[solved]Rear wheel bearing spacer too long?

Hi Folks,

Girlfriend's 1999 CB500 SX has had an advisory on the rear wheel bearings for its last two MOTs.

Have removed the old bearings from the wheel and given it a bloody good clean. It's very clean in there now. Have bought new bearings from Wemoto and fitted the right hand (disc side) bearing and am about to fit the left hand bearing.

However, the end of the steel spacer appears to sit about 0.5mm to 1.0mm ABOVE the level of the bearing seat. (As far as I know the bearing should sit right down flush, all the way down on its seat in the hub).

If the spacer is slightly above the level of the seat, is it going to wreck the bearings when I knock it in? The old bearings didn't seem too bad. 

I'm wondering if this is what is causing the wheel to 'rock' when tested during the MOT.

Anyone got any experience of this? It won't let me upload a picture as it says we're out of storage space. :-(

If the wheel was rocking, it sounds like there is a good chance that the bearing is done. Either that or the swing arm bearing, but that would cause to whole rear end to move. The best approach to installing the bearing is to use an appropriately sized socket on the bearing and drive it in with a hammer. If the socket is applying the force to other outer portion of the bearing, there is very little chance of harm. You will also be able to feel very distinctly when the bearing is fully seated as your hammer starts to make a different sound. 

Remember there are 3 bearing in the rear. One on each side of the the wheel and one in the sprocket carrier. It's best to change all three.

Thanks Liverpool!

The plot thickens...

I took the wheel to the motorcycle workshop where I get the MOTs done this afternoon. I asked their opinion on whether the spacer was too long and if it was safe to drive in the left-hand bearing (which I hadn't done yet as I was worried I'd knacker the bearing). They said it shouldn't be a problem. 

However, they pointed out that the hub look liked it had a machined insert fitted into it (and that's what the right-hand bearing sits in). It's a very experienced, old-school motorcycle workshop with a very good reputation. They were very surprised to see this.

Unfortunately it won't allow me to upload a photo so unless anyone can tell me their right-hand bearing sits in a machined aluminium insert too, then it looks to me like this is non-standard and that the wheel MAY have had a repair at some point. (Bought the bike in 2013. Good condition. HPI clear).

The old bearings I removed feel fine and have no give in them. The sprocket carrier bearing is fine too. Cleaned it up and it feels very smooth and no lateral give in it. I haven't removed it from the sprocket carrier bearing yet, but I have the new one and was planning to do all three.

I had put both new bearings in the freezer overnight, so I ran a bit of grease around the edges and was able to push them a little way into their recesses using just my fingers. Then using the old (cleaned-up) bearing as a drift, I gently hammered them home. I was quite gentle and tapped in a triangular fashion until the bearings were down.

The new bearings are now both jammed tight against the spacer and will not rotate. If I push my finger right in the hole and try really hard I can get them to turn (tight as hell) , but the spacer turns with them.

I can't tell you how pissed off I am.

Ignore what I said about it being a post-manufacturer machined insert. I've found a couple of rear wheels on eBay that have the same machined inserts. It looks like this is how they are made.

All sorted. This is what I've found....

God knows why but the bearings have a seat / ledge on both sides of the wheel. (The wheel in this video I followed has a seated end and an 'open' end with no seat).

https://www.youtube.com/watch?v=dQbKXbhyFQs

When you install the right-hand bearing (disc side), it needs to be tapped in and seated all the way down.

What I've now done on the CB500 is install the left-hand bearing, ignoring the seat and just knock it far enough down that the inner race just slightly touches the spacer as normal.

The bearings are fine now. Lesson learnt. Don't drive them in too far!

Hi Alex

Glad you got it sorted, sorry I didn't reply to your text yesterday, I've been on child duty all weekend, wife having bad crohns flairup.
I've left a message for spitonyourgrave22 the site owner as he's the only one that can deal with the out of space issue.

All the best,

Matt

Interestingly I also have my rear wheel in pieces - one of my rear bearings was definitely shot, I could easily wiggle it from side to side with my finger.

I will have a good look at my wheel/spacer before I hammer it back together - from my recollection of doing this before (and other bikes/hubs/wheels) the spacer should be just slightly short when you have seated both bearings.

