17 replies to this topic

[stevelane]

998 Mini City

A+ Engine 1992

I recently stripped my engine, see other threads for a long story, and have just noticed that the bush on the primary gear has got scratched in a zig zag fashion.

I bought the new part from minispares and carried on putting the engine together and now its getting to the part where I have to put this back.

Now, from what I am reading, I understand that this bush can not be put on at home and will need to be machined in, and also that they need to do it with the crank for a perfect fit.

Can someone confirm whether this is true or not, and if it is then please excuse any language that I may come out with as the crank has been put back in!

[Cooperman]

You can do one of two things here:

1. Measure the diameter of the crank tail and take the primary gear to a machine shop with the crank tail diameter(s). Get the machine shop to machine out the bushes to crank tail diameter +0.0015"/0.0020", or,
2 Here I'll court controversy, but it does work, buy a small 3-legged hone and using an elecric drill on a vry slow speed hone out the bushes until it just slides on nicely. This is not ideal, but if you're stuck it will work.

Edited by Cooperman, 08 July 2012 - 07:02 PM.

[stevelane]

How do I get the current bush out and the new one in if I did hone it?

[Cooperman]

If it's a new part from MiniSpares, you should be able to machine out any marks. But it's not quite clear what you mean by 'zig-zag' lines. Could you post a photo for better advice?

[stevelane]

It's the old one that had zig zag lines on it, can't post a pic as I'm on my phone not Pc, it was caused by taking it off by hand and moving it back and forward, it scratched on the edge where the c shaped washer goes.

I have a new one but need to know how to get the old one out and the new one in, that's if it can be done at home

[Cooperman]

Knock the old one out with a hammer & punch from the opposite end, then lightly grease the bore and press the new one in in a vice with a piece of wood over the flanged end.

[mini13]

whats probably happend here is there is a burr on the slot(s) in the crank that take the C washer. gently try the primary on the crank and see if it catches the bearing, if so give the edge of the grooves some attention with a fine file and generally clean up that area with some fine wet and dry (wet wd40 or similar) give the inside of the bush a polish wth wet and dry too to get rid of the high spots where te scratches are and try it again.

Unless there is any heat discolouration to the bush I would reuse it unless you are putting to gether a high performance engine.

[stevelane]

This is what it looks like - Too bad to reuse?

Edited by stevelane, 08 July 2012 - 08:34 PM.

[stevelane]

Sorry - This is what it looks like

Attached Files

•  photo1.JPG   23.54K   32 downloads

[stevelane]

Anyone?

[mini13]

I'd use it.

[stevelane]

ok - what are the consequences if its too damaged?

[Cooperman]

It is so easy to fit a new one that I wouldn't even consider re-fitting that one.

[bmcecosse]

I would use it too. Bearings often have grooves in them to help retain oil...... Don't worry about it!

[stevelane]

Ok, I'm up against a time limit with this rebuild so will have to decide in the next couple of days. I have a baby due soon and the other half really wants to get out in the car before the baby is born.

Cheers for all your thoughts guys.