Flex plate bolt rubbing

[Macdon221]

Hey All,

Got a bit of an issue. 68 440 with 727.

I have a metal knocking noise from bellhousing area when stationary, in all gears, but foot on brake. Reading the past posts I decided to remove the bellhousing cover. As you can see…I have a witness mark that of course looks like from the flex plate bolts. The bolts however doesn't seem to show any marks to indicate contact.

I checked the 4 bolts. They seem tight.

Is there a way to check the bolts that secure to the crank? I can get a skinny wrench up there in between the plate.

I have replaced the u-joints recently and rebuilt the rear diff…but cant see how that would affect anything. Also been using the car for a bit with no issues there. This noise just started. I also checked almost everything else. Exhaust to manifold, etc

Any other suggestions? Any help appreciated.

macdon221

 

[pnora]

Is the noise gone with the shield off?

 

[davek]

is the shield on backwards? Start the car without the shield and see if it makes the noise.

 

[Roger63]

I agree with the previous post but to add to it I have had flex plates Crack before around the area that bolts to the crank.

 

[Macdon221]

Sorry. Yes. With plate removed there is no sound.

i was able to get a skinny wrench up there and check the crankshaft bolts. They are not loose by no means.

 

[pnora]

Sorry. Yes. With plate removed there is no sound.

i was able to get a skinny wrench up there and check the crankshaft bolts. They are not loose by no means.

Did you rotate it 360 degrees looking for the contact point? You should be able to see something. If not give it a coat of paint, put the shield on and see what happens. Make sure the shield if fitting properly. Only other item you could check is for excessive crankshaft end play.

 

[1 Wild R/T]

You have a 10 3/4" convertor and your dust shield is for the 11 3/4" convertor... The path of the bolts is clearly a smaller circle that the area with clearance designed into it...

This style cover clears both....

 

[1 Wild R/T]

Seeing as the noise just started you might want to check the crank for end play... It should be less than .010 but honestly .025 wouldn't worry me... I've seen engines with upwards of .10 At that point things that shouldn't touch often do....

I still lean to finding the right dust cover & your noise will stop..

 

[steve340]

The flex plate does in fact flex so if the cover is close you may get contact.
Excessive crankshaft end thrust would warrant investigation especially in an automatic car were the thrust surfaces get very little work.
American designed V8 motors generally give little trouble crank thrust wise unless something is wrong.

 

[66 Sat]

You have a 10 3/4" convertor and your dust shield is for the 11 3/4" convertor... The path of the bolts is clearly a smaller circle that the area with clearance designed into it...

This style cover clears both....

View attachment 1161382

Fair play, you might be the most helpful and knowledgeable guy on here. Good work!

 

[BSB67]

Fair play, you might be the most helpful and knowledgeable guy on here. Good work!

That was an impressive catch.

 

[Macdon221]

A very impressive catch!

I double checked all the bolts. They were all tight. I took the cover and placed it on a flat piece of glass and massaged it perfectly straight. Re-installed and all is fine now. Now to find the correct plate!

Thanks to all who chimed in!

 

[pnora]

You have a 10 3/4" convertor and your dust shield is for the 11 3/4" convertor... The path of the bolts is clearly a smaller circle that the area with clearance designed into it...

This style cover clears both....

View attachment 1161382

There is your answer.

 

[Macdon221]

Yup. Mystery solved!

thanks so much.