Scooterotica

I hate throwing away a good quality bearing with lots of life left when changing a crank out. What I find works really well after some experiments:
-crank in freezer overnight.
- put a leather work glove on the gear side and clamp this in a vice
- use a small butane torch with a fine flame. Heat just the bearing race for 20seconds. The key is the temp difference
- using a cold chisel and hammer, strike the spot between the race snd the face of the crank. I find that with 2-3 blows it should move. It won’t move much.
- if it doesn’t, or at this point heat again with the torch for 20 sec
- I use a big enough cold chisel that when I hit in the gap it’s going to move the race before it hits the crank shaft
- once it starts to move you are basically tapping it along the crank with the chisel. Not striking hard. Applying heat for a few secs to keep the race expanded but not heating through to the crank.
- the race comes off in a couple of minutes. No marks on it and no discolouration.
- I’ve done this 3 times now and I don’t leave a mark on the crank either. Earlier attempts failed by over heating the race or using too small a chisel.

Hope this helps someone
David

I made this bearing puller for £20 works great and no damage took this original gp race off in seconds

Sent from my SM-G960F using Tapatalk

garry inglis wrote:I made this bearing puller for £20 works great and no damage took this original gp race off in seconds

Sent from my SM-G960F using Tapatalk

This is is genius. What is the clamp called? Do you have a link?

I got mine from machine mart drilled the two holes out for 10mm bar

Sent from my SM-G960F using Tapatalk

The second one is from screwfix but they didn't have any at the time so I made the rest to fit

Sent from my SM-G960F using Tapatalk

Just tighten all the nuts and apply a bit of heat to the race and turn the top bolt i ended up with a 75mm top bolt to give me enough length to pull the race off without adjusting the whole tool height

Sent from my SM-G960F using Tapatalk

Don't forget to leave the flywheel nut on to prevent threads from being damaged.

garry inglis wrote: ↑Mon Dec 28, 2020 6:38 pm I made this bearing puller for £20 works great and no damage took this original gp race off in seconds

Sent from my SM-G960F using Tapatalk

You may have been lucky! I bought an identical bit of kit with the same intention, though I used bolts to attempt to jack off the inner race sleeve by them pushing on to the web faces. I couldn't get the thing to budge @ all. The only heat that I added was via a propane torch.

The crankshaft was a relatively new one & the sleeve was one that I had fitted, so not joined together by corrosion.

No doubt I shall try again, especially as I have acquired oxy-acetylene.

Warkton Tornado No.1 wrote:

garry inglis wrote: ↑Mon Dec 28, 2020 6:38 pm I made this bearing puller for £20 works great and no damage took this original gp race off in seconds

Sent from my SM-G960F using Tapatalk

You may have been lucky! I bought an identical bit of kit with the same intention, though I used bolts to attempt to jack off the inner race sleeve by them pushing on to the web faces. I couldn't get the thing to budge @ all. The only heat that I added was via a propane torch.

The crankshaft was a relatively new one & the sleeve was one that I had fitted, so not joined together by corrosion.

No doubt I shall try again, especially as I have acquired oxy-acetylene.

I have read that if you over heat the race, to the point it discolours, you are altering its hardness properties. This is logical, but I don’t know if it’s to the extent that it causes it to wear out more easily etc. Would be great if someone who actually knows could comment.

If you freeze your crank you don’t need to heat the race much.

Yes I agree get it two hot and you can ruin the hardness I use a heat gun and you don't need a lot off heat

Sent from my SM-G960F using Tapatalk