Rebuilding 743 front bucket tilt cylinder question

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pondfishr

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My 743 5019 serial number unit front cylinder is leaking a little and I called the Bobcat dealer here in Middle Tennessee and ordered a rebuild kit. I also have the service manual and for that repair it says I need the component repair manual and does not detail the repair procedure. I have never rebuilt anything like this before and I am woindering if I would be better off taking the cylinder off driving it to the dealer and let them install the rebuild kit. Any advice would be appreciated. Also Kudos to Tazza he coached me through fixing an oil leak that was rooted in my throttle coonnector plate on the top of my 743 Kubota engine. Ir cost around 50 bucks in parts but it saved me the hassle of taking the machine to the dealer. Again kudos to Tazza I really appreciate it!! My old user name was bewing but somehow I have been locked out of the forum for weeks and just now changed my user name to pondfishr..
 

Tazza

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You are more than welcome.
Now, the tilt cylinder, this is really quite easy and NO you do not need the service manual for this. Sorry, but this will be quite a long post, you have been warned :)
First, remove the cylinder from the lift amrs and the bobtach (not always an easy job). Remove the 2 hoses and mark and cap them! yo don't want it to work backwards (yes, i have done this before....)
Drain the cylinder of oil by pushing the chrome bar all the way in, then all the way back out. Mount the cylinder in a vice from the bottom so you can see the aloy gland nut where the chrome bar comes out of. You really should use a propper spanner to remove this gland nut, a pair of stillsons (not sure if you call them the same over there) or a large wrench will also work, but will mark the aloy but will not damage it.
When removed, pull the chrome bar up and out, this will have a piston attached to the bottom. Remove the outer of the cylinder from the vice. Put the chrome bar in the vice on the end where it joins to the bobtach. Be VERY carefull not to damage the chrome bar at ANY time. Remove the nut that holds the piston on to the chrome bar. Remove the piston from the bar and also remove the gland nut (aloy bit with 2 seals inside it).
Now, to remove the seals and O rings, you really need an O ring pick for this, first remove the outer O rings, there is one behind the shoulder at the end of the thread, then there will be 1 O ring and 1 backup ring on the part that sits inside the cylinder. Now for the inside ones.
There is a wiper seal and a pressure seal remove the wiper first, this is where the chrome bar comes out of, stick the O ring pick in and twist it out, do the same with the pressure seal, this one is a little harder as it is a fair way in, you are best to attach this one from the end where the nut enters the cylinder. Please be very carefull not to stab your hand doing this, the picks are really quite sharp!
When you remove the seals, take note of the direction they were installed. The pressure seal sits with *lips* facing the pressure side or the cylinder and the wiper sits with the lips facing outwards. Oil the seals up before installing them, don't be worried, but you will need to really flex the seals to get them in. Once they are both in, install the backup ring and the O ring, then install the O ring that sits behind the nut after the thread.
Oil the chrome bar up and the gland nut and carefully re-install it on to the chrome bar. There should be an O ring sitting where the piston was, remove this and replace it.
Now to re-seal the piston. Get a sharp knife and cut the pressure seal and remove it, then remove the energising ring (looks like an O ring), install the new energising ring. Use a hair drier to warm up the pressure seal, installing this ring is really quite hard...... when its warm, pull at it to stretch it a little, then you have to try and get it on with an O ring pick or small screw driver. When it is on, it will slowly shrink back, you can use a cable tie to help it shrink. Oil the O ring on the chrome bar and install the piston, tighten the nut.
Oil the piston up and the bore of the cylinder then carefully push the piston into the cylinder, it will be quite tight, but take it slow, as you need to get the piston seal to close up and if you force it too hard it can get pinched and shear it in half. But it will need a bit of force to do. once in, oil the O rings on the gland nut then screw it in and tighten up. Make sure you have the O ring then backup ring in that order, NOT backup then O ring.
If anything is un-clear e-mail me tazza_ at tpg.com.au with the at being @ of course :)
I can scan in pictures of all of this if required, it really is easier than it seems. Its a good thing to learn, as once you have done one, you can do ALL the rams on your SSL.
The only tricky part is the pressure and wiper seal orientations. NEVER replace wiper/pressure seals and not the piston seal, never do half a job, you will regret it. This should prevent your tilt cylinder falling under its own weight as most do (mine does) i need to get time to do it, i am currently repairing 2 lift cylinders that broke the chrome bar. I need to finish making 2 new pistons and 2 new gland nuts (almost finished).
Again, sorry for the long post, but it should help anyone that wants to re-seal any hydraulic cylinder.
Sorry for the many spelling mistakes too
 

