JD 750c Transmission problems

[Jim Spielman]

Our 98 JD 750C is slipping under a hard push, the engine does not pull down and the dozer just stops, it moves just fine the rest of the time but under a hard load it it slips. Any ideas? Cant afford a new tranny, will try changing filters this week but I am affraid it will be more then that.

 

[Jim Spielman]

We have 350 psi of constent pressure, 80 hours since last filter change in may, machine has 4000 hours on it, we bought it used about 6 years ago and had a new transmission put in under warrenty( still cost $6000 to us) for a simmiler problem.

 

[Countryboy]

Welcome to Heavy Equipment Forums Jim Spielman! :drinkup

 

[ncbschzzt]

might be a multifunction valve

 

[ncbschzzt]

Try traveling up a steep hill in reverse and see if the samething happens, also when the problem happens does the machine try to mistrack. Also is there any indication of track index, that is starts the turn one way or the other at intail movement?

 

[Jim Spielman]

Thanks, very much for the come-back, my brother says it is tracking true on takeoff, he will check it again tomorrow when he gets to the job and he will try it in high reverse to see what it is doing there, he thinks it was the same. But he is pretty sure is tracks true when it starts to slip. The machine is on a job 200 miles from his shop with no cell service, he stays in a camper for the week when he gets to the job, he will come off the job on Friday to give us the test results. He will be installing culverts all week and popping roads with the grader so he will not be useing the 750 much this week, he is affraid to really wreck something. If he can find a place where the cell will work we may hear from him sooner. The Casper JD dealer did not have tranny filters in stock but they only have 80 hours on them anyway.
Thanks, very much,
Jim

 

[ok dirt witcher]

What do you mean when u say slip?

Are there any codes coming up and what number are you pushing with (hence 1.4, 1.5, or 1.6) I have a 98 850c and have experienced similiar problems, If on a steep slope and the transmission hyd tank was not completely full and once in a creek bottom where there was too much mud and solved it by loosening track tension. The worst and most expensive was when I lost one of the inspection plates underneath the drive pumps and a tree stump knocked of one of the speed sensors $$$1500 for the sensor and $2000 for service call I know it doesnt sound like alot but the sensor would fit in my pocket.

 

[Serv]

The 750C doesn't have a transmission as far as I know. It basically uses hydraulic motors (hydrostatic). Again, are you getting any codes? The codes usually start with an "F" followed by a few numbers. Does the "STOP" light on the dash blink when this is happening?

ok dirt witcher,

I was quoted ~550.00 for a speed sensor the other day for my 750C. 1500.00 sounds pretty steep.

 

[ok dirt witcher]

The 750C doesn't have a transmission as far as I know. It basically uses hydraulic motors (hydrostatic). Again, are you getting any codes? The codes usually start with an "F" followed by a few numbers. Does the "STOP" light on the dash blink when this is happening?

ok dirt witcher,

I was quoted ~550.00 for a speed sensor the other day for my 750C. 1500.00 sounds pretty steep.

I'm almost sure I paid $1500 for mine and it was a dealer in TX. Of course when your down and losing money I had to have it fixed ASAP.

 

[Jim Spielman]

We will check for codes this week. the machine is at a very remote location in Wyoming, as far as I know there has been no codes and the STOP light has not been comming on, we have changed the speed sensor before and we will be happy if that is all it is.
Thanks,
Jim

 

[Jim Spielman]

The fluid is full, it happens at 1.5 mostly.

Thanks,
Jim

 

[ncbschzzt]

If you have replaced several sensors then you may have a damaged speed ring, or it has debris on it.

 

[Jim Spielman]

we just changed it once, mice ate the wires a couple years ago.

 

[JackDeere]

Jim
The 750C Dozer has a dual path hydrostatic drive system. Hydraulically they are pretty much independent of each other. There is a mistrack program in the controller that will keep the tracks turning at the same speed when going straight. If one of the drive pumps or motors is having a problem the controller will slow the other track to keep them going straight. You can isolate the problem side by disconnecting the speed sensors on the drive motors and burying the blade to see which track will stall. This may at least give you one pump or motor to diagnose. Check in forward and reverse. There are two Multifunction Valves on each pump. One is for a forward high pressure relief and one is for the reverse.

 

[ncbschzzt]

he will verify with the test I asked him to perform, that way we can determine if it may be a multi valve or a speed sensor. Also he his going to verify that it is not indexing.

 

[smithexcavating]

We have 6 Deere dozers on our crews and we had a similar problem on our 1050C, have to check with the mechanic to see what the fix was. I know we have been real happy with ours, no real problems that are nagging. We have 550G LT's, a 700H LGP, an 850C LGP, 1050C LGP and 1050J LGP. Real happy with the new 1050J, heck of a machine.

 

[dirt4fun]

I have a TD7h that while pushing up against trees, sometimes the tracs will stop spining and if do not push the deacelerator fast enough you can fill the trans. start to slip and hear a a dry squell from it.I believe mine could be the clutch pack getting weak?

 

[Tnvolnfl]

Jd 650g

Newby here looking to purchase a JD 650G LGP for cleaning up a 98 acre parcel that has been clear cut. Unfortunately, i don't know much about dozers ecept what little I have learned researching the net. Found several in the $30,000 to $40,000 + range. Any suggestions as what to look for or stay away from, Etc.? Thanks

 

[dirt4fun]

Tnvolnfl, I have a couple of friends one owns a deere the other a cat. they both like their machines.I have had good luck with my dresser ,it has 5600 hrs. I believe the clutch problem is probably normal wear for the hours.Is there a reason you are looking at low ground pressure machine?I am pretty new at owning a dozer (3 yrs.) but the research that I've done suggested a narrow grouser the better, less stress on your drive train.

 

[Tnvolnfl]

The only reason I thought a LGP machine might work better is the property is bordered by a creek and while the majority of it is dry, there is a few wet spots I will have to deal with. Since the 650 is a kinda small machine either would probably work. What's considered allot of hours on one of these? I have a pretty good idea what wear to look for on the sprockets and pins but what else should i look for?