TH400 Charge flow pressure

[quickt]

Regardless of the source of spiked pressures ,less than 80 psi in the cooler return has been effective at controlling thrust problems for me up until now.I would now reevaluate that and come to a lower # that doesnt restrict cooler volume ,but corrects for overpressured converter because of possible converter,input shaft and cooler restrictions .The stator assembly appears to be the first thing in the way

Thats what we found. The stator plays a roll in the problem. IMO charge pressure has the largest affect. Will be interesting to see results.

 

[Dusty Bradford]

I've found the same thing. Cooler circuit pressure alone doesn't tell the whole story. It's possible in high hp cars that the converter tries to push more fluid out of the converter than can pass through the cooler circuit, or past the input shaft. This drives the internal pressure very high. The 9.5 does have internal mods to help relieve this internal pressure.

Something of this nature can show a decent cooler circuit pressure but the internal converter pressure can skyrocket.

 

[turbobitt]

I found these interesting tech articles on the Sonnax website. I think it is good reading material with regards to charge flow and potential restrictions. I think that this is more revealing to why some people have thrust issues while others do not.

http://www.sonnax.com/tech-articles/TCTIP-01-07.pdf
This is an article called "Converter charge mysteries" Explains the importance of clearance between the stator tube and converter hub.

http://www.sonnax.com/tech-articles/TCTIP-09-09.pdf
This is an article called "Orfice control within the converter part 2" It covers the oil path around the stator and cooling effects of incresed flow.

Don't know if the links will work but they can be found in the Sonnax website.

Allan G.

 

[Alky V6]

With all the variations out there with converter design, input design, cooler plumbing, all the areas that can cause a restriction that can affect T/C push on the crankshaft, I have to say that I still see restricting T/C flow at the beginning of the circuit, as the OEMs have learned to do, as the best overall solution. Unless, someone is planning on coming up with a standardized design level that everyone will use, which of course is very unlikely that one source will become the one and only supplier of T400 components, T/C components and cooler circuit components. Not with the adequate state that those design levels are presently at,... especially if people just learn to simply restrict T/C feed at the start of the circuit.

 

[chris718]

Back by popular demand,anyone have any new info on this?

 

[chris718]

When I retire form this life Ill be found somewhere in Athens playing my bouzouki and when people asked what I did in America with my life Ill explain about what we did on the dyno with cooler pressure and how the way out was a boatride and the way back was a plane.

 

[Alky V6]

Still no change in the modification I've been doing since the late '80s. No side effects, and only success in saving cranks.

 

[chris718]

No news is good news Don.Whats your take on bouzouki and being retired?

 

[Alky V6]

No news is good news Don.Whats your take on bouzouki and being retired?

Retired? Still a pipe dream for me. Bouzouki? I don't know what that is, but it makes me hungry for Greek food. I guess I know what I'm having for dinner tonight.

 

[chris718]

This will xplain Don.http://www.bouzouki.org/

 

[Alky V6]

This will xplain Don.http://www.bouzouki.org/

Ahhh,... I don't do bouzouki.

 

[turbobitt]

Back by popular demand,anyone have any new info on this?

Don't have any new info but would like to know if there are any other ways to reduce pressure through creative venting on the lube side. This would reduce pressure without reducing volume. Not suggesting that we don't use a orfice restriction but maybe a combination of the two. I still believe that there is significant restrictions in these areas, especially after reducing thrust and holding other tolerances tighter.

Allan G.

 

[lazaris]

Don't have any new info but would like to know if there are any other ways to reduce pressure through creative venting on the lube side. This would reduce pressure without reducing volume. Not suggesting that we don't use a orfice restriction but maybe a combination of the two. I still believe that there is significant restrictions in these areas, especially after reducing thrust and holding other tolerances tighter.

Allan G.

You need to open up the return side in the input shaft.

 

[BMR]

I know this is an old thread, but you guys seem to be studying something similar to what I am right now. I have a TH400 in a car and the the 9.5" PTC does not respond to stator or pump changes. I have been studying some things and trying to learn more about converter charge etc. I restricted the converter feed down to .125", and the cooler pressure is around 70psi, down from well over 100. But that made no change in the converters performance.

Last night I pulled the trans, and took the pump out and really studied how the fluid goes into and out of the converter and into the cooler. I found the hole in the stator support that leads the fluid to the cooler to be around 90% blocked because of a misalignment between the hole in the stator support and the hole in the pump. I started to drill the hole out, but though better of it and pulled another pump to look at.

I found it to be probably 75% blocked for the same reason. Is this normal? It appears to be a major restriction in getting the fluid out of the converter and into the cooler. Does this need to be addressed? I have no problems drilling it for experimental purposes, but I also don't want to do it if someone else already has with no or ill effects.

 

[turbobitt]

I know this is an old thread, but you guys seem to be studying something similar to what I am right now. I have a TH400 in a car and the the 9.5" PTC does not respond to stator or pump changes. I have been studying some things and trying to learn more about converter charge etc. I restricted the converter feed down to .125", and the cooler pressure is around 70psi, down from well over 100. But that made no change in the converters performance.

