Hello ,I joined the forum a few months ago and this is my first post.I am currently finishing up a 400 plus page GM TH400 manual after several issues with printing companies.The reason for my post is I am seeking photos of V12 TH400 equipt cars for the book.I have also located some unique to Jaguar TH400 service manuals for the book but am hoping for access to other info I may not have. The book is set to be published at the beginning of the year.I am not on here to push the book, I am only here to get some aditional information for it.I am hoping some members can assist me here.At the end of this post I will attach some content so you will have an understanding of the scope of the book.I have developed and manufacture many components for the transmission and have also authored a 200 page GM 2004R manual.I also am trying to track down an original Jag 400 core for photos etc. and am willing to purchase and pay shipping if one is available.My time is limited to go to print and am hoping to add the Jaguar content immediately.The manual also has Ferrari TH400 content.Thanks and look forward to ant photos or service manual information I can have access to. CRISTOFOROS KOKKONIS @ CK Performance products.





Identify the type of center support in use. The early design center support was used in all 1964 to mid-year 1969 TH400 transmissions. The casting number for this support is 8623138. This support can also be identified by measuring the height of the center support to case lugs. See Figure 5C-1. The height of the lugs on the early support measures approximately .370.” The early design center support does not use the center support to case anti fretting ring (657). See Illustration 5C-1.
The “first design” late design center support was used in all late 1969 to early 1990 TH400 transmissions. The casting number is 8623138. This support can also be identified by measuring the height of the center support to case lugs. See Figure 5C-1. The height of the lugs on the late support measures approximately .330.”
The “first design” late center support incorporates the use of the center support to case anti fretting ring (657). The purpose of this ring is to insulate center support rearward thrust and radial movement during transmission operation from the ledge in the transmission case that the center support rests on. Without the ring, the support tends to eat the transmission case at the lug interface. Because early models do not have the ring they are more susceptible to case wear. To accommodate the ring, the overall height of the center support to case lugs was reduced the same amount of the overall thickness of the ring. To use the early design center support with the center support to case anti fretting ring, simply machine .040” from the rear face of the case lugs.
If you try to install the ring with the early design “thicker” support you will not be able to properly install the center support bolt (79) or the beveled snap ring (645).


ILLUSTRATION 5C-1 FIGURE 5C-1
All TH400 transmissions produced after March 1, 1990 received a revised center support casting. This is what I refer to as the “second design” late support. The casting number is 8678032. This is the same support used in all production 1991 to 1995 GM 4L80E transmissions. This support also uses the anti fretting ring and the height of the lugs also measures approximately .330”. It is fully interchangeable with the “first design” late support. The 8678032 casting has slight differences in non critical dimensions when compared to the 8623138 casting. However, they do no affect fit or function. The “second design” late support also received a different center support to case bolt. This bolt is slightly longer than the original type. See Illustration 5C-2.


ILLUSTRATION 5C-2

Beginning on December 21, 1993 some TH400 GM Goodwrench Replacement Transmissions that use the “second design” late support were built with a new case to center support service bolt. The bolt is coated with zinc chromate and is yellow in color. According to GM, the reaming of the threaded hole and the installation of the new bolt allowed the support to be reconditioned in the field one time before replacement. See Illustration 5C-3. Apparently the engineers believed that the center support was a wear item and was to be replaced during overhaul. This is evident by the lack of a factory replacement bushing for the support. I do not know of anyone that uses this practice. In case you are interested, the center support service bolt and instruction sheet is available under GM Part Number 24202218.


ILLUSTRATION 5C-3
There is a unique difference between the center support to case lugs when comparing “first design” late and “second design” late center supports. The “first design” late support uses 17 full width lugs where it engages the case. See Figure 5C-2. The “second design” late support uses only two full width lugs where it engages the case. See Figure 5C-3. One may be led to believe that lack of full width lugs with the second design support may result in increased lug wear in the transmission case. Oddly enough I have not found this to be accurate at this time. Looking ahead, if this proves to be a problem, the “first design” late support can be used in its place.


FIGURE 5C-2


FIGURE
Illustration 5B-1 is the master schematic of the center support and related components.


ILLUSTRATION 5B-1





ILLUSTRATION 5B-2

Use Illustration 5B-2 as a guide to begin disassembly of the center support and related components. Remove the snap ring ((646) that retains the intermediate clutch spring retainer (647) to the center support (654). See Figure 5B-1. Remove the retainer. See Figure 5B-2.


FIGURE 5B-1 FIGURE 5B-2

Remove the three intermediate clutch release springs (648) from the aluminum intermediate clutch piston (650). See Figure 5B-3. Note that some models will use 12 intermediate clutch release springs. Remove the intermediate clutch piston from the center support. See Figure 5B-4. Inspect the release springs for cracks, fatigue, and distortion.


