2000 bobcat 863 bucking/jerking

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thejrancher

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Apr 3, 2008
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I recently bought a 2000 bobcat 863 with 2100 hours. Runs strong at full speed but something is going on with it at slow speeds, like when you have it in tight spaces and are trying to go slow. Does it both right and left sides, when I press the stick forward slightly it does nothing for a second or 2 then jumps like it caught then goes back to nothing. Right side is worse, I removed the K strain filter before the right drive motor and replaced with a new one, had some junk in it but not a lot..tiny little metal particles, I also drained hydraulic tank and put on new filter there and refilled with bobcat fluid. Still jerking at slower speeds, anybody have any ideas? thanks in advance
 

skidsteer.ca

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Are you slowing the motor down when trying to go slow? You machine will operate best at 2/3 rpm or higher.
Ken
 

Tazza

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the jerking/slipping is at slow drivetrain speeds with high rpm's, shakes the loader arms pretty good. Bill
Its almost as if your park brake is sticking? this could cause jerking, but i would think you would hear a awful noise coming from it.
There is no reson for it to hesitate then go like you describe, thats what makes me think something is sticking causing it to delay.
Just an idea.
 

siduramaxde

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Its almost as if your park brake is sticking? this could cause jerking, but i would think you would hear a awful noise coming from it.
There is no reson for it to hesitate then go like you describe, thats what makes me think something is sticking causing it to delay.
Just an idea.
I would check all the linkage between the control sticks and the hydros. Check the movement with the cab up and the loader OFF. You should be able to see the linkage.
 

thetool

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Like sid.....said, You seem to have a steering linkage problem.
Your linkage, depending on s/n, could have three different setups. You will have straight bars going from your bellcranks to your pump levers, steering cables, or rods and a swivel pedestal mounted to your chaincase, all under the cab. Loose and or worn parts cause the problem, but we need to know what kind of system you have before we can help with the fix.
Let us know and g/l.
 
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thejrancher

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Like sid.....said, You seem to have a steering linkage problem.
Your linkage, depending on s/n, could have three different setups. You will have straight bars going from your bellcranks to your pump levers, steering cables, or rods and a swivel pedestal mounted to your chaincase, all under the cab. Loose and or worn parts cause the problem, but we need to know what kind of system you have before we can help with the fix.
Let us know and g/l.
I jacked up the machine and put jackstands under all 4 axles, flipped up cab and the steering linkage looks tight, when I push right stick forward slightly, right wheels turn sporadically,almost as if drive motor gets enough pressure to turn then loses it then gets it back again..over and over..Machine runs great at full speed,both sides with a full bucket. I changed right side k strainer in front of drive motor, are they any other filters or solenoids I can replace? I ordered a service manual but not here yet. Can I switch drive motor hoses at thr hydraulic pump right side for left side to see if hydro pump issue?
 

skidsteer.ca

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I jacked up the machine and put jackstands under all 4 axles, flipped up cab and the steering linkage looks tight, when I push right stick forward slightly, right wheels turn sporadically,almost as if drive motor gets enough pressure to turn then loses it then gets it back again..over and over..Machine runs great at full speed,both sides with a full bucket. I changed right side k strainer in front of drive motor, are they any other filters or solenoids I can replace? I ordered a service manual but not here yet. Can I switch drive motor hoses at thr hydraulic pump right side for left side to see if hydro pump issue?
Yes you can either swap motor by connecting longer hoses or physically moving them. The screen/filter on the case drains you changed just filter oil that bypasses inside the motor, and is low pressure oil returning to reservoir. I can't see that having much effect other then if the motor is falling apart, that catches the debris.
Ken
 

