Media

I have a Shimano UN72 that I am having trouble with. I can't figure out how the threaded retaining ring comes off the right side. I know unlike other Shimano BBs it can be removed, hell, it's why I bought the thing. I have tired a few simple things, but I wanted to post before I busted out the vice. So if you have come across how it is affixed to the casing, please throw me a bone.

Luv ya!

Media

TallRider

I'm not sure what you're asking. All of the UN-7X series of square-taper bottom brackets are the same in my experience, at least where installation is concerned. Drive-side threads in reverse (counter-clockwise), so it will thread out clockwise. The separate retaining cup on the non-drive-side threads in clockwise and out counter-clockwise.
Here's Park Tool's page on servicing cartidge-type bottom brackets, including the UN-72.
https://parktool.com/repair/readhowto.asp?id=94

Media

I guess the question is, How do I remove the "fixed flange" on a shimano UN72? Unlike the other Shimanos, the threading in on a removable cup, rather than on the cartridge itself.


The Fixed Flange is what needs to come off.


As you can see in this picture, the threading is on a removable ring, how do I get that off?

TallRider

Thanks for explaining. I think you're overthinking this though.
The main things you need to know are:
1. as long as you have a 68mm English-threaded bottom bracket (by far the most common) the drive-side threads are reverse-threaded, and the non-drive-side threads are normal.
2. it's not super-important, but you should probably loosen the removable ring first. I'm pretty sure that the UN-72 has the removable ring on the non-drive-side. But you can tell by which side has the raised edge which sits up against the exterior face of the bottom bracket shell. In the pictures you attached (both the diagram and the photo) you can see which is the fixed flange because it has that raised edge.

In the picture you attached, threading is on both the removable ring (L) and the fixed flange (R). The fixed flange is a different color than the center shell, and it is a separate piece of metal, but I'm pretty sure it is fixed to the cartridge itself and doesn't come off.
Even if both rings/cups/flanges are separable from the cartridge unit itself, you'd still remove the BB from the bike the same way.

DannoXYZ 

You insert the proper tool:



Then use a big wrench and spin it clockwise to remove as it's reverse-threaded.

TimJ

Are you saying you want to remove the "fixed flange" from the rest of the BB assembly?

I don't think all un72's are built like that. I have one and the fixed flange is definitely fixed. If yours does not look like that photo you provided, if the fixed side is aluminum and seems to be machined onto the shell, it is cuz that's how they're made. Maybe it was earlier ones that had removable cups on both sides.

Media

I think you still don't undersatnd the question. I admit I have had a hard time explaining what I am trying to do. So let me run down why I am doing this. I am replacing the BB on my Raleigh 3speed. Raleighs do not use as 24 Birtish ISO threading (26tpi for Raleighs), they also have a 71mm long shell, not 68. So what I am trying to do is remove the flange that is an Itailian threading, and replace it with Phil Wood retaining rings (26tpi that are interchangeable with the shimano bb). This is a Sheldon Brown trick, so I am not just winging it. This, and only this BB can be used. Don't worry its a 70mm bb, so it will fit, and I have the tools to bring in the 1mm extra shell space. So on the UN72 BB, how is the flange affixed, is a it a smaller threading, or is it somthing else?

https://sheldonbrown.com/raleigh26.html is the link for what I am trying to do.

I hope I cleared up what I am trying to do.

Thanks again.

Media

https://sheldonbrown.com/raleigh26.html

Yeah, mine is exactly like the picture. I threw that link up so you could see what I am trying to do. I need to remove the flange form the cartridge to replace it with the correctly threaded rings. I made sure that for sure that I had the correct bb to do this.

Thanks for reading, and responding.

TimJ

I'd try tapping the bottom carefully with a screwdriver or something to see if it budges.

Poguemahone

I've done this, and I just knocked the cup off with the above method. Not hard. Phil rings do work with 'em.

