turbo 400's, flywheels, and Thrust bearings

[turbobitt]

This is all the explanation needed concerning the forces a thrust bearing sees. There should be no other discussion about it unless it is concerning how to control this force. Anyone who wants to post anything different than the simple law of physics Alan explained is a babbling fool. Imo this thread should be locked.

Brian,

This may be a little harsh. Lets not discourage the rewriting of the laws of physics. It's amazing what you can do with a tabletop, and some plywood. Should have thrown out my calculator and bought a table saw.
Allan G.

 

[Alky V6]

Brian,

This may be a little harsh. Lets not discourage the rewriting of the laws of physics. It's amazing what you can do with a tabletop, and some plywood. Should have thrown out my calculator and bought a table saw.
Allan G.

You guys are ruthless lately. What's up? And what is it that you don't understand about my example? I'd be more than happy to explain it to you.

 

[Hutch]

Here is a example of (at least mine) of your converter fill pressures while you go down the racetrack. There are spikes in the gear shifts for a instant. I wonder if a flex plate will help absorb this? The trans is from Rossler. We have had ZERO thrust problems with it.


Don have you logged this on your car yet? I'm curious for comparative reasons.

Nice graph and YES a flexy flexplate will help absorb those spikes along with a nice free crank/converter pilot and enough room between converter parts and any crankshaft attaching hardware to be able to flex properly. Poor desgin converter pilots that are made without an undercut really contribute to this lack of absorbtion by the flex plate also as they bind or **** in the crank pilot.
Have a peek at this guys video, big flex and a thrust eater. YouTube - Torque Converter Pushing


Hutch

 

[Alky V6]

Nice graph and YES a flexy flexplate will help absorb those spikes along with a nice free crank/converter pilot and enough room between converter parts and any crankshaft attaching hardware to be able to flex properly. Poor desgin converter pilots that are made without an undercut really contribute to this lack of absorbtion by the flex plate also as they bind or **** in the crank pilot.
Have a peek at this guys video, big flex and a thrust eater. YouTube - Torque Converter Pushing


Hutch

Interesting. Was that an OEM plate or a thick SFI style flexplate?

 

[Hutch]

Looks like a gold cheapy SFI flexplate, I think they are slightly thicker than stock but still retain the lightening holes.

Hutch

 

[turbobitt]

This flexable shock absorber as you say can have really bad effects.
Example. (Not using plywood)
F=MA
Force aplied to the crank = Mass of converter X acceleration
If the converter pilot collides with the crank, and extra force will be applied to the thrust.
Lets define deflection in the flexplate.
Deflection is caused from stress in units of PSI(pounds per square inch). If a force is applied over an area, there is stress.
Based on the modulus of the flexplate, the deflection may change but the stress remains constant.
(E = Stress/strain) or (Stress = E/Strain)
You can clairly see from these equations that deflection can only occure where there is force applied over an area causing stress. This force can only exist where an apposing force can act against the applied force.

See attached for sketch . Please forgive my handwriting since it is early in the morning and I'm not the best artist in the world.

 

[turbobitt]

Ok,

Here is another theory,

It is possible that the flexplate "Flexing" is acting as a hydraulic accumulator.
Mater of fact , that is exactly how an accumulator would work. The spring force of a weaker flexplate can't provide enough stiffness for the hydralic pressure. If it gives or moves, the pressure will quickly decay. In the same way that it acts as a hydraulic piston and works against the crank thrust, it also works like an accumulator.

Given this information, since we see pressure spikes in the system on gear shifts, it would almost seem like it would be a benifit to have an active accumulator in the PR circuit to absorbe these pressure spikes.

Allan G.

 

[Alky V6]

Ok,

Here is another theory,

It is possible that the flexplate "Flexing" is acting as a hydraulic accumulator.
Mater of fact , that is exactly how an accumulator would work. The spring force of a weaker flexplate can't provide enough stiffness for the hydralic pressure. If it gives or moves, the pressure will quickly decay. In the same way that it acts as a hydraulic piston and works against the crank thrust, it also works like an accumulator.

Given this information, since we see pressure spikes in the system on gear shifts, it would almost seem like it would be a benifit to have an active accumulator in the PR circuit to absorbe these pressure spikes.

Allan G.

There you go! I think you're starting to get it. In the drawings that you posted, simply put a box around your forces. Now you have your press frame.

