Aligning Centurion engine to gearbox

[Malcolm Towrie]

I'm struggling with how to align our Meteor engine to the gearbox. The manual specifies using quite an elaborate tool. The tool has a flange that bolts to the crankshaft oil seal housing face. A 2.500" round bar has a tight sliding fit in the bore of the flange hub and extends out to close to the gearbox flange, where there's another tight sliding fit flange that two dial indicators are mounted on to take face and periphery TIR measurements on the stationary gearbox input flange as the sliding fit flange is rotated.

We don't have this tool, and I can see making one will stretch my limited machining skills.

First of all, I have to make a flange that slips on the crankcase studs precisely enough to keep the 2.501" hole in the flange hub dead concentric to the crankshaft. Then I need to make the slip fit flange at the grarbox end of the shaft so that is it is also concentric to the crankshaft within a couple of thou.

Then I have to get the face and periphery runout reading within 0.010" by shimming and moving the engine mount frame, which is achievable.

Then amazingly, I just scribe around the mounting faces on the engine frame so I can replace the engine to those scribe marks after installing the clutch. But replacing the engine using scribe marks has got to be at least plus or minus 0.020" error.

I see the clutch output flange is mounted on a self aligning ball bearing so the clutch can handle some misalignment. But how much?

Has anybody been through this process?

Malcolm

[Mike Cecil]

Malcolm,

Have you emailed John Blackwell at Pucka? They have been through the process installing the new engine in 005.

Mike

[Malcolm Towrie]

No, i haven't, Mike. I'll try that.
Malcolm

[Lauren Child]

I’ve not been on for a while, but we’ve done it at Duxford. Alas I was out on the day at a family do, but if you’re stuck I’ll ask the question. I’m fairly sure they used a magnetically attached feeler gauge in place of the big version in the book.

[Malcolm Towrie]

I think we have it figured out, Lauren. We're using the shaft from a old clutch installed between the engine and the gearbox. And using magnetic based dial indicators or maybe a laser alignment tool if I can borrow one to measure runouts at gearbox and engine ends.
The photo shows the shaft mounted to the gearbox. We don't have the engine in yet.

Malcolm

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[Lauren Child]

I asked the question today, and apparently we managed to borrow the special tool from a friend.

I guess that means we still have a 50/50 and ask the audience left for when the project restarts, but it looks like you’ve got it sorted anyway. I’d love to know how you get on

TTFN
Lauren

[Malcolm Towrie]

We're restoring a Canadian Centurion at the Oshawa Regiment museum in Ontario, Canada.
I wanted to give an update because it's actually starting to feel like we're getting somewhere!

She's running and driving with the rebuilt Meteor we got from the States, although only inside so far due to my reluctance to get clay mud all over the undercarriage when we are in the process of cleaning and painting it.

The engine starts really well. The key is not to use that stupid choke plate (aka strangler). God knows why that is installed. All that happens is the full intake manifold vacuum acting on the carbs sucks huge amounts of fuel through the main jets and because it's an updraft carb, none of this fuel gets up into the intake manifolds because the choke restricts the air flow so much, and it all dumps down into the plenum and pours out of the automatic plenum drain tubes. Rolls Royce designers obviously weren't idiots so there must have been some logic behind the choke design but I don't know what it was.

Anyway, I have a electric priming pump installed to fill the carbs to save the hassle of using the rather inaccessible priming levers on the installed fuel pumps. After that, 3 or 4 pumps on the gas pedal (which does shoot gas up into the intake manifolds) and she fires right up.

The clutch rebuild showed the massive plain plates and friction plates were all still in spec, and only a couple of new bearings and seals were required. It works well and is much lighter in operation than I expected.

Steering, including neutral steering, also works very well, which is a relief as all I did with the transmission was remove the top covers to do a visual check of gears and shifter mechanism. All looked good and fishing around the bottom with a magnet picked up no worrying pieces, and oil was clean. The final test will be driving it around the arena to confirm that all gears are there and shifting is manageable.
One thing I noticed is that there is a shift lock-out mechanism (to prevent the selector mechanism from trying to select two gears at the same time) in the gear selector box up in the driver's compartment, and also in the transmission. So it is very important to synchronize the two lockout mechanisms so that the driver can easily select each gear. I don't think the manual mentioned this requirement.

Right now we are in external bodywork repair and painting mode. Some track guards were beyond repair so new ones were fabricated. All the side bins were really rough too so repair (cutting, patching, grinding, and painting) is in progress.

I should say at this point that, like most museums, money's a bit tight, so management encourages the use of free internal labour to fix stuff, rather that farming it out to a local fab shop. And when I say "encourages", I mean "insists". So we don't always achieve perfection, even though we aim for it.

The photo below shows our progress so far.

Even though this tank is nominally Mark 5/2, it came with the full gyro stabilizing power elevation and traverse (which I believe was a later Mark?). It looks quite intact so my personal dream is to get this working and have the only tank at the museum with functioning gun stabilizing. Time will tell.
Malcolm

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[Robin Craig]

Malcolm, great progress.

dont forget I have some lights for you here, maybe i should post them to you

[Mike Cecil]

Nice job, Malcolm, looking much better than when I saw it a couple of years ago.

I think you will find that stab was a feature for all the Cent marks.

Regards

Mike

[Malcolm Towrie]

Robin, to tell you the truth, I'd forgotten you had lights! We've just started working on the lights. Can you mail them and I'll refund the postage?

Mike, I got confused. What I meant to say is we seem to have a later style, more sophisticated stab control, not the system described in the Mk 3 tech manual. Does that make sense?

Malcolm

[Lynn Eades]

Malcolm, just to update your post #30, There are two Centurions in the south Island of New Zealand. The one I previously mentioned owned by the gold miner on the west coast, and the one John mentioned in ChristChurch (east coast) Both at similar latitudes. The Christchurch one was for sale on Trademe at one stage. I thought it was cheap, so it may have moved. No idea.