A square taper bottom bracket for a lifetime?

[SimonCelsa]

Here we go, in a similar vein to the earlier thread entitled 'A Hollowtech bottom bracket for a lifetime?'
Well, a bit cheaper maybe.

Thanks to good ole RJ the bike guy;

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

[cycle tramp]

Nice - thanks for posting that it's deeply appreciated, and something I'm going to try when the time comes.

As older forum members may remember Brucey was very keen on punching a whole in the sleeve of the bottom bracket to allow more fresh grease to be injected into the bottom bracket... and did so once a year -I guess if you drilled a hole (and removed all the swarf) part way through the bottom bracket's reconstruction and only used bearings which were shielded on one side.. you could take your reconstructed bottom bearing out of the frame once a year for an injection of fresh grease, things making it last even longer.

[TheBomber]

I’d watched that but don’t recall seeing the threaded nut on any of my UN-52/UN-72 units. Not that I’ve been out to check yet.

[fastpedaller]

Nice - thanks for posting that it's deeply appreciated, and something I'm going to try when the time comes.

As older forum members may remember Brucey was very keen on punching a whole in the sleeve of the bottom bracket to allow more fresh grease to be injected into the bottom bracket... and did so once a year -I guess if you drilled a hole (and removed all the swarf) part way through the bottom bracket's reconstruction and only used bearings which were shielded on one side.. you could take your reconstructed bottom bearing out of the frame once a year for an injection of fresh grease, things making it last even longer.

Good advice (as always) from Brucey. Lubrication seems to be the key to long bearing life.
I wonder if carefully cutting away the aluminium sleeve from a new unit and removing the sleeve would be a good move? This doesn't compromise the structural integrity of this type of cartridge. Doing this would give good access to the inner seals of the bearings so the seals may be removed to allow good greasing. I shy away from removing the outer seals as I don't have Brucey skills. Assuming there is no ingress of dirt or water through the seat tube this shouldn't present a problem - (no drilled /lightened bb shells allowed ). A smear of grease on the outer seals (or better still, a grease-soaked disc of felt?) should minimise any water/grit from entering via the external seals.
The other issue with this type of unit is that it relies on an accurate width tolerance - if tightening the cups in the frame preloads the bearings they may meet an early demise. This can sometimes be detected as a slight resistance if turning the spindle after final tightening, Using a 73mm unit in a 68mm shell and fitting a lockring to the adjustable cup (ala old, lose-ball type unit) may be the way of eliminating this danger? - although it may be imperative to put some bearing retainer between the left cup and the bearing to prevent the bearing spinning in the cup.

[rjb]

The shell of most sealed bottom brackets is hardened so almost impossible to drill hence the use of an angle grinder to partially cut through before using a punch. This limits any swarf getting into the bearings. If you want to try this it might be sensible to mark the drive side cup so you make the hole in the sleeve at the top.

[Pneumant]

If you purchase a Shimano UN style clone BB with the aluminium centre sleeve then it is possible to regrease the bearings.
Like this >>https://www.ebay.co.uk/itm/154702222039 ... BM0oa177Zh
As with the Shimano BBs it is easy to partly access the non-drive bearing. However if a two arm puller is used then the drive side bearing housing can be pulled away from the bearing. The alloy centre sleeve is then loose and can be removed. Both bearing shields can be removed and the bearings flushed and repacked with decent bearing grease. A rub of Copaslip on the bearing housing faces to stop any corrosion. Reassembly is easier if a vice / G clamp & socket is used to press the drive-side bearing housing back on. Not much force needed and once the bond is broken the job is easier next time. Once a year and the BB is noticeably smoother after being serviced in this way.

[slowster]

Two different designs of cartridge bottom bracket are being mentioned, without noting the difference.

1. UN55 bottom brackets (and I believe the various lower and higher grade alternatives, i.e. UN26, UN72 and UN91) do not use cartridge bearings. Instead the bearings run on the axle and the outer sleeve, which allows the use of larger ball bearings than in a cartridge bearing.

At least some Kinex bottom brackets and the Stronglight JP400 (which I believe is a rebadged Kinex) use the same design.

As noted by 531colin and peetee when they examined a Stronglight JP400 and a UN55, they only have 7 balls per side, which is surprising given their general longevity.

viewtopic.php?p=1615561#p1615561

viewtopic.php?t=153069

The expensive SKF bottom brackets are a superior version of this type of design.

Brucey described the process for creating a hole in the shell here - viewtopic.php?p=608089#p608089

2. UN100 and UN300, which have replaced UN26 and UN55, use the same generic design comprising cartridge bearings and a central sleeve as found now on most other bottom brackets, including generic chinese models.

