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