BB External bearings - The cheap rebuild

[dirtrider]

mmmmm , everything is clean , bearing got right ID , no visible damage on shaft . Not to sure , bring it around I got a very big hammer that solves most of my little problems .

[Kona Kula]

Not sure about the shaft. Can it get damage while riding. the old bearing were a mess. Got a suggestion to use a very fine water paper like a 1200 and go very easy on it. really don't want to ruin it completely before I have heard others advice on it. But its looking like thats my next step.

[brussel]

OK guys some interesting things I have found out and would be interested in your comments. I rebuilt half of my XT BB today

 

 

 

1)bearings locally sourced are same ID and OD but thicker. The only difference I can see is that they will make your cranks 2mm further apart all else still fits as well as it did originally.

 

 

 

2) The slight ridge on the plastic inserts needs to be sanded off as the OEM bearings had a slight rebate in ID to hold the plastic insert. This prevents them slipping out when you put the cranks on.

 

 

 

3) new bearings have insufficient grease IMHO so I carefully pulled on seal off and packed it full of marine grease. hopefully this will keep the bearing life longer. FYI the locally sourced bearings are 2RS whereas the OEM ones are 1 RS with the larger loose seal. So using new bearings one actually gets an additional level of sealing too...

 

 

 

brussel2009-12-21 06:29:10

[dirtrider]

Brussel I think the difference is only on XT/XTR rebuilds on your points 1 and 2 . LX and Raceface bearings are 100% same as AM bearings and the Plastic fingie has got no ridge .

[Jules]

I'm thinking of leaving these BB troubles behind by buying the Chris King unit. It's guaranteed for five years and has a tool that purges old grease. Just a pity the tool is not available on CRC

[brussel]

Dirt-rider - do you also recon that the extra 1mm must make no discernible difference?

[Johan Bornman]

I bit the bullet and bought the Race Face tool and started replacing  bearings in BBs since about November last year. I've done perhaps 20, with half of those turing into abortions. Most of the Shimano cups all have the 5mm proprietary 6805 bearing instead of the standard 7mm wide 6805.

I find this extremely strange that there even exists a non-standard 6805 and investigated this with Bearing Man. They have no answer other than to suggest that Shimano commissioned a bunch of non-standard bearings and a) either decided to simply use standard seals with the 6805 number already moulded into it or B) Shimano is showing us a middle finger and decided to trick us.

 

Some Shimano BBs do use the standard 6805 though but I haven't figured out which ones, since the bearing's pedigree is usually obscure - who knows if it is LX, XT or whatever.

 

My feeling on fitting a wider bearing in the narrow cup is that it is not a good idea. It will take away 4mm of spline fitting on the left crank, unless of course you have plastic thread spacers you can take out.

 

Does anyone have an inkling of which cups have 5mm and which have 7mm 6805s?

 

A comment on bearing cost. A good 6805 costs about R114-00. Live with it. Never, ever, ever, never, bother with a Chinese or Indian bearing. The balls are square. The better Chinese ones have balls with one less bump - they're triangular. I also think they're made from pig iron.

 

 

 

[GoLefty!!]

the road and mountain BB have different width bearings.

I think the road is the wider cup and the mountain is the narrower.

 

Saint also uses a wider bearing than the rest of the MTB kit.

 

I could have it the wrong way, since going BB30 I've not had a need to replace bearings.

[_im_from_earth]

We are now supplying X-Type upgrade kits for Shimano, FSA, RaceFace and Truvativ/ SRAM. SRP is only R165.00 on these puppies and  it includes everything needed to rebuild your BB, only snag is you need to correct tool in order to do the job without bush mechanics

 

http://www.rushsports.co.za/Product/?product=87

 

^^ store is not quite up and running yet but we should be live by April fools!

 

I also have those pesky press-fit and BB30 bearings... Sorry, sales pitch over

[Johan Bornman]

Regarding Morewood's post above.

 

I've now tried these bearings and I think the future for brand new BBs from OEM suppliers is dim. At R160-odd (plus some labour for fitting), I cannot see why anyone would buy a brands new BB adapter set ever again.

 

There are several problems in replacing bearings in these cups as per the original (and very much needed) description by Dirt Rider. One of the problems is that the stock 6805 bearings you and I can source are 7mm thick whereas the Shimano ones are 6mm thick, in spite of sharing the same code. This is obviously a red herring trick by Shimano and others to put us off the trail.

 

Another problem is the fragile plastic insert and seal. Damage this and you are back to getting new bearings.

 

Now with these kits things have changed. Firstly, the bearings are 7mm thick but the seal accommodates that. Secondly, the nylon insert is no longer needed as these bearings fit direclty onto the shimano crank spindle. Press-fit like Campag and BB-30.

Thirdly, you  buy a kit of two, but you only need to use one at a time - the left one usually goes first. So, only replace the left one and keep the other bearing for next time.

 

Morewoodkid suggests you need the special press. I have one and it makes the job easy. However, the way Dirt Rider describes is still good. You can replace the bearing the McGyver way, no problems.

 

I suggest you guys keep a spare set of cups that gets overhauled and waiting for the next service when you simply swap cups. That way you keep on recyling the spare set.

 

I've purchased a quantity of these and now have a use for the press I originally bought for replacing the supposedly standard 6805 bearings. If anyone wants to send me an old set of cups for refurbishment, you know where to get hold of me. Otherwise, purchas the bearings from the Rush Sports website and DIY away.

 

Next time I do one of these, I'll take some photos.

[wac1]

Just for my 2 cents . Can the cups not be machined 1mm deeper to comadate the thicker bearings that we can source in this country . I have neve seen a bb cup so I do not know how much material there is to machine off . Any machine shop should be able to square the cup in a lathe and skim 1mm of off the inside . I have a small engineering shop and would love to see if it can be done .

 

Thanks

[steelhearted]

You can also take a look at Enduro bearings. They supply replacement bearings for shimano as well as truvativ bb's (including the non-drive shim for truvativ)

 

You do need the special tool to remove and fit the bearings and the shim.

 

I have the contact details for the guy who does this in the gauteng area. He is a wholesaler so you can do it through your local shop.

[Weight Weenie]

Johan have you managed to take some pics of the x-type kit fitting process yet, I need to get that BB of mine sorted

[Brighter-Lights]

Enduro is the way to go... and cheap too...

[stewie911]

I assume I can do the same on my truvativ gxp road bb?

 

What bearings would I need?

 

I'm not looking for the cheapest option, rather the most reliable/smooth/whatever solution

[The Drongo]

<P>oops i guess you just voided the warrantee.</P>

 

<DIV> </DIV>

 

<DIV>i think we should have a "Tech to keep" then we can move these there, and not clutter up the first page with stickys</DIV>

 

<DIV> </DIV>

 

<DIV>erm, not related, does anyone know where i can get el- cheapo bevel gears? just to play around with</DIV>

 

Nice Signature there lowracer - I miss the street though !

 

Your avatar, along with your request for beveled gears has got me curious!

Who else is curious?

 

Care to share if it is not something that is going to make you rich?