Stuck Preload Bolt

armoureddrummer

Hi All,

Had a very frustrating couple of days.

I bought this bike second hand a while ago (2010 Spesh Allez) and it has a Hollowtech external BB and a shimano crankset.

So.... I had a recent fall (chain off top of cassette while setting off, clicked into spuds, legs spin out, fall sideways at junction in front of many spectators :oops: type fall). Bottom bracket didn't seem to be turning smoothly after that so I have assumed knackered bearings from impact of fall.

I bought a new BB ready to be installed and set about removing the cranks. Crank bolts completely removed to ensure no pinch.

The preload cap is lodged in so hard I can't get it out. The plastic removal tool stripped almost immediately so I bought an aluminium one which has stripped the preload cap itself. I am definitely turning the correct direction and even tried the other just make sure it wasn't me doing something stupid.

So with cap stripped of any teeth I had to go at it with a trusty hammer and screwdriver to try and get purchase and a turn. No luck - the aluminium cap was too soft and just got worse. So I tried to create a slot in the cap to get a screwdriver into it. Managed to do that, got a monkey wrench on the driver for leverage - thought I had finally cracked it as it turned but alas just created a nice round screwdriver sized hole in the aluminium.

I am completely stuck now and have run out of ideas. Have a look at the photo link below for the carnage and if anyone has any ideas which will avoid having to write off my cranks I would be eternally appreciative.

Yossie

Any chance of drilling the fekker out, sliding the crank off then getting the BB out? As you're fitting a new one it doesn't matter of the remains of the bolt are in there.

Obviously then throw the BB into next door's garden.

schweiz

Without getting my hands on it it's hard to say what the next step is short of a pillar drill but it's certainly been butchered! If and when you get it out, the preload cap should only have been installed with a about 1 Nm of torque which is light finger tight when using the plastic tool (that's why the Shimano tool is made of plastic as it doesn't need to be any stronger). That way you shouldn't have the same problem in the future.

k-dog

My cap is plastic. Could you just heat it and pull it out? That or cut into it a bit and yank it out.

You're going to need a new one anyway but what you want to try and do is avoid damaging the crank.

desweller

All I can think of is that maybe your crankshaft has had a whack from the non-drive end that's left a high axial load on the cap. Obviously you'd also need a lot of friction between the crankshaft and the bearing inner races for this to be the case.

Try giving the crankshaft a few hefty whacks with a soft mallet from the drive side and maybe drill a small off-centre hole in the cap that you can get a pin punch in to to unscrew it.

I might also be tempted to place something wide, flat and strong between the closing faces on the crank arm to open the crank clamping up a bit. Might help relieve the load on the preload screw.

I'd

denniskwok

The standard Shimano preload caps are plastic for a reason, so you cannot overtorque them. Is your preload cap plastic or alloy, as the pic looks like the standard plastic item, but your description says that it is alloy.

If the latter, then it sounds like the previous owner has installed the cap and not greased it, or applied anti-seize before fitting it, resulting in the two alloy surfaces becoming seized together.

Did you try and use WD40/GT85/Plus Gas to try and penetrate into the threads before attempting butchery?

crankycrank

Oh, that's ugly. Looks as though the lip of the bolt has been crushed against the crank causing it to be so difficult to remove. If you have a dremel type tool, carefully grind out the top of the bolt from the inside to just remove the lip. If you have a spare bolt you can see exactly where to grind. I suspect you will then be able to remove the crank first and then the remaining bolt stub fairly easily.

