What oil clearance is recommended for a Babbitt ball cap? Lang's catalogue states 0.004" to 0.006" is required. That seems too much clearance when new and would allow too much oil leaking past the 4th main?
Lately have read and heard a lot about the ball bearing ball caps and the trouble with oil leaking past them as well.
I would figure on .002” total clearance for a babbit one
I also like ball bearing ones but I have VERY specific installation criteria and I don’t feel like dealing with all the other experts. I will discuss it in a PM if you are interested or we could probably visit on it next week sometime
I machine ball cap .0015 - .002 over the measured diameter of the clutch plate tailshaft ...this is based on recommended clearances of .0008" -.0012" per inch of bearing diameter for this type bearing and Babbitt bearing lining ( Machinery handbook ,and Federal Mogul bearing ) ....004"-.006" seems excessive in any condition of operation ...always an optimist...gene french
Babbitt ball cap clearance is .002-50, and not under, to not over .003
The reason for .002-50 minimum, is when the ball cap tightens up, most of the surfaces where the ball cap lays is very uneven, and tightening the four ball cap bolts will twist the ball cap Babbitt bearing, putting a bind on Babbitt, and tail shaft.
The factory bored the Ball Cap to 1.9/16, or 1.562-50, the standard shaft tail shaft measures 1.560-00, giving clearance of .002-50 thousandths.
At 4 to 6 thousandths, You will put a lot of oil down the driveshaft tub.
A Bearing, is a Bearing. What if a rod, or main bearing was set to 4, or 6 thousandths?
The FORD factory bored the ball caps to .005” to .008” over the driving plate shaft and this fact CAN NOT be disputed because many, many people have seen copies of the ACTUAL FORD PRINTS.
The clearance was so wide because FORD knew what their manufacturing variances were. It was easier to make a wide ball cap clearance than to machine other parts in such a way that they had zero runout. These wide clearances did leak some oil, but prevented other issues like a burned out fourth main, loosening of drive plate rivets, loosening of brake drum rivets, etc.
HOWEVER, anyone doing a comprehensive, precision engine and trans rebuild, that takes the time and potential expense to insure that the drive plate shaft has virtually no run-out will be very satisfied with the results they get from using a clearance of anywhere from .0018” to .0025” as Gene and Herm have advocated. I, personally will set a ball cap at .002” over the drive plate shaft if it is an engine I, or a customer have blueprinted and we know the runout is less than .002”. If a customer does not know the amount of runout on their engine, I will machine the ball cap at .005”, which is FORD’s minimum recommended “safe” clearance.
This is a good discussion. Thanks, guys.
A potential solution to Herm and Adam’s conundrum is to use a “floating” transmission shaft. Available in the US from Dan Hatch
Debunking 11:10, PM Post.
Paragraph 1. Any good machinist knows you don't give any bearing .005, to .008 thousandths, unless it is a 5 and 8 inch shaft. Ford Prints are prone to the same mistakes that any other prints are. Like in housing, doors, and windows, that go no where, but nobody questions it till its all done.
Paragraph 2. LOL, " manufacturing variances " LOL, really, That's what you think, and that is a long ways from fact. All of the engines we have built, I have NEVER seen a tail shaft, other then 1.560, unless it was wore, that was always tapered, and at the front was still, 1.560. the only variances in my opinion is in your machine work. You make up a lot of stuff, don't you.
This size is just like the rods. They ground the crank to 1.250,-.002. The same way as the tail shaft, Tail shaft was 1.560, and the hole in the cap is 1.562-50, or 1- 9/16's. Very simple.
Paragraph 3. A Clearance of .001-80, will smear Babbitt. The shaft when hot will be at least one and a half thousandths larger in brake in. Some even go close to double that. Brake in Temp. in the crankcase can be 380, to almost 500 degrees, in the crankcase. A .005 thousandths ball cap for clearance, is already wore out.
When building a engine, run out is O to not more then a half thousandths. If it's over that, you screwed up in your center line, some place. Every thing has to fit, piece by piece, in a straight line.
Crank shaft, and crankshaft in the Babbitt. The next would be transmission shaft, the last would be Brake drum bushing, and tail shaft bushing, has to be in perfect alignment, and also the crankcase, and the ball cap machined in alignment.
To get the tail shaft bushing in alignment with the one bushing in the brake drum. This job can NOT be done on a lathe, the tail shaft will never be centered. That is one of the reasons the tail shaft won't turn center.
You Guys with broken crankshafts, it is all bad Alignment. Every time the crank flexes, it's heading for a crack, its NOT the cranks fault.