I was reading past threads on the subject and was wondering if only the V6's are affected buy the higher pressure in the 400 when the modulator is removed for a brake set up? Is it the surface area of the bearing or lack of mass or both, when compared to a sbc/bbc? Is there a way of checking this pressure? TIA Dean
TH400/ Thrust Bearing
- Thread starter TURBO D
- Start date
everything mechanical has structural and design limitations.in the case of the v6 verses the 400 there is definately more forward thrust generated by the 400 that is being applied to a surface area not capable in most cases to absorb thrust without quickly wearing out the overstressed thrust surfaces .also the thrust surface is in the middle of the block on the v6 verses a sb chevy allowing more driveline run up to be exerting a force on the thrusting surface.hi line pressure without proper regulation such as that used with most transbrake designs causes overcharging of the torque convertor at a rate faster than the oil can exit the convertor resulting in the torque convertor,flywheel and crankshaft being shoved towards the front of the engine overstressing thrusting area.this also causes torque convertor swelling / ballooning which tears up thrust bearings. improper endplay in the form of excessive flywheel to convertor or crankshaft to block/bearing end play causes these items to see saw back and forth beating the oil cushion out from between the crankshaft and thrust bearings causing failures.we have a pump at ck performance that has been proven to reduce these failures when it is installed properly using the technical information above. if attention to endplay details is not followed dont bother using it because the pump is only part of the cure.there is also no reason to run more than 170 psi line pressure with a th400 and transbrake application unless you are looking to spend some quality time removing your oil pan and crankshaft on a regular basis to change the main bearings.extra clamping force can be furnished to the transmission in the form of increased clutch pack clearance.SEE PASCALS LAW.when using any manufacturers brake except ours or griners always use the factory pressure regulator spring.increased clearance in the 400 hi drum and rear band only enhance transbrake and hi gear performance contrary to popular opinion.hope you find this information usefull.
the more clearance a clutch pack has increases the amount of oil pressure (clamping force)you can build up behind the clutch piston .the more oil in volume the more pressure .if the area behind the piston when applied was less than 1 square inch then 100 psi sent to the drum would not exert 100 psi of force .if you have 5 square inches of area behind the piston the 100psi is now 500 psi of clamping force.this is how a garbage truck can compress so much garbage into a small space with the use of 2 small hydraulic pistons.the larger the volume of oil that is accumulated in an area the more the supply psi is multiplied into clamping force.hope this helps .if you have no clutches in the drum on an air check of course youll blow out the lip seals .there is always a fixed amount of lip seal travel in all hydraulic systems .a general rule of thumb is .010 per clutch as opposed to less than 005 that most use .this also generates unwanted horsepower loss dragging clutches along with rotating parts when they are not applied and glazes the surfaces of the steels and frictions resulting in less than acceptable holding power.signs of not enough clutch pack clearance besides this are fretting of the internal teeth of the frictions by not enough clamping foirce being built up behind the piston causing the engine to try to pull through the applied element of the gear set ..this is the absolute truth to the best of my knowledge,and i have applied this principle to some of the fastest cars in quick 8 going in the 7s with my stuff.it has proven itself to me to be a very valuable thing for one to understand.
- Joined
- May 28, 2001
Jake's right on this one!!
Area of the piston X the pressure applied is the clamping force. The volume has nothing to do with it.
The volume is taken into consideration when the speed of the piston comes into the picture.
IE: 5gpm at 100psi will apply 1000# of clamp force on a pack w/ a exposed area of 10 sq. in and a volume of 1 gallon. This will take 12 sec to fill and apply.
At that same 5gpm, etc. The application will occur at 6 sec's w/ a volume of 1/2 gallon. The apply pressure will remain the same.. It just got applied sooner.
Want to find out about the industry study on the thrust brgs vs converter out pressure? GOTO: www.atra.com Click on customer bulletins, then on "what caused the engine to fail". A good discussion on this subject is contained there.
FWIW:
I don't like to see converter out to the cooler to be more than 70psi....
I use a 3/32" restrictor in the converter circuit to keep the psi at 70. You can tee into the lower cooler outlet and see this pressure.
back under my rock...
Area of the piston X the pressure applied is the clamping force. The volume has nothing to do with it.
The volume is taken into consideration when the speed of the piston comes into the picture.