HillRider

I've had the older UN72 bb you are describing and the "fixed cup" is indeed a separate item from the cartridge body but it's a fairly tight press fit with a sealent in between to keep it from clicking and making noise. I never separated one but it should be fairly easy to do by supporting the cup's edges in a vise and tapping on the drive-side spindle end with a mallet.

What everyone else seems to be describing is the new Shimano UN-7X or UN-5X design where the cartridge body is one piece and threaded on the drive-side.

ParaWK4

It's a press fit. I knocked one off using two wrenches, one secured in a vice with the thinner middle section of the BB in this wrench. The other an adjustable wrench loosely tightened on the threads and against the shoulder of the ring. Bang on the adjustable wrench with a hammer and it will come off. Not a proper way to treat an adjustable wrench I know. I would not bang on the spindle as I would think all that force is going onto the bearings.

griftereck

Oh its the old Phil Wood cups in a Raleigh tale.

I always say you should recut the bottom bracket.
Ive done this at home with no special tools
or at work with a BB cutting tool

If its a 20 your modding...it would cost £10 to do that...on a maintenance plan.
So any maintenance would be covered under that too.

Where as the cups are at least £40...then your stuck with the BB you can find.
Recut it and you can fit any modern English thread BB

So you could even fit external bearing BBs

totes

Sorry to resurrect a dead thread, but I'm having problems with my UN72 cups too, and figured I'd ask my question here instead of making a new thread.

I bought a UN72 bb off of ebay after reading that both cups could be removed and that Phil Wood's french retaining cups would fit. Now the non-drive side cup (cup with the shoulder) came already removed, and from what I've been reading that's the cup that you need a vice to remove. So should I just be able to remove the remaining cup with a bottom bracket tool or what?

arborohs

https://house-of-yes.com/phil-wood-y-bottom-bracket/

dobber

Nota bene:

in situ

Secundum nota bene

post fabricatum

What the ****?

arborohs

what part don't you understand?

dobber

A well written article otherwise marred by the pretentious use of faux latin.

lymbzero

I remember going to the bike shop and asking for a UN-72 BB.
The BB was for my Bianchi which had Italian threads.
The shop owner told me that he had some but these specific ones were hard to find.

I believe the old UN72 (now discontinued) came in different threading and lengths, maybe even dual sided removable cups.

The later UN71 or UN73 are a different design from the old UN72's
It seems to me you might have purchased a newer UN7X BB.
This design of the newer UN series BB's, from my experience, only has one removable ring and a "fixed" cup.

Do post your solution, I am curious...

edit: I just read the Sheldon Brown site, and it does state exactly what I had mentioned above.

due ruote 

How would one change 26tpi to 24tpi with no special tools?

Squeazel

One trick is to use a dremel tool to grind a few narrow slots into the threads of an old pair of 24 TPI cups (making sure the forward face of the slot is at a slight overhang) to make thread cutters. Cups are much harder steel than any BB shell, and should work for a few re-threading jobs if you use alot of oil and do it slowly. Stick a bolt through the hole in the cup to hold it. The tool will align itself pretty well since the first three threads of a 24TPI cup are a pretty good fit into a 26TPI BB shell.

due ruote 

Thanks; that's pretty much what I expected. Although a modified set of cups would constitute a special tool in my book, albeit a home-made one. I have a feeling I'll be attempting this one day, but hopefully not for a long while.

Media

https://www.sheldonbrown.com/raleigh26.html

You are going to have to order a set of rings from phil wood that fit. and then get the un-72 BB. It is going to be a pain in the butt, but you will get it to work with just a wrench and some time.

Sixty Fiver

You need special tools as the bb shell has to be re-tapped and taps are too expensive for the average DIY'r.

I used a 73 mm cartridge after I re-tapped the bb on my Twenty and the conversion is splendid.

I work in a bike shop so have access to bb taps.

Media

I honestly just held it with my hand and used a screwdriver with a hammer. I came off really easy with a few taps.