rear wheel bearings

[scracha]

Rear wheel bearings seem to only be lasting 1 or 2 races. Dunno if LBS is making an arse of installing them or if there's something more problematic. Any ideas what could cause this?

[TDC]

Rear wheel bearings seem to only be lasting 1 or 2 races. Dunno if LBS is making an arse of installing them or if there's something more problematic. Any ideas what could cause this?

What model of bike?

[scracha]

What model of bike?

It's an 89 CBR400

[HDTboy]

The spacer tube between the bearings is the incorrect length

[smudge]

What you need to do is have a look at the wheel bearings while they are in the wheel. Are they loose in the housings? It may be there where the play is. If the bearings are knackered then they are either being fitted incorrectly or as said earlier the spacer may be loading the bearings up because it is the wrong length.

[Robert Taylor]

The spacer tube between the bearings is the incorrect length

This is plausible, indeed if the spacer is worn from previous bearing failure. Most bearing manufacturers are notorious for only grease packing with a whiff of grease. If as I suspect there are more bearings being made in ''nasty'' places then that may well be part of your answer, and any grease they use would be just as dodgy.

Also the graded clearance of the bearing. If you stick with SKF, NTN etc there is a much better chance that their quality control is much much better than the ''ding dong dit'' offerings.

Do though with any bearings carefully prise off the seals and pack with a high quality grease to no more than two thirds capacity

[TDC]

It's an 89 CBR400

Ok Then, the usual cause of premature bearing failure on a ball race is excessive side load. The things to check are, the wheels hub is not deformed (in reality not very likely). The next most common is the spacer between the two bearings in the wheel assembly is too short (wrong one or modified for some reason) or not even there (have seen this before!). On some bikes this spacer is made of aluminum, and if the axle has been over tightened it can crush this spacer meaning that any bearing fitted will fail quickly. This mans that when the axle is tightened the bearings are under considerable side load and will fail in very short order.

So take the wheel out and see if there is a spacer between the two wheel bearings, if not you have your problem. If the spacer has any play side to side, or that is it is not being held in place by the bearings (there should be a slight force being exerted by the bearings holding the spacer in place) you have your problem.

Hope this helps

[Coldrider]

Are the bearings being belted in to the housing like a Butcher would.
Sorry, someone had to say it. How many bike shops have bearing heaters so bearings can be slid over shafts by gloved hands as they should be.
Bearings being held by the outer shell should be frozen to shrink down for placement. Incidentially of intersest I have seen bearings crack at 85deg C while being heated.

[scracha]

Are the bearings being belted in to the housing like a Butcher would.
Sorry, someone had to say it. How many bike shops have bearing heaters so bearings can be slid over shafts by gloved hands as they should be.
Bearings being held by the outer shell should be frozen to shrink down for placement. Incidentially of intersest I have seen bearings crack at 85deg C while being heated.

Dunno. LBS have put in correct spacers and other gubbins that were far too technical for me. Mechanic told me he'd replaced the standard aluminium gubbins with steel gubbins. Hopefully it'll all be good now.

[Squiggles]

Are the bearings being belted in to the housing like a Butcher would.

or screwdrivered

[Paul in NZ]

if they are ball bearings they are often in standard sizes.. The temptation is to think any bearing with the same dimensions will suit all applications suitable for those dimensions but thats NOT the case.

There are different cage materials and numbers of balls as well as quality and other variations. If the problem continues I would discuss with the local bearing retailer a suitable upgrade over the mass produced in a hot country by people that were eating sand for dinner 2 generations ago type bearing that is cheaply availiable these days..

Cheers

[Coldrider]

If you stick to Saeco, NTT, KTN, SKF or Timken you should be OK, dollar wise the chinese stuff won't be much cheaper so there is no point taking the risk. The off the shelf bearings are about a 'C' grade anyway, perfectly good for the purpose provided they are fitted correctly. The same roller bearing types used in motorcycle wheels (for size) are used in 0.5hp to 15 hp electric motors and gearboxs, running at up to 3,000rpm for thousands of hours. You pay big money for 'B' grade bearings an 'A' you don't even want to ask, as you are not reconning a jet engine.

[roadracingoldfart]

I was a Rep for an SKF retailer in Wgtn for 5 yrs and i can say with confidence that most bearing failures are from either fitment fault or contamination from the operating enviroment. Another failure reason is that the bearings are simply replaced when the old ones fail and the reason for failure may be overlooked when new ones are installed. I would look at the whole rear wheel and see if the housings and axles are ok and not worn out.
Check to see if the sprocket carrier bearing is still ok and not spinning and floppy. I also have a NC23 CBR and it is a common problem for them to have the carrier bearing move in the housing. This upsets load on the inner bearings and makes things crap out. I have also seen 2 other racers with the same bikes that had no spiggot spacers from the carrier.
Cheers Paul.

[pete376403]

... The same roller bearing types used in motorcycle wheels (for size) are used in 0.5hp to 15 hp electric motors and gearboxs,...

Not many bikes using roller bearings in wheels - think you mean ball bearings (6200 series usually)

[Coldrider]

Not many bikes using roller bearings in wheels - think you mean ball bearings (6200 series usually)

You are most likely correct in that, though I only specify a bearing by its number, no matter what type. But that factor does not diminish the problem at hand, considering two 6204 bearings & seals only cost $25, but how much is this problem costing scracha, ongoing.