In my metal versus wood examples, I was aware of the box in my mind, but left that out in conveying the example into words for everyone. Forgive me if I caused any confusion for some of you. I was relying too much on other's imagination to put the box, or press frame into the example.

Are the laws of physics safe and intact now?

 

[turbobitt]

There you go! I think you're starting to get it. In the drawings that you posted, simply put a box around your forces. Now you have your press frame.

In my metal versus wood examples, I was aware of the box in my mind, but left that out in conveying the example into words for everyone. Forgive me if I caused any confusion for some of you. I was relying too much on other's imagination to put the box, or press frame into the example.

Are the laws of physics safe and intact now?

Don,

It's not a matter of "Getting it" but explaining it with logic. Your explaination lacked the fluid pressure relation to applied forces. The flexplate "Flexing" load will still transfer the load to the crank thrust. The only difference is that the flexing will lower the fluid pressure and effectivly reducing the pressure spike. In the same instance, the stiffer plate may allow a greater load to be transmitted to the crank thrust. It still says the same thing, whatever forces it takes to bend the flexplate will still be seen in the crank thrust. Only difference is the fluid pressure element. Pure logic.
Allan G.

 

[S2V6RACER]

It all makes sense, but the another question is WHAT PRESSURES wipe out the thrust bearings, what duration ect.

I can tell you we have run this setup for YEARS and there is no issue with the thrust bearing, so while it might make theoretical sense to take things a step further, I don't see a reason to in my application since there is nothing causing bearing failure. I am running the reactor AL flexplate.

Just a note: In my graph, the 0 mark is where I zero'd the log when the driveshaft actually moves. The rest is the run. The TPS trace is at the top.


I really hope this graph helped guys out. My reasons for doing this was to see what actually does happen during the pass. I would love to see other information for comparison reasons, but it's going to take a good logging system (not 10 frames/second) to really see in definition of what is going on.

 

[turbobitt]

It all makes sense, but the another question is WHAT PRESSURES wipe out the thrust bearings, what duration ect.

I can tell you we have run this setup for YEARS and there is no issue with the thrust bearing, so while it might make theoretical sense to take things a step further, I don't see a reason to in my application since there is nothing causing bearing failure. I am running the reactor AL flexplate.

Just a note: In my graph, the 0 mark is where I zero'd the log when the driveshaft actually moves. The rest is the run. The TPS trace is at the top.


I really hope this graph helped guys out. My reasons for doing this was to see what actually does happen during the pass. I would love to see other information for comparison reasons, but it's going to take a good logging system (not 10 frames/second) to really see in definition of what is going on.

Looking at these pressure traces raises some questions in my mind.

First, if you were to map out the PR valve motion during a gear shift, this is what I would expect.

1 – Since there is a need to fill an empty void, the PR valve would slam shut to compensate for the sudden pressure decay. This would effectively shut down the converter charge circuit if it was a stock unmachined valve.
2 – The pressure would rise in the circuit as the spring force increases on the intermediate piston while stroking. This would happen very fast.
3 – Once the Intermediate piston completed the stroke, the PR valve would stabilize in a certain position. May or may not be in its original position before the gear shift.
4 – On the Third gear shift, The pressure would rise in the circuit as the spring force increases on the direct piston while stroking. This would happen very fast but with a different signature as intermediate

a – Itermediate springs are much lighter.
b – Intermediate fluid volume is most likely different
c – Direct springs are stiffer
d – most direct pistons use a bleed hole and tax the regulator.

5 – Once the direct piston completed the stroke, the PR valve would stabilize in a certain position. Most likely won’t be in its original position before the gear shift. See below.


The pressure in the PR circuit near the valve will probably be much different then the pressure near the drums simply due to pressure loss from leaks, losses from turns and flow restriction and fluid orfice restrictions.

The pressure spikes would almost indicate that the PR valve is modified to allow full flow at any position. Restricted orfice downstream can’t compensate for varying flow rates.

Allan G.

 

[turbobitt]

It all makes sense, but the another question is WHAT PRESSURES wipe out the thrust bearings, what duration ect.

I can tell you we have run this setup for YEARS and there is no issue with the thrust bearing, so while it might make theoretical sense to take things a step further, I don't see a reason to in my application since there is nothing causing bearing failure. I am running the reactor AL flexplate.

