TH400/ Thrust Bearing

[transfixleo]

I will have to assume that CK is somehow thinking about an open chamber, I.E. Air Pressure will have more pressure with more volume. The taller column of air would exert more downward pressure than that found in a higher altitude, all things being equal. In a closed chamber as in a Clutch Drum it is simply Force = Pressure X Area so the "volume" has no affect as long as it is full of oil, it is strictly the area of the Piston. Period.

 

[Chuck Leeper]

Not too old to remember!!

Thanks, Alan! I guess I'm not to the point of being senile yet!
My "thesis" on the psi and area and volume is right!.
Evidently all that money my folks spent on school wasn't wasted after all!
[Thanks to the fluid dynamics class instructor!!] He always told us to remember where to get the info, not to try to keep it all in the cranium. I have the book in hand right now. Copyrighted 1965.]
Chris, I think the "tide" has turned, and you are being outmanned here!!

Have fun, guys! I'm outta here....

 

[WE4]

Yes

I was trying to say in lame man's terms what Alan said. I couldn't figure out a way to convey with as little as technical as I could , but I beleive alan is right.

Bruce
WE4

 

[chris718]

if this is true why do looser clutch packs apply with more force?anyone have an idea?if you leave a clutch pack at .005 it will slip when applying .try transbraking a car with .005 and .005 in both drums and prepare to smell burnt oil.the increased force im talking about is generated during the clutch apply.

 

[WE4]

this is my explanation.....for what it is worth...

The reason is it has firmer shift with more clearence is the piston has a run at the pack instead of appling with minimal travel. Looser the pack on a stack shifting trans (GM) the harder the hit. Now on a apply and release trans such as a TF or Ford or a 2004r or a 7004r the clearence is crtical to shift "timing" which becomes very important.



For the record ................ I prefer to see no more than 50 psi converter discharge. I do not restrict the pressure cooler line because by restricting you INCREASE pressure. Want to increase volume, open up an oriface. Want to increase pressure restrict an oriface.
There was a formula floating around and I think Chuck there had it once before. It was something about 200 psi in converter would exert so much forward thrust. Something like that.
Anyway as I have preached before, It is highly unlikely the converter or trans takes out a thrust bearing. Can it happen and/or has it? Well sure, but in 99 out of 100 cases , it is NOT the trans or converter no matter what pressures are run that is the underlying cause. Has it or can it? Yes , but is it normal, no...
My take.........



Bruce
WE4

 

[6PacktoGo]

Do not equate shift firmness with clamping force, they are not always necessarily the same.

The reason a looser pack will have a firmer apply is just what Bruce said. Like anything else, when you take up slack, there is a sudden thump, the more slack the bigger the thump.

Of course you cannot run the clearance too tight. And of course you cannot run transbrake clutch packs at 0.005", nor can you run any other clutchpack that tight. The reason is that they'll burn on the release.

But don't take my word for it, I'm just a dumbass country boy. I have no idea what I'm talking about.

I agree with Bruce on the converter fill pressure. Never restrict the fill pressure, open up the dump. If you restrict the fill pressure, you run the risk of the converter not having enough pressure to operate properly.

 

[TURBO D]

Great info guys! About how much larger should the dump side be? Thanks

 

[6PacktoGo]

Originally posted by TURBO D
Great info guys! About how much larger should the dump side be? Thanks

Depends on how high the pressure is. And how big the relief is to start with. In other words, be prepared to experiment. And remember, it is always easier to go bigger next time than it is to fix it if you go too big this time.

 

[2quiktocare]

ALAN HAS IT RIGHT

Alan hit the equation that covers it. It is the surface area of the apply, rather than the amount of fluid being applied to the piston.
You put 100 psi on the backside of anything, and the opposite side will still read 100 psi. Doesn't make a bit of difference if you apply the 100psi to 1", or 10". The opposing pressure will still be 100 psi. Try it with a scale. Put a one cubic foot box on a scale that weighes 10 pounds, it will show 10 pounds. Put 10 pounds in a much smaller box, you will still see it weighes 10 pounds on the scale. You have increased volume, but the effect is the same. The only way you can increase the force is to increase pressure. .My 2 cents, plus some change.

 

[lazaris]

The only way you can increase the force is to increase pressure

Not true, you can also increase force by increasing velocity. Double the pressure you double the force, double the velocity you quadruple the force. Dont know that it applies here in transmissions with fluids but it is a fact of physics.

 

[2quiktocare]

force

Laz, you are right on an object in motion, but we are talking where a fluid subjecting the force(pressure) on the piston is constant. The only resulting increase would be a short moment where the velocity of the mast of the piston hits. The apply pressure is constant with the fluid pressure, regardless of volumn of fluid applying it.

