Cracks in Separator Plate
#1
02-17-2017, 11:31 AM
#3
02-17-2017, 04:51 PM
I found this write up on a vendors website: not sure I can quote it but can someone translate it to layman's terms for me?
What I really want to know is if I loose 1st and 2nd with the cracks and deflection? here it is without the article's pictures:
Up through 2000, these units had a twobolt stiffener plate located underneath the 2-3 accumulator. The purpose of the plate was to clamp the separator plate and lower valve body gasket against the valve body casting. Beginning with 2001 models, the two-bolt stiffener plate was eliminated. The 2-3 accumulator retainer now sits directly on the separator plate. Another change in this area was that the Capacity Modulator Valve and plug were eliminated from the valve body and the valve bore was cast closed. The un-used casting pocket is also directly under the 2-3 accumulator. At first glance, you might assume that the cracks we see in the separator plate (see Figure 1) are caused by the 2-3 accumulator retainer's rounded end smacking against the plate. You might also assume the cracks are a problem, but the cracks and the accumulator retainer seating directly on the separator plate are not the problem. The cracks are a symptom of a completely different and bigger problem related to the Forward and Direct clutch circuits.
In these units, the Forward clutch is fed through the pump at the front of the unit and the Direct clutch is fed through the output shaft at the rear of the unit. Forward and Direct clutch oil circuits are separate and, for the most part, kept isolated from each other except for one area. That area is in the casting under the separator plate, below the 2-3 accumulator (See Figure 2).
In the 2001 up units, there is no mechanical clamping of the separator plate and valve body gasket to maintain the seal between the forward and direct circuits. To confirm this on the next one you tear down, look at the imprint the valve body passages leave on the gasket. Lay the upper gasket over the lower gasket and look closely in the area of the 2-3 accumulator (the smaller of the three openings in the upper gasket). What you will see is a heavy imprint of the valve body castings across most of the lower gasket except in the area of the 2-3 accumulator. I cannot think of any other transmission where the separator late/valve body gaskets have such a large gasket area that is not mechanically compressed.
The biggest problem caused by eliminating the two-bolt plate is not cracked separator plates; rather, the biggest problem is cross leaks between the Forward and Direct clutch circuits. Without mechanical clamping of the gasket, pressurized oil seeps into the unused valve body passages and pushes upward on the separator plate, similar to how oil pushes on a servo. Figure 3 shows the unit when the Forward clutch is applied and Direct clutch is not applied.
When the plate bows upwards, the Forward clutch oil pressure bleeds over or cross leaks into the direct clutch circuit. I have measured the plate bowing upwards as much as .011", with normal (forward) oil pressure.
Cracks in the plate may not look good, but dragging clutches is far more destructive. The problem is not with the separator plate. The problem is that the two-bolt retainer was eliminated.
What I really want to know is if I loose 1st and 2nd with the cracks and deflection? here it is without the article's pictures:
Up through 2000, these units had a twobolt stiffener plate located underneath the 2-3 accumulator. The purpose of the plate was to clamp the separator plate and lower valve body gasket against the valve body casting. Beginning with 2001 models, the two-bolt stiffener plate was eliminated. The 2-3 accumulator retainer now sits directly on the separator plate. Another change in this area was that the Capacity Modulator Valve and plug were eliminated from the valve body and the valve bore was cast closed. The un-used casting pocket is also directly under the 2-3 accumulator. At first glance, you might assume that the cracks we see in the separator plate (see Figure 1) are caused by the 2-3 accumulator retainer's rounded end smacking against the plate. You might also assume the cracks are a problem, but the cracks and the accumulator retainer seating directly on the separator plate are not the problem. The cracks are a symptom of a completely different and bigger problem related to the Forward and Direct clutch circuits.
In these units, the Forward clutch is fed through the pump at the front of the unit and the Direct clutch is fed through the output shaft at the rear of the unit. Forward and Direct clutch oil circuits are separate and, for the most part, kept isolated from each other except for one area. That area is in the casting under the separator plate, below the 2-3 accumulator (See Figure 2).
