Backhoe Bushing Boondoggle - Advice needed!

john_bud · Mar 9, 2006

Hi!
I am redoing the bushings and pins in a Ford 723 backhoe. First off, I am slowly getting the bushings out with the old heat and hammer method, are there any tips on getting them out easier?

Next, and more importantly, there is damage to the bushing mounts on the bucket, dipper stick and boom. (I won"t even get into the pivot having washers welded on to hold the pin in! I really could slap that person around...) On the bucket, it must have been run without a bushing for a while as the holes are really bad wallered out. There is only a small segment in the center where the ID is about right for a new bushing. The outside edges in places are about 1/8 inch too big. I was thinking about putting in a new bushing and the filling the gaps with braze. Good idea, stupid idea? Got a better idea? I"m all ears!! I know, in 10-20 years, someone is going to be calling me an idiot.

On the dipper stick and boom the problem is the same, but the cause is different. I looks like someone used a cutting torch on the bushings and cut into the tube that holds the bushing. These are only bad in a few places and may even be ok to just slip in a new bushing.

Last, there is extra plate steel welded onto the boom and dipper stick. Quite a lot in fact, every side has been over plated with 3/8th. There are a couple issues with it. It really makes the tractor nose light. Should I just put up with it or cut it off and fix any hidden cracks/damage? Next, the cylinder bushings on the top of the boom (actuates the dipper stick) have been covered up by the plate. They are real loose and have to be replaced. I have a hole saw, but how to pilot it? The pin is 1.5", bushing is 3/16 wall.

Thanks!
jb

Soundguy · Mar 9, 2006

If the bushings are ferrous (sp?)... weld a bead around the circumference of the id.. let cool.. they should shrink and easilly knock out... if they are yellow metal.. beat them and fold them in.. then beat out.

Another way is to use a hacksaw blade to cut thru but stop when you hit base metal.. this makes a relief, and a way to get penetrating oil in.

Use canfdle wax.. heat joint then apply.. hot joint will suck wax in as it cools.. .. wax acts as a lube when the bushing is pounded out..

heat cool.. repititions.. I sometimes heat then quench with pb oil. then heat and let cool naturally, then start over... that usually breaks the rust free..

well that's all the tips I got..

Soundguy

MossRoad · Mar 9, 2006

More heat, a bigger hammer and a guy with arms like Popeye!

Last fall I attempted to beat a steering pin out of it's bushings and couldn't. I used my torch and a sledge hammer. Not a budge. I took it to a shop and the guy did the exact same thing as I did.... except he beat on it for 1/2 hour non stop, then took a break. The next day he said it took about 20 more minutes and it came out. 50 minutes of beating with a sledge hammer and heat to get it out. Oh, yeah, he was hard of hearing, too! WHAM! WHAM! WHAM! /forums/images/graemlins/tongue.gif

5030 · Mar 9, 2006

John:

Your bucket and probably the dipperstick bushings can be bored on a vertical mill and new bushings pressed in. They can also be line bored right on the machine for a price.

Last year, I made new bushings for a friends Michigan 10 yard articulated loader bucket out of 660ca high shock bronze. The bushing diameter was over 11". He had AIS Machinery Service come out and line bore the bushing holes on the machine. I made the bronze inserts 0.005 oversize and then chilled them in dry ice, slipped them in and away he went. Of course he greases them like the previous owner didn't.

Your loader is much, much smaller so, any competent machine shop can bore your old bushings out and replace them with bearing bronze or steel, whatever your prefer.

Like Soundguy stated, if you want to remove a steel bushing, run a bead from one end to the other, let it cool and it will shrink and can be driven out easily. That works for dry linered diesels too.

