743 lift arm pins and bushing replacement

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Centurion

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Jul 17, 2008
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Hello everyone. I have come to the conclusion that I need to replace the upper pins and bushings in the lift arms. They are worn bad, and allow the arms to shift from side to side, and spread at the pivot pins. It got so bad, it cracked the cross member in the front, that was previously welded when I bought the machine. I have done a search to see if there was any advice in this area, but I could not find anything. Basically I am looking for advice on how to proceed with this repair, and if i have the pins and bushings made, what kind of material should i use? anything would be helpful.I have an idea how to proceed, but figured why re-invent the wheel.

Fred
 

Kermode

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Dec 15, 2009
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You should be able to buy pins and bushings from your local Bobcat dealer for less than you can have them made. After that, you need to support the boom with some kind of hoist and knock the pins and bushings out. Be prepared, there may be more damage to the boom and mounting points. You may have to build up holes and line bore the boom. Might be very expensive.
 

Tazza

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Hi Fred
What pins are you talking about? the ones for the tilt ram or the main pivot ones on the top rear of the machine?
I mad new pins and bushings of 4140 and got them heat treated, they will not wear out in my life time! they are that hard.
Give a few more details and hopefully i'll be able to give you some advise.
 
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Centurion

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Hi Fred
What pins are you talking about? the ones for the tilt ram or the main pivot ones on the top rear of the machine?
I mad new pins and bushings of 4140 and got them heat treated, they will not wear out in my life time! they are that hard.
Give a few more details and hopefully i'll be able to give you some advise.
THe main pivot pins on the top rear of the machine. There is a lot of play at that point.
 

Tazza

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THe main pivot pins on the top rear of the machine. There is a lot of play at that point.
The way i did it was to cut the old bosses out of the arms, as stated you need to support them, there is a lot of weight here. I machined a new pin and boss, slid the boss into the arm, lowered the arm into position, put the new pin in and welded the boss in. The pin acts like a locator so you can weld the inside. Lift the arms and weld around the boss like it was before you removed it.
I did this about 5+ years ago now, there is still no wear in this machine.
 
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Centurion

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The way i did it was to cut the old bosses out of the arms, as stated you need to support them, there is a lot of weight here. I machined a new pin and boss, slid the boss into the arm, lowered the arm into position, put the new pin in and welded the boss in. The pin acts like a locator so you can weld the inside. Lift the arms and weld around the boss like it was before you removed it.
I did this about 5+ years ago now, there is still no wear in this machine.
Did you have to remove the hydraulic lines completely from the arms, or just drop them form the clips? The process you described is what I had in mind, so I guess I am heading in the right direction. Once I get the parts, I will begin the task, and let you know how I make out.

Fred
 

Tazza

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Did you have to remove the hydraulic lines completely from the arms, or just drop them form the clips? The process you described is what I had in mind, so I guess I am heading in the right direction. Once I get the parts, I will begin the task, and let you know how I make out.

Fred
When i repaired the cracks in the arms i removed the lines, just twist the metal clips down. To do the bosses you could leave the lines attached. If you have a lathe, you can make all new bosses with replaceable bushings if you are that motivated. I have pictures of mine somewhere.
 
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Centurion

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When i repaired the cracks in the arms i removed the lines, just twist the metal clips down. To do the bosses you could leave the lines attached. If you have a lathe, you can make all new bosses with replaceable bushings if you are that motivated. I have pictures of mine somewhere.
Well, got all the bushings for replacement, ended up removing the arms completely from the machine. The bushings are the most difficult to remove that I have run into, has taken evry night after work this week to remove the arm bushings and so far 2 of the frame bushings, one more to go tonight. Plan is weld in the bushings in the frame, then slide arms in place, tack inside and then weld the outside, as tazza suggests. I think if I had not removed the arms, I would have had a more difficult time, also, did not want to use cutting torch near engine and fuel. Once these are done, next step is to replace lower tilt cylinder bushings in bobtach. Will let you know how i progress
 

Tazza

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Well, got all the bushings for replacement, ended up removing the arms completely from the machine. The bushings are the most difficult to remove that I have run into, has taken evry night after work this week to remove the arm bushings and so far 2 of the frame bushings, one more to go tonight. Plan is weld in the bushings in the frame, then slide arms in place, tack inside and then weld the outside, as tazza suggests. I think if I had not removed the arms, I would have had a more difficult time, also, did not want to use cutting torch near engine and fuel. Once these are done, next step is to replace lower tilt cylinder bushings in bobtach. Will let you know how i progress
Good to hear you are making progress.
The bobtach bushes are fun...... I have had to replace the bosses on a few machines because the wear was so bad. I used a plasma cutter to gouge it all out, took some time, but worked well.
 
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Centurion

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Good to hear you are making progress.
The bobtach bushes are fun...... I have had to replace the bosses on a few machines because the wear was so bad. I used a plasma cutter to gouge it all out, took some time, but worked well.
Well finally am up and running again, was not able to change out the bob tach bushings, wrong parts from dealer again, I guess i am going to have to find material, and make my own for that part of the project. Since I changed all the pins and bushings in the arms, everything lines up great, and I am not cracking the cross member anymore. Had to remove arms completely to complete the job. One thing that helped was for one week prior to project start, I sprayed PB blaster on all the hydraulic connections, they were much easier to loosen with that being done. Previously I had tried loosening them and was twisting metal hyd. lines.

Fred
 

Tazza

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Well finally am up and running again, was not able to change out the bob tach bushings, wrong parts from dealer again, I guess i am going to have to find material, and make my own for that part of the project. Since I changed all the pins and bushings in the arms, everything lines up great, and I am not cracking the cross member anymore. Had to remove arms completely to complete the job. One thing that helped was for one week prior to project start, I sprayed PB blaster on all the hydraulic connections, they were much easier to loosen with that being done. Previously I had tried loosening them and was twisting metal hyd. lines.

Fred
Good to hear you had success with the job. Some of the hydraulic fittings sure can be tight!
 
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