My Muncie is making a clattering noise.

I just rebuilt it and must have missed something. I've rebuilt a Muncie a while back on my old Camaro so I'm not an expert but have some experience with them. The Camaro one I did came out fine.

It sounds like something is rattling loosely against the case. It's quite loud but doesn't do it all the time. I sure can't find anything wrong on the outside, so it must be coming from the inside. But it is such a clanging rattle, it sounds like it is coming from the outside.

It's most noticeable in 3rd and 4th gears at slow speeds and seems to do it whether the car is under power or coasting. It does not make a noise in sitting in neutral.
When I'm rolling, I can't hear it when I let off and push in the clutch either.

I just put the rear on blocks under the shock mounts so the geometry of the rear would be as running. Using a stethoscope, the noise is loudest on the transmission and non existent on the rear end housing. I can hear it on the bell housing but not aa loud as the transmission. Other than the noise, the tranny seems normal.

I put new synchros, new front and rear main shaft bearings, and new reverse gear on top of the small parts kit. The end play in the cluster gear was within specs. It's also all new is the clutch, throw-out bearing, pilot bushing, pressure plate with a resurfaced flywheel.

My next thing to do before pulling the tranny back out is to put it up on jackstands and pull the driveshaft and then run it to make sure it's not the front U-joint making the noise. I don't think it is that though since the I just put in a whole new driveshaft and U-joints when I did the tranny.

Any educated guesses what I have done wrong?

 

No expert here. Its pretty hard to get something out of place they usually just wont go back together if you do. The one thing that comes to mind would be the spring loaded preload gear on the cluster. I've seen them come loose and make noise. I remember one time the reverse gear making racket but cant remember if it was just adjusted wrong or what. Thats all I've got.

 

Found the noise.

I started out pulling the starter because I figured I would be pulling the bell housing for a clutch inspection as well as the tranny. Wow, I'm glad this is what I decided to do first.

It was simply a warped clutch inspection cover. Once I took it off I could see that it was hitting the flywheel up near where it bolts to the crank.

I put the starter back on without the inspection cover and drove the car around town and no noise.
I am not even going to try to straighten the cover out. Just going to get a new one. I should have done that in the first place.

I just ordered a new one. The picture of it shows 2 tabs near the crank area that I suppose keep it away from hitting. My old one doesn't have those tabs.

 

The tabs are a bit of a pain to get on right if someone does have patience.