Problems shimming JD 445 hydraulics

[Turbo Goat]

Hey tractor people,

I'm taking my first stab at modifying my 445 hydraulics. Aaaaaaannndd something's weird.

The first issue that I discovered was that the stock hydraulic pressure was 750 PSI. Not a good sign, but not necessarily a show-stopper. Second, the stock IRV seemed to be missing some packing and a washer, and it was also very worn. The brass shim was deformed into an oval in the ID, and the plunger cone was visibly worn. I received a new IRV today and began shimming. I pretty consistently get less than 50 PSI for each 0.3 mm shim. So at 1.2 mm of shims, I get 900 PSI. Now this seems WAY low. I can't reasonably put any more shims on and I think it would be asking for trouble anyway. I'm about to conclude that the charge pump needs an overhaul. However, I could be missing something. So I want to ask the community for a sanity check.

The hydraulic fluid is full. The fluid and filter were very recently changed. The fluid is HyGard, Low Vis. Pressure is measured at W.O.T.

My assumptions are:

1) The stock hydraulic pressure in a properly functioning system should be about 950-1050 PSI.
2) Most people that have made this mod get around 1250 PSI with 0.5-0.6 mm of added shims.
3) It is OK to measure charge pump pressure at the bucket wrist, raise port (top left looking forward).
4) It is OK to use a cheap 2000 PSI gauge, cobbled together with some fittings from ebay to measure the pressure.
5) Visible wear on the IRV sealing surface is indicative of a problem. This problem could have been caused by the missing packing, allowing the plunger to wobble.
6) The machine has about 2000 hours on the meter, and I suspect that it was not so well maintained. It's a '97. So, some wear is to be expected.
7) A charge pump rebuild is improbable, and replacement of the transaxle is likely the only solution.

When I ordered the IRV, I thought about ordering the valve seat as well, but the JD parts diagram doesn't give a number for it. I'm not sure if valve seat wear would have an impact on pressure when mated with a new plunger. I'm not sure if I could get it out of the transaxle case anyway.

Just for giggles, I have to more gauges on the way. I don't completely trust a $10 gauge from Ebay.

If anyone has any ideas, questions that might lead to a solution, or useful info, I would really appreciate the help.

 

[zzvyb6]

JD or WIX filter ?

 

[Spanner]

Without answering any of your questions (yet) what prompted you to commence this 'mod'? Did you have 'low' hydraulic pressure?

Charge pump replacement, alone, is possible. The viability of repair is dependent on your budget, means, condition of the rest of the machine and what you are using it for.

You can try lapping the relief valve into the seat. You would dismantle the transaxle to do this anyway so you're half way to a rebuild.

 

[Turbo Goat]

JD or WIX filter ?

Not sure. The dealer changed it. What are the implications of one vs. the other?

 

[Turbo Goat]

Without answering any of your questions (yet) what prompted you to commence this 'mod'? Did you have 'low' hydraulic pressure?

Charge pump replacement, alone, is possible. The viability of repair is dependent on your budget, means, condition of the rest of the machine and what you are using it for.

You can try lapping the relief valve into the seat. You would dismantle the transaxle to do this anyway so you're half way to a rebuild.

Spanner,

Thanks for the info.

My reason for wanting to increase the hydraulic pressure is that the loader can only lift around 200 lbs. A loader that can't lift at least a level bucket of gravel isn't that useful to me. I discovered the issue when trying to lift my newly acquired 3-point tiller out of my pickup. That was a total no-go. Of course I understand that this is a garden tractor. It is limited in what it can do without damage.

I believe that I have low hydraulic pressure. I measured 750 PSI. However I plan to verify with a second gauge. I have the second gauge and might be able to do the test this evening.

I have the budget, and probably the means, but it's a bigger project than what I really want to get into. The over-all condition of the machine is 7 of 10. It's worn, and rough around the edges, but runs great.

Goat

 

[Spanner]

Understood Goat.

FWIW I think you will be wanting to operate the old 445 at 10/10ths capacity often. Maybe you should sell it and buy a bigger machine which can handle your workload at 60-70% with room to spare?

You start stripping the 445 rear-end and the wallet may open wider than you want. :2cents:

 

[Turbo Goat]

Understood Goat.

FWIW I think you will be wanting to operate the old 445 at 10/10ths capacity often. Maybe you should sell it and buy a bigger machine which can handle your workload at 60-70% with room to spare?

