6 replies to this topic

[Chappb]

What size reamer do i need to ream the crown wheel/diff cage bronze bushing. old one has worn so will be buying a new one. Also, any tips on removing the old one? good old punch and hammer? 

[Chappb]

anyone?

[tiger99]

Can't find it in the Rover manual (all it says is what we know anyway, you need to renew the crownwheel and pinion as a pair, and the differential gears as a full set, nothing about the bushes, or the other larger bushes in the side covers), so you may have to measure the shaft on which it runs and allow about a thou of clearance. But there is no way that it is going to be economical to buy a reamer of adequate quality to do the job. Best have a machine shop do it, instead of wasting money on an expensive tool that you will use once.

 

It really is a machine job anyway, as because the bush is short it will need some kind of machinery like a lathe or milling machine to do it, as the reamer must go in truly perpendicular, and the short bush will not provide sufficient guidance.

 

I don't imagine that it would be a hugely expensive job.

[Ethel]

Me either, 1thou clearance seems reasonable, that's the figure given for cam bearings, which are similar.

[Chappb]

i've had the mic on the output shaft journal and measured it to be 1.029", just for future reference. Thanks for the help.

Edited by Chappb, 12 October 2013 - 08:35 PM.

[Fast Ivan]

ideal is to use a pin punch with a point ground on it with a small radius on the tip, use this to prise open the slot that these split bushes have.

to size the hole you need to press the bush in then it will need to be put in a lathe, 4 jaw being ideal, 3 jaw and shims working just as well, and clocked in using the journal where the roller bearing sits, using a dti, and bored out, possibily finished with some fine grit emery cloth to size, unsure of clearance but a sliding fit without slop from side to side, .001 would seem reasonable, so long as it isnt to slack and you cant feel it picking up.

or a milling machine, still using a dti to clock in

concentric to the roller bearing journal being the key

[ACDodd]

I go for 0.0005 to 0.001" of clearance. You cannot ream, they need to be clocked to the cage register in the crown wheel.

 

AC