Topics

Main bearing clearances


Jerry Summey
 

What, if any, should the clearance be from the outer face of the rear main bearing to the crankshaft counter weight. I have a new set of bearings and when you lay the crankshaft in the crankcase and try to turn it, the bearing turns as well. There is no clearance at all. This is being done with the bearings in the crankcase only, none of the bearing caps have been installed. I have built several Crosley engines and this is a first for me.


Steve Olinger
 

 I ran into the same problem if you are speaking of the thrust main bearing (the one with the flanges). Spoke to Butch when he ran Service Motors and he had never had or heard any customers have this problem with the new bearings. Everything plastigauged fine as far as the clearances but the thrust bearing was too thick on the flanges. I carefully sanded the flanges on flat glass and miked till I got the correct clearance. and even flange thickness.
Steve

September 20 2020 12:35 PM, "Jerry Summey via groups.io" <gaelecsol@...> wrote:

What, if any, should the clearance be from the outer face of the rear main bearing to the crankshaft counter weight. I have a new set of bearings and when you lay the crankshaft in the crankcase and try to turn it, the bearing turns as well. There is no clearance at all. This is being done with the bearings in the crankcase only, none of the bearing caps have been installed. I have built several Crosley engines and this is a first for me.


David
 

I race a Crosley powered H mod and I change bearings once a year.  With a new set of main bearings, the crank will be very hard to turn.  I sand the thrust flange on the rear main until I get .004” clearance (not sure if this is the ideal clearance).

 

David

 

Sent from Mail for Windows 10

 

From: Steve Olinger
Sent: Sunday, September 20, 2020 10:27 AM
To: crosley-gang@groups.io
Subject: Re: [Crosley-Gang] Main bearing clearances

 

 I ran into the same problem if you are speaking of the thrust main bearing (the one with the flanges). Spoke to Butch when he ran Service Motors and he had never had or heard any customers have this problem with the new bearings. Everything plastigauged fine as far as the clearances but the thrust bearing was too thick on the flanges. I carefully sanded the flanges on flat glass and miked till I got the correct clearance. and even flange thickness.
Steve

September 20 2020 12:35 PM, "Jerry Summey via groups.io" <gaelecsol@...> wrote:

What, if any, should the clearance be from the outer face of the rear main bearing to the crankshaft counter weight. I have a new set of bearings and when you lay the crankshaft in the crankcase and try to turn it, the bearing turns as well. There is no clearance at all. This is being done with the bearings in the crankcase only, none of the bearing caps have been installed. I have built several Crosley engines and this is a first for me.

 


Jerry Summey
 

Steve, that is the bearing that I am speaking of. How did you determine the correct clearances? Guess I could measure the one that came out of it but how do I know that it is right or not. This is the first time that I have had any issues with new bearings. I reall appreciate your input.
Jerry


-----Original Message-----
From: Steve Olinger <olinger@...>
To: crosley-gang@groups.io
Sent: Sun, Sep 20, 2020 1:27 pm
Subject: Re: [Crosley-Gang] Main bearing clearances

 I ran into the same problem if you are speaking of the thrust main bearing (the one with the flanges). Spoke to Butch when he ran Service Motors and he had never had or heard any customers have this problem with the new bearings. Everything plastigauged fine as far as the clearances but the thrust bearing was too thick on the flanges. I carefully sanded the flanges on flat glass and miked till I got the correct clearance. and even flange thickness.
Steve

September 20 2020 12:35 PM, "Jerry Summey via groups.io" <gaelecsol@...> wrote:
What, if any, should the clearance be from the outer face of the rear main bearing to the crankshaft counter weight. I have a new set of bearings and when you lay the crankshaft in the crankcase and try to turn it, the bearing turns as well. There is no clearance at all. This is being done with the bearings in the crankcase only, none of the bearing caps have been installed. I have built several Crosley engines and this is a first for me.


Jerry Summey
 

Thanks David


-----Original Message-----
From: David via groups.io <drlamber@...>
To: Crosley-Gang@groups.io <Crosley-Gang@groups.io>
Sent: Sun, Sep 20, 2020 1:47 pm
Subject: Re: [Crosley-Gang] Main bearing clearances

I race a Crosley powered H mod and I change bearings once a year.  With a new set of main bearings, the crank will be very hard to turn.  I sand the thrust flange on the rear main until I get .004” clearance (not sure if this is the ideal clearance).
 
David
 
Sent from Mail for Windows 10
 
From: Steve Olinger
Sent: Sunday, September 20, 2020 10:27 AM
To: crosley-gang@groups.io
Subject: Re: [Crosley-Gang] Main bearing clearances
 
 I ran into the same problem if you are speaking of the thrust main bearing (the one with the flanges). Spoke to Butch when he ran Service Motors and he had never had or heard any customers have this problem with the new bearings. Everything plastigauged fine as far as the clearances but the thrust bearing was too thick on the flanges. I carefully sanded the flanges on flat glass and miked till I got the correct clearance. and even flange thickness.
Steve

September 20 2020 12:35 PM, "Jerry Summey via groups.io" <gaelecsol@...> wrote:
What, if any, should the clearance be from the outer face of the rear main bearing to the crankshaft counter weight. I have a new set of bearings and when you lay the crankshaft in the crankcase and try to turn it, the bearing turns as well. There is no clearance at all. This is being done with the bearings in the crankcase only, none of the bearing caps have been installed. I have built several Crosley engines and this is a first for me.