How to polish the connecting rod journal?

[zacksstacks]

OK, I had one of those 'accidents'.    My connecting rod bolt dinged the journal on the crankshaft and made a dent!    It's a single thread's edge impression, not so much that I am sobbing but too much to ignore. I understand there may be ways to polish out the journal finish. So, what do you all think? Should I take up knitting or can it be fixed? Anyone tried the utterpower shoestring trick? I could use some advice here, especially anything that can be accomplished with the flywheels still on. Double especially where to get the materials and what to shop for...

Anyone?

Bueller?

[Doug]

Bob, Jack and the other "undoers" of bad things will probably have some advice.

I won't comment, but I did get some good advice from them and others to buff up my grooved and scored crank.

Doug

[abbamovers]

Ditto what Doug said.

Not the end of the world, easy to fix.
The dent more than likely raised the metal up in the area around it , but only a little.
You have to knock it back down level to the journal surface.

I would highlight the area with Prussian blue or a magic marker and obtain a sharpening stone with a fine closed grain structure.
Machinists/tool makers use these for just these sort of problems.
The stone is roughly the size of an O'Henry chocolate bar, is rectangular, brown in colour and is super flat on all it's sides. Roughly 1/2 inch thick X 1" wide X 6-7 " inches long.


Can be obtained at any good store that supplies Machine shops, check the Yellow Pages.

Light the area to be worked on well and place some rags to catch debris under where you will be working.
The stone should be used at it's narrowist edge ( 1/2 in. side ) , gently rub in a forward stroke about an inch with pressure applied down.
Use it with a bit of solvent to help it bite in.
Continually check, reapply marker, to see if you have knocked some metal off the high spot.
It will be very easy to see, since the rubbing marks will be different to the grind marks in the journal.
When you are close to getting near the journal preceed with caution and use slow deliberate curving strokes ( twist your wrist as you stroke, sounds pornographic  ) until the high spot just blends in with the journal.
It may help to use your other hand as a steady rest for the one doing the action.
Now you can polish that area with the shoe string method or some fine wet/dry paper.
The object is to knock down the high spot without taking any metal off the surrounding journal, a little tiny amount from polishing is okay but don't get carried away.
Clean the entire area spotlessly, oil and reassemble. 

The little dent won't make any difference for now, but if the high spot was left on it would wear out the rod bearing in that area.

Another method if you were anal, would be to tack weld that little indentation and remachine the journal back to perfection, a little too much work in my humble view.

I'm sure some others can chime in on other methods to fix it.



.

[zacksstacks]

On the wet/dry sandpaper - will emery cloth 320 grit do? Will that leave the surface smooth enough?

Also, I've read somewhere here someone used crocus cloth for a final polish. I believe afterward they decided it made the surface too smooth, not enough nooks and crannies for the oil. I have no experience to form an opinion about this, anyone have one for me? 

[Doug]

I can't offer any advice on dent removal but I did polish the abuse out of my Petteroid.

I was told to stop at 600 and went all the way to 2000. At this point Jack told me to stop before I used up all the factory packed elbo grease and needed some niples installed.

The grits above 600 remove very little barely even the marks from the 600.

This crank is still rough but that's life I'll regrind it downthe road I guess....


http://www.putfile.com/pic.php?img=4482328
http://www.putfile.com/pic.php?img=4694385

[gpkull]

if this is a ding from no vac hose on the rod bolts during assembly. smooth out the crank and carry on. the high spots will destory the bearings the lows will retain oil and any other metal that may be floating around

[Doug]

Do the Listeroid rod bolts come out?

Just currious, when I assembled my Petteroid I put the bolt in after I had the rod and cap in place...
A little STP oil treatment on the parts provided enough Stick-um" to hold everything together.

Another thing I noticed wat bolt stretch.....
Did anyone notice any stretch on the factory torqued bolts in their roids ?

Doug

[zacksstacks]

Yes they do.    I realized this just after the 'ting'....

