Drive side inner bearing race -68 Commando help?

Installing superblends on my 68 Norton commando rebuild and timing side went on slick by freezing crank and heating race, but I broke the inner race lip trying to tap it in place on the drive side. Any hints/tips/things to check on next attempt?? I'm tempted to take Emory cloth to the taper but don't want to scre up the ability for the oil seal to do its job.

Thanks in advance,
Dave

Put two new ones in only yesterday. Both just dropped in after few minutes heating with powerful propane blow torch (not one of disposable can type a 4kg refillable bottle and large proper torch). Heated cases till old ones fell out then just dropped new bearing straight in.

If you haven't got a big torch put case in kitchen oven on full till its realy hot. It wont hurt it an of course clean it very will first an do it when your other half is out.

If you are hammering the case hard enough to damage the bearing it will do damage to the case as well as the bearing is much stronger than alloy. Don't be afraid to heat it an if it sticks heating case so it drops out will not hurt bearing as long as flame is not allowed to touch bearing.

Use a tubular brass or alloy drift , and keep it SQUARE . Really a PRESS is more like it , supported behind crank web flank adjacent
rather than over the frigging assembly - or youll ' chip that ' too .

Get a piece of round ally pipe the size and firmly tap it on. I don't heat the inner race at all just firm taps and it goes on, mind I have only done two engines.

J

I'm wondering if now is the time to invest in a shop press. Hate to spends another $120 for a bearing and screw it up. Timing side - heated/frozen slipped on with only finger pressure (wearing welding gloves).

Mick Hemmings recommends heat. Norton themselves say heat the case. Friends of mine who have been doing it for 60 years say heat the case but they are your cases so its your choice. But the bearing is an interference fit (it is larger than the bore it fits in) heating the case to expands it is the correct method. Pressing hammering or fitting by force risks stressing or damage to the case. These cases are known to crack in use so putting unnecessary stress on them by changing them by force is not a good idea.

toppy said:

Mick Hemmings recommends heat. Norton themselves say heat the case. Friends of mine who have been doing it for 60 years say heat the case but they are your cases so its your choice. But the bearing is an interference fit (it is larger than the bore it fits in) heating the case to expands it is the correct method. Pressing hammering or fitting by force risks stressing or damage to the case. These cases are known to crack in use so putting unnecessary stress on them by changing them by force is not a good idea.

Click to expand...

I'm i missing something here?

J

toppy said:

Mick Hemmings recommends heat. Norton themselves say heat the case. Friends of mine who have been doing it for 60 years say heat the case but they are your cases so its your choice. But the bearing is an interference fit (it is larger than the bore it fits in) heating the case to expands it is the correct method. Pressing hammering or fitting by force risks stressing or damage to the case. These cases are known to crack in use so putting unnecessary stress on them by changing them by force is not a good idea.

Click to expand...

Fitting the outer section of the bearing into the case isn't Dmftoy1's problem. He's having trouble fitting the inner spool onto the crank.

Doh !!!
The inner race just taps on the crank. As already said by those read the OP correctly (doh again) a piece of softer metal to protect the bearing is a good idea. I had an old fork bush in scrap bin that was just right. Be sure to tap opposite places in four areas 12 o'clock then 6 9 an 3 o'clock as you look at it. Never just hit same place over an over. The start as bearing start to slide down is very important to keep checking its level. I have fitted thousands of bearings this way. Dont rush if it stops hit the opposite side to where you last hit it.
I would stiĺl not press it as it really is not such a tight fit.

It's very simple. Gently heat the inner race with a hot air gun to approx. 120c / 240f. It will slide on easily. Do not let the race get too hot! If you don't have a hot air gun stick the part in the oven.
Martyn.