Just a note: In my graph, the 0 mark is where I zero'd the log when the driveshaft actually moves. The rest is the run. The TPS trace is at the top.


I really hope this graph helped guys out. My reasons for doing this was to see what actually does happen during the pass. I would love to see other information for comparison reasons, but it's going to take a good logging system (not 10 frames/second) to really see in definition of what is going on.

This is an interesting question since I ran a T-brake 400 for the last 3000 miles with UNREGULATED converter charge flow with line pressure that I can garrantee were over 200 PSI. I never actually checked any of the pressures in this transmission and replaced it with my new and improved version with the restricted feed orfice of .113" and still have 100 psi charge flow. I was convinced that I would find something wrong with the crank thrust but found that the clearance was maintained at .007" with no visable wear.
Why was I so lucky ??? Would love to put this on Chris's dyno and see what I had. I still own this transmission and would like to take these measurments.

 

[Alky V6]

Here is a example of (at least mine) of your converter fill pressures while you go down the racetrack. There are spikes in the gear shifts for a instant. I wonder if a flex plate will help absorb this? The trans is from Rossler. We have had ZERO thrust problems with it.


Don have you logged this on your car yet? I'm curious for comparative reasons.

Where did you pick up this pressure reading? Cooler line? Or, somehow closer to the T/C?

 

[S2V6RACER]

Don they are taken out of the cooler line within 18" of the connection on the trans.

My thoughts were they seemed a little low, I remember talk of low pressures increasing stall and slippage, but I don't see this as a problem in my case. I have some datalogs from back when I ran tractor fluid in the trans, also with a different converter. The logs you see are running Amsoil ATF. I'll check and see if there is any difference with thicker fluid vs. the Amsoil.

 

[Alky V6]

Don they are taken out of the cooler line within 18" of the connection on the trans.

My thoughts were they seemed a little low, I remember talk of low pressures increasing stall and slippage, but I don't see this as a problem in my case. I have some datalogs from back when I ran tractor fluid in the trans, also with a different converter. The logs you see are running Amsoil ATF. I'll check and see if there is any difference with thicker fluid vs. the Amsoil.

That was my same impression. Hey, if it works and you're not overheating the T/C and fluid, looks good to me.
What kind of slip numbers are you calculating on the top end?
Are you using a T/C feed orifice? If so, what size? What main line pressure setting are you using? Are you using a bypass to T/C feed at the PR valve, or is it all still controlled by the PR valve.
I'll try to get my readings next time I go out.

 

[bison]

Ok,

Here is another theory,

It is possible that the flexplate "Flexing" is acting as a hydraulic accumulator.
Mater of fact , that is exactly how an accumulator would work. The spring force of a weaker flexplate can't provide enough stiffness for the hydralic pressure. If it gives or moves, the pressure will quickly decay. In the same way that it acts as a hydraulic piston and works against the crank thrust, it also works like an accumulator.

Given this information, since we see pressure spikes in the system on gear shifts, it would almost seem like it would be a benifit to have an active accumulator in the PR circuit to absorbe these pressure spikes.

Allan G.

Imo the pressure spikes are so instant they dont have time to break down the hydraulic wedge of oil film between the bearing and the crank of we would be seeing thrust failures all the time. Im not convinced that the pressures many have seen on gauges mean much since they are not usually simulating what happens on most of the really high hp applications that use TH400's. If you think about it most guys dont let their trans temp get high enough before they are on the trans-brake beating the balls off it on their first pass of the day. Ted's logs are very interesting though.

 

[bison]

Just a note: In my graph, the 0 mark is where I zero'd the log when the driveshaft actually moves. The rest is the run. The TPS trace is at the top.

Id like to see the pressures on the first pass when on the t-brake before its released.

 

[S2V6RACER]

Id like to see the pressures on the first pass when on the t-brake before its released.

You can. Look at the sub 0 second timeline. It's also on the 2 step there.

 

[S2V6RACER]

Expanded a little bit

I expanded the log a little bit. It's got the pre-stage, trans brake and the pass.


A driveshaft trace is there too...

So does all this make sense to the trans gurus?? About all I know about transmissions is how to bolt them up and put fluid in them...

 

[Alky V6]

If I knew the mods done to the pump, I would have a better reference to use in my attempt in understanding it all. Allan made some good points, but then something is missing in the trace that I would expect to see.

At this point, all I can say is, "very interesting".