TH350 rebuild tech

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(Valve body gasket check: Minor clean up.)
(Minor clean up; format.)
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=Valve body=
 
=Valve body=
 
==Separator plate==
 
Here's a pic of the feed holes. These regulate the amount of fluid, or how fast, it can apply the clutches. Drilling them bigger allows a faster apply. However, bigger is not always better.
 
 
[[file:TH350feedholes.jpg]]
 
 
Remember that as the load increases on the trans, so does the pressure. The increase in pressure will cause the fluid to move faster and shifts to be firmer. If you drill the holes too big the shifts become too harsh at light throttle openings. This causes undue wear on the internal transmission parts, rear differential and axles, drive line and u-joints.
 
 
The ideal situation is a shift that gets progressively harder with greater throttle openings. I recommend drilling the 2nd feed to 0.125" and the 3rd feed from 0.125"-0.140"
 
 
Also note above the 2-3 accumulator hole marked in the upper portion. This hole can be blocked but it is easier to block the passage in the VB or the 2-3 accumulator piston as previously mentioned.
 
 
 
==Valve body gasket check==
 
==Valve body gasket check==
 
Always check the valve body gaskets against the separator plate to see if any holes in the plate are covered by the gasket. Place the gasket behind the plate and hold both up at light to check for covered holes.
 
Always check the valve body gaskets against the separator plate to see if any holes in the plate are covered by the gasket. Place the gasket behind the plate and hold both up at light to check for covered holes.
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[[file:T-350_v-body_gasket02.jpg|frame|none|Notice the open line in the gasket, this gasket installs against valve body, not the case.]]
 
[[file:T-350_v-body_gasket02.jpg|frame|none|Notice the open line in the gasket, this gasket installs against valve body, not the case.]]
  
==Racing valve body==
 
Coan reverse manual valve body. Notice the machining of passages. Please note the DIY cannot just mill the valve body as valves have also been changed in the valve body.
 
 
[[file:TH350reverseVB.jpg]]
 
  
 
==Valve body modifications==
 
==Valve body modifications==
 
Removing check balls and opening up orifices in the separator plate is a common modification to firm up shifts. Just remember the one check ball that needs to stay is the one just below the modulator.
 
Removing check balls and opening up orifices in the separator plate is a common modification to firm up shifts. Just remember the one check ball that needs to stay is the one just below the modulator.
 +
 +
==Separator plate==
 +
Here's a pic of the feed holes. These regulate the amount of fluid, or how fast, it can apply the clutches. Drilling them bigger allows a faster apply. However, bigger is not always better.
 +
 +
[[file:TH350feedholes.jpg]]
 +
 +
Remember that as the load increases on the trans, so does the pressure. The increase in pressure will cause the flu id to move faster and shifts to be firmer. If you drill the holes too big the shifts become too harsh at light throttle openings. This causes undue wear on the internal transmission parts, rear differential and axles, drive line and u-joints.
 +
 +
The ideal situation is a shift that gets progressively harder with greater throttle openings. I recommend drilling the 2nd feed to 0.125" and the 3rd feed from 0.125"-0.140"
 +
 +
Also note above the 2-3 accumulator hole marked in the upper portion. This hole can be blocked but it is easier to block the passage in the VB or the 2-3 accumulator piston as previously mentioned.
  
 
===Shift kits===
 
===Shift kits===
 
Often shift improver kits are installed at the time of the tranny rebuild. Various manufacturers make shift improver kits, Trans Go has a good reputation.
 
Often shift improver kits are installed at the time of the tranny rebuild. Various manufacturers make shift improver kits, Trans Go has a good reputation.
  
===Filter===
+
==Racing valve body==
Brass screened filter allows for more flow. Avoid the cloth looking material filters for the T-350
+
Coan reverse manual valve body. Notice the machining of passages. Please note the DIY cannot just mill the valve body as valves have also been changed in the valve body.
 
+
[[file:TH350HPfilter.jpg]]
+
  
 +
[[file:TH350reverseVB.jpg]]
  
 
==Governor==
 
==Governor==
Image below of an OEM T-350 governor and cover.  
+
Image below of an OEM T-350 governor and cover.  
  
