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Old 10-21-2013, 03:36 PM
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thrust bearing clearance

how is it going everybody, im building a 383 , i ordered a stroker kit,
had the block cleaned and machined, im checking my clearances ,
my crank endplay is at .020 which is on the loose end of things,
whats my remedy to bring it closer to the tight end ??? this is a street machine. . thanks guys

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Old 10-21-2013, 04:02 PM
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Quote:
Originally Posted by 81camaro1 View Post
how is it going everybody, im building a 383 , i ordered a stroker kit,
had the block cleaned and machined, im checking my clearances ,
my crank endplay is at .020 which is on the loose end of things,
whats my remedy to bring it closer to the tight end ??? this is a street machine. . thanks guys
Different crank and or different bearings. This clearaance is usually pretty tight and .020 is at or beyond the upper limit. For a street automatic you can get away with this but not a stick nor a race engine with an automatic.

Bogie
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Old 10-21-2013, 04:40 PM
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Some SBC rear main caps are pinned and others are free to move back and forth in the register. You can oversize the holes in the cap if it has pins. Then when the cap is lightly tightened you can move it, forward or back, to reduce thrust play.. Common cure..
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Old 10-21-2013, 05:35 PM
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IMHO .020 is about double the max I would run.
On a new stroker kit I would expect to have .003-.008.
Are you checking with a new or old bearing?
If indeed you have .020 thrust clearance on a new crank and new bearing I would call the supplier you bought it from and try and get a better fitment crank.
I'm sure that is not what you want to hear, but .020 is just way to much.
If you look up factory thrust clearance you will see something like .002-.010
How are the rest of the bearing clearances?

Best of success with what ever you decide to do.
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Old 10-21-2013, 06:38 PM
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had a screw up on a crank one time and federal mogal (sp) makes a fat thrust bearing fixed it.
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Old 10-21-2013, 06:50 PM
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thanks guys, all the oil clearances are within spec. but the end play was little too high,,, I will contact the manufacture on this ...
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Old 10-22-2013, 03:16 PM
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Originally Posted by 81camaro1 View Post
thanks guys, all the oil clearances are within spec. but the end play was little too high,,, I will contact the manufacture on this ...
Since this didn't really go anywhere let me add this to my earlier comments.

Solve Crankshaft Endplay Problems | King Engine Bearings

This is King oversized thrust face bearing to allow regrinding of a crank's thrust faces. It is available in +.010, +.020 and +.030. Sine your measures indicate that the movement on the crank is .020 the .010 bearing ought to dial it in pretty darn close to spec without having to either replace the crank or regrind it.

A lot of talk is given to ballooning torque converters as a cause of the more and more common thrust bearing failures, but I rather think that lower viscosity oils, reduced operating oil pressures and improper bearing shape, finish and tolerance as well as similar problems on the shaft thrust faces have more to do with this than anything else. This bearing doesn't lube well yet is made of the same stuff as the journal bearings and is expected to live with journal throw-off not direct pump pressure.

My prep on these things is to lightly chamfer the bearing mating edges to provide a pressure passage from the center groove of the upper bearing to feed the thrust faces. I carry this idea around the thrust faces as well for the upper and lower halves but for a different reason. This is an area where a mismatch of the plainer surface between the upper and lower will wipe the lube off the bearing. This mating surface needs to be carefully checked in the mock up drill to insure this is minimized or non-existent. The slight chamfer at the mate helps eliminate an edge that squeegees the oil off the thrust faces.

Setting up the thrust faces takes some time. It is a good policy to install the bearing shells to the block and the respective caps. Install the crank with little oil onto the mains, then set the main caps on tightening their bolts or studs to 10-15 foot pounds. Then coax the crank back and forth a few times with a large pry and or soft mallet. I good leather mallet is excellent for this as you can whack the crap out of the crank and not harm it. Then check the thrust clearance and with a bright light inspect the gap between the thrust bearing faces and that of the crankshaft. With a pair of feeler gauges one unmolested by feeling down to the interface of the halves you can tell if it hangs up on the bearing edge facing toward you. With another gauge that you modify to put a small lip on its end edge you can check to see if it catches a bearing edge facing away from you upon removal.

You may find it necessary to assemble and diss-assemble a couple times to coax the halves to smooth interface. The chamfer helps I suggest gives this some working space to be a little off without this becoming an oil wiper. The crank's thrust faces also need to be smooth and hopefully flat with the bearing faces. We had an incident a few years ago where a major crank supplier delivered thrust faces that looked like they were whittled at Boy Scout camp. These tore up bearings almost faster than you could get the engine started.

