BB lock rings

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Trigger
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BB lock rings

Postby Trigger » 27 Jun 2020, 6:09pm

I'm still trying to fix up this Gazelle that I bought locally, it was only supposed to be a quick job and it has turned into a right pain in the 'arris :roll:

I eventually managed to get the crank off with the stripped thread but both bottom bracket lock rings are seized solid, cheater bars, hammer and cold chisel haven't shifted either of them yet. It's only going in the bin anyway so is destruction my best option? if so what's the best way of doing it without potentially damaging the frame?

gregoryoftours
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Re: BB lock rings

Postby gregoryoftours » 27 Jun 2020, 6:49pm

Photos please

Pneumant
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Re: BB lock rings

Postby Pneumant » 27 Jun 2020, 7:20pm

+1 Pics would help! What make is the BB and what are the cups made out of - steel or aluminium? I would firstly try some heat using a heat gun for a minute or so followed by a blast of penetrating oil. Repeat a few times and try drifting off again. It helps to gently drift the wrong way to start as tightening can be a good way to start loosening if you follow me. If that does not work then carefully 'weaken' the lock rings by cutting/grinding with a hobby tool. Always eye protection when doing stuff like this.

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Trigger
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Re: BB lock rings

Postby Trigger » 27 Jun 2020, 7:43pm

It says Mavic on it, I don't have a picture at the minute. It looks very much like the one below:

http://velobase.com/ViewComponent.aspx? ... &AbsPos=79

Which implies I might be in for some trouble when it eventually comes out as they seem to be the solution to a stripped BB shell. Great.

Pneumant
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Re: BB lock rings

Postby Pneumant » 27 Jun 2020, 8:00pm

That is a Mavic 610, aluminium rings, worth preserving as rebuildable and compatible with 90's Campag. To fit one of these BB's the bottom bracket shell has to be bevelled as the Mavic BB does not rely on the shell threads at all. The bevelling process does not prevent the future use of a std BB and the threads should be OK. Having said that sometimes these units were fitted due to the BB threads being damaged! I think the lockrings have become corroded onto the bare metal of the bevels. Both rings have right handed threads. To loosen try what I suggested upthread.

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Trigger
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Re: BB lock rings

Postby Trigger » 27 Jun 2020, 8:05pm

They're well mangled now so it's scrap anyway. It felt gritty and not very free which is why it was coming out. I don't have a heat gun only a blow torch and I'd rather not use that. I'll have to find a bigger hammer.

I see from the spec it has ISO square taper yet it had a Shimano crank on it...

Pneumant
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Re: BB lock rings

Postby Pneumant » 27 Jun 2020, 8:06pm

Could also be an earlier Mavic 600 (I have one of these somewhere) which does have cups!
Take some pics please........

fastpedaller
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Re: BB lock rings

Postby fastpedaller » 27 Jun 2020, 8:08pm

I had one of these on a steel frame - It had corroded so much I had to cut it out!

Pneumant
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Re: BB lock rings

Postby Pneumant » 27 Jun 2020, 8:09pm

You can use a soldering iron instead - rest the tip on the ring for 15-mins or so.
Yes a Shimano crank will go on too far and be ruined.

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Trigger
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Re: BB lock rings

Postby Trigger » 27 Jun 2020, 8:14pm

Pneumant wrote:Could also be an earlier Mavic 600 (I have one of these somewhere) which does have cups!
Take some pics please........


Definitely not one of them. Like I say, it's identical to the one in the link.

I'll put some plus gas on it and then try again tomorrow.

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Trigger
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Re: BB lock rings

Postby Trigger » 29 Jun 2020, 1:10pm

Bigger hammer got the lock rings off in the end, but the cups are solid. I can get a good grip with a pair of footprints but I don't have a cheater bar big enough to go over the handle so this is the next problem.

Brucey
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Re: BB lock rings

Postby Brucey » 29 Jun 2020, 1:21pm

Trigger wrote:I'm still trying to fix up this Gazelle that I bought locally, it was only supposed to be a quick job and it has turned into a right pain in the 'arris :roll:

I eventually managed to get the crank off with the stripped thread but both bottom bracket lock rings are seized solid, cheater bars, hammer and cold chisel haven't shifted either of them yet. It's only going in the bin anyway so is destruction my best option? if so what's the best way of doing it without potentially damaging the frame?


IIRC provided you can unscrew the adjuster (LHS), the axle and bearings can be drifted out of the assembly in this model Mavic BB. At this stage you can either rebuild using new bearing parts (IIRC if the axle is good you can use parts from cartridge bearings) or you can cut the aluminium housing out of the frame.

Once the lockrings are off the main housing should just slide out of the frame. Too late now of course but IIRC the spindle is cross-drilled and the whole unit can be purged with grease using a grease gun. I would probably have greased it and used it for a while before trying to do anything with it; 'feeling gritty' is perfectly normal for cartridge bearings with the slightest corrosion in them, which might be terminal, but then again might not be, as revealed by further use.

Probably the threads in the frame are banjaxed anyway (which is why the Mavic BB was fitted in the first place; BTW it might be glued in place) so you will have another repair to do...

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

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Trigger
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Re: BB lock rings

Postby Trigger » 29 Jun 2020, 1:34pm

Brucey wrote:
Trigger wrote:I'm still trying to fix up this Gazelle that I bought locally, it was only supposed to be a quick job and it has turned into a right pain in the 'arris :roll:

I eventually managed to get the crank off with the stripped thread but both bottom bracket lock rings are seized solid, cheater bars, hammer and cold chisel haven't shifted either of them yet. It's only going in the bin anyway so is destruction my best option? if so what's the best way of doing it without potentially damaging the frame?


IIRC provided you can unscrew the adjuster (LHS), the axle and bearings can be drifted out of the assembly in this model Mavic BB. At this stage you can either rebuild using new bearing parts (IIRC if the axle is good you can use parts from cartridge bearings) or you can cut the aluminium housing out of the frame.

Once the lockrings are off the main housing should just slide out of the frame. Too late now of course but IIRC the spindle is cross-drilled and the whole unit can be purged with grease using a grease gun. I would probably have greased it and used it for a while before trying to do anything with it; 'feeling gritty' is perfectly normal for cartridge bearings with the slightest corrosion in them, which might be terminal, but then again might not be, as revealed by further use.

Probably the threads in the frame are banjaxed anyway (which is why the Mavic BB was fitted in the first place; BTW it might be glued in place) so you will have another repair to do...

cheers


Well it's an ISO taper and I have Shimano stuff to go on it so wouldn't have been wise to reuse it I think. The lock rings are well dead, straight in the bin.

From what I can see it may just be that they're corroded in as there is a lot of white al oxide coming off when I wire brush the exposed threads, looks like its never been out to me. Can't shift either cup, tried a punch in one of the holes but it is just boring its way through the ally.

I wondered about making some flats on the cups and trying a big spanner?

rjb
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Re: BB lock rings

Postby rjb » 29 Jun 2020, 1:50pm

Hope you have better luck than one i had a go at. This frame eventually went for scrap. Story here viewtopic.php?f=5&t=94465&hilit=dawes+bottom+tool
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D

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Trigger
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Re: BB lock rings

Postby Trigger » 29 Jun 2020, 2:03pm

rjb wrote:Hope you have better luck than one i had a go at. This frame eventually went for scrap. Story here viewtopic.php?f=5&t=94465&hilit=dawes+bottom+tool


Well I'm hoping that because it has been stored well and nothing else on it was seized that I am in with a chance.

Were these types of Mavic BBs fitted just as a regular BB even if the frame threads weren't knacked?