[Florida Cracker]

I am in process of rebuilding my first Lister so take this with a grain a salt.  I have had luck using 400 grit emory cloth (thin strip roll) to polish journals an other engines and it works well. After a good cleaning I apply a good coat of white lithium grease, wipe it off, and then use plasti-guage to see how much clearance I have (has to be torqued). This won't show you where the high spots are but should be done on any bearing replacement. The previously mentioned methods will work...just don't take any more off the journal than you have to. I have used STP and lithium grease on engine rebuilds (not Lister) and it works well. After plasti-guaging I put a heavy coat while assembling.
Don

[gpkull]

cracker check the nip. do not assemble with grease or any other thick lube. these will retain what you want to wash out.

[cujet]

In the old days, we would draw file a crankshaft that had exactly this problem. We used a large fine pitch high quality file. We would carefully draw it across the "high spots" at about a 45 degree angle. In other words the file was not pushed from the handle end, but rather pulled across sort of sideways. This keeps the cutting edges of the file in perfect alignment with the direction of the cut, preventing any sort of "file marks" on the crank.

Before you dismiss this method, a careful craftsman could remove high spots without removing any additional material, or producing any other sort of new problem. The same cannot be said for using any form of sandpaper or polish to remove high spots. A gentle polish afterwards rounded the edges of the "thread marks" and the crank was good to go. Not once did we have a long term problem.

If you use caution, you will be fine.

Chris

[abbamovers]

Ah yes the days of " the " bastard file.
In my apprentice days , I had an old journeyman that made me true up some metal blocks to within a few tenths of a thou. using the file, before he would even let me go near let alone touch any machinery.
O happy days.
He was convinced you could build Rome with that old file as long as you had enough time and the moxie to do it.
The way he handled it I'm sure he could, me I always preferred the tools that had electricity running through them.   

[rcavictim]

The draw file sounds like a good idea to me.  I have always used white lithium (Lubriplate) grease on engine assembly including lower rod bearing.  I have been known to wrap a strip of paper and PVC electrical tape around the lower rod crank journal while the piston and rod is removed to prevent such dings.  I see where the rubber hose would be a good idea as soon as the cap comes off to protect the journal during piston/rod removal.

Can someone elaborate about the bolt stretch issue?  Does re-using the rod bolts at factory recommended tightening torque cause a problem?  10% over torque a good idea second time?  New lower rod cap bolts are seldom available when you need them I find.  How much `stretch` are we talkin` here anyhow?  This bolt stretch has always confused me since some bolts are suppossed to get their strength in this plastic state and others do not and will break.  How can one know what they have?  Some bolts are single use and I`ll bet usually get re-used.

[cujet]

rcavictim,

You already know the answer to your question about rod bolts. Use new ones of known good quality. However, there are so many different types and applications of rod bolts that it would be the subject of a 5 year thesis.

I suspect the Listeroid has the type that can be used over and over again. Think about this for a sec, they use cotter pins. Just how much torque/stretch did you apply? I thought so. I also believe that the Listeroid rod bolt loading is very low, even with cast iron pistons running 1000 RPM.

Back on topic, remember that certain methods of polishing will remove material that you do not want to remove.

Chris

[rosietheriviter]

rcavictim,
You already know the answer to your question about rod bolts. Use new ones of known good quality. However, there are so many different types and applications of rod bolts that it would be the subject of a 5 year thesis.
I suspect the Listeroid has the type that can be used over and over again. Think about this for a sec, they use cotter pins. Just how much torque/stretch did you apply? I thought so. I also believe that the Listeroid rod bolt loading is very low, even with cast iron pistons running 1000 RPM.
Chris

Chris, rcavictim, and Doug,

I was told by an extremely qualified mechanic (my daddy) that ALL bolts will stretch when torqued.  The higher the quality the bolt, the less stretch remaining after removing.

Lots of high power machinery have their bolts tightened by measuring the free length and then tightened to the specified length (stretched length).

If you are interested, you might try setting a dial indicator on the top or a head bolt and see how much stretch occurs when you torque to the appropriate value.

Rose is Rose