[[file:T-350_governor.jpg|thumb|left|300px|Note the direction of the plastic drive gear teeth. If the plastic gear breaks or wears out, there will be no upshifts since the governor is not rotating.]]
+
[[file:T-350_governor.jpg|thumb|left|300px|Note the direction of the plastic drive gear teeth. If the plastic gear breaks or wears out, there will be no upshifts since the governor is not rotating.]]<br style="clear:both"/>
+
[[File:B&M Governor recalibration kit.jpg|thumb|300px|left|B&M Governor recalibration kit.]] <br style="clear:both"/>
+
  
 
==Shift point changes==
 
==Shift point changes==
 
 
===Modulator adjustment===
 
===Modulator adjustment===
 +
[[File:B&M Governor recalibration kit.jpg|thumb|300px|left|B&M governor recalibration kit.]] <br style="clear:both"/>
 +
 
The following is from Dean Mason of TransLab Engineering:
 
The following is from Dean Mason of TransLab Engineering:
  
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===Detent cable adjustment===
 
===Detent cable adjustment===
 
<Blockquote>  Unclip the cable locking mechanism and then press the accelerator pedal to the floor. Be sure there's nothing under the pedal and the linkage is allowing full throttle at the carb. Floorboard the gas pedal and the detent cable should just pull tight as the throttle reaches wide open. THAT'S IT! If it doesn't pull tight, readjust, bend bracket, or whatever is necessary to achieve this. If it doesn't pull tight you will not have full detent at wide open throttle. If it pulls tight BEFORE full throttle, you'll break the cable end.</Blockquote>  
 
<Blockquote>  Unclip the cable locking mechanism and then press the accelerator pedal to the floor. Be sure there's nothing under the pedal and the linkage is allowing full throttle at the carb. Floorboard the gas pedal and the detent cable should just pull tight as the throttle reaches wide open. THAT'S IT! If it doesn't pull tight, readjust, bend bracket, or whatever is necessary to achieve this. If it doesn't pull tight you will not have full detent at wide open throttle. If it pulls tight BEFORE full throttle, you'll break the cable end.</Blockquote>  
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 +
<Blockquote>  Now that the detent and modulator are set correctly, we are ready to think about shift scheduling. Road test the car. You will need to know minimum and maximum throttle shift speeds for the 1-2 and 2-3 shifts, the RPM for the max throttle shifts, and the highest speed you can get a 3-1 and a 3-2 kick down. Also, what is the [http://www.crankshaftcoalition.com/wiki/Gear_ratio_check axle ratio].</Blockquote>
 +
 +
<Blockquote>  From this point we work with governor weights, springs, and shift valve springs.</Blockquote>
 +
 
{|
 
{|
 
|[[File:Kickdown1.jpg|thumb|180px|center|Unlock detent clip by prying up on it.]]
 
|[[File:Kickdown1.jpg|thumb|180px|center|Unlock detent clip by prying up on it.]]
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|[[File:Kickdown4.jpg|thumb|180px|center|Push clip down to lock.]]
 
|[[File:Kickdown4.jpg|thumb|180px|center|Push clip down to lock.]]
 
|}
 
|}
<Blockquote>  Now that the detent and modulator are set correctly, we are ready to think about shift scheduling. Road test the car. You will need to know minimum and maximum throttle shift speeds for the 1-2 and 2-3 shifts, the RPM for the max throttle shifts, and the highest speed you can get a 3-1 and a 3-2 kick down. Also, what is the [http://www.crankshaftcoalition.com/wiki/Gear_ratio_check axle ratio].</Blockquote>
 
  
<Blockquote>  From this point we work with governor weights, springs, and shift valve springs.</Blockquote>
+
==Filter==
 +
Brass screened filter allows for more flow. Avoid the cloth looking material filters for the T-350
 +
 
 +
[[file:TH350HPfilter.jpg]]
 +
 
  
 
==Fastener size and torque values==
 
==Fastener size and torque values==
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==Gear ratios==
 
==Gear ratios==
 
 
Ratios of the T-350 were consistent throughout its production:
 
Ratios of the T-350 were consistent throughout its production:
  
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*Reverse- 1.93:1  
 
*Reverse- 1.93:1  
  
An aftermarket low-gear planetary is available that will lower the first gear ratio to 2.75:1.
+
==Aftermarket parts==
 +
*An aftermarket low-gear planetary is available that will lower the first gear ratio to 2.75:1.
  
  

Revision as of 21:36, 25 March 2012

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