Jump to content

Babbitt BearingTolerances


Mark Shaw
 Share

Recommended Posts

My 1931 57 lost a rod bearing (probably a blocked oil passage). Since this rebulilt engine has less than 3,000 miles on it, I would like to pour new babbitt for just that one bearing. However, the crank is 0.015" out of round.

I have no reference info on what tolerances are allowed for rod bearings, but I expect that this is way too much. I have been told that some old shops had a tool to true the crank bearing without removing the crank from the car.

Does anyone know of this tool? What tolerance is acceptable before the crank requires resurfacing?

Thanks,

Mark Shaw

Link to comment
Share on other sites

Yes, it is really 0.015 out of round. My BrassBuicks group has already indicated that 0.0015 is about the limit. So it looks like I will be sending my spare crank to the machine shop. My spare has never been touched, so if there was a blockage in the rebuilt crank that caused this problem, it will be eliminated.

Thanks,

Mark Shaw

Link to comment
Share on other sites

I saw a fellow with lots of time and patience take .002" out of a crank throw. He used emery cloth like you would shine shoes. It took him three days. He lay under the car and with the high spot up pulled the emery cloth back and forth, remiking it about ever fifteen minutes then turning the crank a shade and starting over.

Link to comment
Share on other sites

That's what I did with my crank , although it was not all that bad just needed a touch up.

What I also did was re-size the 5 main and 6 big-end bearings by filing off the faces then re-scraping them all to the correct clearance .0015 -- .002 " Took me over 2 weeks to do this , but saved thousands $$$ by not having to have 11 bearings re-poured and then line bored.

I'm afraid .015 out of round journal is too far gone. It may be cheaper for you to drop the crank and if all the other journals / bearings are OK then just get the one re-done ??

Ken.

'29 Standard Tourer

'71 Centurion

Link to comment
Share on other sites

  • 11 years later...
2 hours ago, dibarlaw said:

They had babbiting molds and line boring fixtures etc.  Gone are the days..... 

The other Larry.

 I bought out a machine shop in Fresno 12 or 9 years ago and think I bought a engine line boring set it is buried  in a lot of hydraulic supply stuff I got the same day took days to move all the stuff and have never really looked at it yet . I think that is the problem with a emergency repair job shop never slows down enough to look at all the little stuff that gets shoved in storage ''C  TRAIN '' . cross that with a Foundry set and we could rebabbit a couple of motors pretty easy --kyle 

Link to comment
Share on other sites

I have an electric one and it is in Virginia at the moment. I'm in New York right now taking care of loose ends so can't even get a photo of it. Even with that type of tool .015 (about 1/64 of an inch.) is a mile and a half in machine shop talk and too much to grind out this way. If the .015 is on one side then the crank may have to be turned as much as .030 or .040 to be usable. Yes, Best to mic your spare crank and have that either turned or polished as needed. You have something that has gone though the engine and every oil galley, line and even the oil pump should be cleaned. Even a piece of dirt under the relief valve in the oil pump can lead to bigger problems. Also keep in mind that if either crank has already been turned your bearings may not work as they are. You will need to know if they are standard or .010, .020, or even as much as .040 under. Depends on what was done when the engine was rebuilt. Tolerances should be about .0015 to.003 on the bearings. Dandy Dave!   

Edited by Dandy Dave (see edit history)
  • Like 1
Link to comment
Share on other sites

  • 4 months later...
On 2/20/2018 at 9:27 PM, sligermachine said:

 I bought out a machine shop in Fresno 12 or 9 years ago and think I bought a engine line boring set it is buried  in a lot of hydraulic supply stuff I got the same day took days to move all the stuff and have never really looked at it yet . I think that is the problem with a emergency repair job shop never slows down enough to look at all the little stuff that gets shoved in storage ''C  TRAIN '' . cross that with a Foundry set and we could rebabbit a couple of motors pretty easy --kyle 

 