What R J The Bike Guy does not show in his video above is Brucey's tip of removing the inner seals of the new cartridge bearings before re-assembly, and filling/part-filling the centre sleeve with grease. Brucey also mentions below that with some of these BBs he has been able to push the centre sleeve out of alignment sufficiently to remove inner cartridge seals and add more lubricant without removing the cartridge bearings.

viewtopic.php?p=1550687#p1550687

[zenitb]

Useful post Simon and I like all the references to Brucey's older stuff suggesting greasing the bearings from the inside.

To some extent the consclusions are similar to an earlier one we had on Hollowtech II ("Replacing Hollowtech II Bearings" viewtopic.php?t=79765 ) where it came down to a choice of buying the complete bottom bracket including the "screw in bits" from Shimano or drifiting sealed bearings out and buying the commercial bearings of your choice. I have both types of BB so could try both when the time comes.

Another Brucey tip I have used in the past (on pedals) is adding external "O" rings to improve sealing and next time I take a BB apart I will probably have a look to see if this sort of thing is possible.

[Bice]

Two different designs of cartridge bottom bracket are being mentioned, without noting the difference.

1. UN55 bottom brackets (and I believe the various lower and higher grade alternatives, i.e. UN26, UN72 and UN91) do not use cartridge bearings. Instead the bearings run on the axle and the outer sleeve, which allows the use of larger ball bearings than in a cartridge bearing.

At least some Kinex bottom brackets and the Stronglight JP400 (which I believe is a rebadged Kinex) use the same design.

As noted by 531colin and peetee when they examined a Stronglight JP400 and a UN55, they only have 7 balls per side, which is surprising given their general longevity.

viewtopic.php?p=1615561#p1615561

viewtopic.php?t=153069

The expensive SKF bottom brackets are a superior version of this type of design.

Brucey described the process for creating a hole in the shell here - viewtopic.php?p=608089#p608089

2. UN100 and UN300, which have replaced UN26 and UN55, use the same generic design comprising cartridge bearings and a central sleeve as found now on most other bottom brackets, including generic chinese models.

What R J The Bike Guy does not show in his video above is Brucey's tip of removing the inner seals of the new cartridge bearings before re-assembly, and filling/part-filling the centre sleeve with grease. Brucey also mentions below that with some of these BBs he has been able to push the centre sleeve out of alignment sufficiently to remove inner cartridge seals and add more lubricant without removing the cartridge bearings.

viewtopic.php?p=1550687#p1550687

Fascinating thread. But wouldn't it all just be simpler to stick with a square taper BB that is just a spindle, bearings and the cups? I do hope people keep making them.

[NickJP]

I fitted two Bullseye square taper needle roller bottom brackets to our tandem in 1982. Those BBs are still in place, and last time I disassembled them a couple of years ago, the bearing surfaces were essentially unworn. Given how high the bearing forces on the stoker's BB are with a crossover drive, that's pretty good.

The BBs have a lubricant port on the LH cup, and no internal seals, so I can re-lubricate the entire BB every few months merely by removing the LH crank and the grub screw from the port.

[rogerzilla]

Decent cup-and-cone BBs haven't been made by the big manufacturers for decades. They can work very well and be very long-lasting - as long as you never ride the bike in the wet. Most of them failed due to water ingress and pitted races.

The best cartridge BBs, especially the now-discontinued Shimano unit design, were far better sealed even if the bearings were smaller. The prevalent ST design these days is the axle, two 69032RS bearings, a sleeve and two cups. It is not usually very well sealed and doesn't last long. You can replace the bearing cartridges on most of them but two good quality 69032RS bearings cost about as much as most of these BBs.

[Brucey]

ST BBs with cartridge bearings fall into 2 main categories; those using a 17mm axle and 6903-2RS bearings, and those with a 16mm spindle and 311610-2RS bearings. The former permits a Ti spindle, Al cups etc. and the latter has slightly stronger bearings, so it is very much swings and roundabouts here. Either type of bearing can be rebuilt as a much stronger DFC type, using my recipe (in the 'cheap bearings' thread I think).

[gregoryoftours]

I’d watched that but don’t recall seeing the threaded nut on any of my UN-52/UN-72 units. Not that I’ve been out to check yet.

What threaded nut are you referring to? I didn't see one in the video.

[TheBomber]

I posted that over a year ago so hard to be sure. Watching (some) of that video again I would say that either the link now goes to a different video, or I had mistaken the video at the time for another RJ one that I had just seen where something is unscrewed to disassemble the BB. Either way ‘threaded nut’ is a strange phrase, ‘spanner flats’ or even just ‘a nut’ would have made more sense.

[Brucey]

some BBs are made with octagonal lockrings; is it possible you were thinking of those?