msl109

Hi folks - I have what's close to a NOS Suntour / Kajita bottom bracket I was intending to use with a Sugino AT triple (not an easy crank to find a BB for, and the adjustability of this makes it ideal) - - until, upon disassembling it to refresh the grease, I discovered the drive side bearing has a crack in the bearing housing. Looking for some advice on possibly replacing the bearing - how I might pull it, type of bearing puller necessary... I haven't much experience with sealed units like this - I usually am dealing with cup and cone systems, so please assume I know nothing about how to pull it or install a new one. Any advice / tips appreciated. I don't mind the work and would prefer to stick with this unit.
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Crack from side

With dust shield removed

Side view

Assembled - just for identification purposes

philpeugeot 

Aside from the asinine proprietary cup pattern, these are pretty nice bottom brackets. The bearings, I believe, just slide on and are stopped by a circlip. If they're stuck, it may just be some old grease gummed up in there; maybe a squirt of WD-40 should loosen up that grease and you can pull the bearing out. If that doesn't work, I would lightly tap the spindle with a hammer while supporting the bearing, that my free it up.

Stolen photo from an eBay ad. There should be nothing preventing the removal of the bearing, really. Probably just needs some gentle coaxing.

dddd

Identify the bearing from the text on the seal, then remove the outer race using force/prying to open the crack.
Remove the ball retainer and blast the inner race with a pencil-tip propane torch which will expand it probably within ten seconds so it will slide off.
Maybe first put the other end of the spindle in the vise, I think it will best grab the rounded corners better than the tapered flats.

The new bearing should be driven on so as to fully compress the load path between the two inner races, not the outer races.
Warming up the new bearing will ease the fit onto the spindle so the inner race meets the circlip.

What is the length of the VX bb spindle? I recall these were spec'd as OEM with the AT cranks on some Cannondale touring bikes.

msl109

Thanks!
I'm getting 126 mm on my digital caliper. I think the Sugino cup and cone original to the AT was 127, assymetrical. I sized the VX up with the crank and frame without fully installing it and it looks like it would work. So you're saying pry off the outer race, destroying it, and remove the balls and retainer, then heat up the inner race so it should pull right off. Guess I'll have to get a pencil tip propane torch. Any chance a soldering iron with a flattened tip would do the trick? Not 100% clear what you mean by using the vice on the rounded tips of the spindle taper - I want to be careful not to bugger up the taper.
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msl109

Just caught this reply - that sounds a lot easier than heating up the bearing after destroying the outer race. I'm sure this is simple and I'm just oblivious to it, but how do I get the center dust shield out of the way to get behind the bearing? You're saying with some wd40 the whole assembly should pull apart?

msl109

Ok, so I managed to pull it apart. I'll remove the circlip and see if I can tap it off with some WD

40.

msl109

Bearing is an IKS 6903 RSP. Can't find an exact match with the RSP suffix but it seems all the 6903s are dimensionally the same. Opportunity for an upgrade, I suppose. Just not sure what's most appropriate for a bottom bracket application. There are ceramics, roller bearings...

Reads 6903RSP

msl109

Anyone know what the RSP means?

Pompiere

They don't address RSP specifically, but it has do do with the seal. The 6903 refers to the bearing size. https://www.pinkbike.com/news/To-the...ings-2013.html

1simplexnut

after a hundred years of working in the industrial bearing industry(not quite) my guess is it means Rubber Seal P??
Is the P possibly a damaged R ?
RSR is standard bearing seal designation for japanese etc bearings .
6903 is a pretty standard industrial size deep groove ball bearing .

msl109

​​​​​​Appreciate your reply - It looks the same on both sides, and I looked pretty carefully - the bottom bracket had next to no use, so I doubt both sides would have a damaged B. But it is a single seal, not a double, which I understand would be designated 2RB.

Any suggestions for replacement? Looks like Enduro has some good options, SKB look a bit pricey. Would roller bearings be appropriate, maybe less likely to develop wear over time? I confess to a shamefully limited knowledge of bearing technology and applications.
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msl109

That's helpful, thanks - the RSB suffix is still a mystery, but it's a single seal, so I'm going to look to upgrade to a double anyway.

1simplexnut

Hi yep - RSR (or similar) relates to one side sealed . 2RSR = both sides of bearing sealed .
The P may reference the rubber material of seal ?
Some manufacturers used different material for different applications .

You would struggle to get a roller bering that size with seals .
Stick with the existing bearing type . .
NSK or NTN were good brands BITD . They also both do a good full contact seal that would be good for a BB
Suffix for the contact seals is LLU (NTN) or DDU(NSK)
SKF also manufacture that series . Their numbering is slightly different . They will call it a 61903-2RSR .

msl109

Thanks - very helpful, I'll look into what's available.

1simplexnut

ah ! RS = rubber seal one side
P = PLAIN one side only sealed ?

Why leave the inner seal out ? Not like you can grease it without taking it apart
Agree you should put a double sealed one in .

msl109

I think you've got it. It does indeed look like it's single sided - can't think of a reason they'd do that deliberately. I suppose in 1983 it was a big deal to have any seals.

DiegoFrogs

They probably did it for cost savings. A few extra bucks doesn't seem like a big deal on your example when you'll install it and get another 30 years out of it, but they probably had cost pressure across mass manufacturing scale.

Yesterday I replaced the original serpentine belt in my 12 year old car. The best price I could find on the OEM part was $13. I opted for the premium one that was $35, which was _almost_ the most expensive one I could find. There was a small discount over the most expensive one.

If I'm going to bruise and dirty my arms, I might as well put something in that'll last until it goes to the junk yard. Still whines like an SOB, though, so now I have to figure out where the next component replacement is...

msl109

I feel your pain.

dddd

The inner seal wouldn't do anything useful since the shell of the cartridge keeps that side completely enclosed.

An inner seal only adds drag, weight and cost, however slight.

msl109

But the shell of the cartridge isn't sealed, and a rainshower or two is all you need to start water seeping down the seat tube, no? It's why so many bottom brackets are coated with rust and why BB shells are often drilled out.

machinist42

No.

When the cups are seated against the O-rings on the shell of the unit, there is no way for water to enter from "inside" the frame.

(Have a few of these and favour them. They are unsung inexpensive alternatives to what is essentially the same Phil option.)

msl109

Got you. That makes sense. So there's really no need for a double seal. The O rings seem soft and in good shape. The unit is really well done, and I'd agree, more or less on par with Phil for a fraction of the cost.

dddd

I'd guess that Suntour had these made by Sugino.

msl109

I believe it was Kajita, actually. Sugino made many (all?) of their cranks and probably a lot of their BB's, but this unit is identical for the most part to sealed Kajita units called "Runner" and Runner Pro (which had a hollow axle) I'll clip a pic if I can find one.

msl109

I had mistitled the post, it's Kajita, not Takagi. Will try to get it changed. Here's a pic of the standard Kajita, lifted from an online ad. Suntour apparently had custom specs for theirs, PARTICULARLY the proprietary notches for which they sold a specialized tool - and now we must improvise.. .