Tazza

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I jacked up the machine and put jackstands under all 4 axles, flipped up cab and the steering linkage looks tight, when I push right stick forward slightly, right wheels turn sporadically,almost as if drive motor gets enough pressure to turn then loses it then gets it back again..over and over..Machine runs great at full speed,both sides with a full bucket. I changed right side k strainer in front of drive motor, are they any other filters or solenoids I can replace? I ordered a service manual but not here yet. Can I switch drive motor hoses at thr hydraulic pump right side for left side to see if hydro pump issue?
You can swap motors. You can probably swap the hoses at the pump but that wouldn't tell you if there is a problem with the linkage between motor and chain. But it would tell you if its a pump issue. I personally would start with swapping hoses.
The case drain filters wouldn't cause the issues you have. Its almost as if there is a problem with the rollers in the motor its self, or shaft.
I'm just wondering if it could be the chain or sprockets allowing a bit of slack that you feel as jerking....
There are so may *could be* things. Start with swapping hoses, if it moves you know its the pump. If it doesn't i'd swap motors and if it moves you know for sure its a motor.
 

thetool

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I suggest checking one more linkage-related item before you dig into motor issues, in case you've overlooked it.
If you have the straight linkage, there are aluminum levers attached to square shafts on top of your pump. The square openings in the lever wear and wallow out and although the linkage may be tight, this problem will cause the symptom you describe.
You'll have a plate on top of your pump with a spring, that slides back and forth as you stroke your drive levers. Under this plate are the aluminum "pump levers." They attach to a square stub shaft which is your swash plate inside the pump.
You can tell if this is the problem right away if the lever is down resting on top of the pump, which is where it falls when it loosens.
If this is your problem, and the square stub shaft is galled and worn, your dealer may want to sell you a new pump. Don't do it. There is a tricky fix.
And if I just told you a bunch of stuff you already know-sorry. Good Luck.
 
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thejrancher

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Apr 3, 2008
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I suggest checking one more linkage-related item before you dig into motor issues, in case you've overlooked it.
If you have the straight linkage, there are aluminum levers attached to square shafts on top of your pump. The square openings in the lever wear and wallow out and although the linkage may be tight, this problem will cause the symptom you describe.
You'll have a plate on top of your pump with a spring, that slides back and forth as you stroke your drive levers. Under this plate are the aluminum "pump levers." They attach to a square stub shaft which is your swash plate inside the pump.
You can tell if this is the problem right away if the lever is down resting on top of the pump, which is where it falls when it loosens.
If this is your problem, and the square stub shaft is galled and worn, your dealer may want to sell you a new pump. Don't do it. There is a tricky fix.
And if I just told you a bunch of stuff you already know-sorry. Good Luck.
I appreciate all the help you guys have given me..I am waiting for the manual to arrive before I go any further with it..I will let you all know as more is revealed..thanks again,bill
 

skidsteer.ca

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I appreciate all the help you guys have given me..I am waiting for the manual to arrive before I go any further with it..I will let you all know as more is revealed..thanks again,bill
153_5327.JPG

Here is a picture of a 751 hydro pump. The bellcranks that come loose (as the tool mentioned) would attach to the square shafts coming out of the top. However my 853 is different, with morse cables from the steering levers to the pump, so I'm not sure if your 863 is like the photo or the cable style.
I can see how slack in the linkage could cause the problem you mention.
(I uploaded my quota of pictures today, Tazza)
Ken
 

Tazza

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Here is a picture of a 751 hydro pump. The bellcranks that come loose (as the tool mentioned) would attach to the square shafts coming out of the top. However my 853 is different, with morse cables from the steering levers to the pump, so I'm not sure if your 863 is like the photo or the cable style.
I can see how slack in the linkage could cause the problem you mention.
(I uploaded my quota of pictures today, Tazza)
Ken
Geez Ken, that pump looks awfully familiar :)

I do agree that its a good spot to start, i have heard a few people mention this in the past. It does explain every symptom you describe.
 

AZ skidmark

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Sep 14, 2010
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I suggest checking one more linkage-related item before you dig into motor issues, in case you've overlooked it.
If you have the straight linkage, there are aluminum levers attached to square shafts on top of your pump. The square openings in the lever wear and wallow out and although the linkage may be tight, this problem will cause the symptom you describe.
You'll have a plate on top of your pump with a spring, that slides back and forth as you stroke your drive levers. Under this plate are the aluminum "pump levers." They attach to a square stub shaft which is your swash plate inside the pump.
You can tell if this is the problem right away if the lever is down resting on top of the pump, which is where it falls when it loosens.
If this is your problem, and the square stub shaft is galled and worn, your dealer may want to sell you a new pump. Don't do it. There is a tricky fix.
And if I just told you a bunch of stuff you already know-sorry. Good Luck.
Thank you thetool. You are 100% correct in diagnosing the uncontrollable drive on my 98 863. I pulled the aluminum bellcrank to find it is badly worn in square bore where it attaches to the shaft on the pump. The shaft has no measurable damage, but the pump lever itself will need replacement or at least repair. You mentioned a "tricky fix". Is there a simple method of building up the worn surface to fit tightly on the shaft without replacing the bellcrank itself? This is a great forum and has saved the day for me on several occasions now. Thanks to all, and happy new year 2012.
 