Thanks Matt - hope the wife feels better soon. We'll have to catch up when convenient, now that I'm more "local" than Gateshead!

ET - yeah, that's what I was expecting. The only thing I wonder is if the spacer I had was not the original one. This one is steel and appears to sit about 0.5mm proud of the left-hand bearing's seat. It would have made more sense to me if the spacer sat absolutely level with it.

magicman-alex wrote:
ET - yeah, that's what I was expecting. The only thing I wonder is if the spacer I had was not the original one. This one is steel and appears to sit about 0.5mm proud of the left-hand bearing's seat. It would have made more sense to me if the spacer sat absolutely level with it.

It doesn't want to be level - this would make it hard to manoeuvre the spacer out of the way, so very slightly less than level would be ideal.

For the record:

My rear wheel spacer is approx 123 mm long, measured with a ruler.

I couldn't measure it accurately because my callipers aren't big enough!

Well that's interesting. I've just put the bearings back into my wheel.  Essentially mine has exactly the same issue as magicman-alex's - the spacer seems slightly too long.

When I whacked the bearings *all* the way in then they were getting tight and the inside was not turning... I bashed one of them out (slightly - I know you shouldn't do this) and it is now OK, just as alex described.

They aren't expensive and I'll keep an eye on them, but there is definitely something going on here as I didn't have this problem last time I did this job.

@magicman-alex - what type of bearings did you get from Wemoto?  I know that they would have been 6303, but where there any other numbers/letters e.g. 6303 2RS1 C3 (or similar)?

The 6303 bit is the size/load rating of the bearing, the 2RS1 means that it is sealed on both sides the C3 means 'C3 clearance tolerance' which is to do with the internal clearance of the bearing (essentially, how much play there is in it, kind of).

The ones that I *took out* were C3, the ones that I *put in* were not C3.  Don't know if this as anything to do with it - it could just be that I am cack-handed when it comes to wielding a hammer at bearings :)

OK,

The pair of rear wheel bearings I took OUT have this embossed on the side:

"JAPAN NTN 6303LU"

(I searched online and there also exists an 'LLU' and some other notations, but these are definitely just 'LU')

Can't seem to find them in the UK, but here they are in America:

https://www.amazon.com/gp/product/B00DBOCEZ6/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A30MM8B7IBXGD7

The new bearings I got from Wemoto are stamped "KYOTO 6303 RS"


SPROCKET CARRIER BEARINGS:

OLD: "JAPAN NACHI 6304NSE" (There is a very small number '27' between the word 'JAPAN' and 'NACHI')

NEW: "6304 2RS C3" (Still in its sealed bag in the freezer. The box says "Code: ROU6304 - SIFAM TRADING (Made in China)."

I ordered these before and they fit well although they don't come with seals and I got the garage to fit them for me. http://www.ebay.co.uk/itm//110833899283

magicman-alex wrote:OK,

The pair of rear wheel bearings I took OUT have this embossed on the side:

"JAPAN NTN 6303LU"

(I searched online and there also exists an 'LLU' and some other notations, but these are definitely just 'LU')

Can't seem to find them in the UK, but here they are in America:

https://www.amazon.com/gp/product/B00DBOCEZ6/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A30MM8B7IBXGD7

The new bearings I got from Wemoto are stamped "KYOTO 6303 RS"


SPROCKET CARRIER BEARINGS:

OLD: "JAPAN NACHI 6304NSE" (There is a very small number '27' between the word 'JAPAN' and 'NACHI')

NEW: "6304 2RS C3" (Still in its sealed bag in the freezer. The box says "Code: ROU6304 - SIFAM TRADING (Made in China)."

Interesting. I'm pretty sure that the LU or LLU just means the same as 2RS - i.e. sealed on both sides/permanently lubricated. The 6303 bit is *definitely* the standardised load/size designation.

Your sprocket carrier bearing is a C3 clearance - I really don't think this matters.

Have a look at the SKF cross reference on page 374:

http://www.skf.com/binary/79-66347/457013.pdf

TBH as long as you don't whack the bearing in too much (i.e. do what delboy does the video - not what I did!) and just so it is snug against the spacer then it will be fine - if it is against the spacer at both ends it can't go anywhere, anyway! (which is the whole point of the spacer....)