You start stripping the 445 rear-end and the wallet may open wider than you want. :2cents:

Thanks. I do appreciate the advice. I was hoping, perhaps naively, that I wouldn't be operating so close to the limit.

And my wife won't let me get a bigger machine. :laughing:

 

[Spanner]

Maybe need to trade her in with the tractor? :stirthepot:

 

[zzvyb6]

Not sure. The dealer changed it. What are the implications of one vs. the other?

I saw on another help site where a 445 had the same issue and a change from WIX to a JD filter 'solved' the problem. Of course, just changing to a new filter might have done it, too though.

 

[Turbo Goat]

I saw on another help site where a 445 had the same issue and a change from WIX to a JD filter 'solved' the problem. Of course, just changing to a new filter might have done it, too though.

zzvyb6,

Thanks. I'll check the filter make when I can get back to the tractor.

Goat

 

[Spanner]

To state the obvious: The (JD) dealer should have fitted a JD filter. Anything less would raise a red flag!

 

[Turbo Goat]

Maybe need to trade her in with the tractor? :stirthepot:

Hmmm. I hadn't considered that. Perhaps a newer model is in order...

I guess I should consider myself lucky that I get to own one at all.

 

[Turbo Goat]

To state the obvious: The (JD) dealer should have fitted a JD filter. Anything less would raise a red flag!

Yeah. I would be surprised if it were anything else.

 

[Turbo Goat]

Thanks for all of the replies and info. I think I solved my own mystery.

I got another gauge from the local hydraulic shop. It turns out that it's the same cheap gauge sold on Ebay, but a second unit at least. Yeah, so the second gauge reads twice what the first does. I'm really glad that I had the hunch to verify the gauge. I could have blown up the transaxle. I don't have profanity or expletives strong enough.

I have a third, better quality gauge on the way.

I have 12 yards of poo blend arriving tomorrow. I really hope I have the loader squared away in time!

Goat

 

[Spanner]

2 x cheap gauges. 2 x different readings. Which one do you believe?

Still have the question mark surrounding that 'ovalised' washer.

 

[Turbo Goat]

I'm going to go with the high-reading gauge for now. While there is still some risk in that, I think that the system pressure will at least be in the ballpark, if not a little low. I can adjust as necessary when the better gauge arrives. I also had a conversation with the local hydraulics shop. They said that they can test a gauge for a small fee. I'd have them do that today, but I don't have it with me.

The oval washer is a mystery that I may never be able to solve. I suspect that it's due to the valve being short a couple of bits. One of the missing parts is an o-ring that JD calls "packing". I'm not sure what the intended purpose is, but it would also serve to keep the valve plunger centered. It seems to me that allowing the plunger to wobble would cause both of the unusual wear problems that I found in the old valve. For now, I plan to check the replacement valve periodically for wear and address the issue if and when it comes up again.

While this may not seem like the best practice, time is not on my side. I return to school in a few weeks. My property grows into a jungle each year while I ignore it for 9 months. I have my summers to get the place in shape again. This year my wife wants to restore her Karmann Ghia in our garage, so I have that to clear out, in addition to the usual list.

Thanks again for the suggestions, info, and wisdom. I'll update with the final result when I'm confident that I have it worked out.

Cheers!

Goat

 

[Spanner]

Good luck with JD & VW.

 

[Turbo Goat]

Thanks Spanner!

It turns out that I had cause to go home yesterday after all, so I was able to pick up the gauge and get it tested. It's spot on, apparently. I took all of the shims out of the IRV and started over. My hydraulic pressure is now about 1300 PSI, right where I want it. The bucket should lift a heaping scoop of poo now. Just in time too. I will have a veritable mountain of it arriving this afternoon.

Goat

 

[Spanner]

Which gauge was spot-on Goat? The 1st or the 2nd?
Either way be careful of overloading your FEL.

I'm always in the poo. It's just the depth that varies!

(PM returned)

 

[Turbo Goat]

Spanner,

It was the second cheap gauge that proved to be more accurate. I have not yet received the third gauge. Thanks. Yeah, I understand that the machine has limits. If it can do occasional duty with 500-600lbs, that's enough for me. Any more than that would probably wear out the front wheel bearings pretty quickly. The mod I made is supposed to be very common and the tractor is known to be able to take it. I just have to stay clear of 1500PSI. I have some suitcase weights or a tank of a rototiller for counterweight, but most of the time it's just for cutting the grass.

I saw your PM. Thanks. I'm doing a little reading to educate myself so that I can have a reasonably intelligent conversation.

Cheers!