Camshaft bushes - Dominator 99

hello now do try Rodger At  RGM  Motors will give you some guidance on bronze cam bushings. But how I fit new camshaft bushies is by heating the cases in the oven with two case half screws in the bottom and the 1/4 nut and bolt  at the front for quick disassembly   then when very hot you unscrew the two bottom case screws  and the 1/4 nut and bolt at the front of the cases and on a wooden chopping block  taps out the bronze bushies with a leather hammer  with a couple  of taps they fall out  then back in the oven after a quick clean of the case then have ready the two new ones to fit back in  the same way they came out  but you need the camshaft with heavy grease on the end and fit the bush over this  and tip back in place  with you leather hammer  no machining need all that needed is some  fine lapping paste  and rub in  with the camshaft end  to bed in the bushies then try fit the two case halves  and 3 bolts  and try his out for fit  and free play  if you have free play at each end then you next job is  clean every thing down  and oil up the bushies  to reassemble  the engine.  the bushies should fit inline if the cases are matched correctly,  And you may have these made, that a machine shop in bronze,  And do make sure when fitting make the oil holes line up with the cases oil holes at each end.     yours    Anna J Dixon 

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Are you seriously advocating using valve grinding paste in bronze bushes? Bronze is relatively soft, and the paste will bed into the surface and no amount of washing will ever get the residual bits out of it, meaning that it sits in there wearing away your nice new cam.

Is this why you have so much experience changing bushes?

I would never let you near one of my engines!

George

... grinding paste should never be let anywhere near bronze bushes.

... grinding paste no. I'm sure you got away with it Anna but it's still the case that you'd never be able to get all the grit out of soft bearing metal.

Ian is absolutely right. Scrapers or reamers yes, abrasive compounds no.

There is a huge difference between a 120rpm ship diesel engine and a 7000rpm bike engine.

Anna, I wonder what your oft quoted craftsmen in Bracebridge Street would have made of your "grinding paste is ok" bodge?

I bet you would have been laughed out of the shop.

George 

hello   You guys  I think you all need to read practical machinist  or Newman tools  websites on lapping in hard bronze   and you find the quick way of lapping in with fine lapping paste  silicon carbonate  fine ground  is the same as Clover fine lapping in paste  and Norton Camshaft Bronze bushies are made in Hard Bronze if there were not they would not last very long   So some of you are overreacting  and need to read up on lapping in valves and bushings  you only use a very small amount  just to lap in and free up the bush   then you can wash it all away with your paraffin gun at 40 psi  with white spirt in, and you can clean up  hard bronze with fine clover  lapping and grinding paste which is used for valve lapping in too and other jobs,and you can also use chrome cleaner  too for lapping in   I done more engineering then some you has hot dinners  in the last 50 years  , A old bike and a Old bugger riding it,   Yours  Anna J 

Do not allow any form of grinding paste near bronze bushes that have a shaft revolving in them. You will wear them or the cam out prematurely.

Plain bronze or white metal bearings are machined and then scraped to fit. (in the case of our cam bearings, being line bored after fitting)

In the course of my working career i have had to machine quite a few large and not so large white metal bearings for steam turbines, electric motors and pumps and the like. The use of grinding paste anywhere near these would have got you fired.

Grinding paste does have its uses but this is not one of them.

One does wonder, Anna, if all your 'engineering' is the reason why your bike isn't running?       

When I did my apprenticeship toothpaste was recommended for easing tight fitting components.

HAPPY CHRISTMAS to all you Norton enthusiasts. Keep going, Anna, always entertaining... Rolls Royce used jewellers' rouge to lap their timing gears until they were silent. Norton certainly did not, you can hear mine a mile away, above the clatter of the tappets! (1959 Dommi 99)

I have posted this here, instead of the 'motorcycle lockdown' thread as it directly follows on.  

In her first reply on this thread Anna states to use 'valve paste fine' when easing a tight cam bush.

When brought to task on this advice Anna took umbridge and eventually posted info on a company that supplies a product called 'Timesaver lapping paste'

Having looked at the Timesaver lapping paste info on the Newman tools Inc website (for those who don't know what this is, it is claimed to be a non embedding abrasive lapping paste)

This is a completely different product than the 'valve paste fine' that she purported to use. Valve grinding paste is a silicon carbide paste specifically used on grinding or lapping in the valves on IC engines.   

I suspect, that when Anna was pulled up on her advice, she trawled the net looking for info to use as evidence that 'her advice' was good. 

Hi Tony

how was this problem resolved, Im having similar problems with my Commando bushes

She hasn't posted for a while.

I agree with Lionel the bush houses should be perfectly concentric after manufacture. If the cam spins freely in new bushes, with detectable play, that should be fine.

Sorry to drag this out of the past again..but I'm planning a good look inside my Dommie when the nights draw in again.  There are a couple of reasons - I'm not happy about piston clearance although I must do a plug chop first to see if the main jets might be bigger.

But by using the listening trick with a variety of sounding rods, I'm thinking the cam bushes might be worn.  A bit of YouTube "research" turns up a method for Triumphs - with a tool - but their drive side bushes are smaller.  Is there a Norton tool?

The method they use explains why the bushes are such a small amount undersize.  The cases are bolted up,with the drive side bush in place but not timing side.  A parallel reamer is put into the entrance of the drive side bush,  A steel flanged guide bush follows onto the parallel shank of the reamer.  This holds in in line.  The bronze bush is then reamed by hand.  It's only a very small amount so it's not hard work - no need for machines.

Then the timing side bush is fitted.  Now the clever bit - a hard ball bearing is gently tapped through the timing side bush!  Otherwise of course there's  no way to guarantee alignment of the reamer.

It should be fairly easy to make up the tool using a standard reamer of the correct length and making a guide bush on the lather - but is there one on the market?  I imagine a 7/8" ball bearing could be bought somewhere.

Maybe of course the bushes are OK anyway!  Apparently it's not uncommon for the old camshaft (if it's OK for re-use) to fit into new unreamed bushes, because although most of the wear is in the bushed, a small amount occurs on the camshaft.

Does the above match others' experiences? Otherwise it's a machine shop job - if only there were a few machine shops left in England.