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70mm 36x24tpi Bottom Bracket Fun!

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70mm 36x24tpi Bottom Bracket Fun!

Old 08-08-15, 11:13 PM
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70mm 36x24tpi Bottom Bracket Fun!

Hey all,

Picked up a Benotto frame recently- sanded it down, painted, replaced the decals, and clear coated it. The old bottom bracket was a 36x24 so I bought a shimano UN55 with the proper specs. Only problem is- this bike has a left & right cup thread, not two right threads like a true Italian thread. Are there any products that can help? I've put a ton of work into this bike and do not want to scrap it. Help!!
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Old 08-08-15, 11:53 PM
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Think this might work for you...Go to Velo Orange and check out their Grand Cru Threadless Bottom Bracket. They also offer an Italian BB as well.
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Old 08-09-15, 05:52 AM
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I suspect your frame is not Italian thread. Many Benottos were made in Mexico and may have English thread bottom brackets. I'm not aware of any bicycle that uses a 36mm x 24tpi left hand thread bottom bracket, nor any commercially available bottom brackets with that thread.

Can you thread your Italian bottom bracket into the non-drive side (right hand thread) bottom bracket shell? Have you tried English thread cups in either side? An Italian thread shell is enough wider diameter that an English thread cup will drop in without engaging any threads.

Perhaps the threads have paint in them and just need chasing?

Last edited by JohnDThompson; 08-09-15 at 05:55 AM.
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Old 08-09-15, 10:24 AM
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I checked into Velo Orange- they state that their bottom brackets will not accommodate a 70mm shell.

i also cleaned out the shell threads- the right hand 36x24tpi fits perfectly, the other side is indeed left hand thread so I can't check. The old bottom bracket (open ball bearing style) also stated that it was a 36x24tpi. I have not tried the English cups- I may have to go to a bike store and give that a try. I have a feeling this thing is Benotto specific- somewhere around the time that the threads became more standardized
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Old 08-09-15, 10:43 AM
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I wonder how long it would take to face down to 68 mm ?!?!
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Old 08-09-15, 06:07 PM
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Originally Posted by In_technicolor
i also cleaned out the shell threads- the right hand 36x24tpi fits perfectly, the other side is indeed left hand thread so I can't check.
How, exactly, do you know that the other side is left hand thread? It seems you have the original cups; how are they marked for thread? Is the "right hand 36x24tpi [that] fits perfectly" the drive side (fixed cup side) of the shell, and the presumed left-hand thread side the non-drive (adjustable cup) side? If so, this would be precisely backwards for what the left hand thread on English and Swiss bottom brackets is supposed to accomplish: prevent precessional loosening of the cup. There's either something seriously messed up about your frame, or it isn't actually what you have described here.
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Old 08-09-15, 08:47 PM
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Johndthompson: you are right- drive side is left hand thread, non drive side is right hand thread. Got them mixed up. The old bracket cap says 36x24t Japan si on it
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Old 08-10-15, 07:04 AM
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Originally Posted by In_technicolor
you are right- drive side is left hand thread, non drive side is right hand thread. Got them mixed up. The old bracket cap says 36x24t Japan si on it
Is this the fixed cup or the adjustable cup? AFAIK, there is no commercially available left-hand thread fixed cup with 36mm x 24tpi thread, nor any commercially available tooling for a shop to prep such a frame.

Now, does the 36 x 24tpi cup you have fit into the non-drive (right-hand thread) side, or the drive side (left-hand thread) side? For the side in which the 36 x 24tpi cup does not fit, does an English thread cup (left or right hand thread) fit? I suppose it's possible that ypur frame was originally English thread, and one side got stripped and was re-tapped to larger Italian thread, while leaving the other side English thread. That's an ugly cobble-job I wouldn't send out, but anything'as possible in the big, bad world.
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Old 08-10-15, 08:13 AM
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This is getting confusing! The cup on an Italian thread bracket that I have fits the non drive side- the drive side is reverse(left hand thread) but I cannot confirm the size on that side. It seems funky, but does not seem to have been re-threaded. Looks like filing down and using a thread less BB may be my only option
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Old 08-10-15, 01:24 PM
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Any chance you can take it to a bike shop and have them run a set of Italian taps through just to clean things up? The chances of the non-drive side being a 36 x 24tpi left-hand thread are so vanishingly small that I continue to doubt that this is what you have.
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Old 08-10-15, 01:30 PM
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Its not an owned since new frame I guess, so past owner may have 'screwed-the-pooch' and had the NDS tapped out to Italian,

but the Fixed cup was not changed .. its British LH thd.

swear someone in past months posted having the same problem , there 2 of you?
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Old 08-10-15, 04:55 PM
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I'll check it out and let you know. Ordered a Velo orange threadless and got a hold of a friend who's a welder to take it down a hair on each side with his tools. This is the first time I've posted this- so there must be some other unlucky person out there.
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Old 08-10-15, 08:46 PM
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Originally Posted by JohnDThompson
Is this the fixed cup or the adjustable cup? AFAIK, there is no commercially available left-hand thread fixed cup with 36mm x 24tpi thread, nor any commercially available tooling for a shop to prep such a frame.
I'm 90% certain that 36mm x 24tpi BB threading with left-threaded fixed cup is known as "Swiss" threading. Anyone got an old Sutherland's manual they can look at?

These IRD "cups" say they come in Swiss threading. I would double-check that, also: Italian, French and Swiss Bottom Bracket Conversion Cups ? Interloc Racing Design / IRD
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Old 08-11-15, 06:36 AM
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Originally Posted by Jeff Wills
I'm 90% certain that 36mm x 24tpi BB threading with left-threaded fixed cup is known as "Swiss" threading. Anyone got an old Sutherland's manual they can look at?
No, Swiss is 35mm x 1mm with left hand thread fixed cup:

https://www.sheldonbrown.com/cribshee...mbrackets.html

Last edited by JohnDThompson; 08-11-15 at 06:40 AM.
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Old 08-11-15, 09:24 PM
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Originally Posted by JohnDThompson
No, Swiss is 35mm x 1mm with left hand thread fixed cup:

Sheldon Brown's Bicycle Bicycle Bottom Bracket Crib Sheet
Darn... I'm sure I've seen "Italian" left-thread fixed cups. Frames made in Argentina? It was something truly bizarre.
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