clunking noise from bottom bracket

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nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

clunking noise from bottom bracket

Postby nottscycle019 » 16 Jul 2017, 3:54pm

Hi, please can you help, when peddling hard on my mountain bike I get a clunking from my bottom bracket. Does anyone know what could be wrong. Thanks.

Brucey
Posts: 35850
Joined: 4 Jan 2012, 6:25pm

Re: clunking noise from bottom bracket

Postby Brucey » 16 Jul 2017, 5:42pm

the detail will vary with the type of cranks and bottom bracket bearings you have, but in essence something is wrong; the usual suspects are

- the bottom bracket bearings have slack in them. Some are adjustable, some are not and will need to be replaced if they have slack in them. Or

- the bottom bracket is loose in the frame. This should be attended to PDQ as if it is neglected in this state, the frame can be damaged, or

- the cranks are loose where they attach to the BB spindle. Again parts may be damaged.

So wiggle everything about and see which parts actually move. Often the BB bearings are loose where they fit into the BB shell and if this is on the RH side it is difficult to see the movement.

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

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 16 Jul 2017, 6:12pm

Thanks, will have a look.

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 22 Jul 2017, 11:47am

Hi All, decided to change bottom bracket (shimano). I have managed to get both sides of chain set off and the right hand side bottom bracket retaining nut off. I am really struggling to get left side off. Any tips??? I have just left it with plenty of a well known lubricant on. Thanks,

Brucey
Posts: 35850
Joined: 4 Jan 2012, 6:25pm

Re: clunking noise from bottom bracket

Postby Brucey » 22 Jul 2017, 12:03pm

a picture of what you are up against would be useful.

BTW apologies if this is obvious but the BB threading is LEFT HANDED on the drive side and RIGHT HANDED on the non-drive side. If you don't know this and you are working upside down, this might perhaps explain the 'can't get the LH side out' comment.

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

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 22 Jul 2017, 12:49pm

Hi thanks I am managing to move it a bit, few mm at a time. I did look on YouTube before starting. And yes one side is LH And one RH. Going to perceivire might take me while but I think leaving it soaking in penetrating oil for a bit may help. Thanks for the advice so far.

tim_f
Posts: 245
Joined: 12 Oct 2009, 10:37pm

Re: clunking noise from bottom bracket

Postby tim_f » 22 Jul 2017, 2:48pm

If you do not have a bench vice, often helps to get friend to hold bike up against fence (or similar) then can apply a lot of force to spanner. (if bracket has hole through may be able to use quick release axel to hold tool on splines.

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 23 Jul 2017, 3:43pm

Hi Everyone, good news, it's took me all weekend on and off, but I have finally taken my well knackered bottom bracket off.

Most of the label has some off or is damaged from rust but I think it is BB 7420. Does anyone know what size I need to purchase and is there a better quality one??? :D :D :D

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 23 Jul 2017, 4:33pm

Hi Everyone, just measured to make sure of size, it is 110.5 x 68mm, please help with recommended replacement.

Thanks again for all of you're help and advice.

tim_f
Posts: 245
Joined: 12 Oct 2009, 10:37pm

Re: clunking noise from bottom bracket

Postby tim_f » 23 Jul 2017, 5:12pm

If it is a square tapper one then a shimanio UN55

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 23 Jul 2017, 5:21pm

Hi Tim, Thank you, Evans have two brands UN55 & Karyotype JIS. Is one better than the other? Thanks again, Martin

tim_f
Posts: 245
Joined: 12 Oct 2009, 10:37pm

Re: clunking noise from bottom bracket

Postby tim_f » 23 Jul 2017, 6:14pm

Karyotype JIS is more expensive but lighter. No experience of it.

The UN55 can be had for about 15.00 GBP mail order. (Evans may price match)

The UN55 lasts for ages and is well sealed. So I would go for a UN55.

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 23 Jul 2017, 6:27pm

Hi Tim, thanks, I think I'll go with the UN55. Thank youagain to everyone that has given advice. I'll let you know how I get on with the installation. Martin

tim_f
Posts: 245
Joined: 12 Oct 2009, 10:37pm

Re: clunking noise from bottom bracket

Postby tim_f » 23 Jul 2017, 7:13pm

Remember to use grease or anti cease on the threads, and take care not to cross the threads.

nottscycle019
Posts: 9
Joined: 16 Jul 2017, 3:45pm

Re: clunking noise from bottom bracket

Postby nottscycle019 » 29 Jul 2017, 1:37pm

Hi Everyone,

I have just finished installing my new shimano bottom braket, which was easier than taking the old one off. I also cleaned and tightened my chain ring before reassembling it. The videos on YouTube are great for someone that's never done this before. All in with replacing my front tyre and giving my brakes a service it took around an hour. Many thanks for your help and advice. ( I did use copper anti lock grease) :D :D :D