FIGURE 5B-3 FIGURE 5B-4

Note that the intermediate clutch piston may be either cast aluminum or stamped steel. See Illustration 5B-1. The stamped steel piston is shown in Figure 5B-5. Because the stamped steel piston does not have machined spring pockets to locate the intermediate clutch release springs, a plastic intermediate clutch spring guide (649) is used. See Illustration 5B-1. The cast aluminum piston is shown in Figure 5B-6. Stamped steel piston usage in performance builds is not encouraged. With increased line pressure, the steel pistons suffer from deflection as well as a small work surface area which reduces clutch pack performance. The “clutch piston work surface” is the area of the front face of the piston that contacts and pushes on the first steel in the clutch pack. Notice the narrow clutch piston work surface of the stamped steel piston in comparison to the wide clutch piston work surface. The aluminum piston is fully interchangeable with the steel piston and plastic spring guide.


FIGURE 5B-5 FIGURE 5B-6
Remove the inner (651) and outer (652) lip seals from the piston. Examine the seals and become familiar with how they fit the piston and seal in the support. Do not discard the seals. You will use them to identify the replacement seals later on during assembly. See Figures 5B-8 and 5B-9. Inspect the piston for cracks. Inspect the piston seal grooves for nicks or damage.


FIGURE 5B-8

Inspect the lip seal sealing surfaces for scratches or damage. See Figure. Remove and discard the four oil seal rings (653) from their ring grooves in the center support. See Figure 5B-7. Please note that some models are equipt with iron interlocking oil seal rings.


























FIGURE 5B-7


Visually inspect the four ring lands on the center support for signs of wear or damage. See figure 5B-15. It is very common for the direct drum to have excessive radial runout .When this occurs, the seal ring bore on the inside of the drum comes in contact with the ring lands. This results in the peening over or closing of the ring land openings. Insert the outside diameter of the oil seal ring into the ring land and rotate it around the full diameter of the ring land. See Figure 5B-16. The ring should rotate smoothly in the land. If the ring fails to rotate smoothly inspect the land for nicks or burrs. Remove any imperfections with a small file and recheck ring rotation.


FIGURE 5B-15 FIGURE 5B-16























Verify the presence of the bleed orifice cup plug in the rear of the support. See Illustration 5B-3. Verify the bleed orifice in the cup plug is not obstructed. The purpose of the bleed orifice cup plug is to purge trapped air from the center support. Because the center support is filled from the bottom up, air tends to get trapped in the cavity when the circuit is exhausted or not charged with intermediate clutch oil. Without a bleed orifice, this trapped air acts as an accumulator in the circuit. This prevents maximum apply pressure to be obtained during the 1-2 upshift, increasing slippage. Note that some production Cadillac TH400 transmissions do not have the bleed orifice cup plug in the rear of the support. These models used twelve intermediate clutch release springs (648) instead of the usual three installed in all other models. It is not recommended to use this type of support in any performance type TH400 build. If you have this type of support you can drill the boss and install an orifice cup plug. This cup plug is available from CK Performance. You can also interchange the support for one with the bleed orifice cup plug. If you did not remove it during initial disassembly, remove the thrust washer (656) from the rear of the center support. See Illustration 5B-3.


ILLUSTRATION 5B-3








The reaction carrier bushing journal is an integral part of the center support. See Figure 5B-10.Visually inspect the bushing journal for any signs of abnormal wear. Use you fingernail to check for scoring or grooving of the journal. Minor scoring can sometimes be removed with a fine grit emory cloth. Lubrication for the reaction carrier bushing is supplied thru a hole in the bushing journal. See Figure 5B-11. Verify the oil hole in the bushing journal free of obstruction and/or debris. Prepare the journal by gently polishing it with a fine grit emory cloth.


FIGURE 5B-11 FIGURE 5B-12

Measure the bushing journal with a micrometer. The specification for the bushing journal diameter is 2.187” to 2 .1875”. See Figure 5B-13. The low roller clutch inner race is an integral part of the center support. See Figure 5B-14. Visually inspect the race for any signs of abnormal wear or spalling. Use you fingernail to check for scoring or grooving of the race. The inner race is pinned and bolted to the center support. Verify the integrity of the attachment of the race to the support.


FIGURE 5B-13 FIGURE 5B-14





Visually inspect the tapped threads for the center support to case bolt for signs of damage or stripping. See Figure 5B-17. It is recommended to replace the center support bushing during the initial overhaul, and then perform inspection during future service. Install the sun gear shaft (664) into the support. Install a feeler gage between the bushing and shaft to obtain the clearance value. See Figure 5B-18. The specification for the clearance is .0015” to .004”. If there is excessive clearance, the bushing should be replaced.


FIGURE 5B-17 FIGURE 5B-18


Using a press and bushing driver, remove the center support bushing from the center support. Always remove the bushing starting at the rear end of the support, “pushing” the bushing out the front end of the support. See Figure 5B-19. The center support bushing is shown in Figure 5B-20.