 

[chris718]

i agree with this last post..maybe im explaining it wrong?alan how could you burn the forward clutch on release in a tbrake application?try running tight clearances in the forward drum with a brake and see if the motor dont pull through the clutches .the pack will not hold.additional clearanceis the answer.2 quick ,no offense please but i think you are using a poor example to point out an idea.anyway ,the clearance thing is used as part of a total assembly procedure that has worked for us sucessfully so lets all pay attention to the other information in the post because if no one is disputing it there must be some truth in there.

 

[6PacktoGo]

I don't know how you'd burn the forward clutches on a transbrake period, I've never had that problem. It is however possible to scorch the direct clutches in a 400 with a brake if it is too tight, just as you can do it to the reverse clutches in a PowerGlide if you put them up too tight. I never mentioned forward clutches to begin with, and neither did you until now. Besides that, by the time you engage the brake, the forward clutches are already applied and locked, or at least they better be. I don't know anyone who runs or tries to run 0.005" clearance anyway.

I just don't use big clearances, and I don't have burnt clutches. I only run loose clearances in the reverse clutches in a PowerGlide with a brake, and I still stay on thr tight side there. Of course, I don't run anything at 0.005". But I've NEVER seen anyone even come close to proving that bigger clearances increase clamping forces.

Regarding velocity theory, you're dealing with inertia there, and a piston will never develop or retain enough speed during application for inertia to become a factor in apply force. Realize that even in a loose drum, you'd only have 0.120" of travel. Besides, a piston simply doesn't weigh that much. Anyway, the force gain would only be momentary, once the piston stops, inertia is no longer a factor, and we're dealing with a static clamping force.

 

[WFO]

Originally posted by 6PacktoGo
But don't take my word for it, I'm just a dumbass country boy. I have no idea what I'm talking about.

hehehe...

i'll state my opinion like this:with over a thousand hours of aircraft hydraulics schools(usmc),4 years wrenching on high-tech jet aircraft,~3 years in an industrial hydraulic fab shop and 4+ years in heavy agricultural industry there is nothing i can think of to add to alan's posts.

i will say that i don't know sh!t about trannys,but the hydraulic part i can follow ok.

later,sean

 

[ThikStik]

Originally posted by lazaris
Not true, you can also increase force by increasing velocity. Double the pressure you double the force, double the velocity you quadruple the force. Dont know that it applies here in transmissions with fluids but it is a fact of physics.

I agree. The equation of F=MA would work here. Thats why you wind up an ax when chopping wood or hammering. The Force=Mass x Acceleration. Try to stop a spinning object with your hand. It would be easier if you had the chance to strike from a distance. This method, with ultimate clamping (psi) pressure held constant, would stop the object ,(cluthc pack) with more INITIAL force. Or, for the hammer analogy, try driving a nail with a little hammer stroke.

 

[chris718]

IM NOT A FAN OF ZOMBIES OR BRINGING THINGS BACK FROM THE DEAD BUT THIS IS ONE ZOMBIE IM GLAD TO SEE RESSURRECTED .IT MADE ALOT OF PEOPLE DO SOME THINKING INCLUDING MYSELF BUT IN MY STUBBORNESS I STILL AGREE WITH MYSELF.ALL OF YOU WHO HAVE NO THRUST BEARING PROBLEMS AFTER SPEAKING WITH ME AND FOLLOWING MY PROCEDURES PLEASE RESPOND.AND THIS INCLUDES IF IT DIDNT WORK OUT EITHER as per my instructions.on a sad note returning home from the bronx tonite it was once again troubling to view the airpocket where the twin towers once menaced all the other buildings of our massive skyline.take time to remember why it pays to be nice to others in a world of uncertainty.ME INCLUDED.

 

[2quiktocare]

Right on Chris. I can't imagine the impact it has there, but I do see how it effects those I work with and know, that are from New York area and see how they react to it. The emotional void that is felt by us that have not been there is so intense, I can't even fathom what it is in reality. It is changed forever, and we shall never forget. If we do, we will be vunerable to have a repeat. No matter if you are on the left or right wing of the political spectrum, the thing we all need to remember is we are dealing with a small yet capable group of fanatics that has a sole aim of bringing our way of life to ruins. They are pledged to that end and won't stop until we completely wipe them out. As Bush said on 9-12-01, this will be a long campaign and will take all our resolve to end this threat. Now here 2 years later and people are trying to blame us for this happening. People even in our own government. REMEMBER 9-11-01 FOREVER AND WHEN YOU VOTE, MAKE SURE YOU GO WITH THOSE THAT ARE WILLING TO MAKE THE SACRIFICES FOR US TO KEEP OUR WAY OF LIFE. AND NOT BUCKLE UNDER TO THE TOUCHY FEELY FORCES WITHIN OUR GOVERNMENT. GIVE ME LIBERTY, OR GIVE ME DEATH. IT'S JUST AS MEANINGFUL TO DAY AS IT WAS BACK THEN.
Chris, thank you for bringing this forward and I pray all is well for you and your family there near groung zero. Mark