In the 2001 up units, there is no mechanical clamping of the separator plate and valve body gasket to maintain the seal between the forward and direct circuits. To confirm this on the next one you tear down, look at the imprint the valve body passages leave on the gasket. Lay the upper gasket over the lower gasket and look closely in the area of the 2-3 accumulator (the smaller of the three openings in the upper gasket). What you will see is a heavy imprint of the valve body castings across most of the lower gasket except in the area of the 2-3 accumulator. I cannot think of any other transmission where the separator late/valve body gaskets have such a large gasket area that is not mechanically compressed.
The biggest problem caused by eliminating the two-bolt plate is not cracked separator plates; rather, the biggest problem is cross leaks between the Forward and Direct clutch circuits. Without mechanical clamping of the gasket, pressurized oil seeps into the unused valve body passages and pushes upward on the separator plate, similar to how oil pushes on a servo. Figure 3 shows the unit when the Forward clutch is applied and Direct clutch is not applied.
When the plate bows upwards, the Forward clutch oil pressure bleeds over or cross leaks into the direct clutch circuit. I have measured the plate bowing upwards as much as .011", with normal (forward) oil pressure.
Cracks in the plate may not look good, but dragging clutches is far more destructive. The problem is not with the separator plate. The problem is that the two-bolt retainer was eliminated.
Last edited by Lariat04; 02-17-2017 at 04:54 PM.
#4
02-17-2017, 05:28 PM
Senior Member
When I did a J-mod on my 2001 Mercury GM (4R70W), I saw the marks but mine was not yet dented or cracked. I used the Sonnax #76507F-01K reinforcement plate kit and I drilled and tapped two holes for 1/4-20 and installed the reinforcement. Kit came with metric bolts, but my metric tap was broke and I hated to drive to town ..... so I improvised.
I then found out about a "Tough Plate" that is a thicker separator plate.
I then found out about a "Tough Plate" that is a thicker separator plate.
#6
04-30-2017, 07:17 AM
I found this write up on a vendors website: not sure I can quote it but can someone translate it to layman's terms for me?
What I really want to know is if I loose 1st and 2nd with the cracks and deflection? here it is without the article's pictures:
Up through 2000, these units had a twobolt stiffener plate located underneath the 2-3 accumulator. The purpose of the plate was to clamp the separator plate and lower valve body gasket against the valve body casting. Beginning with 2001 models, the two-bolt stiffener plate was eliminated. The 2-3 accumulator retainer now sits directly on the separator plate. Another change in this area was that the Capacity Modulator Valve and plug were eliminated from the valve body and the valve bore was cast closed. The un-used casting pocket is also directly under the 2-3 accumulator. At first glance, you might assume that the cracks we see in the separator plate (see Figure 1) are caused by the 2-3 accumulator retainer's rounded end smacking against the plate. You might also assume the cracks are a problem, but the cracks and the accumulator retainer seating directly on the separator plate are not the problem. The cracks are a symptom of a completely different and bigger problem related to the Forward and Direct clutch circuits.
In these units, the Forward clutch is fed through the pump at the front of the unit and the Direct clutch is fed through the output shaft at the rear of the unit. Forward and Direct clutch oil circuits are separate and, for the most part, kept isolated from each other except for one area. That area is in the casting under the separator plate, below the 2-3 accumulator (See Figure 2).
In the 2001 up units, there is no mechanical clamping of the separator plate and valve body gasket to maintain the seal between the forward and direct circuits. To confirm this on the next one you tear down, look at the imprint the valve body passages leave on the gasket. Lay the upper gasket over the lower gasket and look closely in the area of the 2-3 accumulator (the smaller of the three openings in the upper gasket). What you will see is a heavy imprint of the valve body castings across most of the lower gasket except in the area of the 2-3 accumulator. I cannot think of any other transmission where the separator late/valve body gaskets have such a large gasket area that is not mechanically compressed.
