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MGB Spigot Bushing Chewed Up

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Mickey Richaud

Mickey Richaud

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Yesterday I separated the donor engine and transmission for the Victor TF, and pulled the clutch assembly. When I removed the assembly, some little chunks of bronze fell out. The spigot bushing had broken, the rear 3/8" or so shattered into seven or eight pieces. Wondering what caused that; anyone know? The input shaft of the transmission looks fine, and there's very little play in it. Clutch looks OK as well; disk is glazed, but no apparent damage.

Also, Moss lists two sizes, 1" and 1 1/2" long, for the spigot bushing for the 5 main engine, but no explanation as to application of either one. Anyone have any insight here? The bushing in question was 1 1/2" long.

Thanks,
Mickey

Edit: By the way, the bushing was not tightly fit - slipped out quite easily.
 
A picture - two of the fragments fell to the floor when I removed the clutch; the rest were where you see them. No idea of the history of this engine/trans.

spigot bushing.jpg
 
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That's not likely to be good for transmission longevity. :grin:

I'm curious what answers you get, was not aware there were multiple options for these.
 
almost looks like the spigot was just a hair too long - or not seated properly. Nothing looks misaligned - that would be oval or a longitudinal crack. That looks like it has been nibbled from the end.
 
As for length differences, I found out that either length will work; the longer giving more bearing surface area.

And still a bit of a mystery, though the fact that it was somewhat loose may have allowed it to move back and forth in the crank, which I would think contributed to the problem.
 
JPSmit said:
almost looks like the spigot was just a hair too long - or not seated properly. Nothing looks misaligned - that would be oval or a longitudinal crack. That looks like it has been nibbled from the end.
Click to expand...

Oh, when I separated the engine and transmission, there was a substantial mouse nest in the bell housing! (Thought mice just ate cheese and peanut butter...)
 
Mickey, did you get a new bushing yet? If the longer bushing fits tight and is flush with the surrounding surface, I would use it. In my estimation, that bushing has worked loose and caused the problem. Test the new bushing for fit at room temperature, it should be very tight, if it is, freeze it then insert it. If at room temperature it can be pushed in almost by hand, knurling the outside could solve that problem. Machinist work. Those bushings should be installed using the proper tool as not to distort the the bushing in any way. JMHO. PJ
 
No, too early to get a new one. I'll be building this engine over the winter and attaching the rebuilt overdrive to it. Then install it in the Victor frame while the body's at the paint shop.
 
As Paul noted, if it's loose, that would allow for odd vibrations twixt the crank and input shaft. Various RPM differences as gears are changed, running in neutral with the clutch in or out. It would be similar to hammering on the bushing. Bronze is a fairly brittle material and doesn't take kindly to being impacted. Low Charpy numbers!
 
I'm curious when you get into the engine, if there is front to back play in the crankshaft... not sure if that is even a possibility for the bushing failure, but it could have eaten a few thrust washers.
 
Pretty sure it somehow worked loose and spun in place; there are very faint striations on the outer surface indicating that. Not sure yet if it damaged the crank inner surface; will find out when I get into it. But the marks on the bushing aren't really grooves, so hopefully no harm. I did find out that the spec for the hole in the crank is 1.125". I measured this bushing and it's 1.12". And apparently either the 1" or 1 1/2" size will work, as long as it's a snug fit.

And yeah, Kenny, I'm anxious to get it opened up and see what's what. This will be getting a thorough and proper rebuild; should be fun!
 
Judging from the fact that the flywheel bolts are narfed up and the lock ring was re-used , so also could the spigot bush . If too long a bush is used it bottoms in the crank and the input shaft has nowhere to go but to break the end away like you see. Or the gearbox could have been tightened down with the input shaft off center a bit. I wouldn't overthink it , just make sure it is set in deep enough so the shoulder of the input shaft doesn't bottom on the bush.
 
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