[roger1]

My Muncie is making a clattering noise in my Corvette.

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?

 

[302 Z28]

Excessive clearance on input shaft where the small bearing interfaces with the main shaft. Did you use a quality rebuild kit, or one off Ebay ain: .

Vince

 

[roger1]

Thanks Vince. I suspect you may be right.
I got the overhaul kit from Transmission Exchange out of Portland.
http://www.txchange.com/
I bought the kit with a telephone order but I see that they do a lot of selling on eBay.

I probably wont get the tranny pulled out until later this week.

What actions do you recommend I take once I get it out. I am not familiar with how to check that clearance or what to do about it if that is the problem.

Should I order another rebuild kit that is a certain brand?

Roger

 

[302 Z28]

If the bearing race on the end of the main shaft shows any wear at all it can cause some noise. I used to get all my overhaul kits from 5speeds.com their kits are top shelf and even include a new counter shaft, not cheap but well worth it IMO. They also have a lot of Muncie parts.

Vince

 

[RippinRon]

The people atD and L Transmission are very knowledgeable as well.

 

[roger1]

Thank guys. Both those places look like they should have knowledgeable people on Muncies.

I probably won't be able to pull the tranny till near the end of the week. Yard work today and then I'm going to make a trip tomorrow to go look at a '55 Chevy 2dr hardtop that I'm interested in. I tell you, this retired life is rough.

Once I pull the tranny out, I will probably have more questions here and I might phone one or both of those places. In any case, I'll keep you posted on the progress.

I don't care what the problem is or how much it cost, I want to get it right this time. Pulling a tranny on a C3 Corvette is a PIA and I don't want to have to do it any more times than I have to.

Btw, Vince, I'm in San Angelo. How far away are you from me?

 

[302 Z28]

Thank guys.

Btw, Vince, I'm in San Angelo. How far away are you from me?

Quite a ways, I'm about 35 miles from the Oklahoma border, straight up 75 from Dallas.

Vince

 

[roger1]

Well,

I bought that '55 hardtop yesterday.

I spent this morning getting my shop cleaned up and organized enough to start on pulling the tranny.

I got the car up in the air and disconnected the driveshaft at the rear of the tranny and then started the car. I can't make it make the noise in any gear or any speed.

Any change of thoughts of what the problem might be based on this?

 

[ericnova72]

No change in my thoughts
Vince could still be right, because with the driveshaft out you have removed all load from the mainshaft, and thereby taking all load off the bearings in question at the front of the mainshaft. In first and second gear you are sideloading the middle of the mainshaft, in third and fourth you are sideloading the front of the mainshaft.

 

[roger1]

No change in my thoughts
Vince could still be right, because with the driveshaft out you have removed all load from the mainshaft, and thereby taking all load off the bearings in question at the front of the mainshaft. In first and second gear you are sideloading the middle of the mainshaft, in third and fourth you are sideloading the front of the mainshaft.

OK that makes sense. I didn't know that the load from just turning the wheels off the ground versus the no load at all would make that much of a difference.

I'll pull the tranny in the morning.

Thanks.

 

[roger1]

Found the noise. :thumbup: :embarrass

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. :spank:

Thanks everyone.

Edit:
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.