The biggest problem caused by eliminating the two-bolt plate is not cracked separator plates; rather, the biggest problem is cross leaks between the Forward and Direct clutch circuits. Without mechanical clamping of the gasket, pressurized oil seeps into the unused valve body passages and pushes upward on the separator plate, similar to how oil pushes on a servo. Figure 3 shows the unit when the Forward clutch is applied and Direct clutch is not applied.
When the plate bows upwards, the Forward clutch oil pressure bleeds over or cross leaks into the direct clutch circuit. I have measured the plate bowing upwards as much as .011", with normal (forward) oil pressure.
Cracks in the plate may not look good, but dragging clutches is far more destructive. The problem is not with the separator plate. The problem is that the two-bolt retainer was eliminated.
What I really want to know is if I loose 1st and 2nd with the cracks and deflection? here it is without the article's pictures:
Up through 2000, these units had a twobolt stiffener plate located underneath the 2-3 accumulator. The purpose of the plate was to clamp the separator plate and lower valve body gasket against the valve body casting. Beginning with 2001 models, the two-bolt stiffener plate was eliminated. The 2-3 accumulator retainer now sits directly on the separator plate. Another change in this area was that the Capacity Modulator Valve and plug were eliminated from the valve body and the valve bore was cast closed. The un-used casting pocket is also directly under the 2-3 accumulator. At first glance, you might assume that the cracks we see in the separator plate (see Figure 1) are caused by the 2-3 accumulator retainer's rounded end smacking against the plate. You might also assume the cracks are a problem, but the cracks and the accumulator retainer seating directly on the separator plate are not the problem. The cracks are a symptom of a completely different and bigger problem related to the Forward and Direct clutch circuits.
In these units, the Forward clutch is fed through the pump at the front of the unit and the Direct clutch is fed through the output shaft at the rear of the unit. Forward and Direct clutch oil circuits are separate and, for the most part, kept isolated from each other except for one area. That area is in the casting under the separator plate, below the 2-3 accumulator (See Figure 2).
In the 2001 up units, there is no mechanical clamping of the separator plate and valve body gasket to maintain the seal between the forward and direct circuits. To confirm this on the next one you tear down, look at the imprint the valve body passages leave on the gasket. Lay the upper gasket over the lower gasket and look closely in the area of the 2-3 accumulator (the smaller of the three openings in the upper gasket). What you will see is a heavy imprint of the valve body castings across most of the lower gasket except in the area of the 2-3 accumulator. I cannot think of any other transmission where the separator late/valve body gaskets have such a large gasket area that is not mechanically compressed.
The biggest problem caused by eliminating the two-bolt plate is not cracked separator plates; rather, the biggest problem is cross leaks between the Forward and Direct clutch circuits. Without mechanical clamping of the gasket, pressurized oil seeps into the unused valve body passages and pushes upward on the separator plate, similar to how oil pushes on a servo. Figure 3 shows the unit when the Forward clutch is applied and Direct clutch is not applied.
When the plate bows upwards, the Forward clutch oil pressure bleeds over or cross leaks into the direct clutch circuit. I have measured the plate bowing upwards as much as .011", with normal (forward) oil pressure.
Cracks in the plate may not look good, but dragging clutches is far more destructive. The problem is not with the separator plate. The problem is that the two-bolt retainer was eliminated.
#7
05-01-2017, 07:59 AM
Senior Member
If it concerns you I would get the Superior Tuff Plate kit.
This won't cause a loss of reverse. I would remove your reverse servo and stick a screwdriver into the pin bore to see if the band applies. They have a habit of breaking and you will lose reverse with no fluid discoloration or debris.
D
This won't cause a loss of reverse. I would remove your reverse servo and stick a screwdriver into the pin bore to see if the band applies. They have a habit of breaking and you will lose reverse with no fluid discoloration or debris.
D