Carbonated

I bought a new crankset for my old 1997 Trek 820 beater as the current one is the original. To make a long story short, I stripped the inner threads on the drive side crank arm and cannot get the crank arm off the square shaft BB. I did manage to get the non-drive side crank arm off.


I thought of taking off and replacing the Bottom Bracket as a remedy off but I cannot access the BB nut on the drive side with the crank/chainring still on.


I am going to take it to the LBS unless I get some solid info from the experts here


Thanks in advice.

Hoopdriver

Jacobs Wedges (#6 recommended). Here's a link to some of the posts involving their use. Of course if you plan to trash your old crank, a hacksaw would work as well.

travbikeman

YouTube has some great video's on fixing this:

Carbonated

OK, I was able to remove the BB nut on the non drive side amazing easy considering it's been on for 20 years.

The drive side is a mystery. There isn't a nut but a fairly large metal piece that covers the end of the BB. Does anyone know how to remove it?

JohnDThompson 

The plate is where the front derailleur mounts. To remove it, you first remove the drive side arm, then remove the cup behind which the plate is mounted.

madpogue 

Why exactly are you replacing the crankset? Does it have riveted-on chainrings that are worn?

If you don't opt for one of the wedge / puller options above, and you want to just replace the BB along with the crankset, a 36mm Park bottom bracket wrench (it's only a few mm thick) should be able to slide in between that inner chainring and the front der mount. Might be a time to swap in a cartridge. Just remember, that side is reverse threaded.

Oh, um, is it cartridge that's in there now? If so, your only options are the wedge or puller method.

12boy

That is excellent. BTW, my LBS chased some threads for me and said the chasing is done withe the arm still on the spindle, so there is no need to use the 3arm puller first.

Carbonated

I decided to take the bike in to the LBs and have it removed. He had a special forked tool and easily removed it.

It turned out the new crank I bought which was a 42-32-22 tooth caused a problem for the old front der as it couldn't clear the 42 tooth. The old crank had a 38-28-18. Since the front der was attached to the bracket as you mentioned and not adjustable, he had to replace it with a new Altus front der.

In the end I got a new Acera 22-32-42 crankset, Altus front der, BB, cassette and chain. The mechanic installed and tweaked it all and it in the end it was around $180.

A lot of money but the bike is in great shape and is ideal for greenway and gravel riding so I'm OK with it.

I can't wait to get out and ride tomorrow - shifting was much smoother

Hoopdriver

Sounds like what they call a "Pickle Fork". Used in the auto repair industry for separating suspension ball joints and the like.


Excellent!