The transmission on Euro tractors are compact and robust. If opening up your transmission, consider replacing the needle bearings which are found inside a few of the gear sets. Pictured at the right is an example of the bearings found in the transmission. Often, these bearings wear out before deep groove ball bearings. The bearings are relatively inexpensive and are worthwhile replacing as a preventative maintenance issue.
Always inspect gear teeth and any ball bearings. Bearing failure is the number one cause of case failure, a major component no longer available new.
Always replace seals when the opportunity presents itself.
Early Pasquali tractors are essentially the same tractors with different engines. The exception to the Pasquali rule (transmission) is the 988.30 model. While the 986, 991, 993, 997 and early 988 tractors shared transmission components, the later 988.30 (identified by the welded box type articulation frames) differed significantly. While some components (about 50%) were the same, there were significant differences. Later model transmissions for the 490, 492, 494 were again significantly different again, but shared components from the 988.30 transmissions. The evolution of the transmissions makes tractor identification critical. Always look at the tractor stamping tag for the "series" to identify your tractor. About 50% of a 988.11 transmission is incompatible with a 988.33 transmission. The "series" is the second part of the model number after the decimal point (11 or 33). There were differences in shafts, gears, bearings and seals.
Please note: While the earlier tractors allowed for splitting the transmission case from the articulation components, the 988.30, 993.30, 490, 492 and 494 tractors differ significantly. To remove the transmission from these later tractors:
1) Prepare a rolling dolly to support the rear half of the articulation frame.
2) Drive the split pins from the upper and lower front universals (split pins anchor universals to the transmission shafts).
3) Split the tractor by removing both upper / lower articulation pins (roll rear of tractor back out of the way).
4) Remove the six nuts holding the front articulation frame to the transmission housing.
5) Place a small hydraulic jack horizontally against the lower transmission shaft.
6) Use a chain or build a strong back to attach to both power steering pins for jack base.
7) Use two bolts on the top of transmission case to hang case from an overhead crane.
8) Use jack to break the front articulation frame free from the lower outboard bearing around PTO shaft (this is a press fit).
Trying to remove the transmission by splitting the tractor at the rear of the transmission case is risky and can damage the machine.
These later series tractors have a problem with the original second gear in normal range. Often these tractors develop a loud growl in second gear - especially noticeable when going downhill and not under load. While the transmission looks the same as the earlier tractors, it is not. There was a change in gearing that unfortunately did not work out well. The gear affected is 439.206.0 - the original gear had 20 teeth, the replacement has 21. This growling can go on for quite some time before failure, but if affected, you should think about upgrading to the 21 tooth gear. We measured the tooth pitch and diameter of the new gear and it is only 3mm larger in diameter. That means the root clearance would only be out by 1.5 mm, which is not much. Calculating the original gear set pitch circle diameters and the shaft offsets, we realized the original 20 tooth gear had excess clearance and resulted in "smudged" teeth. At first we had no idea what would cause tooth damage on only one side of a gear, but after working the math out, the 21 tooth upgrade makes sense. Here are two pictures:
Notice in the picture on the left, the teeth are in decent shape. The picture on the right is of the same gear, but turned 180 degrees. This is the original 20 tooth gear.
The Universal series of tractors seem pretty robust and shared parts. Again, the tractor number designated the engine type.
The early Ferrari's (76, 85) differed significantly from each other and share little in the way of parts.