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  #1  
Old 29-08-19, 08:29
Malcolm Towrie Malcolm Towrie is offline
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Default Aligning Centurion engine to gearbox

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

Last edited by Malcolm Towrie; 29-08-19 at 08:34.
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  #2  
Old 29-08-19, 16:08
Mike Cecil Mike Cecil is offline
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Malcolm,

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

Mike
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  #3  
Old 31-08-19, 06:27
Malcolm Towrie Malcolm Towrie is offline
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No, i haven't, Mike. I'll try that.
Malcolm
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  #4  
Old 28-09-19, 18:51
Lauren Child Lauren Child is offline
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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.
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  #5  
Old 29-09-19, 04:03
Malcolm Towrie Malcolm Towrie is offline
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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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  #6  
Old 29-09-19, 19:06
Lauren Child Lauren Child is offline
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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 youve got it sorted anyway. Id love to know how you get on

TTFN
Lauren
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  #7  
Old 17-10-19, 05:54
Malcolm Towrie Malcolm Towrie is offline
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To close the loop here, I got the engine and gearbox aligned. Using the shaft from an old beaten-up clutch we had worked well. If you don't have an old shaft, seems to me you'd have to make something similar, which is quite a machining challenge.

I got really lucky. The runout readings taken with the dial indicator on the gearbox flange face and the crankcase face (see photos) indicated the engine was sitting about 1/4" low, relative to the gearbox. I made shims out of 3/16" plate and installed them under all four engine mounts. That brought the total indicated runout down from 0.060" to 0.020". Another 0.075" under each mount brought the TIR down to 0.008", which is within spec.

I was dreading this job, but it turned out to be simpler than I thought. I suspect that is due to the factory ensuring that the gearbox mounts and the engine mounts are parallel and that simply shimming up and down will correct misalignment.

I also suspect this spec is far too conservative for those of us running Centurions today. We're more likely to do 3 miles a year rather than 3000. So wearing out clutch, crankshaft, and gearbox components is pretty unlikely.

Malcolm

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  #8  
Old 17-10-19, 13:27
David Herbert David Herbert is offline
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Well done Malcolm !
That is not a job that I would have looked forward to. Now you get to install the world's heaviest clutch !

David
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  #9  
Old 17-10-19, 20:24
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Robin Craig Robin Craig is offline
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Good old fashioned engineering not requiring a USB stick or an I phone. Great to see such work going on by such skilled dedicated people. Thank you for sharing your work Malcolm
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  #10  
Old 18-10-19, 04:28
Malcolm Towrie Malcolm Towrie is offline
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Quote:
Originally Posted by David Herbert View Post
Well done Malcolm !
That is not a job that I would have looked forward to. Now you get to install the world's heaviest clutch !

David
Thanks, guys. Luck's been with me lately - I've also been finding parts that I thought I would have to fabricate, including one exhaust pipe from the manifold to the hull penetration.
The one part I can't find, despite seeing photos of it in this very tank, is the voltage regulator for the main engine-mounted generator. (I've no immediate plans to install the auxiliary Morris engine powered generator, although I think we'll have to if we get the turret traverse working.)
We have a few deuce-and-a-half's in the boneyard so I hope I can find a suitable regulator there. They're 28 volt, approximately 40 amp rated, so close enough.

David, the clutch in a T-55 is a beast too, but I think you're right, this one has it beat. In fact, that's my new worry, can I get it in without having to remove the engine or gearbox? The manual doesn't help - in the clutch removal section it says, remove the engine. In the replacement section, it says replace the gearbox. A bit confusing.

I can install and remove the bare clutch shaft I used for alignment easily by sliding the engine forward a few inches (I have the starter removed at the front and the fan drive pulleys and tensioners removed at the back) but the complete 450 lb. clutch might not be so cooperative.

By the way, that exhaust pipe I mentioned above - where it passes through the hull, it's a loose fit sealed by 2 piston rings! I thought that was a clever idea. It allows for thermal expansion and hull flex and still maintains a decent seal. And the old piston rings I removed from a Staghound engine recently were a good fit!

Malcolm
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  #11  
Old 18-10-19, 22:00
MikeV MikeV is offline
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Malcolm
And His guys are doing a great job I am Lucky to be a member of the same museum. Can't wait to see this tank roll out of the MVCC.
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  #12  
Old 22-10-19, 16:57
45jim 45jim is offline
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Default Centurion Clutch replacement

We found it easier to move the engine forward to replace the clutch. We marked the location of the engine on the mounts and cut some wood for positive reference between the engine and gearbox. It was a bear to lift out and replace the clutch but once installed it proved relatively easy to re-align the engine to transmission. The wood was used as a rough check as we were moving things into place and final alignment came from the reference marks we made during disassembly. We did have the element of experience as we had two old RCEME Cent guys assisting. I believe that while the suggested tolerances exist, the design is far more forgiving and while adhering to the suggested tolerances provides the maximum clutch and seal life a slight error will not affect its life as a parade vehicle.

As a side note, when a Centurion had sat for a period of time it is important to preserve the clutch during initial start up. Centurions stored outside often suffered from seized track pins, stuck brake shoes and there is always the possibility of a stuck clutch disc. We were told to warm the engine with the transmission in neutral clutch engaged. Once warm, a couple of light applications of steering tiller (while still in neutral) is applied to each side, not enough to effect a turn but to put some stress on the track and clutch. Once this was done and the brakes were known to be free only then was it moved forward or back to free everything up. Wonky track link got a smart smack with a sledge.

The Strathcona's stored their Centurions in Wainwright Alberta and they sat for up to 9 months a year (several months below -30C) with only a skeleton maintenance crew. All the training was done in a 3 month window from spring to early summer so every time the unit went up to train there was caution in how the tanks were brought out hibernation.
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  #13  
Old 23-10-19, 05:01
Malcolm Towrie Malcolm Towrie is offline
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45jim, I need to talk to you about this! I'll send a PM.
We've tried to drop the clutch in from the gearbox side (with the gearbox installed) but no go.

We are going to try rotating the engine 45 degrees in the hull to see if there is enough room to get the clutch in from the engine side, but it seems a faint hope. Now you are saying it can be done. I'll be in touch.

Thanks for the info on the risks of long term storage. Right now we have very frozen tracks from being a gate guard for decades, so I am certainly concerned about the first movement under power.

Malcolm
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  #14  
Old 23-10-19, 18:31
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We suffered a frozen clutch in our Centurion this year, and it was a real bugger to break free, finally followed Rick from the UK's advice and gave it a good shot with the steam cleaner as it was running, clutch depressed, worked like a charm. This winter she is coming inside!
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  #15  
Old 24-10-19, 04:37
Malcolm Towrie Malcolm Towrie is offline
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Do you mean ice frozen or rusted frozen, John?

Malcolm
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