are cheaper than Yamaha ones for the main/crank bearings,
Can any one confirm that the transmission bearings are C3 or not as I've ordered C3 ones and don't want to fit them if there wrong ?

Thanks GuyGraham
That link helped

Edited by Overson, December 13, 2015 - 03:00 AM.


  • GuyGraham

Posted December 13, 2015 - 03:19 AM

#7

Prox don't actually make bearings, they will just be repackaged bearings from a bearing manufacturer and unlikely to be SH grade

 

I've actually got some gen Yam main bearings which are shown below

 

IMG_2383.jpg

 

Yam have probably got exclusive rights to this bearing


Edited by GuyGraham, December 13, 2015 - 03:21 AM.


  • Overson

Posted December 13, 2015 - 04:30 AM

#8

The person who advised me said he has rebuilt loads of bikes and always used prox bearings and never had any problems, and prox sell a lot of bike parts so hope they would not sell anything that are no good.
Not sure on the SH grade until I get them this week.
I'll make sure to run them in properly, put them through lots of heat cycle's before riding it to harden up the bearings.
Any advice on the C3 gear box bearings ? Will they be OK as C3 or should I order normal ones, he said he uses C3, but would like adavice on this.

  • GuyGraham

Posted December 13, 2015 - 06:48 AM

#9

The person who advised me said he has rebuilt loads of bikes and always used prox bearings and never had any problems, and prox sell a lot of bike parts so hope they would not sell anything that are no good.
 

 

ProX are a reasonable aftermarket parts supplier but their stuff is average for the more price conscious buyer rather than the quality buyer IUSWIM

 

 

I'll make sure to run them in properly, put them through lots of heat cycle's before riding it to harden up the bearings.
 

 

This is just nonsense. Heat cycles do not harden steel. For steel to be hardened it needs to be heated to 800°C approx (cherry red) and quenched in oil or water (depending upon type of steel).

It then needs to be tempered back to removed brittleness, which is 200 - 300°C depending upon what final hardness is required.

Even at 200°C the steel is turning a pale straw colour.

Bearings do not get near this temp in use. If they did they would be on their way to failing

 

 

Any advice on the C3 gear box bearings ? Will they be OK as C3 or should I order normal ones, he said he uses C3, but would like adavice on this.

 

Best advice is replace like for like with whatever is in there (ie what Yamaha put in there) - check the bearings you take out for the code on them. C3 will have C3 on them. Nothing apart from the bearing code (such as 6002) is a std clearance






 
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