Right bottom bracket - BB question.

[MrMoar]

Hi guys,
First of all sorry if this question will be stupid. And second, sorry - im a noob building my first bike.
I did tried to look for information and googled the stuff out of a google, but there is so many numbers, letters and measurements that confuses me.
My frame BB fitting (shell?) is ITA 36x24f, and i got DA 7700 group. Need a BB.
1. I found that I need 109.5 as my group is 9spd double. Am I right?
2. Any Shimano BB with octalink v1 will do the job (5500, 6500, 7700) yes/no?
3. I found few brackets, but what is the first number in marking - 70(6 - 109.5? 109.5 is the width of the shell, and 68 or 70 is the width of the fitting right?
4. Is there any other measurements I should be aware off?
5. Whats the difference between 36x24f and 36x24t?

 

[stringfellow1946]

You need an Italian BB which has a shell width of 70mm (english BB are 68mm wide)
The Italian BB cups are both right hand thread 36x24 TPI
English BB are Left hand tread for the chain wheel side & right hand thread for the non drive side, 1.370 X24 TPI (BSC) 1.375 x 24 (ISO)
70mm & 68mm refer to the width of the BB shell, 109.5 is the length of the BB axel

IMHO If you have a D/A groupset the fit a D/A BB as they are much better quality & lighter.

Hope That helps

 

[MrMoar]

You need an Italian BB which has a shell width of 70mm (english BB are 68mm wide)
The Italian BB cups are both right hand thread 36x24 TPI
English BB are Left hand tread for the chain wheel side & right hand thread for the non drive side, 1.370 X24 TPI (BSC) 1.375 x 24 (ISO)
70mm & 68mm refer to the width of the BB shell, 109.5 is the length of the BB axel

IMHO If you have a D/A groupset the fit a D/A BB as they are much better quality & lighter.

Hope That helps

Thanks for your reply. But just to confirm, if I'll buy ITA BB any of those will fit my frame or is there is more then one BB with italian thread? Something like width of the bottom bracket?

 

[mattr]

All ITA BBs are the same, no 68/73 confusion.

Just need to get one with a 109.5 axle. And the Octalink V1 spline, so essentially any of the shimano road bottom brackets of that era will work.

 

[MrMoar]

All ITA BBs are the same, no 68/73 confusion.

Just need to get one with a 109.5 axle. And the Octalink V1 spline, so essentially any of the shimano road bottom brackets of that era will work.

Thanks, thats really helpful. "from that era" was the thing that confused me. The current 105 still comes with Octa V1. So hopefully there will be no "era" difference.

Thanks man.

 

[mattr]

Current 105 is actually hollowtech 2, I've got 2 of them.
You probably need a bottom bracket that is 2 (?) generations old. Possibly 3, if the newest 105 has hit the shops yet.

 

[MrMoar]

Current 105 is actually hollowtech 2, I've got 2 of them.
You probably need a bottom bracket that is 2 (?) generations old. Possibly 3, if the newest 105 has hit the shops yet.

Sorry, my bad, wanted to say that there is plenty 5500 in shops, where 6500 and 7700 is out of stock :/

 

[MrMoar]

All ITA BBs are the same, no 68/73 confusion.

Just need to get one with a 109.5 axle. And the Octalink V1 spline, so essentially any of the shimano road bottom brackets of that era will work.

You've been really helpfull. So by any chance you could help me to solve one more headache.

I was trying to fit BB today and one thing happened.
So long story short. The drive side of BB (where threads are non removable) fitted perfectly right to the end. But!
Non drive side cup is where the problem starts. Its to wide (deep)? The shell doesnt have that much thread so the cup stop half way in. As it has almost twice thread then drive side.
Solution 1. I was thinking to cut half of the cup. Unfortunately its not an option cause of rubber sealing inside.
Solution 2. Put few big spacers on the non drive said. Not sure as I heard that both cups should sit at the same distance from the center.
Solution 3. Just sit and cry. That works for now, but not sure how long it will last.
Any ideas?

 

[Wold Ranger]

Re:

What frame is it? The problem is a common one, older Italian frames only needed threads about 5/8th of an inch deep, as BB;s of that day, had much shallower depth cups. I have a nice Benotto, with just this problem (common problem) So it has having the threads cut deeper by my local frame builder, prior to being enamelled.
Are you sure the left cup is not just "sitting", on the BB-if you have inserted the driveside cup with BB all the way home first?
The proper way to mount, is to insert the left side cup first, about three quarters of the way in, make sure the threads are greased with a waterproof quality grease and the inside of the shell. Then insert the right hand side with the BB.
Have you checked the depth of your threads? also, have you cleaned the threads out? I would always use a steel wire or Phosphor bronze brush, to give them a good clean out.
PM me if you want a chat about this, it shouldn't be too difficult to resolve.

 

[mattr]

Yup, you need both cups engaged with the bottom bracket body before you snug up. Or you can wedge the bottom bracket.
But cutting the threads deeper is the right way to do it. Trimming the cup is something you'd really need access to a lathe to do properly (or with any chance of success)