armoureddrummer

@ Yossie - not sure if drilling out would work without damaging the cranks? Its quite close for comfort. As for what will happen to the BB once it is done - you are close but it may end up 3 or 4 gardens down the road!
@ Schweiz - this is what irritated me most. I think it must have been whacked in there at quite some force and without grease (or even worse with some locktight or similar product. It is well wedged in this is beginning to seem more likely).
@ k-dog - Definitely alloy in this case. I am also beginning to wonder whether it is a cap off a different manufacturers crank which might have caused the problem (especially if it has stripped the thread).
@ DesW - The cranks have a fair amount of play in them while the bolts are undone. It seems the tension cap and bottom bracket are well fused up. I wondered whether a knock has cause the threads to shift and jam together? Out of interest - should the cranks have any play when unbolted? Could this be the cause? - I like the idea of the offset hole.
@ Dennis - Tried some WD40 towards the end but didn't work at it too much after that as I thought it was getting to the point where further advice should be looked for before going at it any more.
@ crankycrank - Your user name is quite amusingly suitable for this post! I was wondering about a method like this. Is the tension cap threaded into the BB or the crank from the other side? I was wondering whether the cap could have the lip taken off then the rest of the bolt could be abandoned inside the BB? But then I thought it was far more likely to be threaded into the drive side crank?

armoureddrummer

ps - thanks for all the advice so far :-D

denniskwok

armoureddrummer wrote:

@ crankycrank - Your user name is quite amusingly suitable for this post! I was wondering about a method like this. Is the tension cap threaded into the BB or the crank from the other side? I was wondering whether the cap could have the lip taken off then the rest of the bolt could be abandoned inside the BB? But then I thought it was far more likely to be threaded into the drive side crank?

The preload cap screws into a thread on the inside of the hollow axle of the BB.

Watch this clip from 45sec in: http://www.youtube.com/watch?v=TCDcJ1W9Doo

darrenharris

I would try a screw removal tool , its a drill bit that is threaded the other way so that when you drill into it in reverse it actually cuts into it and will turn it, as it is ally it is there fore quite soft so should cut in very easily

k-dog

It's threaded into the end of the BB axle - like you say it's just to load the bearings. Essentially it pulls the crank tight against the bearing - once you've tightened the crank bolts you could remove it. The only part holding the crank on at the moment is the lip.

I would still try and cut it out or something - you might ruin the BB axle but that is fine, just widen that hole you've already made - offset it if you can - and then you should be able to pull the cap out. It shouldn't be very thick.

armoureddrummer

Was just looking at the vid above. It still looks to me like the axle is part of the crank and that is what the tension bolt threaded into? Just after the 45 second mark you mentioned, the crank is taken out leaving the BB in place. Threads are in the axle.

k-dog

Good spot! The axle is attached to the drive side crank - if you remove the cap then you can remove the non-drive crank and then just pull the drive side off.

I would still remove it - just carefully. Darren's suggestion is probably worth a go first.

desweller

armoureddrummer wrote:

Was just looking at the vid above. It still looks to me like the axle is part of the crank and that is what the tension bolt threaded into? Just after the 45 second mark you mentioned, the crank is taken out leaving the BB in place. Threads are in the axle.

If the crankshaft was part of the crank on that side then the screw would do nothing.

I still say, lever the split in the arm apart a little to release the tension on the screw,

armoureddrummer

When I say part of the crank, I mean the axle is joined to the chainset on the driveside and is part of the crankset. ie when I change the BB the axle will be going back in and therefore the threaded bit will still need to be ok.

Does the lip on the bolt not just pull the 2 cranks together lightly around the BB before the bolts are secured?

I have tried levering apart with a hefty screwdriver. I am pretty sure the threads have fused or skipped and jammed tight. The crank on the non DS is moving free of the tension bolt a couple of mm each way.

armoureddrummer

I will try and get hold of a screw removing bit. Might see if a friend has a hand held electric screwdriver/dremmel rather than trying it with a chordless drill :-D

k-dog

Yes, you're totally right - the axle is attached to the non drive side - so save the threads if you can. (When you get the non drive crank off then the whole drive side and axle can be pulled off in one piece).

If the non drive crank is moving is there enough space to get a hacksaw in and cut the lip off? Once you've got that crank off it would be easier to get the remainder out.

nicklouse

is the tag still there in the slot of the arm?

if no try some thing to open the slot up just a smidge to make sure it is not clamping the out radius of the bolt. then smack a screw driver or a torx bit into the hole and undo.