Flywheel Housing Specs

[ursus]

I am familiar with the need to measure run-out on the flat surface of the flywheel housing rim as well as run-out on the flywheel surface itself. But what about the narrow ledge where the flywheel housing mates up with the raised ring on the bell housing?

Since this is necessary for correct alignment of the crankshaft with the transmission input shaft and clutch I wonder if anybody has measured the run-out on the ledge and what the allowance is for run-out on this aspect?

 

[alexiskai]

My understanding is that the run-out is measured between the two planes, I.e., the machined surface that mates with the block and the one that mates with the bell housing must be parallel to each other and the run-out spec is the tolerance for that parallel relationship.

 

[Jim Mason]

From the krw catalog and the service bulletins

 

[BRENT in 10-uh-C]

I am familiar with the need to measure run-out on the flat surface of the flywheel housing rim as well as run-out on the flywheel surface itself. But what about the narrow ledge where the flywheel housing mates up with the raised ring on the bell housing?

Since this is necessary for correct alignment of the crankshaft with the transmission input shaft and clutch I wonder if anybody has measured the run-out on the ledge and what the allowance is for run-out on this aspect?

Since that flanged is recessed, there is not much you are going to be able to do, -plus that area is fairly strong.

FWIW, I have not measured runout on the flywheel mating surface nor the Flywheel Housing in probably 3 - 4 years because there is not any need in it if the proper machine work is done by the rebuilder. Before I grind a crankshaft, I straighten the crank. Then when I am finished grinding I straighten the crankshaft. Therefore I know my flange is exactly perpendicular to the crank's centerline.

Also, I have found that probably 80% of the Flywheel Housings I see are warped. Therefore I restore every housing on engines that we do. That way I know the housing does not have any runout from the crank's centerline. A little tip for you. Folded aluminum foil can be used for determining the gap between the boss on the Block and the Housing. Keep folding the foil material until you have the proper thickness. Mic it and then add the proper amount of shims.

BTW, this is how I know the Flywheel Housing is coplaner with the Clutch Housing flange; Flywheel Housing Restoration


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