Tazza

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You are more than welcome.
Now, the tilt cylinder, this is really quite easy and NO you do not need the service manual for this. Sorry, but this will be quite a long post, you have been warned :)
First, remove the cylinder from the lift amrs and the bobtach (not always an easy job). Remove the 2 hoses and mark and cap them! yo don't want it to work backwards (yes, i have done this before....)
Drain the cylinder of oil by pushing the chrome bar all the way in, then all the way back out. Mount the cylinder in a vice from the bottom so you can see the aloy gland nut where the chrome bar comes out of. You really should use a propper spanner to remove this gland nut, a pair of stillsons (not sure if you call them the same over there) or a large wrench will also work, but will mark the aloy but will not damage it.
When removed, pull the chrome bar up and out, this will have a piston attached to the bottom. Remove the outer of the cylinder from the vice. Put the chrome bar in the vice on the end where it joins to the bobtach. Be VERY carefull not to damage the chrome bar at ANY time. Remove the nut that holds the piston on to the chrome bar. Remove the piston from the bar and also remove the gland nut (aloy bit with 2 seals inside it).
Now, to remove the seals and O rings, you really need an O ring pick for this, first remove the outer O rings, there is one behind the shoulder at the end of the thread, then there will be 1 O ring and 1 backup ring on the part that sits inside the cylinder. Now for the inside ones.
There is a wiper seal and a pressure seal remove the wiper first, this is where the chrome bar comes out of, stick the O ring pick in and twist it out, do the same with the pressure seal, this one is a little harder as it is a fair way in, you are best to attach this one from the end where the nut enters the cylinder. Please be very carefull not to stab your hand doing this, the picks are really quite sharp!
When you remove the seals, take note of the direction they were installed. The pressure seal sits with *lips* facing the pressure side or the cylinder and the wiper sits with the lips facing outwards. Oil the seals up before installing them, don't be worried, but you will need to really flex the seals to get them in. Once they are both in, install the backup ring and the O ring, then install the O ring that sits behind the nut after the thread.
Oil the chrome bar up and the gland nut and carefully re-install it on to the chrome bar. There should be an O ring sitting where the piston was, remove this and replace it.
Now to re-seal the piston. Get a sharp knife and cut the pressure seal and remove it, then remove the energising ring (looks like an O ring), install the new energising ring. Use a hair drier to warm up the pressure seal, installing this ring is really quite hard...... when its warm, pull at it to stretch it a little, then you have to try and get it on with an O ring pick or small screw driver. When it is on, it will slowly shrink back, you can use a cable tie to help it shrink. Oil the O ring on the chrome bar and install the piston, tighten the nut.
Oil the piston up and the bore of the cylinder then carefully push the piston into the cylinder, it will be quite tight, but take it slow, as you need to get the piston seal to close up and if you force it too hard it can get pinched and shear it in half. But it will need a bit of force to do. once in, oil the O rings on the gland nut then screw it in and tighten up. Make sure you have the O ring then backup ring in that order, NOT backup then O ring.
If anything is un-clear e-mail me tazza_ at tpg.com.au with the at being @ of course :)
I can scan in pictures of all of this if required, it really is easier than it seems. Its a good thing to learn, as once you have done one, you can do ALL the rams on your SSL.
The only tricky part is the pressure and wiper seal orientations. NEVER replace wiper/pressure seals and not the piston seal, never do half a job, you will regret it. This should prevent your tilt cylinder falling under its own weight as most do (mine does) i need to get time to do it, i am currently repairing 2 lift cylinders that broke the chrome bar. I need to finish making 2 new pistons and 2 new gland nuts (almost finished).
Again, sorry for the long post, but it should help anyone that wants to re-seal any hydraulic cylinder.
Sorry for the many spelling mistakes too
*phew* that really was a long post......
 

Tazza

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Well-done -- I'm sure it will be much appreciated!
I think i almost wore out my keyboard on that one :)
From that long winded explination it may seem difficult, but honestly it is easy for anyone, even with little mechanical experience.
As for seals, you don't have to use genuine. I go to my local hydraulic/pneumatic seal shop and get all my seals. It cost me $25 australian for a full set of seals for my lift arm rams. I don't know what bobcat want for one of these sets, but i'm sure it would be quite alot more. If you go non-genuine, make sure you take all the pieces down with you for them to measure. You can't take too many parts with you to be sure you get the rite parts.
 

pondfishr

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I think i almost wore out my keyboard on that one :)
From that long winded explination it may seem difficult, but honestly it is easy for anyone, even with little mechanical experience.
As for seals, you don't have to use genuine. I go to my local hydraulic/pneumatic seal shop and get all my seals. It cost me $25 australian for a full set of seals for my lift arm rams. I don't know what bobcat want for one of these sets, but i'm sure it would be quite alot more. If you go non-genuine, make sure you take all the pieces down with you for them to measure. You can't take too many parts with you to be sure you get the rite parts.
Tazza, I ordered mine form Bobcat here in Nashville Tennessee USA but still need to pick it up. They quoted $11.00 USD so that makes me wonder if I got the complete kit. I will let you know how it turns out when I get it and give the rebuild a shot. Thanks for taking the time and concentration to complete the detailed repair procedure. It will help me and I am sure other members of this forum Thanks, Bill
 