Too bad you don't live close. I'd do it for you in the shop for a barley morsel or two. /forums/images/graemlins/grin.gif

Bigbear · Mar 9, 2006

john_bud I don't think a slap would get some of those fellers attention, they just seem to have a knack for messing things up. I have sometimes heated the bushing pretty good, so the heat goes into the surrounding metal and then put ice into the bushing to make it shrink, and they come out pretty quick. In reverse, it's called a press fit, heat the OD pc, cool or shrink the ID pc, when them stabalizes, there almost welded. Usually about .005 makes a tight fit.
As far as fixing the ID, I have brazed a few rings around the hole (half way through) and then come from the other side with a hole saw to true it up. When you use this method and the brazing is cool, make a pc of wood that will tap into the hole, so the hole saw can use this for a pilot hole, otherwise your hole will be egg shaped. It's takes a big mill to lay the boom and dipper stick on, in order to do it right, but this is a down and dirty way of saving one. If your making your own bushings, you can make them to fit the finished hole, along with the new pins. Make sure you through drill the pins so you can add grease fittings, usually the cause of the failure to start with. Hope this helps. BEAR
OH, you can make round ice cubes with dixie cups and add a stick to hang on to, wear gloves, they tend to spit steam back when they hit that hot metal. /forums/images/graemlins/grin.gif

markct · Mar 9, 2006

( It's takes a big mill to lay the boom and dipper stick on, in order to do it right, )

your lookin at it all wrong, dont take the boom to the machine tools, take the machine tools to the boom. portable line boring is a very common thing, it ranges in setups that cost thousands to the way i have done it a few times, which involves either my mag base drill and some pillow blocks and a shaft, or my 3/4 milwaukee drill and the same type setup

Bigbear · Mar 9, 2006

Sorry for not giving good advice, I just try and do the best I can with whats on hand. BEAR

john_bud · Mar 9, 2006

Guys,

Thanks for the replies. I did get the one stuck pin out. Had to heat the linkage up with the rosebud for about 30 minutes to get it red hot, pound reheat pound repeat. Tried pounding from one end - no go. Reheated and pounded from the other end. It started to go! Yippie! Then it stuck. The head of the pin had mushroomed a bit. Pounded it back and ground the head down. Started some paper towel on fire from the sparks. THAT was fun. Put out the smoldering embers and damped down the area. Reheated the linkage and pounded out the pin --> with the bushing still attached. That sucker is on there for good!

Did the weld a bead trick on a half dozen other bushings. It didn't make them "fall out", but it did seem to help. At least it gave a place for the old pin to sit so it was easier to pound them out.

The bushings are all hardened steel. I tried to cut them and wasted 2 of my reciprocating saw blades and didn't do much to the bearings. These blades normally can cut 3-4 feet of 1/2 inch plate and still have life left, so the bearings are hard.

Yeah, I am doing the swap my self, as there is no extra $ for a machine shop to do it the right way. Last trip to the shop for something simple was too spendy. I figure there are 40+ bushings total including the pivot and stabilizers, and most are in some way buggered up. No way that size job is being farmed out!

I checked with Ford NH. Most everything is NLS - no longer serviced. The price of one (1) pin for the boom cylinder was $298, but fortunately it was not available. Who are they kidding anyway?? I'll be making my own pins from 4140. Yeah, it's a lot more time, but my time is cheap this time of year.

5030 - You line bore out the wallered spots and I'll provide the pickled barley anytime!

Oh, I started grinding out some cracked areas to repair. Oddly, the cracks are in previously repaired spots. Hmmm grinding the cracks, I quickly found out why they cracked. Weld is NOT strong if you don't chip out the slag between passes! Man oh Man, now I really want to slap that dumb SOB!

Farmwithjunk · Mar 10, 2006

No worthwhile advice on my part. But when you get yours done, if you want another "project", I've got an old Case 580C that needs the same treatment. It had a hoe-ram on it for a couple years, and is loose as the proverbial goose. It has the "plated" dipper arm too. Most likely, that's covering up a broken arm. Butt welding something like that won't hold long enough to put the welder away, so usually, it gets plated.

When I was looking for a used hoe, I found a bunch of 'em that'd been in a rental fleet. Most had hydraulic lines to run a hoe ram. That's a GIANT red flag. Those things beat a good hoe into submission.

