jd400 yellow tractor with backhoe- shuttle shift misery

[markmc60]

I have an old JD400 yellow version, has a front end loader and backhoe attachment.
for years it has been slow to go into forward, well, it sat longer than usual, like 8 months, had no forward, none, nada. so, I pulled the screen and replaced the filters new hyd oil, still no forward, I raised the rear off the ground with the stabs and blocked it up. reverse works, forward just creeps. (I forgot to mention before I blocked it up, had an old fart tell me tow it to "release" any stuck clutches, I did. no work).
was told it was a reverser leaking, I pulled the reverse block and rebuilt it, nothing to it, pulled the in pipes and put new orings on them feeding the reverser. new hyd oil, now, I have nothing in forward or reverse, no pressure at all at the side test points.
HELP

 

[Tx Jim]

Could be leaking fwd clutch pack seals. Does linkage shift reverser control valve correctly IE no loose motion in linkage? Was filters & screen dirty?

 

[markmc60]

Could be leaking fwd clutch pack seals. Does linkage shift reverser control valve correctly IE no loose motion in linkage? Was filters & screen dirty?

nothing loose and shifter moves fine. filters and screen are clean.

and just where in Texas is coyote flats? LOL

 

[jb1390]

nothing loose and shifter moves fine. filters and screen are clean.

and just where in Texas is coyote flats? LOL

I used to own a JD 300 industrial, that I lost forward motion (twice, actually). Here is what I remember off the top of my head:

There is an internal transmission gear pump that provides low pressure (200 psi) oil for a variety of functions. There are priority valves contained in the shifter control block, which is located under the right-hand footrest. The clutch pedal works a valve in this control block, which provides low oil pressure to the reverser valve (contained in the same valve body). The shuttle shifter valve directs that oil to the forward or reverse clutch pack pistons.

Did you split the tractor when you performed work earlier?

Do your other hydraulic functions work correctly?

Before you lost both forward and reverse, did you have pressure at the reverse port, but no/low pressure at the forward port?

 

[markmc60]

I used to own a JD 300 industrial, that I lost forward motion (twice, actually). Here is what I remember off the top of my head:

There is an internal transmission gear pump that provides low pressure (200 psi) oil for a variety of functions. There are priority valves contained in the shifter control block, which is located under the right-hand footrest. The clutch pedal works a valve in this control block, which provides low oil pressure to the reverser valve (contained in the same valve body). The shuttle shifter valve directs that oil to the forward or reverse clutch pack pistons.

Did you split the tractor when you performed work earlier?

Do your other hydraulic functions work correctly?

Before you lost both forward and reverse, did you have pressure at the reverse port, but no/low pressure at the forward port?

did not split the tractor, the "external Hyds work as always. I can't answer your last question, I do not know the answer.

 

[jb1390]

did not split the tractor, the "external Hyds work as always. I can't answer your last question, I do not know the answer.

There are test ports located on the valve body underneath the right footrest. They are straight thread, o-ring seal plugs. ( I think 3/8" fine thread). You will need an adapter fitting, but you need to check pressure at these ports. I believe there are 3 - one overall pressure, and one each for forward and reverse.

When you push the clutch pedal, it rotates a bar which opens a valve. There is a roll pin in the bar that runs underneath the tractor - make sure the roll pin is intact and that the linkage moves correctly.

What did you take apart when trying to fix? Did you take any pictures?

 

[Tx Jim]

and just where in Texas is coyote flats? LOL

30 miles South of Ft Worth according to Google and me

 

[Billrog]

If it doesn't have enough power to spin the wheels when up against something the torch converter may be shot. If so and you replace it , it's a good time to replace the pump as well while your in there it's a 4.5 hr. job.

 

[jb1390]

If it doesn't have enough power to spin the wheels when up against something the torch converter may be shot. If so and you replace it , it's a good time to replace the pump as well while your in there it's a 4.5 hr. job.

I'm pretty sure that his tractor does not have a torque converter. It's a dry clutch, and then 2 sets of wet clutches - one forward and one reverse.

If it's the forward clutch pack or o-ring that needs to be replaced, that's way more than a 4.5 hour job.

 

[Tx Jim]

I'm pretty sure that his tractor does not have a torque converter. It's a dry clutch, and then 2 sets of wet clutches - one forward and one reverse.

Ditto on NO torque converter. It sounds as if reverser clutch linings are toast.