Tazza

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Tazza, I ordered mine form Bobcat here in Nashville Tennessee USA but still need to pick it up. They quoted $11.00 USD so that makes me wonder if I got the complete kit. I will let you know how it turns out when I get it and give the rebuild a shot. Thanks for taking the time and concentration to complete the detailed repair procedure. It will help me and I am sure other members of this forum Thanks, Bill
You may be lucky, it may indeed be a complete kit.
But if its only for the gland nut, do make sure you get the kit for the piston too. There is no point in half doing a job like this, it will only cause you grief as you will disturb the piston seal and the oil will by-pass the seal causing the bucket to creap down towards the ground.
Remember, if you have any problems or questions you can e-mail me or post on the forum.
I will try to remember to take a few pictures just to clarify the direction of the pressure and wiper seals, this is most important.
 

StuZ

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Nov 22, 2003
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You may be lucky, it may indeed be a complete kit.
But if its only for the gland nut, do make sure you get the kit for the piston too. There is no point in half doing a job like this, it will only cause you grief as you will disturb the piston seal and the oil will by-pass the seal causing the bucket to creap down towards the ground.
Remember, if you have any problems or questions you can e-mail me or post on the forum.
I will try to remember to take a few pictures just to clarify the direction of the pressure and wiper seals, this is most important.
The seal kit for a tilt cylinder is $ 11.00 and change AMERICAN. You shouldn't need anything else unless the head gland won't hold the wiper seal anymore, and if you use a spanner wrench on it, that shouldn't be a problem either.
 

dannym

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*phew* that really was a long post......
Tazza, excellent writeup. I recently rebuilt my tilt cylinder and did one thing differently. I don't know if it would work for other folks or not. I left my cylinder and hoses on. I unbolted only the end of the cylinder from the bucket and laid a pices of plywood under the ram. I then turned the motor over without cranking which pushed the ram fairly gently out of the cylinder. I then went about the rebuild as you described.
 

Tazza

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Tazza, excellent writeup. I recently rebuilt my tilt cylinder and did one thing differently. I don't know if it would work for other folks or not. I left my cylinder and hoses on. I unbolted only the end of the cylinder from the bucket and laid a pices of plywood under the ram. I then turned the motor over without cranking which pushed the ram fairly gently out of the cylinder. I then went about the rebuild as you described.
I have done something close to that before with a 6” ram that i worked on. I was trying to get the piston in the cylinder and it got stuck, there was no way to get it out so i hooked up a hydraulic pump and pushed it out. Your way i see no problems with except you will loose more oil, if thats not a problem for you thats fine, it helps flush the system a little bit.
I do agree having the cylinder held in the machine sure does help to remove the gland nut, that or a length of bar through the base and lay it on the ground then haul on it.
If it works for you, its the rite way :)
 

Bobpuddy

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*phew* that really was a long post......
Thanks for the info. The problems I have, is that the tilt drifts down under it's own weight and faster if loaded. Do all the 743 tilt cylinders use the same rebuild kit?
 

Fishfiles

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Thanks for the info. The problems I have, is that the tilt drifts down under it's own weight and faster if loaded. Do all the 743 tilt cylinders use the same rebuild kit?
There are 4 different cylinders used on a 743 , I know there are at least 3 different seal kit , may be 4 , just went thru that last week ------sounds like the piston ring is blown or the nut came loose on the end of the chrome rod ----but you may have an external leak somewhere on a tube or hose going to the cylinder , or possiblly a internal leak in the controll vavle
 

Bobpuddy

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There are 4 different cylinders used on a 743 , I know there are at least 3 different seal kit , may be 4 , just went thru that last week ------sounds like the piston ring is blown or the nut came loose on the end of the chrome rod ----but you may have an external leak somewhere on a tube or hose going to the cylinder , or possiblly a internal leak in the controll vavle
What's the best way to get the correct kit? Is there a part # on the cylinder. I also wonder if I have the correct cylinder on my 743 because it was changed by the previous owner. My cylinder over extends to the point where it pinches the metal Hyd lines underneath, between the cylinder and the cross support under it. When this happens the bucket free swings and I have to lower the arms about 3 feet before the tilt cylinder will retract. Do you know the length measurement of your tilt cylinder housing so I can compare it to mine? I still have not figured out if there are suppose to be any kind of stops for the bucket tilt. My unit is a 1987 model. Thanks
 