IE: 5gpm at 100psi will apply 1000# of clamp force on a pack w/ a exposed area of 10 sq. in and a volume of 1 gallon. This will take 12 sec to fill and apply.
At that same 5gpm, etc. The application will occur at 6 sec's w/ a volume of 1/2 gallon. The apply pressure will remain the same.. It just got applied sooner.
Want to find out about the industry study on the thrust brgs vs converter out pressure? GOTO: www.atra.com Click on customer bulletins, then on "what caused the engine to fail". A good discussion on this subject is contained there.
FWIW:
I don't like to see converter out to the cooler to be more than 70psi....
I use a 3/32" restrictor in the converter circuit to keep the psi at 70. You can tee into the lower cooler outlet and see this pressure.
back under my rock...
- Joined
- May 28, 2001
40 to 70??
I would suggest that a reading of 70 or less would be just fine. I think you are going to find it considerably more unless the restrictor is in place.
I put a pres transducer in the line and recorded it on my data recorder.. kinda scary! I tried a 7/64" to begin with, found it still too high and went to 3/32". Right o n now.!!
I would suggest that a reading of 70 or less would be just fine. I think you are going to find it considerably more unless the restrictor is in place.
I put a pres transducer in the line and recorded it on my data recorder.. kinda scary! I tried a 7/64" to begin with, found it still too high and went to 3/32". Right o n now.!!
guys i am speaking about the area below the piston .between the piston and the drum.the more oil volume that is present here ,the more force is exerted against the piston which results in more pressure holding the clutches applied.why do you think everyone dual feeds the direct clutch in a 400 ?this generates increased clamping forces .seems i am not wording this principle properly,sorry if i am not explaining it in a manner that you can comprehend .lets try it this way ,........increasing the amount of oil accumulation / volume under the piston by leaving the clutch pack loose allows the piston to travel up towards the pressure plate further increasing the amount of oil volume that is built up during clutch application generating more force to hold the frictions clamped down.
It is the area of the piston and not the volume of the drum behind the piston that determines the area that pressure applies clamping force to. Pressure is measured in Pounds per Square Inch. Since the piston is the only part that is moving, and is providing the clamping force, the only thing that the volume of the drum behind the piston determines is apply TIME, and NOT apply FORCE.
The reason dual feeding changes shift feel is it supplies the drum with a greater volume of fluid, thereby filling the drum with fluid quicker. This speeds and firms the apply, but DOES NOT increase apply force.
This is an application of the simplest laws of hydraulics. The apply force is measured as the amount of pressure in Pounds per Square Inch, times the area of the piston the pressure is applied to. The cylinder or drum the piston is in is irrelevant with regards to apply force. Remember that the cylinder or drum itself does not move, therefore it applies nothing, and contributes nothing to clamping force, other than being the containing vessel.
With regards to the direct drum in a 400, the reason dual feeding makes a difference in apply force is that you ALSO remove the inner lip seal, allowing apply pressure to act against the entire surface of the piston instead of only one section of it. What you're doing there is increasing the AREA of the piston that the apply pressure is applied to. Again, the ability to flow more volume firms and quickens the application, but does not increase the total apply force.
Now, regarding the thrust bearing failure with a transbrake, what we do with big and small Chevy engines is drill an 0.060" hole in the bearing (and a corresponding 0.125" hole in the cap) to feed oil pressure directly to the thrust flange. I have not tried this with a Buick V6.
The only brake I use in a 400 is the ATI, and I've never had it kill a thrust bearing. With the exception of the Griner, which is double the price (the reason we don't sell them), the ATI has been the most reliable and consistent brake we've tried in the past 15+ years.
Converter spacing appears to be somewhat of a factor in thrust bearing failure, and keeping the converter spaced out of the pump to the high side of tolerances appears to allow it to vent fluid more quickly. I've seen converters run deep in the pump cause thrust failures even without a brake. The 400 is bad about this, as is the 200 4R in some cases.
The reason dual feeding changes shift feel is it supplies the drum with a greater volume of fluid, thereby filling the drum with fluid quicker. This speeds and firms the apply, but DOES NOT increase apply force.
This is an application of the simplest laws of hydraulics. The apply force is measured as the amount of pressure in Pounds per Square Inch, times the area of the piston the pressure is applied to. The cylinder or drum the piston is in is irrelevant with regards to apply force. Remember that the cylinder or drum itself does not move, therefore it applies nothing, and contributes nothing to clamping force, other than being the containing vessel.