Bogie
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Old 10-22-2013, 05:03 PM
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Also to add to bogies comment, the purpose of coaxing the crank forward and aft is to allow both thrust bearing face surfaces in the block and cap to become aligned in the same plane so the thrust face on the crankshaft is contacting both of them equally. Offsetting the cap to tighten excessive clearance is something you do if your working in a shop out in the middle of nowhere, 500 miles from civilization and a tourist comes in with a problem and you do this because you know you will never see him again. Doing this forces only half of the thrust bearing surface to contact the crank thrust flange and it then has to endure 100% of the cranks thrusting forces, and will speed up thrust wear. Oversize thrust bearings are a better alternative to correct this, other than trying another crank or consulting the manufacturer of the crank since it was purchased as a "new" part.
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Old 10-22-2013, 10:10 PM
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thanks guys, I did hear about offsetting the caps before , but I thought it was just a getting by remedy,, also is there any chance you would be able to post a pic of this "My prep on these things is to lightly chamfer the bearing mating edges to provide a pressure passage from the center groove of the upper bearing to feed the thrust faces"
kinda to give an idea of how it looks like? this is the 1st time I hear that .
thanks
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Old 10-22-2013, 10:11 PM
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Quote:
Originally Posted by oldbogie View Post
Since this didn't really go anywhere let me add this to my earlier comments.

Solve Crankshaft Endplay Problems | King Engine Bearings

This is King oversized thrust face bearing to allow regrinding of a crank's thrust faces. It is available in +.010, +.020 and +.030. Sine your measures indicate that the movement on the crank is .020 the .010 bearing ought to dial it in pretty darn close to spec without having to either replace the crank or regrind it.

A lot of talk is given to ballooning torque converters as a cause of the more and more common thrust bearing failures, but I rather think that lower viscosity oils, reduced operating oil pressures and improper bearing shape, finish and tolerance as well as similar problems on the shaft thrust faces have more to do with this than anything else. This bearing doesn't lube well yet is made of the same stuff as the journal bearings and is expected to live with journal throw-off not direct pump pressure.

My prep on these things is to lightly chamfer the bearing mating edges to provide a pressure passage from the center groove of the upper bearing to feed the thrust faces. I carry this idea around the thrust faces as well for the upper and lower halves but for a different reason. This is an area where a mismatch of the plainer surface between the upper and lower will wipe the lube off the bearing. This mating surface needs to be carefully checked in the mock up drill to insure this is minimized or non-existent. The slight chamfer at the mate helps eliminate an edge that squeegees the oil off the thrust faces.

Setting up the thrust faces takes some time. It is a good policy to install the bearing shells to the block and the respective caps. Install the crank with little oil onto the mains, then set the main caps on tightening their bolts or studs to 10-15 foot pounds. Then coax the crank back and forth a few times with a large pry and or soft mallet. I good leather mallet is excellent for this as you can whack the crap out of the crank and not harm it. Then check the thrust clearance and with a bright light inspect the gap between the thrust bearing faces and that of the crankshaft. With a pair of feeler gauges one unmolested by feeling down to the interface of the halves you can tell if it hangs up on the bearing edge facing toward you. With another gauge that you modify to put a small lip on its end edge you can check to see if it catches a bearing edge facing away from you upon removal.

You may find it necessary to assemble and diss-assemble a couple times to coax the halves to smooth interface. The chamfer helps I suggest gives this some working space to be a little off without this becoming an oil wiper. The crank's thrust faces also need to be smooth and hopefully flat with the bearing faces. We had an incident a few years ago where a major crank supplier delivered thrust faces that looked like they were whittled at Boy Scout camp. These tore up bearings almost faster than you could get the engine started.

Bogie
also is there any chance you would be able to post a pic of this "My prep on these things is to lightly chamfer the bearing mating edges to provide a pressure passage from the center groove of the upper bearing to feed the thrust faces"
kinda to give an idea of how it looks like? this is the 1st time I hear that .
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Old 10-23-2013, 01:40 PM
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i looked into it this is what i found,,, for anybody who might be interested
Thrust bearing failures
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Old 10-23-2013, 05:24 PM
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Quote:
Originally Posted by 81camaro1 View Post
also is there any chance you would be able to post a pic of this "My prep on these things is to lightly chamfer the bearing mating edges to provide a pressure passage from the center groove of the upper bearing to feed the thrust faces"
kinda to give an idea of how it looks like? this is the 1st time I hear that .
Try this; pictures just don't do what's needed justice so I drew it out on a photo. Uploading is always a PIA from my computer into this forum so I have to twist around to get a file type that hot rodders computer will accept.



Bogie
Attached Files
File Type: doc Thrustbearingmods.doc (290.0 KB, 21 views)
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Old 10-24-2013, 10:22 AM
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well bogie i apreciate you taking your time to explain this with the image,
i have read a bunch of stuff on this and never really got it , until now, now i understand where to modify the bearing, thanks again, and i contacted the king company they are shiping me a new bearing,
thanks again
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