I'm also reasonably certain grease guns must be getting extinct.

john_bud · Mar 10, 2006

Farm,

Grease guns extinct? No way! I must have a dozen. Let's see... I have a few mini gun for the tractor tool box, etc, a couple with the cartridge verticle and 4-5 regular ones. And yes, they all have grease in them. Some have synthetic for winter use, some have marine for places that get washed down and one even has "junk" grease (it's for borrowing out...he he he). I even have one with a slide on tip for those grease fittings you can't get to head on.

I borrowed a buddies 9" grinder with metal cutting discs last night and just sliced off one of the "barnicles" slabbed on the dipper stick. It had to go as there was a crack running under and around it. Half of the time, it was throwing sparks the other half it was throwing hardened flux. {Initiate Flaming Rant Mode} Jeeze, if you're too F-ing stupid to chip the flux off, buy a big mig ! It's people like that, that give stick welding a bad name. Lord knows, I gave some bad names this morning to that unknown person. {End Flaming Rand Mode}

Whew, that felt good!

Oh, I'll let you know about your "project". Drop it by. Let's see, is the price 2 or 3 brews per bushing? Steak or lobster per pin? I'll have to look that up ...

jb

3RRL · Mar 10, 2006

john,

( I'll be making my own pins from 4140.)

That's a pretty good choice of material. Consider that they will be about 300 Brinnel (about 26-30Rc) hardness. You may want to case and carburize them 1/32 to 1/16" deep for a hard surface. They'll end up super strong. You can use them in the pre-hard stage as bought, but they will wear a lot faster.

If you're going to heat treat them, you can also use any low carbon steel (either HRS or CRS) and case and carburize them too and still get super hard, strong pins out of it. The case and carburize heat treat for any of the 3 steels will be the same process so you can save a little on the material and turning cost. If it was me, I'd also OD grind after heat treat to guarantee size and concentricity...but maybe you won't need to do that depending how good your bushing job turns out and the running clearance between the pins and bushings?

I'm sure 5030 would love to turn some mild steel for you. /forums/images/graemlins/grin.gif

5030 · Mar 10, 2006

Rob:

Like I need the work. I'm playing around with anodizing at the moment. Vegetable dye makes nice colors. Besides, I'm trying to get my Triumph and sidecar back together for warm weather.

One thing for sure is that you can start with the cheapest steel and with a good heat treat technician, turn it into a silk purse. Just ask General Motors. /forums/images/graemlins/grin.gif

I'm thinking about buying a radius draw tube bender and one of the manufacturers who's bender I am looking at has a distributor in Chicago that also sells line boring equipment complete with that Miluakee drill and nice insert tooling. It's only money. /forums/images/graemlins/grin.gif

john_bud · Mar 10, 2006

Rob, Daryl,

I was planning on heat treating the pins after any drilling or welding that is needed. I am NOT a heat treat technician, but I can turn a silk purse into a sows ear! Uh, well where was I going with that?

Oh yeah, Heat Treat! Right. My method is just to torch heat the pins until red hot and quench. Have been using water and snow in a metal bucket. Then temper at 450F for about an hour in an old toaster oven in the shop. I don't have any way to turn or machine other than going to a machine shop and the $ just aren't there for that right now. Do you have any hits tips or tricks to help the process?

Ugly Pictures

Before

Under the barnicle

In the crack - Slag --yuck /forums/images/graemlins/frown.gif

My welds

Pivot / boom lift cyl --note repairs and pin trap welded by a washer

Thanks!
jb

Egon · Mar 11, 2006

John:

Looks like you have some serious rebuild here. Have you considered just ctting off some of the ugly parts and frabricating new. It may be easier in the long run.

On Heat Treating:

Have you considered a propane tiger torch and some high temp bricks pilled up to make a little kiln. Would allow for better heating and even post quenching temperature control.

Please note I do not weld.

