Replacing Bronze Bearing end of Crankshaft

Post by **paulb2** » Wed Mar 03, 2004 3:58 pm

Any tips on the best way to replace the bronze bearing in the end of the crankshaft that the gearbox first motion shaft goes into?

Paul

Post by **rayofleamington** » Wed Mar 03, 2004 4:13 pm

I heard of one 'tip' that has been used.
Find a shaft that just fits the bearing - then pack the spigot bush with thick grease with as little air as possible. Put the shaft in the bush and whack it hard with a big hammer! The pressure made in the grease and should push the bearing out.

Personally I'd just dremmel one side of the bush to weaken it.

Post by **Willie** » Wed Mar 03, 2004 5:16 pm

Hit it with a screwdriver to split it (it is much softer than
the metal housing so will break without damaging the steel).
I have seen RAY's method also suggested for removing the rear
dynamo bearing but have never heard if it has been tried
successfully??

Post by **brixtonmorris** » Wed Mar 03, 2004 6:12 pm

i can turn up a piece of ali to do the job if any one wants
that right Wille. do need it any more so who cares how it comes out.

Post by **Alec** » Fri Mar 05, 2004 4:41 pm

Hello all,
I use the gease packing method and my universal clutch alignment kit as the 'piston'. On hit with a hammer and its out.

Alec

Post by **twinkle** » Sat Mar 06, 2004 6:51 pm

I WONDER WHO THOUGHT ABOUT THE GREASE AND THUMP IT METHOD--But you know it does work ,and well.A time served M.M. Mechanic told me about this way to dislodge the bronze bush I know it doesnt sound right and its one of those seeing is believing things, He worked on gas board vans back in the sixties Morris Minor of course - what a good old work horse,-The van I mean-. Bill.

Post by **Kevin** » Mon Mar 08, 2004 11:33 am

Bill if we have a hydraulics expert on here they can probably give a good technical answer.

Post by **rayofleamington** » Mon Mar 08, 2004 11:47 am

Kevin,
I used to be a design engineer in automotive hydraulics... Hence the comment about removing as much air as possible.
Technically - you would have to hit it hard (BIG hammer) and it would leak through the gap, so I expect you would need a very close fitting shaft to get it to work. The problem there is that the old bush will be worn, so maybe an o-ring on the shaft would give an improvement, however o-rings will get damaged easily if the extrusion gap is more than 0.2 mm (ish). Mind you - that's more related to hundreds/thousands of operations..
If there is too much air, the impact of the hammer is cushioned so you won't build up enough shock load.

From a design point of view, the downside is that the surface area of the shaft is big compared to the bush, that it is hard to remove all the air, and that it' won't always be easy to get a very close fitting shaft - so in principle its a bad design to do that
Doesn't mean it wont work though!

Edited,
Had completely missed Alec's post above. Sorry fella!
Wouldn't have written any of that if I'd seen some practical tips from someone who's already done it

Post by **Kevin** » Mon Mar 08, 2004 1:32 pm

Right RAY so its a get you of of jail card solution thats worth giving a try as it often works.