Author Topic: 1978 850 T3 Restoration  (Read 4931 times)

Online n3303j

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Re: 1978 850 T3 Restoration
« Reply #90 on: January 22, 2023, 07:31:57 PM »
I am so close to finally rebuilding the top end (the whole purpose of the rebuild in the first place!)

But, I'm worried that I may have done something wrong in the reassembly, I am on the following step in the reassembly (see attachment). Bottom end is all but back together, excluding the oil sump.

However, in one of the two guides on thisoldtractor, he says,

"the best way to check if things are right are to set the case on its sump and the lift the rod to its highest possible point. With a decent assembly lube in the bearing, when released, the rod should slowly drop to the other side of the crankcase mouth under it's own weight. If it goes 'Clonk!' or doesn't want to move without force then there is something wrong."

I don't have that on my rebuild and so I'm pausing where I am for now. The crank does not move under it's own weight. It isn't binding anywhere, but it does need to be pushed. Not pushed too hard, it just doesn't move freely. I am using a brand new rear main bearing and rear seal. As well as new timing chain and timing chain tensioner.

I'm using this assembly lube, perhaps that is the culprit?

Is this common or have I done something wrong somewhere? I've been following instructions and torque specs to the letter, but it is likely that the guide wasn't thorough and I may have missed something due to inexperience.

The Crank won't move freely with timing chain, tensioner and seal drag added to the equation. That free fall is main or rod bearing friction only.
« Last Edit: January 22, 2023, 08:07:54 PM by n3303j »
'98 MG V11 EV
'77 MG 850T3 FB

Offline texasmoto

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Re: 1978 850 T3 Restoration
« Reply #91 on: January 22, 2023, 10:16:30 PM »

For a bonus lap I put together the pistons and cylinders this evening. Went so smoothly. What a dream working with those Gillardonis.

And now, the actual thing that was wrong with the motorcycle is fixed.  :grin:

Still got a long way to go!


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