Last night I pulled the trans, and took the pump out and really studied how the fluid goes into and out of the converter and into the cooler. I found the hole in the stator support that leads the fluid to the cooler to be around 90% blocked because of a misalignment between the hole in the stator support and the hole in the pump. I started to drill the hole out, but though better of it and pulled another pump to look at.

I found it to be probably 75% blocked for the same reason. Is this normal? It appears to be a major restriction in getting the fluid out of the converter and into the cooler. Does this need to be addressed? I have no problems drilling it for experimental purposes, but I also don't want to do it if someone else already has with no or ill effects.

Please explain how you determined this. The return hole in the stator support is in the ID of the tube and dumps into a cast-in pump cavity behind the OD of the stator tube. The cavity is then joined to a cross drilling IIRC and is forgiving to some stator clocking errors. The stator would have to be pressed out to check the alignment of the hole in the stator tube to the inner pump cavity as this is basically blind as installed. I have never seen one blocked of clocked wrong from the factory but have seen concerningly small drilled hole in the stator tube that can restrict flow (can be corrector once the stator tube is pressed out).
The restrictions in the stator tube are typically a few areas, such as the stator hole return size( again, can be corrector once the stator tube is pressed out) , and using a grooved bushing in the front of the stator tube helps return flow and not completely relying on the cross drilling in the input shaft.
AG.

 

[BMR]

Please explain how you determined this. The return hole in the stator support is in the ID of the tube and dumps into a cast-in pump cavity behind the OD of the stator tube. The cavity is then joined to a cross drilling IIRC and is forgiving to some stator clocking errors. The stator would have to be pressed out to check the alignment of the hole in the stator tube to the inner pump cavity as this is basically blind as installed. I have never seen one blocked of clocked wrong from the factory but have seen concerningly small drilled hole in the stator tube that can restrict flow (can be corrector once the stator tube is pressed out).
The restrictions in the stator tube are typically a few areas, such as the stator hole return size( again, can be corrector once the stator tube is pressed out) , and using a grooved bushing in the front of the stator tube helps return flow and not completely relying on the cross drilling in the input shaft.
AG.

I was not aware of the cavity. I was going by what I could see with a light and the fact that a piece of welding wire was almost impossible to coax up through the hole. Either way, I swapped the pump, and inspected the cooler ports on the case making sure they were not obstructed by some left over flashing or anything like that.

The car has never had thrust problems, we are just WAY past where we should be with the converter and have barely made any difference on the rpm drop on shifts. It started out as a 16-0 stator (PTC 9.5) and we are at 19-4 right now and it moved about 300rpm. We believe the converter is backing up with fluid even though the pressure in the cooler lines is in check.

 

[turbobitt]

I was not aware of the cavity. I was going by what I could see with a light and the fact that a piece of welding wire was almost impossible to coax up through the hole. Either way, I swapped the pump, and inspected the cooler ports on the case making sure they were not obstructed by some left over flashing or anything like that.

The car has never had thrust problems, we are just WAY past where we should be with the converter and have barely made any difference on the rpm drop on shifts. It started out as a 16-0 stator (PTC 9.5) and we are at 19-4 right now and it moved about 300rpm. We believe the converter is backing up with fluid even though the pressure in the cooler lines is in check.

I've seen no difference with charge flow pressure vs. stall speed. I've had it as low as single digits pressure while going down the track with no effect. As long as the converter is full of oil it will still function the same. The only time I been able to effect the stall is shutting the oil off completely.
AG.

 

[BMR]

I've seen no difference with charge flow pressure vs. stall speed. I've had it as low as single digits pressure while going down the track with no effect. As long as the converter is full of oil it will still function the same. The only time I been able to effect the stall is shutting the oil off completely.
AG.

What can be causing the converter to not respond? It only slightly cares how much power is applied. It is a turbo LS deal and even with 30psi boost, the rpm drop is basically the same as with 15psi.

 

[turbobitt]

What can be causing the converter to not respond? It only slightly cares how much power is applied. It is a turbo LS deal and even with 30psi boost, the rpm drop is basically the same as with 15psi.

It sounds like your looking at RPM drop between shifts and not comparing flash stall with converter stator changes. Once the converter is at RPM and near its peak efficiency I would think that's more a function of the core design. So in other words I would think changing the stator would not effect that very much given the same core design and your RPM drop is more fixed on the ratio change of the transmission and not the converter slip at near lock-up/peak efficiency.
AG.

 

[BMR]

It sounds like your looking at RPM drop between shifts and not comparing flash stall with converter stator changes. Once the converter is at RPM and near its peak efficiency I would think that's more a function of the core design. So in other words I would think changing the stator would not effect that very much given the same core design and your RPM drop is more fixed on the ratio change of the transmission and not the converter slip at near lock-up/peak efficiency.
AG.

That is where I have ended up. I have checked and checked the converter fluid circuit in my transmission. I have lost count on how many times it has been out. As a last ditch effort to be 100% sure it was nothing in the trans, I borrowed one from a friend and the result was exactly the same.

I am having another converter built out of a 10" Toyota core (not the basic 245mm GM core most companies sell as a 10"). I am hoping this is the magic bullet that FINALLY fixes this POS.

Thanks for the input.