Egon /forums/images/graemlins/grin.gif

5030 · Mar 11, 2006

Egon & John:

Egon: Nice barbecue. /forums/images/graemlins/grin.gif Bet that would do some Ball Park Franks real fast. /forums/images/graemlins/grin.gif

John: I don't heat treat any parts other than the AGD indicator extensions I sell on E-Bay when I'm bored. That's is oil hardening drill rod and I harden the spherical tips only. Once in a while I anneal copper sealing washers because I'm too cheap to buy new ones too.

I use AST in Perrysburg, Ohio for all heat treating. The problem with hardening most any alloy is that it has to be done in a controlled atmosphere furnace and then normalized to remove the internal stresses that are created in the first process. Normally, most heat treaters do small quantities, you just have to wait until they are running a compatable alloy run and they will incorporate your parts in that run. It should be quite reasonable to outsource it. By the way, those pictures are ugly and so are the welds. Looks like a 6013 goober job with the old Lincoln buzz box to me. I'd be rightfully ashamed of that job. Hope whomever you got the backhoe from gave it to you real cheap and I hope it's not a poster here.

The reason I mentioned GM before was that AST does the rocker arms for GM and GM buys the absolute cheapest steel they can get and then AST turns it into a "silk purse". /forums/images/graemlins/grin.gif

It's actually more cost effective to obtain and machine a cheap, mild steel and then heat treat it to the specification you desire. You can internally alter most characteristics of steel to suit your needs with a competent heat treater.

jmc · Mar 11, 2006

John,

Have you considered using an unhardened pin since it is easy to replace and may be less likely to wear the bushings?

John

john_bud · Mar 11, 2006

JMC,

One of the bucket pins was unhardened. To get it out, I had to grind one end down so it would fit out of the bushing and hammer the living snit out of it to get it out the other side. It has about 1/4" of banana bend and a couple of 1/4" grooves worn in it. The pin next to it was hard and it only has 1/16" wear and no bending. Oh, both sets of bushings were worn. My biggest fear is not future wear, but bending the pins and not being able to get them out.

I think the biggest factor is the use of $.98 of grease every 10-20 hours of use. Yup, the prior owner must have saved a hundred bucks or more! What a thrifty individual. (Or was that shifty? --> oops! sorry for the mis-spelling! How did that "f" get in there?)

jb

3RRL · Mar 12, 2006

John,
I had to give myself a little refresher class on heat treat by reading my Machinery's Handbook. These are very general, basic steps and vary on the kind of carbon steel you use, but in general should work for what you're doing.

In regards to heat treat of carbon steels, I think you've got the right idea by heating to cherry red or orange around 1335° to 1355°F. The purpose is to get the alternating bands of ferrite and cementite (known as pearlite) to merge into each other forming what is known as austentite. Tool steels need higher temps to get this done....not in your case.

A little about quenching baths... The purpose of the quenching bath is to remove heat faster than the critical cooling rate so the metal keeps it's merged characteristics and won't revert back to it's original characteristics. When a piece of steel is cooled at this rate or faster, a new structure is formed which is called martensite with very high hardness, but also brittle.

Then quenching in water or a salt solution or oil is Ok. There are several others too. To minimize cracking and distortion without sacrificing depth of hardness penetration it is desireable to select a quenching media that cools rapidly at higher temperatures and more slowly at the lower temperatures (below 750°F). Oil quenches in general meet this requirement because it cools at a slower rate than water....I've used motor oil (used and black) and the steel comes out nice and black too like it's been parkerized. Heat the oil quench to between 90° to 130°F for the quench....You can use water but but I've had bad luck with the steel remaining too brittle (too hard) and cracking.

Then drawing (tempering) between 300° to 750°F for at least 1 hour to reduce the brittleness and remove the internal strains of the hardened steel. When the steel is first quenched, it is mostly martensite. On reheating to the draw temperature and holding for 1 to 2 hours a structure known as troosite is formed. It is slightly softer and tougher than the brittle super hard martensite. Heat treaters know all this stuff and EXACTLY the right heating and drawing temperatures for the kind of steel used.

So yeah...you're on the right track. It should work fine for you.
Hope this helps,