Re: John Deere 455 L&G Tuff Torq K92 Hydro Rebuild
I have more pictures. If there is anything you need in the way of photos or part numbers please let me know.
The "seal" that you mention between the center case and main case is a gasket. Before going through all of this, one might also want to check if the vent valve on top is venting fluid due to an overfill but I assume you already checked that.
As far as what can be removed without removing the transaxle assembly from the tractor frame, the hydro pump does come out and that is how the JD Tech Manual recommends to remove it. It MIGHT be possible to remove the entire hydro front end (pump, motor and center case) from the transaxle with it in the tractor frame but there are some things that may fall out in that process that are really best to keep clean and organized.
It is not difficult to get the transaxle out of the frame. These things (doing this from memory) have to come out or get disconnected and the first few have to happen anyway to get the pump itself out:
Drain trans fluid and filter. I recommend putting the empty filter back on after draining to keep residual fluid in the housing as you move it around.
Remove seat pan (rear fender assembly) one 6mm bolt on each side
of seat and four 6mm nuts and bolts holding floor pan to rear fender assembly. Bolt threads are 6mm. Hex heads are 10mm.
Remove tail light bulb holders from sockets and disconnect connector to seat switch prior to lifting seat pan off frame.
Lift and move fuel tank off to the side or disconnect the two hoses to fuel pump and fuel pump wiring connector and remove the tank completely.
Remove drive shaft from engine to hydro pump- two bolts @ pump end on splined shaft. Three bolts from underneath at rear of engine at coupler. You may need a strap wrench or other means to keep the coupler/shaft from turning as you loosen the three bolts.
If you are going to remove the transaxle completely from the frame you will need to disconnect on the left side the brake linkage and differential lock linkage. These are both simple cotter pin fasteners.
On the right side disconnect the linkage from the GO pedal to the swash plate linkage a.k.a. forward/reverse control arm. Access the bolt through the hole provided for this in the frame rail. You will have to hold the nut on the back side of the linkage.
The hydraulic lines and cylinder to raise/lower the mower deck can remain as they are.
Disconnect the connector for the PTO solenoid.
Take out the two bolts on each side of the frame that go into the axle housings of the transaxle. Preferably with a helper for five minutes, chock the front wheels and jack up the frame in front of the transaxle high enough so all transaxle components will clear the frame (it helps to first remove the two bolts that hold the transaxle dipstick). Removing the dipstick and its housing reduces the height one must raise the tractor frame to get everything clear of the frame. Pull the transaxle out to the rear. Lower the tractor frame on jackstands.
If you take the rear wheels off after separating the tractor from the transaxle it is now easy to get the trans unit on a bench. Estimated weight is ~ 100 pounds or so.
It took me about two hours to get the transaxle out and about 1/2 hour to put it back in. BY FAR, most of the time was spent in rounding up the parts.
There are two O-rings behind a snap ring and washer that seal the swash plate shaft. These sometimes leak. There are also seals where the mid-mount PTO shaft exits the case at the bottom front and a differential lock shaft seal on the left side near the back. There is also a seal cap on front of the hydro motor. The hydro pump is sealed at its rear face to the center case with six O-rings. The center case seals to the main housing with a large gasket. The hydro motor is sealed to the center case with a gasket.
The rear cover, right side case cover and both axle housings are sealed with silicone type form-in-place gasket material where they mate to the main case. There are also axle shaft seals out toward the ends of the axles.
Other than basic rachets, metric sockets, extensions, wrenches and pliers (for cotter pin and hose clamp removal), you may also need snap ring (retaining ring) pliers depending on how far you go into the disassembly process. As with any transmission related project, it is important to have a clean work table.
I am an engineer and a very experienced DIYer but a relative newbie on this forum. That said.....happy to answer any questions or provide photos, part numbers, etc. This forum has been a huge help to me.
1995 John Deere 455 (Diesel)