 

[jd110]

If you lost reverse after removal of valve body, my guess is you got one of the oil lines out of place. They are very difficult to install with out splitting the tractor. The forward clutch probably needs to be resealed and possibly linings replaced. Forward clutch is accessed when split at clutch housing. Reverse clutch and oil lines are accessed at split between clutch housing and transmission case.

 

[jb1390]

If you lost reverse after removal of valve body, my guess is you got one of the oil lines out of place. They are very difficult to install with out splitting the tractor. The forward clutch probably needs to be resealed and possibly linings replaced. Forward clutch is accessed when split at clutch housing. Reverse clutch and oil lines are accessed at split between clutch housing and transmission case.

Those lines should not generally come out when removing the valve. There is a plate behind the valve assembly, with an additional couple bolts that holds the lines in place. However, there are a few check valves and regulator springs that need to be carefully reassembled. I concur with the general theory of the forward o ring being shot, though that can be tested with compressed air fairly easily.

 

[markmc60]

Those lines should not generally come out when removing the valve. There is a plate behind the valve assembly, with an additional couple bolts that holds the lines in place. However, there are a few check valves and regulator springs that need to be carefully reassembled. I concur with the general theory of the forward o ring being shot, though that can be tested with compressed air fairly easily.

with compressed air?, injected where? I am a little weary of this old JD, I have worked on a many a tractor but not much good on transmixers.......... just tore my jd450 dozer down past the rear quills and back together, that was a chore. still scraping cash together to replace the tracks and rollers..........soon. then I get my backhoe in the shop and play with it

 

[jb1390]

with compressed air?, injected where? I am a little weary of this old JD, I have worked on a many a tractor but not much good on transmixers.......... just tore my jd450 dozer down past the rear quills and back together, that was a chore. still scraping cash together to replace the tracks and rollers..........soon. then I get my backhoe in the shop and play with it

Picture 1: you see the screws labeled as "11" - those screws are test ports for the forward and reverse control circuits. You may be able to apply compressed air to those ports. I did not try that when I had my machine, and if you have leakage, that may indicate a valve problem not necessarily an internal issue.


Picture 2: If you remove the reverser control valve, there are oil lines that go directly to the reverse/forward clutch cylinders. If you apply air to those, they should engage either the reverse or forward clutch pack, depending on the line you are pressurizing. I believe the lines you need to pressurize are labeled 8 and 9. This is what I did when I had this problem on my 300. After replacing the forward o-ring, it would hold pressure. It would not hold pressure on forward clutch pack originally.

 

[Tx Jim]

Ditto what jb1390 stated about checking for hyd leak with air. BTDT several times when I was a JD dealer service manager.

 

[markmc60]

thanks for all the help, when I get my backhoe in the shop I will let yall know where we are, I have a couple of projects in front of it, my 450 dozer and a 401 ag tractor that wont start and needs the water pump rebuilt............. just typical.

 

[Jet A]

Any update on the JD 400 reverser issue?

 

[markmc60]

Any update on the JD 400 reverser issue?

sorry, not yet, I have not moved the backhoe into the shop yet............. just swamped, trying to get my 613 scraper going and my allis chalmers D12 engine rebuilt.

 

[TonyDeb]

I am having the same issue as Mark. My '72 JD 400 works in reverse not forward. Test pressure is 145 as it should be at rev test port but only 25 at forward test port. I bought used rev control valve $150 (cheaper then the rebuild parts) but has same issue. I assume there is a leak in the forward circuit after the valve. I must split tractor. How do I know if I need to rebuild the forward clutch pack or can I assume it's just the oil line O ring that goes to forward clutch? Also, should I split it at the differential side of housing or the engine side? Thanks!

 

[jb1390]

I am having the same issue as Mark. My '72 JD 400 works in reverse not forward. Test pressure is 145 as it should be at rev test port but only 25 at forward test port. I bought used rev control valve $150 (cheaper then the rebuild parts) but has same issue. I assume there is a leak in the forward circuit after the valve. I must split tractor. How do I know if I need to rebuild the forward clutch pack or can I assume it's just the oil line O ring that goes to forward clutch? Also, should I split it at the differential side of housing or the engine side? Thanks!

If I recall correctly, I think you need to split at both sections. Your choice on which one first. The center section that is removed contains the clutch packs. I would test with air as discussed above before splitting, but chances are your forward O-ring is shot. Your decision on what parts need to be replaced will come after internal inspection. If the clutches are in ok shape, you may be able to get away with just seals. I did everything when I split mine for peace of mind.

Get a manual for the machine if you do not already have one. The manual for this machine is pretty detailed.