TH400 Charge flow pressure

[turbobitt]

By measuring the cooler line pressure, we're trying to get our best clue as to what the pressure is inside the torque converter. That is the most important consideration here. I hope by now we all know what excessive T/C pressure does. Bleeding off pressure after the fact seems useless to me in terms of trying to determine what the internal pressure of the T/C is.
I've always set clearancing tight on the 400s I've done. Didn't seem to affect cooler line pressure.

What you really need to do is set up some pressure taps in the T/C feed circuit after the feed restriction and at the T/C outflow circuit before it gets to the case fitting. Now that would peak my interest.

I would agree to that. But it would seem that there would be neglagible pressure drop between the case and the cooler line. If there was, then it would suggest that the cooler itself is a restriction and/or the lines. I am running 3/8 cooler lines and a dedicated cooler and know that it is not going to be a source of restriction. With that being said, if the pressure drops after the cooler, the converter pressure will more likey drop. BUT....
Chris hinted to me that there are oportunities for oil to get trapped in the converter depending on make/model. This would indicate to me that the charge pressure may not be the "tell all". This is probably why some thrust bearings don't fail with high pressure and others do. It sounds like there can be a scenerio where the cooler pressure is low but converter pressure is extreamly high do to inability to vent.
If I can find a way to instrument my pump to provide for this type of measurment than I am all for it. I will look tnight and see if there is clearance. Maybe we can make this experiment very informative.
BTW, I want dibs on the first copy of your book.
Allan G.

 

[chris718]

you can drill and tap the back of the pump and run a line out the filler tube hole on the dyno .there are plenty of gages on it.

 

[Alky V6]

I would agree to that. But it would seem that there would be neglagible pressure drop between the case and the cooler line. If there was, then it would suggest that the cooler itself is a restriction and/or the lines. I am running 3/8 cooler lines and a dedicated cooler and know that it is not going to be a source of restriction. With that being said, if the pressure drops after the cooler, the converter pressure will more likey drop. BUT....
Chris hinted to me that there are oportunities for oil to get trapped in the converter depending on make/model. This would indicate to me that the charge pressure may not be the "tell all". This is probably why some thrust bearings don't fail with high pressure and others do. It sounds like there can be a scenerio where the cooler pressure is low but converter pressure is extreamly high do to inability to vent.
If I can find a way to instrument my pump to provide for this type of measurment than I am all for it. I will look tnight and see if there is clearance. Maybe we can make this experiment very informative.
BTW, I want dibs on the first copy of your book.
Allan G.

You're correct. Some converters will flow in to out with less restriction than others. That's exactly why a pressure reading right after the feed restriction would be very important. That would be the most accurate picture into what kind of charge pressure a given converter/cooler/lube circuit design is causing.

 

[chris718]

YouTube - Despina Vandi - Tolis Voskopoulos... Eulekta ulika

 

[turbobitt]

you can drill and tap the back of the pump and run a line out the filler tube hole on the dyno .there are plenty of gages on it.

OK, I think I know what I want to do to make this work. I'll drill down parallel to the stator tube then drill 90 degrees to intersect that drilling. This will be in an are oposite the PR valve and in an area that will not interfer with the forward drum. The drilling will be in the inside of the inner gear but not in the actual converter feed passage. Pressure in this area will be the same. This will take me a few days and will post pictures when complete. I am going to press the stator tube out to make sure I don't hit any blind passages.
Allan G.

 

[turbobitt]

Chris,

If we are going to make this experiment happen, we may want to lay out a test plan so that we can have all the "stuff" ready. I will talk with Brian and see If I can get him to stop pumping iron for a day and plan a trip. Some saturday near the hollidays would be good for me or something later if more convienient for you.

 

[Otto J]

Chris,

If we are going to make this experiment happen, we may want to lay out a test plan so that we can have all the "stuff" ready. I will talk with Brian and see If I can get him to stop pumping iron for a day and plan a trip. Some saturday near the hollidays would be good for me or something later if more convienient for you.

I am interested in going also if im available

 

[chris718]

Lets do it.I would enjoy it.

 

[Alky V6]

YouTube - Despina Vandi - Tolis Voskopoulos... Eulekta ulika

Was this meant to increase or decrease line pressure?

 

[chris718]

It slightly biases it to the higher side

 

[turbobitt]

Ok, The pump modifications are almost done. I attached some pictures to show the port added to the pump body. The fitting pictured probably won't be the one I use. I will have to see how everything will package once installed in the case.
One other thing, I was looking at the input shaft and noticed that the holes appear to be small. The converter return holes in the top of the shaft are about .125" and the lower one pictures appears to be smaller. The lower hole is the lube feed that gets oil from the back of the stator support after the cooler. Is this enough to be a restriction ?
Allan G.

