Spdrcer34
Explorer Addict
- Joined
- March 14, 2002
- Messages
- 3,833
- Reaction score
- 16
- City, State
- Bremerton, WA
- Year, Model & Trim Level
- 1992 Explorer XL
Since I broke my current transmission case
And shattered the countershaft in 1st gear
....it came time to get another transmission and from those 2 transmissions, I needed to make 1 good transmission from the parts.
The 4WD and the 2WD use different output shafts. So the first thing I had to do was swap the output shafts. While I was in there, I noticed all the differences.
Transmission #1 is a 2WD that my sister had installed about 30k miles ago. Turns out it is a Transmission originally meant for the 2.9L. casting date says it's a 1991.
Transmission #2 is a 4WD that I scored off craigslist for $200. It had recently been opened up, as there was fresh RTV on the bolts, and top cover. This is a TRUE 4.0L transmission. Unknown mileage. Casting Date says it's a 1994.
If you have ever gone shopping for replacement parts for the M5OD, you will see a few different versions, and 'updated' parts of the same part. There doesn't seem to be any hard evidence of when they went from one design to another. Or for what application they used 'this' part over 'that' part.
One of the biggest, yet subtle changes are the input/counter shaft changes.
The 2.3L/2.9L/3.0L used a counter shaft has tooth count of 16-24-32-38.
The Explorers 4.0L used a counter shaft has tooth count of 17-25-34-38.
Eventhough it is an increase of only 1 or 2 more teeth for the 4.0L shaft, the difference is pretty big. For example, here on the gear that counters the Mainshafts 1st Gear, you can see the difference.
4.0L on the Left, 2.9L on the Right
The teeth are wider at the base, and not nearly as 'pointed'. They also don't go nearly as deep on the 4.0L Countershaft.
Another thing that changed somewhere along the way, is the revers gear set-up. The early M5OD's had 36 teeth on the syncro's, ring and gear. While the later ones had 30 teeth. The engineering principals in this application is the exact opposite of what is normally done. 30 teeth are stronger than 36.
As you will see in this application, the 30 tooth version uses broad teeth to help engage the gear. The 36 tooth version uses narrow, sharp teeth. The narrow teeth cup easily. While the broader teeth aren't nearly as prone to this type of damage. You'll also notice that I cracked the 36 tooth synchro in the thin area. While the 30 tooth ring is about 20% thicker in the same spot.
And just for the sake of keeping everything in 1 place, the famous 'rubber plugs' in the top plate need to be replaced. As you can see, the Dorman part number is 555-108. You will need 3.
Another change that happened somewhere along the way, is a change in the casting of the case.
You can see where they added stiffening ribs to the bellhousing area to strengthen the case. I don't know if they strengthened the case for use behind the 4.0L, or if they did it for use in the 4WD application. Maybe both.
Here is 1 area on the case where they actually removed a stiffening rib in the newer design. Right above the Main (output) shaft rear bearing, there is a vertical rib in the casting on the old design. On the newer design, they seem to have deleted it.
One of the smallest things I noticed was actually the one that bugged the most.
The Early design incorperated a Spot welded multi-piece stamped steel trough that feeds the front bearing. As oil is slung onto the top cover, and side of the transmission the trough will catch the oil, and slowly feeds the front bearing.
The later design was obviously a cheaper design. It was a 1 piece plastic that was TOTALLY clogged when I opened up the transmission. The cause of the clog was partially due to the fact that the plastic had become deformed, and there was some RTV in the trough. This is CLEARLY a case of the bean-counters @ Ford getting their way. I will be using the stamped steel version in my rebuild.
Hope this helps SOMEONE out there.
Ryan
And shattered the countershaft in 1st gear
....it came time to get another transmission and from those 2 transmissions, I needed to make 1 good transmission from the parts.
The 4WD and the 2WD use different output shafts. So the first thing I had to do was swap the output shafts. While I was in there, I noticed all the differences.
Transmission #1 is a 2WD that my sister had installed about 30k miles ago. Turns out it is a Transmission originally meant for the 2.9L. casting date says it's a 1991.
Transmission #2 is a 4WD that I scored off craigslist for $200. It had recently been opened up, as there was fresh RTV on the bolts, and top cover. This is a TRUE 4.0L transmission. Unknown mileage. Casting Date says it's a 1994.
If you have ever gone shopping for replacement parts for the M5OD, you will see a few different versions, and 'updated' parts of the same part. There doesn't seem to be any hard evidence of when they went from one design to another. Or for what application they used 'this' part over 'that' part.
One of the biggest, yet subtle changes are the input/counter shaft changes.
The 2.3L/2.9L/3.0L used a counter shaft has tooth count of 16-24-32-38.
The Explorers 4.0L used a counter shaft has tooth count of 17-25-34-38.
Eventhough it is an increase of only 1 or 2 more teeth for the 4.0L shaft, the difference is pretty big. For example, here on the gear that counters the Mainshafts 1st Gear, you can see the difference.
4.0L on the Left, 2.9L on the Right
The teeth are wider at the base, and not nearly as 'pointed'. They also don't go nearly as deep on the 4.0L Countershaft.
Another thing that changed somewhere along the way, is the revers gear set-up. The early M5OD's had 36 teeth on the syncro's, ring and gear. While the later ones had 30 teeth. The engineering principals in this application is the exact opposite of what is normally done. 30 teeth are stronger than 36.
As you will see in this application, the 30 tooth version uses broad teeth to help engage the gear. The 36 tooth version uses narrow, sharp teeth. The narrow teeth cup easily. While the broader teeth aren't nearly as prone to this type of damage. You'll also notice that I cracked the 36 tooth synchro in the thin area. While the 30 tooth ring is about 20% thicker in the same spot.
And just for the sake of keeping everything in 1 place, the famous 'rubber plugs' in the top plate need to be replaced. As you can see, the Dorman part number is 555-108. You will need 3.
Another change that happened somewhere along the way, is a change in the casting of the case.
You can see where they added stiffening ribs to the bellhousing area to strengthen the case. I don't know if they strengthened the case for use behind the 4.0L, or if they did it for use in the 4WD application. Maybe both.
Here is 1 area on the case where they actually removed a stiffening rib in the newer design. Right above the Main (output) shaft rear bearing, there is a vertical rib in the casting on the old design. On the newer design, they seem to have deleted it.
One of the smallest things I noticed was actually the one that bugged the most.
The Early design incorperated a Spot welded multi-piece stamped steel trough that feeds the front bearing. As oil is slung onto the top cover, and side of the transmission the trough will catch the oil, and slowly feeds the front bearing.
The later design was obviously a cheaper design. It was a 1 piece plastic that was TOTALLY clogged when I opened up the transmission. The cause of the clog was partially due to the fact that the plastic had become deformed, and there was some RTV in the trough. This is CLEARLY a case of the bean-counters @ Ford getting their way. I will be using the stamped steel version in my rebuild.
Hope this helps SOMEONE out there.
Ryan
