4 stop Tac 20 hydro. Car shoes r those plastic slides and piston guides are truck with rollers ... I'm getting a 1068 jack sync shutdown once a week or so. They r def getting unbalanced I can feel it when it arrives and leaves the top floor. I do see one side with a heavy weep compared to the other jack. But I am not losing any oil in scavenger or down over casing to pit .. I wanna change seals to fix this problem but I'm not that confident it will solve the problem. I'm thinking I should see oil in the pit for the seals to b the problem.. what do u guys think ?

I've had same issues with 2 and 3 Stage tk jacks. You do have to change all the packing seals, internal and external. There are check valves at the bottom of the lower plunger on a 2 stage and the lower and middle plunger on a 3 satge. TK says they haven't had issues with these since 2003 so it's more than likely the packings. I have instructions on the procedure so pm me an email address if you need it. You will need to hang the car and have a couple of good chain wrenches and a strap wrench to disassemble the heads. I've had to do this on a few that were less than 2 years old. Bad batch of packings or poor design???

"You can feel it when it arrives and leaves the floor".
Sort of a slight racking due to tight packing on one side. Well, short of a repack, which if you can feel it, your customers can too, you might try adding some Caterpillar Hydraulic Oil additive to the tank. Some guys will also spill or brush some on the heads too, but I don't know if that's all too effective. There are times when this does help. Also, be sure your jack resync time is sufficient.

I was told that my problem could be a valve that controls the flow of oil thru to the upper stage. Has any one ever had a problem with this ?

Thanks Jc. Email sent.
ELmcannic thanks. How do I change my jack resync time? I have ims

Those valves can cause the issue but I've never had a problem with them except when I was with tk in construction, they sent a jack out from the factory missing the check valve. The ones I've had issues with, when we pulled plungers out, the packing at the base of the plungers had broken into pieces.

We had a job that the resink wouldn't work unless the pistons came fully down. So we added longer bolts on top so at night when it went to resink the pistons would lower down enough to open the inner valves to allow a complete resink. We also had Dover jobs we had to pump in special oil to the inner jacks.

Either bad internal seals or check valves can cause the same problems. You have to remove the pistons to get to both the internal seals and check valves so I would just change them all while you have it apart. Also when finished make sure you bleed each jack head out individually.

Also another more obvious issue could be that the jacks are out of plumb and binding on the platinum plate. This can cause the jack not to do a proper re-sync.

I had to change the seals and check valves on a two stage that was doing this . Make sure you have a decent chain wrench . There is a write up someone was good enough to send me I will see if I can find it . There are a couple of tools it recommends you have to make it easier .

You must have a minimum of 8-1/2" of dovetail with 6" runby and 2-1/2" stroke buffers. These numbers are critical for the system to be able to correctly re-sync. If these numbers are right, when the car drops to the springs, the bottom 2 jacks are bottomed out, check valves open and 2-1/2" left on the upper stage. The jacks are not meant to fall away from the platten, this creates the possibility to suck air. The Jump Bolts are only for inertia, keeps the jacks from pulling apart if the car hits the stop rings at full speed. The jump bolts have to be free and turn by hand or the holes on the platten should be torched out to prevent binding. Jacks need to be level to each other and buffers level. Make sure O30 is set to 1 and JRT about midnight so the car syncs every night. Try a quart of CAT oil but it needs to be poured directly into the jacks to really help. Always do a manual re-sync before you leave ( pull springs and manual lower the car), set a piece of paper on the buffer stands to make sure the bolster channel doesn't touch the stands. It won't if runby/ dovetail are right. If it still shuts down on a 1068, re-pack it but replace every seal and all the check valves while you're in there.

If you're going to replace the seals, get them from gorman. We've had issues in the past with the ones from vertical. Vertical does have a manual on their website for the 2 stage and 3 stage jacks.

I cant' remember the parameter name, but one is for the actual time the re sync takes place like IDWT suggests (JRT=midnight), but there is also the time in duration the system is given to accomplish the resync (like 30 seconds etc). I think I set mind at 45 seconds.
You can "force" a resync too while you've got control of the unit to see how it takes place, but these acronyms/commands escape me at the moment (FJR?...ForceJackResync?)

I have an older tac 20 that was used on a mod. It's a 2 stage with a car sling that's seems like it's not the typical one used. The removable brackets on top of the styles are longer making the crosshead higher. I know this was engineered to create more rise. The jack sync sensors are the optical type , not the magnets like on newer tac 32's. I've tried to set up the jack RESYNC time but it seems as this feature was not on this older version of software? , and I'm guessing this unit will only RESYNC when the sensors see its out of sync. And of course the previous service company has taped up the sensors after a few went bad so it never resync's. I'm going to replace the sensors but I'm I right about the older version not having a feature to auto resync at a set time?

Ya, oldest versions did not have the re-sync interval O30 if I remember correctly.
O29 is the lowering time 30 sec. is max so I usually set it to that but I have been told by those who know more than I that it just needs to bottom out so the pistons don't fall away and suck air. Actually DMCs would drop the valve coil when the pressure switch opened for this reason. FJR is the Force Jack Re-sync command, WJR is the When Jacks Re-sync command to show every time the car has done one. I will look and see if I can find the bulletin from when the software with O30 came out, I think in that same bulletin they suggested deleting the static sensors since the car would be syncing nightly, but don't do that.

Looks like it wasn't until V4R1 that the timed resync interval was introduced.