240GL

The hex head bolt on the drive side crank is stubborn to come out (tapered square spindle). Before I strip any threads, could someone please confirm that it should come off anti-clockwise?

I should add that before attacking the drive side, I first removed the bolt and crank on the non-drive side. I fear that pressing the crank off may have pressed the BB spindle and the opposite hex head centre bolt together beyond loosening. If this might be the case, then what do I do? Reinstall the removed crank and try again?

Bob Dopolina 

Both should be normal threads. Just in case, what brand is the crank?

240GL

Thanks. It should be some kind of Shimano crank. The bike in question is my ten year old Nexave-equipped Merida hybrid. I am fixing it up for winter use and need to replace the BB - a first for me.

JiveTurkey

The drive and non-drive side bolts are independent of each other, so removing the NDS bolt and crank will not affect the DS.

Maybe the bolt didn't have any grease on it and a little corrosion is making the threads stick (do you know if the NDS bolt's threads were dry?). It might take a bit of pressure to knock it loose, but then it ought to come out pretty easily. (I'm assuming you haven't gotten it to budge at all yet.).

The spindle is made of hard steel, so I imagine it'd be difficult to strip threads by over-loosening.

By the way, generally, the only parts that are reverse threaded on a bike are the NDS pedal spindle and DS bottom bracket cup/cartridge. Everything else, including your hex bolt, should be standard (clockwise = tighten, counter-CW = loosen).

HillRider

As mentioned the threads are normal right-handed for both crank fixing bolts. I assume the bolt has an 8 mm recessed hex socket. Try a brand new 8 mm hex to assure it has sharp corners and gets a good purchase on the bolt. A worn wrench can slip and damage the bolt too.

Halthane

Try a little liquid wrench, squirt it in and let it sit for a couple hours, then try again. If that doesn't work try a little heat from a propane torch, a couple seconds should do the trick.

Thumpic

try the penetrating oil fer sure....position the bike so you can fill up the hole where the nut is and let it sit......if you try the torch be sure to clean off all the oil first or you might "light up your life"..........

JiveTurkey

Just noticed on a spare sq. taper cartridge BB that the axle is hollow all the way through. I wonder if laying the bike on it's right side and putting the penetrating oil down through the NDS spindle would work well, too.

tellyho

You need a breaker bar or a piece of pipe to put over your wrench. This is a case where you can really do no damage with more force. Try hitting the wrench/pipe/breaker bar with a hammer.

HillRider

I'm still not sure if this is an 8 mm recessed hex bolt or a 14 mm regular hex head bolt. If the later, then a 14 mm 6-point socket and a breaker bar will get ANYTHING loose. If it's an 8 mm Allen head bolt, it is possible to damage it with a worn wrench. What are we dealing with?

240GL

Thanks for your comments everyone, much appreciated!
It is indeed an 8 mm recessed hex bolt. I have been attacking it with a brand new key, the problem is that the tool will bottom out after just 2-3 mm so banging on it just makes it slip and destroy the hex hole. Since posting I have tried penetrating oil and a torch but with no success. I have even tried hitting it in the centre with a pointed tool in an air hammer, hoping to break loose possible corrosion. This axle is not hollow all the way through unfortunately, the penetrating oil will only work from the front.

This evening I will give it a final go with the torch. If that does not do it, I see no other option than to drill it out as I don't have access to a welding machine. >Sigh<
Will a ten year old Shimano bolt like this still be available as a spare part?

JiveTurkey

The hex bolts are standard, so a shop should have them. I'd let the penetrating oil sit all day or overnight to let it work its way through the threads. When you're using the hex wrench, utilize the crank as leverage --with both hands, squeeze the two like you're using a nutcracker. Edit: A better way might be to immobilize the crank (put your bike upright on the ground, the crank facing back, and a block under its end), that way all your force is pressing down on the wrench.

kycycler

I would try the penetrating oil, I like triflow. Let the oil soak in overnight, as has been previously suggested. If all else fails drill the head of the bolt off and then use a crank puller to remove the crank. If the crank is frozen on also you may need a ball joint fork to remove. After the bolt head is removed pull the bottom bracket and replace witgh a new one. Be sure to grease the bolts upon re installation.

thomson

You are a lot better off with a long handle than beating a short handle with a hammer. The latter has a better possibility of stripping the head. With a long handle, like a 3 of 4 foot pipe over the tool handle, you can ensure the tool is well connected to the head while slowly pushing the tool handle down.

Ncoastbykr

Here's a method I've used and if you’re using a repair stand to hold the bike stationary this might help you too. Use a piece of 2x4 lumber cut to a length that supports the crank arm horizontally with the other end of the 2x4 on the floor. This will help apply all the removal forces to the stubborn bolt while reducing stresses to your frame.

240GL

UPDATE:
I did try most of what has been suggested (thanks!) but in the end I had to drill the bolt out. Simple enough, but it left a bad taste of defeat. However, when moving on the the splined cup/cartridge behind the crank I got my suspicions confirmed: the drive side parts really have been mounted by a gorilla. Even when stepping on a 2 ft. long breaker bar I am not able to break the cup loose. I think I have to take the bike to the LBS. >sigh<