Kermode

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Dec 15, 2009
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Thank you thetool. You are 100% correct in diagnosing the uncontrollable drive on my 98 863. I pulled the aluminum bellcrank to find it is badly worn in square bore where it attaches to the shaft on the pump. The shaft has no measurable damage, but the pump lever itself will need replacement or at least repair. You mentioned a "tricky fix". Is there a simple method of building up the worn surface to fit tightly on the shaft without replacing the bellcrank itself? This is a great forum and has saved the day for me on several occasions now. Thanks to all, and happy new year 2012.
Buy new bellcranks. They are cheaper than you might think. Certainly cheaper than trying to build up the old ones. Read this thread in its entirety: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=30622 Lots of good info on adjusting Bobcat steering.
 

Tazza

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Buy new bellcranks. They are cheaper than you might think. Certainly cheaper than trying to build up the old ones. Read this thread in its entirety: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=30622 Lots of good info on adjusting Bobcat steering.
I threw mine into my mill and cut it so they were square, i then used shims to take up the extra space made by machining them. Worked great, but you need access to a mill.
New parts were cheap, but when i did the project, it was a weekend when the dealer was not open, so i did it my way. I thought they were about $30 each fromt he dealer. Don't quote me on the price though.
 

mrdeere1959

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Nov 1, 2011
Messages
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Thank you thetool. You are 100% correct in diagnosing the uncontrollable drive on my 98 863. I pulled the aluminum bellcrank to find it is badly worn in square bore where it attaches to the shaft on the pump. The shaft has no measurable damage, but the pump lever itself will need replacement or at least repair. You mentioned a "tricky fix". Is there a simple method of building up the worn surface to fit tightly on the shaft without replacing the bellcrank itself? This is a great forum and has saved the day for me on several occasions now. Thanks to all, and happy new year 2012.
I think you mean pintal arms not bellcranks. $13.66 ea. you will also need the larger sized torsion bushings. the new arms have a bigger hole in them. bushings are $5.85. also should replace the bushings in the bellcranks and check the adjustor blocks and the cams
 

AZ skidmark

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Sep 14, 2010
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I think you mean pintal arms not bellcranks. $13.66 ea. you will also need the larger sized torsion bushings. the new arms have a bigger hole in them. bushings are $5.85. also should replace the bushings in the bellcranks and check the adjustor blocks and the cams
I fixed it for for free. I pulled the aluminum bell crank off, found it was badly worn from being loose where it attaches to the to the square shaft on the pump. I simply cut some shims and forced them into the worn gap. Nothing else was in need of service. Reassembly was easy (somewhat) using the zip tie trick on the spring. I put a large beam under the back of the tractor and raised all 4 wheels off the ground using the bucket. After adjusting the neutral positions all is well. No need to buy anything. Tractor is better than before I bought it. Not much to it with the help from this forum. Thanks you guys! Now it will creep without jumping and lurching uncontrollably. It had been slowly getting worse as time on. I have a great respect for Bobcat mechanics. These are tough little animals to work on. After making a few repairs things do get easier.
 

paulfarmall

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Dec 7, 2022
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If you have cables going from the handles to the pump look at the top of pump where the cables attach to the control arm. If you have a t looking arm that the cable hooks too with two bolts holding it, look under that and you will see a nut that hold the control lever that goes into the pump. That is on a slotted shaft and that is worn out. so, if you have the control handle and you see the linkage moving ,look at the nut under there and you will see there is play in the connection. and that is why you have uncontrollable movement when trying to move slow. Like when you want to hook up the bucket and the machine wiggles and will not go straight forward.
Paul
 
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