Honing a bore (verses piston cylinder)

[Richard]

I finally got the kingpin on my backhoe popped out. There are some deformations, though slight...they're enough to prevent the new kingpin from going in.

The king pin has a SLIGHT taper on the top/bottom so is difficult to measure accurately.

So let's just say the kingpin/cylinder are right at 1 3/8" diameter. I have a 1 1/2" ball/hone and it seems that it's doing more spinning in the bore than polishing. (the balls are now slightly flattened where they have been doing some work on the bore)

I might buy another hone....and this has me wondering.... am I better off buying another 1 1/2" hone or get (a size I know exists) a 1 3/4" hone or, (if it happens to exist) a hone between the two sizes???

i currently have the new kingpin sitting in a cooler with some dry ice above and below it, hoping to shrink its diameter a bit.... and I bought a new (small) tank of MAP gas to try to heat the bore. (I don't have an oxy/acet torch to heat it with)

Makes me wonder if the new pin is supposed to be pressed in or "simply" slide in...

 

[RickB]

Reverse the power tool if you can, the balls will contact the bore differently and maybe work better. If you need a different hone I'd look for a coarser one rather than a larger one.

The kingpin should be a semi press fit. Your pending temperature differential should let it just about drop in. Be sure to check the fit of the kingpin against the rotating part of the assembly.

 

[Peter 315]

Maybe a brake wheel cylinder hone will work...Amazon.com: Lisle 1 Brake Cylinder Hone: Automotive

 

[Richard]

Yeah, I did the forward/reverse. I also have two hones, one 80 grit and then one at 120 grit. both of them now have some flat spots on them where they ARE honing the cylinder but, the very top lip of the bore has a 'ding' where (most likely) a sledge either hit it or, some mushrooming dinged it.... I'm not worried about that deformation.

On the bottom though... (we used a 30 ton bottle jack to finally break it free and push it out) I'm suspecting that one of the pins we used to extend the push of the jack might have gouged the very bottom of the bore. Not huge when you stick your finger in there but when we're talking the tolerances that this uses, it's probably a Mount Rushmore size!! So I've been focusing the hone a bit on the top 'ding' (which by finger feel is gone) and "Mount Rushmore" at the bottom.

Reason I think it got gouged when using the jack is the OLD pin doesn't show any sign of scraping and it would have to if it had to pass by this intrusion spot.

Fortunately, it's not "big" in the real world, but it's sure blocking the new pin from going any further. (I've tried to trial fit the pin from both the top and bottom)

 

[Richard]

I had one of those brake wheel hones in my hands yesterday....and put it back. I still have a voice in the back of my head that says that might be the perfect tool for those two 'dings' in my bore, and then after a tool like that smooths them down, THEN go to the ball hone. Having never used these before though... is why I'm asking.

 

[RickB]

Take a round file or a carbide burr to the ugly stuff. You're trying to hone the full diameter to cure a problem in a specific spot.

 

[ruffdog]

Spray a liquid like kerosene or just wd40 while you are honing as it will help the process.

 

[Richard]

Had plenty of oil.

Ended up going through 4 hones to get it done. Two flex/ball hones and two brake cylinder hones (why doesn't anyone carry replacement stones for those anymore...)

Got it done, got it back together and I'm finally mobile with the machine after probably 4-5 months of sitting there getting worked on intermittently.

That said, in the meantime, I've put new hydraulic fluid in, flushed & replaced transmission fluid, new motor mounts, put new seals in the valve control box on the back for backhoe controls, had steering pump rebuilt, rebuilt steering cylinder (which is what started this whole mess).

All of that to get it ready.... just in time for winter (sigh)

But, it's done...so now, if a tree falls across road, I can get it done without having to wait 5 hours for the county to maybe show up!!