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JD400 Reverser - No Forward

12700 Views 27 Replies 6 Participants Last post by  Mattharter
Reverser on my JD400 Industrial is malfunctioning. Works in reverse, does not do forward. Checked hydraulic pressures at forward tap and reverse tap on reverser control valve. Pressure is good on reverse pressure tap, there is almost no pressure at all on the forward tap. As clutch is nearly released, see pressure creep to maybe 3-5 psi, then feel a small "bump" then jumps back to zero. I have just changed hydraulic fluid and both filters - all checke done per tech manual SM-2074. Where is most likely place to find problem?
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Bad news... I did compression test on fwd oil line inlet to housing/front/fwd clutch. Not good, almost no compression at all, I could even hear air rushing out in the housing as I tried to pressurize. Tube may have been leaking, but apparently is not major culprit.

Now I'm removing the reverser/clutch housing assy to tear it down to get at the front clutch disc pack.

I removed the clutch/reverser housing from tractor, and after a series of simple presure tests, removed the fwd clutch pack/drum, disassembled it, and found the piston seals were %$#@%$#@%. They were pretty bad, holding no pressure at all. They were dried out, chewed up (as if a mouse/rat had eaten them), and stuck inside the grooves (see pics). All else (esp. the shaft seal rings and sleeve/race) looks good.

As soon as I get parts and reassemble, I'll report back.


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Now, its a done deal. The tractor is back on-line, running great.

I completely overhauled the reverser unit, except for replacing the actual disks/plates (they looked to be in great shape); replaced all seals, bushings, o-rings, etc, and polished ends of all oil tubes. The inside end of the fwd oil tube had become just a little bit out of shape, so I tweaked it a bit to get it perfectly round and polished for a good seal on the o-ring. It still seemed a bit floppy, but I did pressure tests and it seemed to hole well (must have been that way from the factory). Got it all put back together, adjusted clutch and pressures, it runs very good.

And oh by the way, I did experiment with the fwd oil tube a bit; everybody kept telling me that if it falls out, there is no way to get it back in without spliting the tractor - I found that it is possible to get that tube reinserted back into its hole from outside the housing, but it is very hard and time consuming. Now, the tube won't come out thru the opening in the side of the housing - there is a bracket behind it to keep it in place when repositioning the side plate. So if the tube must be replaced, the tractor must be split. But if it merely fell out when servicing the reverser control valve, it can be put back in. The real difficulty is that you can't see up in there and there is very little room to maneuver. But since the hole that the tube inserts into faces toward the rear of the tractor, I found it possible to to keep blindly poking the tube forward until it just happens to go right into the hole. You only need to find a way to get a firm grip on the outer end of the tube (I did with a wooden dowel stuck inside it and vise-grips with a rubber sheet to cushion it on the outside) and to possess a lot of patience - it may take a long time and many bruised knuckles to happen upon the right poke that lands in the hole, and then enough force applied forward to get it inserted all the way to seal with the o-ring. (even though I didn't need to do this, I just wanted to prove whether it could be done)

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Glad to hear you are back in action. That reverser should give long service. They are typically very durable.
Good deal. :thThumbsU
Congratulations! A job well done makes a body feel good.
Just in case anyone is still following this thread or stumbling across it looking for similar issues, I am happy to report that the reverser is still going strong after more than 2-1/2 years. This JD400 is a real work horse - consistently above and beyond what I've needed to do. So far, I have dug a pond that is about 100 ft across and about 6 ft deep across more than half of it. And many stumps have gone "bye-bye".

I recently bought a 1967 John Deere 400 Industrial tractor with a loader and rear PTO (and reverser). It sat outdoors in Wisconsin for 3+ years before I bought it. I can't turn the crankshaft with a pipe wrench around it between the front of the engine and the hydraulic pump. So, I assume the pistons are rusted to the cylinder wall. The vertical exhaust pipe had nothing covering it. It's looking like I'll need to overhaul the engine (in frame I hope). Wondering if anyone has advice on the best place to purchase a rebuild kit for this tractor and any other thoughts or tips as I try to get this tractor running.

I recieved some good feedback in the link above. Thought I'd post in this thread also as it seems all those interacting with this thread have good experience with this model of tractor. Thanks for your help!
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