FIGURE 5B-19 FIGURE 5B-20





The following is a short note regarding a bushing interchange I do not recommend. Do not install the longer center lube 4L80E center support bushing in a TH400. It will restrict lube oil to the intermediate sprag and intermediate clutch pack. When the production TH400 bushing is placed at its “as installed” position on the sun gear shaft (664), there is a generous amount of lube oil from the supply hole in the shaft into bushing oil slot that feeds the support. See Figure 5B-24. When the production 4L80E bushing is placed at its “as installed” position on the shaft, lube oil is restricted from flowing out of the supply hole in the shaft into the circular bushing oil slot that feeds the support. See Figure 5B-25. This lube oil is what feeds the intermediate sprag and intermediate clutch pack. The restriction is present even with the production 4L80E sun gear shaft in use.


FIGURE 5B-24


FIGURE 5B-25
Before bushing installation, note the orientation between the bushing oil slot and the center support oil hole. See Illustration 5B-4. The bushing oil slot and the center support oil hole must be in alignment. If not, lube oil to the intermediate sprag and intermediate clutch pack will be reduced or completely cut off.


ILLUSTRATION 5B-4




Using a press, install the bushing into the support. See Figure 5B-21. Note that this bushing does not like to be installed with a hammer and bushing driver. Install the bushing flush with the top of its bore.



Verify that the bushing oil slot and the center support oil hole are in alignment. See Figure 5B-22. Flush the center support out with clean solvent and blow dry with compressed air to remove any material generated during bushing installation.


FIGURE 5B-22





To verify the bushing has been installed properly, lube the bushing and install the sun gear shaft (664) into the support and verify smooth rotation. See Figure 5B-23.


FIGURE 5B-23



























Install the inner (651) and outer (652) intermediate clutch piston lip seals onto the intermediate clutch piston (650). The lip of the seals will point towards the rear of the piston. See Figures 5B-26 and 5B-27 as well as Illustration 5B-5.


FIGURE 5B-26 FIGURE 5B-27


ILLUSTRATION 5B-5

Before attempting installation of the piston, take note of how the protruding spring pockets on the rear of the piston fit into the cavities in the center support. See Figures 5B-28 and 5B-29.


FIGURE 5B-28 FIGURE 5B-29
Lubricate the seals. Install the piston into the center support (654). Install a .008” to .010” feeler gage between the inner seal and the support and guide the assembly into the support. Without cocking the piston apply a slight downward pressure with one hand while rotating the feeler gage around the inner diameter of the piston. See Figure 5B-30. The piston will drop down about .100”. Next, work your way around the outer seal with the smooth, rounded 90 degree corner of your pick tool to gently guide it into the support. Do this while applying a slight downward pressure until the piston is fully seated. See Figure 5B-31.


FIGURE 5B-30 FIGURE 5B-31

Illustration 1 shows the service manual method for installing the piston. This tool is not necessary for the seasoned professional, but may be helpful to the production or novice builder.





















Although the factory installed three intermediate clutch release springs (648) in most applications, there is a benefit to installing 12. The increased spring pressure will allow maximum pressure to be reached in the intermediate clutch circuit before the intermediate clutch piston starts to move to apply the clutch pack. This results in a quicker, firmer shift with reduced slippage. It also speeds up intermediate clutch exhaust during forced or manual 2-1 downshifts. 12 high rate return springs for the intermediate clutch pack are available from CK Performance under part # 400CC/IRSK. Install the 12 intermediate clutch release springs (648) into their pockets in the piston. See Figure 5B-32.


FIGURE 5B-33

If you are working with a stamped steel piston, install the intermediate clutch spring guide into the piston as shown in Figure. Install three intermediate clutch return springs into the guide as shown in Figure. Note that three additional springs may be added to the piston for the reasons previously mentioned.

 

Rolls Royce also used the THM 400. The obvious difference is the bell housing bolt pattern.

I have a NEW-IN-BOX THM 400 for a late 1980s XJ-S/XJ12 but it is in the original shipping crate that has never been opened. It's buried in the corner of the shop so I cannot open it and take pictures.

I have the original Jaguar XJ-S and XJ6/XK12 repair manuals (GREEN HARD COVER 3 RING BINDER) that have chapters on complete rebuilds, specs and fluid schematics for 5.3 liter BW model 12, GM 400, as well as the 3.6 liter ZF 4HP22.

I might could get them copied to .pdf at a copy shop.
I don't know if the info is any different than a CHEVY repair manual.

I did use this Jaguar manual to rebuild a GM400 for my 1988 Chevy 2500.

bob gauff

 

I have some of the Rolls Royce data as well. The Jaguar info in the small book I have (#44 and # 8 on the cover gold with green letters ) only has 33 pages covering overhaul,testing etc. Very concise and well written.I am wondering if what you have is additional .How many pages?Also looking for the 7 bolt case bulletain ,if it exists,when the case was updated with the extra ball and valve body and plate/gaskets was changed.The GM stuff I have ,as I am on board with the engineering and off road division ,is definately different .