On 2/22/2018 at 8:14 AM, Dandy Dave said:

I have an electric one and it is in Virginia at the moment. I'm in New York right now taking care of loose ends so can't even get a photo of it. Even with that type of tool .015 (about 1/64 of an inch.) is a mile and a half in machine shop talk and too much to grind out this way. If the .015 is on one side then the crank may have to be turned as much as .030 or .040 to be usable. Yes, Best to mic your spare crank and have that either turned or polished as needed. You have something that has gone though the engine and every oil galley, line and even the oil pump should be cleaned. Even a piece of dirt under the relief valve in the oil pump can lead to bigger problems. Also keep in mind that if either crank has already been turned your bearings may not work as they are. You will need to know if they are standard or .010, .020, or even as much as .040 under. Depends on what was done when the engine was rebuilt. Tolerances should be about .0015 to.003 on the bearings. Dandy Dave!   

Hi Larry I have done several Types of rods / mains  cast and resized rods and semi finished mains. George.

Link to comment
Share on other sites

Thank you for chiming in George.

 At this time I am waiting for my 1925 Standard engine to be completed at the Reeve's shop in Cazinovia. NY. They finally received the Ross pistons last Friday! (Over 5 month wait)

 After removing the Standard engine to be rebuilt and hoping to be able to drive my 1925 Master in it's place the Master had developed a good "thump" in the bottom end at the end of September 2017. The Reeve shop is also rebuilding a spare 1925 Master oil pump for me since I was concerned about the low oil pressure (around 5 psi.) I have not yet investigated the Master engine problem since I had too much of the Standard spread out over the garage, the house, a shop doing the head in Chambersburg and of course NY. Once all come together for the Standard I can begin the Master. Depending on what I find, can just one rod be removed and re-babbited? That is without total disassembly of the engine? I removed the rods from my spare 1924, 6 cylinder engine from the bottom of the block. But the pistons had been removed at some previous time.

Link to comment
Share on other sites

I pour casting with my foundry it is a grate tool . 30 lb brass and a line boring tool is relay not needed not with my milling machines .I just don't have the time to set it up . 

Soon i will .  I have a few 1925 blocks to work with .just no free time summer is are run-run -run  time .

Edited by sligermachine (see edit history)
Link to comment
Share on other sites

Back in the 60's there was a "Putty's Portable Crank Grinding" in the Dallas area that turned cranks in the vehicle. Prepping the vehicle took some time and included disconnecting the motor mounts (usually), making the flywheel accessible, disconnect the fuel line from pump, remove spark plugs, and of course drop the pan and usually the oil pump. A 110v motor with the correct starter drive fit up to the flywheel to turn the engine while the grinding attachment was mounted to the rod journal. I think(?) the grinding stones were turned by what looked like a heavy duty speedometer cable as the crank went round and round. Putty and his son were very busy so you better have everything ready to his specs or he would leave for his next job. Used to see his rig at various used car lots but our call was for a Chicago police officer where his converted bus had broken down on the highway and stranded him and his family. Rod journal had to be turned 0.040 and have always wondered if it made it back to Chicago.

Link to comment
Share on other sites

On ‎7‎/‎9‎/‎2018 at 4:26 AM, mcdarrunt said:

Rod journal had to be turned 0.040 and have always wondered if it made it back to Chicago.

 

About 20 years ago I had a friend pick up a rod knock in his Jeep up in Quebec, 1000 miles from home. Old school mechanic in an old school gas station took the journal down 0.010 with a file and emery cloth. Told my fiend to keep it under 60 MPH and he would be good to go. He made it back home OK and drove it for a few  months afterward. I'm guessing there aren't too many places like that left..................Bob

Link to comment
Share on other sites

That was one patient "mechanic in an old school gas station"!

 

My cousin seized his Triumph motorcycle in about 1970. My father took out the carborundum stone and went to work on the big end journal. Peter was studying mechanical engineering at the time and was horrified. But the journal was put back into service.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...