Flippy floppy crank problem

naffa

Hi guys and gals I'm wondering whether the bb needs replacing on a bike ive just bought or is it different being an older bike. Basically the crank moves from side to side and up and down within the bottom bracket. I'm not sure of the age of the bike so heres a pic

nicklouse

yes. sounds like it needs replacing.

delcol

sounds like the bearings are fcuk..

naffa

Are they easy enough to replace?
I fancy having a go myself are there any special tools i'll need?
Are the bearings all the same size?

Thanks Nathan

cooldad

Yes if you have the right tools.
Doubt it's loose bearings, most likely a cartridge BB - they come in different sizes and axle lengths.
You need to work out what's on there and replace with like.
Tools depend on type of BB. Common older are square taper - you need a BB tool and a crank puller.

delcol

yeah you will need special tools.

if it's anything like our kids old diamond back ascent (1992) you will need a crank puller to extract the crank arms
and a bottom bracket tool to remove the bb..

if it's the same type of crank and bb, you will be looking at something like these. (i cant say which size you will need,) he got his from halfords even came with greese.
http://www.halfords.com/webapp/wcs/stor ... yId_210159

cooldad

So you need to work out what sort of BB the bike has. Pic would help.

The Rookie

My old Gary Fisher Pirnha has what looks like identical frame to that (probably older as it was on canti's not V-s and Yellow is clearly better than Orange), the BB was cup and cone (and they were FUBARed), I replaced mine with a sealed cartridge one (same axle length) for an easier life!


Taken during the build, it now has the right wheels and decent tyres and CREE8 green pedals on black Deore crankset.

You'll need a crank puller and a BB tool.

Simon

naffa

Well thanks for all the replys and advice. I tried removing the arm and crank today without a crank removal tool but couldn't so I'm gonna have to get hold of one. I can see that the tool needed for removing the bb is a multispline one. I have a multispline tool for removing rear freewheels is this likely to fit and do the job? :?:

@ The Beginner, I've seen your bike over on retro bikes haven't I?

Naffa

cooldad

Probably not. Different splines.

The Rookie

naffa wrote:

I've seen your bike over on retro bikes haven't I?

You will have indeed!

It's a different tool to the freewheel one, a single tool will probably cost you about a fiver (see ebay links below), if you buy a sealed BB from an LBS they'll probably fit it for free. It's possible yours just need spanners and a C-spanner (or hammer and screwdriver) - I can't remember what was originally fitted, but would strongly suggest upgrading to sealed unless total originality is important to you.

http://www.ebay.co.uk/itm/Cycle-Bike-Cy ... 2a172c9ff4
http://www.ebay.co.uk/itm/Bike-Bicycle- ... 3cbf87e49b

Simon

add595

If the bottom bracket has splines, as you say, it is likely a sealed unit. Just get a new one the same length as the old one.

I have just bought one of these crank removal tools and I am very impressed: http://www.ebay.co.uk/itm/160654754587

You will need a torque wrench for putting alloy square taper crank arms back on. You must not over-tighten them, as you will deform the square in the crank arm, which will turn them into bin fodder. You must also not under-tighten them as they will come loose and the square will get deformed, also turning them into bin fodder. Low strength lock tight is recommended also, and make sure the axle and crank square are squeaky clean before attempting re-assembly.

cooldad

No you don't. Nice if you do but...

add595

Cooldad is right obviously

cooldad

I am, nice if you have one, not crucial if you don't, and most people don't. Currently have 5 bikes with square taper, 3 with HTII lying around. No torque wrench and no trashed cranks.
Many, many more in the past.

cooldad

Obviously

add595

I am guessing the OP hasn't changed square taper cranks arms before, therefore are unlikely to know how tight or not-tight to do the crank bolts up. I can only recommend a torque wrench under this circumstance.

I can 'feel' how tight to do the bolts up, as I have done it so many times before. I am sure you may not use one for the same reason.

Just my £0.02, if you don't agree feel free to argue about it.

cooldad

Me argue? Nope reasonable point.
But I don't use one because I'm cheap.

delcol

changing to sealed bb,, thats not very retro is it,,,, thats why we just changed the knackerd bearings, to keep it as it was,, and they were cheaper, cause we are tight..

naffa

Well afer much effort and aggro I have finaly removed the bb which is a sealed unit. I broke a brand new crank removal tool from Halfords in the process. The cranks just wouldn't budge even when I used heat on them so I ended up grinding the cranks off leaving the bottom bracket looking like this,


It was square taper and on the cartridge it says 68mm and BB - 7700. I suppose the other measurement i need is the total length including the tapered bits is that right?

cooldad

Yup.

naffa

Found 1 and 1 only on eBay so I've bought it.

Gotta take the crank tool back to Halfords and either get a replacement or refund from them.