Oversized thrust bearing

-
subcom

subcom

FABO Gold Member
FABO Gold Member
Joined
Sep 17, 2010
Messages
1,968
Reaction score
1,356
Location
South Florida
Is there a source for oversized thrust bearings?
I made a mistake and had my 5.9 magnum assembly balanced without checking the crank thrust first. I put the crank in to discover it has 0.020 of play when measured at the snout or with a filler gauge between the crank and thrust surface. I removed the crank to discover that the thrust face of the crank on the back side has quiet a bit of wear. I tested with a different crank I have lying around with the same bearings and I'm at about 0.04 which is within the 0.02-0.07 margin. I hate to start over with a different crank since this one is already balanced with the rest of my rotating assembly.
Is there a thrust bearing that is wider at the thrust surfaces I can buy? I see that King offers something but couldn't find a part number.
 
I am not aware of anything like that.

As for another crank.... you DON'T have to re-do the whole re-balance job. The bobweights of all of the piston/rod assembles should have been matched in the original process, and there is absolutely no reason to do that part over with another crankshaft. You just take the bobweight that was used to balance 1st crank, and balance the 2nd crank to that same bobweight.

Talk to your shop that did the balance work and see if they kept the bobweight data. That would be easiest. If not, then they should be able to take any of your piston/rod assemblies apart and re-measure the bobweight and use that to balance the 2nd crank.

You'll have to take them the damper, and flywheel or TC+flexplate, that you took them before, if those were used in the balance process.
 
nm9stheham said:
I am not aware of anything like that.

As for another crank.... you DON'T have to re-do the whole re-balance job. The bobweights of all of the piston/rod assembles should have been matched in the original process, and there is absolutely no reason to do that part over with another crankshaft. You just take the bobweight that was used to balance 1st crank, and balance the 2nd crank to that same bobweight.

Talk to your shop that did the balance work and see if they kept the bobweight data. That would be easiest. If not, then they should be able to take any of your piston/rod assemblies apart and re-measure the bobweight and use that to balance the 2nd crank.

You'll have to take them the damper, and flywheel or TC+flexplate, that you took them before, if those were used in the balance process.
Click to expand...
Thanks. Im considering that also. All of the Bob weights are marked on the pistons. I'm calling my machinist next week to see what he says. Maybe he'll cut me a break on the cost even though he's already pretty economical. I paid $250 to have it balanced last time. I feel stupid for not catching this at first.
 
Last edited:
my68barracuda said:
You are looking for King Pro Flange thrust bearings.
They are available in .010, .020 and .030 over size at the thrust face.
I would expect that Clevite has something similar.
Click to expand...
That is excellent info. I just went through the King online catalog since you listed this, and found that the only oversized flange available is in the .060" undersized MB, and is only .010" wider... so not enough to take up the reported wear on the OP's crankshaft. But please check on my reading of their catalog to make sure I have this right. Not sure on the other mfr's.....you'd have to check each catalog to be sure of what specific widths are available.

Hey, crap happens! You caught it which is the most important thing.

subcom said:
Thanks. Im considering that also. All of the Bob weights are marked on the pistons. I'm calling my machinist next week to see what he says. Maybe he'll cut me a break on the cost even though he's already pretty economical. I paid $250 to have it balanced last time. I feel stupid for not catching this at first.
Click to expand...
Yes, if you have to go that route. Not sure it will be cheaper to balance another crank or turn the flange on what you have if you can get the above bearings in a suitable width. BTW, if those marked weights are bobweights, they will normally be in the range of 1800-2200 grams, depending on the actual rods and pistons being used. If the numbers marked are in the 500-700 gram range, then they are piston or piston+ pin weights.
 
please check on my reading of their catalog

If I was looking for these bearings I would be taking directly to one of the King Technical persons.
There are always errors and omissions in any public catalogue. Especially when it comes to low volume parts.
When looking for parts that are outside of the majority of the sales, you want to talk to some one that can look
inside the actual manufacturing data base.
 
Find a new machinist. Any machinist who blindly puts a crank in the balancing machine and balances it without giving it a quick once-over first should find a different line of work. Don't blame yourself for not catching it. Blame your machinist!
 
My 68; thanks for the pdf from King Brgs.com. I never knew those bearings were available. The pdf states that the journal sizes and the flange widths are available in 010, 020, and 030. and that you can mix and match to suit your needs. Cool.

Subcom.; Your thrust main will have to be reground at the damaged side first [grind to clean]. then grind the other side to dimension. This gives you another option.

The guy who balanced the crank might have kept the bobweight specs for your old crank. Talk to him and say that 'we both didn't notice something we should have', can you help me out?' Maybe he'll balance your spare crank for cheap.
 
Be careful what you read into this IMHO: King says elsewhere that they only make them for certain applications so no they are not available for all apps; don't expect to find them in a 'mix and match' configuration for every app. If you go into the current King catalog, it shows them for things like Chevy 350 in .010, .020 and .030. wider flange for certain undersizes, but not for the 360 unless it is in the .060 undersize, and then it is only .010 wider. If anyone actually calls King on the 360 thrust oversize matter, I am sure we'd all like to hear the outcome.
 
Quick update:
I had my other crank balanced. Machinist charged me next to nothing and appologized for missing the problem with the thrust surface on the last one. I got it installed and the thrust is now spot on. Thanks again for all of the recommendations.
 
subcom said:
Is there a source for oversized thrust bearings?
I made a mistake and had my 5.9 magnum assembly balanced without checking the crank thrust first. I put the crank in to discover it has 0.020 of play when measured at the snout or with a filler gauge between the crank and thrust surface. I removed the crank to discover that the thrust face of the crank on the back side has quiet a bit of wear. I tested with a different crank I have lying around with the same bearings and I'm at about 0.04 which is within the 0.02-0.07 margin. I hate to start over with a different crank since this one is already balanced with the rest of my rotating assembly.
Is there a thrust bearing that is wider at the thrust surfaces I can buy? I see that King offers something but couldn't find a part number.
Click to expand...
How much thrust did the first crank have???? ) 0.200 two hundred thou. or .020 twenty thou.
 
Yeah it was 0.020, really sloppy. Should be between 0.002-0.007.
 
Last edited:
Wow sloppy for sure!
Almost a 1/4 of a inch(0.250) WOW Good catch!
 
You must log in or register to reply here.
-

Back
Top