 

[chris718]

Good work.The holes are small to match inlet and to eliminate cracking between holes.some main shafts have a cup plug as well.These are things we will test .2 input shafts with different size holes will be done for sure.Stock shaft and drum verses modded shaft and drum.Remember the hole on the end of the input shaft isnt there for anything other than a means of connecting the 2 holes further down that are on each side of the bushing.We now have a serious mission ahead of us but if we have everything ready we can spend 8 or so hours gathering data no one else has access to right now,very important.My dyno doesnt do breakfast so dont show up with coffe or an egg sandwich for him when you come down Alan.You can bring me 1 however.:biggrin:

 

[turbobitt]

No problem, I'll bring the egg sandwich or doughnuts.

 

[chris718]

some ideas:test 1 /stock pump with properly clearanced gears /stock spring w/1 shim.test 2 /same pump with hd spring and 1 shim.test 3 same pump w/.115 orifice and stock spring w/1 shim.test 4 all same but try hd spring.try test 4 w/ different converter to see what converter differences do .test 5 back to original converter so we can back up test 1 thru 4 and bring orifice down to .100......................towards the end.block off converter charge with unorificed restrictor and note results.remove restrictor and test with grossly undersize pump gears#.721 check converter pressure and line pressure differences to show what improper clearances do.

 

[chris718]

after that I ll grill souvlaki and crank up the YouTube - STELIOS KAZANTZIDIS - YPARXO

 

[turbobitt]

some ideas:test 1 /stock pump with properly clearanced gears /stock spring w/1 shim.test 2 /same pump with hd spring and 1 shim.test 3 same pump w/.115 orifice and stock spring w/1 shim.test 4 all same but try hd spring.try test 4 w/ different converter to see what converter differences do .test 5 back to original converter so we can back up test 1 thru 4 and bring orifice down to .100......................towards the end.block off converter charge with unorificed restrictor and note results.remove restrictor and test with grossly undersize pump gears#.721 check converter pressure and line pressure differences to show what improper clearances do.

Sounds good. Would like to see an A/B test with my pump/orfice/spring and transmission vs. your dyno transmission. My transmission has your input, transbrake, intermediate shaft, and other rollerized mods. I have known front/rear endplay values. I would like to discover why I was unable to get your specified pressures with a stock unshimmed PR spring wit htwo different pumps.
If time permits, I have another transmission with stock input and intermediate shafts, Transking brake with a wicked stiff PR spring and one shim(As specified in there instructions), and no converter charge flow orfice.
this transmission is the one that spent most of the time in my car with no thrust bearing failures. I would be willing to bet line pressure is well over 200 psi.
FYI, This test pump has about .0015 or less gear clearance and was lapped flat on a lapping machine. If you look at the pictures carefully, you will notice the gray appearance accross the entire face. this is the surface finish from the lapping compound.
Allan G.

 

[chris718]

by unshimmed i mean stock shim,stock seat and stock spring.some came with 2 shims but that is not the norm,

 

[Alky V6]

Chris. I would setup one pump at .001-.0015", another at no less than .003", preferably right at .003". If you have to do one at a clearance that's way out there, then do that too, but in the real world you will be much more likely to come across pumps with closer to .003". It would be interesting to see if there is any importance to getting the clearance tighter than the industry excepted max of .003".

You might keep that plumbing idea around for a VSC system some day too.

 

[chris718]

good idea,do have an adjustable stall set up and lock up converter unlike anything else available.not the reverse flow gm lock up either .just sharpening it up.dont want to release it until we are sure of the results,but its coming.it hopefully will be a big contributor to my retirement fund.

 

[turbobitt]

Chris. I would setup one pump at .001-.0015", another at no less than .003", preferably right at .003". If you have to do one at a clearance that's way out there, then do that too, but in the real world you will be much more likely to come across pumps with closer to .003". It would be interesting to see if there is any importance to getting the clearance tighter than the industry excepted max of .003".

You might keep that plumbing idea around for a VSC system some day too.

For my idea on a homemade VSC , I was thinking of tapping into the external linr pressure tap, using a return style regulator and a normally open solenoid valve to supply the converter. Just an idea at this stage. I would want the capability of filling the converter very fast but at low pressure. This would require regulated oil but not through a restricted orfice.
Allan G.