Camshaft Pinion Stuck

[John Cornforth]

I'm in the middle of a partial engine overhaul at the moment.

The timing gear pair (presumed original to the crankcase) has about 10 thou backlash between teeth and the teeth are slightly pitted but I have seen worse.  The gears and crankcase are stamped + 1/2.  Cam gear fore-aft backlash is about 4 or 5 thou, and the bush and square headed peg bolt are good.

Anyway, the plan was to replace said gears with a nice new cast iron set from Dave Dye, which is sitting in wait.

Woodrow says "Using an extractor, remove the pinion from the camshaft" - if only !

I have modified a strong extractor which has two bolts going through the holes in the web, and uses two blocks which bear against the back of the web (The boss is rather hard to grip).  With this extractor wound up as hard as I dare, I have heated the boss with an admittedly small blowtorch and administered blows from a hammer and brass drift.  This has resulted in no perceptible movement of the gear whatsoever. If I didn't know better I would swear they are welded together

I do worry about the thinness of the web and the fact that it's cast iron, otherwise I might take it to an engineering shop and get them to use their hydraulic press

In extremis I suppose I could destroy the original gear, but I'm very reluctant to do that.

Any suggestions ?

[AustinWood]

I always remove the camshaft wheel with the cam in situ in the crankcase and the camshaft bearing located by the square bolt. The centre camshaft bearing need not be in place. I use a 3-leg puller carefully lined up on the wheel with the bolt centred on the camshaft. One of the bolts retaining the front main bearings may have to be removed.
If the nut that holds the wheel on camshaft is loosely in place it holds the puller bolt central. I do up the puller bolt firmly but not very tight.
With it set up like this I strike the head of the puller bolt firmly with a hammer. It's never failed yet.
The camshaft is free to move back out of the gear so striking the puller pushes it straight back.

[John Mason]

When I removed the gear from the end of my camshaft. I like Austin removed it from the crankcase complete with the gear. I then put the camshaft vertically in the vice without tightening so that the gear stopped it falling through.The gear centre needs to be resting on the vice jaws almost to a point where the jaws will grip I slackened the nut which holds the gear onto the taper but not fully removed. Then I held a wooden block on the nut and struck it twice with hard blows to break the taper. The taper joint broke leaving the camshaft hanging loosely on the nut.

John Mason.

[John Cornforth]

SUCCESS !

Thanks for the suggestions which gave me the confidence to persevere.

I ended up tightening the puller to the point where I feared personal injury, belting the puller screw head HARD 6 times with a big club hammer, then tightening a tiny bit more. This sequence was repeated until after two dozen hard blows the pinion was off.

I guess the metal surfaces of the pinion and taper must microscopically fret and become embedded with each other, and it is only the shock waves from hammering that release their grip. I doubt if a straight pull would do the job without shattering the pinion.

[AustinWood]

A straight pull would definitely break it. The hammer is a wonderful invention.

[John Mason]

Yes it’s the shock force of the hammer when the taper is under tension that releases the grip. Similar methods can be used on other tapers such as track rod ends on moderns. Use a long bar to put a downwards force on the bottom wishbone then with the nut removed give a sharp strike the ring the taper goes through.

John Mason

[Parazine]

I guess the metal surfaces of the pinion and taper must microscopically fret and become embedded with each other, and it is only the shock waves from hammering that release their grip.  I doubt if a straight pull would do the job without shattering the pinion.

Probably a correct analysis. 

I find this is another use for the workshop press that no-one had a good word for a couple of years ago. Protect the pulley thread with a nut, support the inner diameter of the gear, close to the boss and press the end of the camshaft square and hard............BANG! Off it comes in seconds. But it does mean the camshaft and gear assembly has to be out of the engine though....