Baggins2012

I have 86 Schwinn Sierra. Has traditional ball bearing BB. I have already cleaned and re greased a couple of times in the past, and thought a sealed bracket would be the way to go this time. Figured I'd update to Shimano BB 55 Got the 68 - 122 with english thread, 1.37 X 24.

I attempt install what I believe to be the drive side As you look the the large bracket piece with the spindles On this center of the bracket, there is a sticker that says "L<- D-NL -> R" then the the cup is to the right of the sticker, closest to the R. I tried to insert this into the right/ drive side of the bike. I know its reverse thread. I really do know its reverse thread.

I just CANNOT get it on. Get a few threads in and just wont go. Tried quite a few starts and re starts. Finally, I just cleaned out the old bottom bracket, re greased and put it back on. No problem of course. The original spun back on with no issue.

I have done the same BB swap operation on my 81 Le Tour with no problem, so I dont think its me.

So, either the 1986 Schwinn Sierra has Italian Threads (I see this as VERY unlikley)

OR

the bracket threads are defective?
the bracket is mislabeled as to which is the drive side, and the little cup goes on the drive side and the big piece goes on the non drive side.
I mis-interpreted which is the drive side of the bracket. I do find the D - NL do be confusing, as the D is on the left side.\


Ok, any ideas?

bradtx

Baggins2012, The "L<- D-NL -> R" is unknown to me. As far as I can recall, all of my Shimano cartridge BBs have the length of the spindle between the L and R.

Brad

ThermionicScott 

"D-NL" is Shimano's code for the 123mm length. They also use "D-H" for the 115mm, "D-EL" for the 127mm, and are prone to throwing extra letters into the others, like "MM110" and "XL118". Don't ask me why.

@Baggins2012, since there's a slight taper to the cups, it's really important to get them on straight. I generally start by spinning mine backward until I feel the threads line up. After that, it's normal to feel a little resistance -- I suspect the threads on these aluminum cups are cut in a way to make the fit tighter since they will wear faster than their steel counterparts, even during the first installation.

RoadGuy

I haven't replaced a Shimano sealed bearing cartridge in a while. But, from what I remember, the Non-Adjustable cup with the flange on it (that doesn't come off the bottom bracket) is the drive side. The cup that comes off the bottom bracket that does not have a flange is the Non-Driveside cup.

Grease the threads of the Non-Adjustable Driveside cup and screw it in until the flange is tight against the frame. Use a torque wrench to tighten to the Manufacturer's spec. Then, grease the treads of the Non-Driveside cup, and grease the inside of the Non-driveside cup. Screw the Non-driveside cup in until it bottoms on the bottom bracket, and use the torque wrench to tighten to spec.

JohnDThompson 

No. Not Italian thread. Italian thread has a wider diameter than English, so you wouldn't get any thread engagement -- it would just drop in.

I suspect you're just a victim of variation in manufacturing tolerances. Chasing the threads in the BB shell would likely help.

Homebrew01

Just look at the cup threads to see which is right or left.

Baggins2012

Well you've definitively answered my question about that code, and confirmed that the one should follow the > R, which means the large piece with the spindle goes into the drive side. What a goofy way for Shimano to code the size. The "D" in the code could confuse. I did use the "R" as my guide.

As for the install, it wasnt a little resistance, and it was a LOT, I forced it a bit, with a 12 inch crescent wrench on the BB tool but gave up after a bit to avoid damaging my bike. I started and restarted 3 or 4 times tho.

My original steel cups spun right back on. Since I ride the bike in on dry, dusty dirt 2-3x per week, tho, it would be nice to have a sealed cartridge, the original cups gummed up within 4 months after my last re-grease.

I found that if I screw the orignal cups in as tight as i can , the spindle wont move. So I have to adjsut the cups much like the cups on wheel hub. Juuuust tight enought to avoid play, but not so tight as to bind. I assume this is correct?

Bill Kapaun

Maybe that's why they call the NDS cup the "adjustable cup"?

bradtx

Thanks for the info!

You might consider having the BB threads chased.

Brad

Baggins2012

Since my original steel ones go on pretty easily, kinda wonder if the problem is with the BB I got. I'd probably try another one before I did anything to the bike.

SquidPuppet

That is very possible since the threads are so fine. You may not even be able to see the defect.

I recently had a threaded fork that would not allow the top race to go all the way down to the bearing. It would just STOP abruptly. I pulled the fork out to closely inspect the threads. I could not see any damage. No burrs, no squished or rounded peaks, no junk in the valleys. Looked fine. I took it to the LBS and after three minutes and five dollars for a nice oily chasing and it was perfect.

Homebrew01

I got some squishy foam for my square taper BB and cut out little foam doughnuts that slip of the BB axle before installing the cranks. They make great seals.

Baggins2012

So you fully install teh BB then add the foam then cranks? Does it move your cranks out a material amount?

bikeman715

Most of the lower Shimano sealed BB go into the BB reveres . Where the lip go on the non drive side and the plastic cup go into the drive side . Look at the sealed unit and compare the treads to your old cups .

ThermionicScott 

That is NOT correct.

bikeman715

Yes it is , I have Done a few in my day and know what I am Talking About . If the person read the info . sleet that come with the BB they would see that .

Homebrew01

Yes
The foam is thin and goes between the cranks and the cups. Foam will not affect the crankarms.

ThermionicScott 

Anyone reading the data sheet included with a UN26 or UN54/55 (like the OP) will see that you are spouting bull****. The cup that is permanently attached to the cartridge ALWAYS goes into the drive side for UN26/UN54/55 and up. Which ones are you talking about? Let's see data sheets.

UN26: https://www.shimano-benelux.com/media...9830694234.pdf

UN55: https://si.shimano.com/php/download.p...-UN55-3281.pdf

bikeman715

Try the LN series . For whatever reason Shimano LN are reverse from the UN .

ThermionicScott 

Bottom brackets with "LN" in the part name are Tange branded and out of the scope of this thread. Even so, they look like they'd install the same: wellcome to Tange seiki

Bezalel

Although I've never seen one, according to Park Tool they exist. Park Tool Co. » ParkTool Blog » Cartridge Bearing Type Bottom Bracket Service

ThermionicScott 

Interesting. I wonder if that was an abandoned early version of the cartridge type BB, included for completeness. I've never seen one either, and this page offers more confirmation (if any should be needed) as to which end goes where if "L" and "R" are marked.

If anyone can find datasheets for these reversed-style BBs, I'd be interested to see them.

AnkleWork

I've installed or removed a few of these -- not too rare. Oddly, you can completely rebuild some of that type with ordinary tools.

bikeman715

They still being made and found on lower price bikes , the ones you see around the $ 400 .00 mark . And can be brought from QBP for replacement . Yes Tange Brand was /is one of them as others .

dr1445

i start the non drive threaded collar in first to support the body of the bb inserted from the drive side. as stated before turn the bb backwards till the tread falls in. on rare occasions i have had to take a needle file to clean up the bb leade threads.