Fishfiles

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What's the best way to get the correct kit? Is there a part # on the cylinder. I also wonder if I have the correct cylinder on my 743 because it was changed by the previous owner. My cylinder over extends to the point where it pinches the metal Hyd lines underneath, between the cylinder and the cross support under it. When this happens the bucket free swings and I have to lower the arms about 3 feet before the tilt cylinder will retract. Do you know the length measurement of your tilt cylinder housing so I can compare it to mine? I still have not figured out if there are suppose to be any kind of stops for the bucket tilt. My unit is a 1987 model. Thanks
I don't own a 743 , I repair equipment , talk to your local dealer parts department , the length from the rod end of the casing to the welded fitting is one way to figure what you got , another is the discription of the base end of the cylinders pin mounting hole , another style has the tube going to the base end welded to the tube and is not removable , I do know that some parts will mix match and cause a problem , there is a gland nut( head) which is about an inch and 1/2 longer and will screw into other cylinders but it would shorten the stroke not make it longer --------I have noticed that over extending the tilt cylinder is a problem with the 743 , there was stops on the boom end that helped that from happening and I have seen a bunch of machines that don't have it , also I find that worn out bobtach pin bushing /weldments add to that problem , when you reseal your cylinder you could install a sleeve over the chrome rod inside the cylinder which would limit the travel , to over extend can bent the chrome rod
 

Bobpuddy

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I don't own a 743 , I repair equipment , talk to your local dealer parts department , the length from the rod end of the casing to the welded fitting is one way to figure what you got , another is the discription of the base end of the cylinders pin mounting hole , another style has the tube going to the base end welded to the tube and is not removable , I do know that some parts will mix match and cause a problem , there is a gland nut( head) which is about an inch and 1/2 longer and will screw into other cylinders but it would shorten the stroke not make it longer --------I have noticed that over extending the tilt cylinder is a problem with the 743 , there was stops on the boom end that helped that from happening and I have seen a bunch of machines that don't have it , also I find that worn out bobtach pin bushing /weldments add to that problem , when you reseal your cylinder you could install a sleeve over the chrome rod inside the cylinder which would limit the travel , to over extend can bent the chrome rod
Thanks for those tips. Soon as it warms up enough here that my hands don't freeze to the metal, I am going to tackle this job.
 

Tazza

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Thanks for those tips. Soon as it warms up enough here that my hands don't freeze to the metal, I am going to tackle this job.
The over extending is because your stops are either worn or not attached. They prevent the bucket curling too far and causing bent ram sticks. It could even be beacuse the previous owner(s) re-welded the pivot point on the bobtach too far up and this allows the bobtach to curl too far.
If you contact your dealer, they can fax you parts lists the cylinders can be identified by the hydraulic lines. You measure how far from the end of the cylinder they are and the really early style had a line that was welded into the base, easily seen when you have a parts list.
 

Centurion

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The over extending is because your stops are either worn or not attached. They prevent the bucket curling too far and causing bent ram sticks. It could even be beacuse the previous owner(s) re-welded the pivot point on the bobtach too far up and this allows the bobtach to curl too far.
If you contact your dealer, they can fax you parts lists the cylinders can be identified by the hydraulic lines. You measure how far from the end of the cylinder they are and the really early style had a line that was welded into the base, easily seen when you have a parts list.
If you cannot get the parts list, let me know, I can scan in the pages and send them to you in a PDF file, I know all about bent rams from over extending, that was my first major lesson! I think it only cost me about $600. to get through it, and about 4-5 weeks. If you need the stuff, I can do it tomorrow and e-mail it.
 

dannym

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If you cannot get the parts list, let me know, I can scan in the pages and send them to you in a PDF file, I know all about bent rams from over extending, that was my first major lesson! I think it only cost me about $600. to get through it, and about 4-5 weeks. If you need the stuff, I can do it tomorrow and e-mail it.
I have noticed the over extending and luckily haven't bent the rod yet. I would like to know more about the stops that are referred to in this post. Also is it possible to weld a stop on the bucket or arm that would work? Any and all help would be appreciated. Also thanks for the previous replies which have helped greatly.... Dannym
 

Fishfiles

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I have noticed the over extending and luckily haven't bent the rod yet. I would like to know more about the stops that are referred to in this post. Also is it possible to weld a stop on the bucket or arm that would work? Any and all help would be appreciated. Also thanks for the previous replies which have helped greatly.... Dannym
the stops were like shim plates that bolted to the boom tip and limited the travel , not all machines had them from the factory , don't see why it couldn't be a plate welded to the boom ---------------------another thing that will bent the rod is not having a restrictor on the down side of the cylinder fitting when using a grapple or heavy attachment , heavy weight will make the bucket or attachment drop fast and jerk , on older machines like the 43 series we always installed the restrictor ( which Bobcat dealers sell ) , it a fitting that goes between the cylinder fitting and the hose that allows unrestricted flow in the tilt up postion and an orifice inside the fitting slows the down stroke to protect the downward surge that will cause rod damage
 
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