With regards to the direct drum in a 400, the reason dual feeding makes a difference in apply force is that you ALSO remove the inner lip seal, allowing apply pressure to act against the entire surface of the piston instead of only one section of it. What you're doing there is increasing the AREA of the piston that the apply pressure is applied to. Again, the ability to flow more volume firms and quickens the application, but does not increase the total apply force.
Now, regarding the thrust bearing failure with a transbrake, what we do with big and small Chevy engines is drill an 0.060" hole in the bearing (and a corresponding 0.125" hole in the cap) to feed oil pressure directly to the thrust flange. I have not tried this with a Buick V6.
The only brake I use in a 400 is the ATI, and I've never had it kill a thrust bearing. With the exception of the Griner, which is double the price (the reason we don't sell them), the ATI has been the most reliable and consistent brake we've tried in the past 15+ years.
Converter spacing appears to be somewhat of a factor in thrust bearing failure, and keeping the converter spaced out of the pump to the high side of tolerances appears to allow it to vent fluid more quickly. I've seen converters run deep in the pump cause thrust failures even without a brake. The 400 is bad about this, as is the 200 4R in some cases.
sorry your not following along but it is the volume of oil accumulated behind the piston that controls clamping force with a given constant drum and piston configuration.the more oil that is available behind the piston the harder it will push the clutch piston against the drive and driven plates.think of it this way ,its easier for three people to push the same car than for one person to do it .this is because the more psi (people per square inch) the more force is generated to push .hahaha...............i am disturbed.griners brake is the one of the best in the nation ,imo.ours uses 2nd gear and the band to apply the brake making it truly unique.ati brakes ,select performance ,and fb transmissions all use the same design brake with small differences but they seem to work well. now unless you have raced with a griner,kilgore ,joels on joy ,motor city,or ckperformance brake you really cant understand the difference of a truly unique design that leaves properly.all the external design brakes leave much to be desired .much respect to everyone in the business including those who have helped me in the engineering of my products .special thanks to my dear friends steve griner ,john kilgore,joel and richie in detroit,john at master in minnesota,willie early in detroit,and everyone at turbo buick .com
I'm not following because your statement is incorrect. Volume does not affect clamping pressure, so long as suffucient volume is available to create maximum pressure. The area of the piston that pressure is being applied to multiplied by the amount of pressure being applied determines the amount of force the piston exerts. Again, this is why pressure is measured in pounds per square inch.
100 psi is only 100 psi when applied to 1 square inch .what happens when the area is bigger than 1 square inch?the force is multiplied.how does it get multiplied/? because the pressure is generated and multiplied equally in all directions .more piston travel more square area more force.very simple.if its 10 square inches it becomes 1000 psi.this is hydraulic principles.although the piston is the same the area below is greater so the force multiplication is as well.
WE4
TBcom Admin /Prayers NYFD/NYPD
- Joined
- May 24, 2001
Hrrmmm
Clamping force is a principal of pressure. Area of volume multiplies the effective holding force. So what Chris was trying to explain is that there is more VOLUME with more clearence but the PRESSURE is still equal to or greater with more volume. The amount would be almost immeasurable, however line pressure and clutch disc surface area are the players here.
As far as Brakes, I exclusivly use Hipster for 400 and Griner for Torqueflite. But I have also known both these guys for almost 20 years.
I had one 400 with 300 psi line pressure eat a thrust bearing once. (It also broke the int lugs , but same story different chapter) I have had NO 2004r's eat one.
That does not mean it cannot happen? no , just my experiance.
I will say that everytime you thin steels to add clutch area you are actually headed the wrong way as the KEY is in the steel. Don't believe me? Ask any of the clutch manufactures as they are discovering this too. More heat you can "suck" out of a clutch plate before and after apply, the longer that clutch will live. Thats why the 9 pack in the direct 2004r is a bad way to go.
But that is a whole nother debate we can have at another time.
My take anyway....
Bruce
WE4
Clamping force is a principal of pressure. Area of volume multiplies the effective holding force. So what Chris was trying to explain is that there is more VOLUME with more clearence but the PRESSURE is still equal to or greater with more volume. The amount would be almost immeasurable, however line pressure and clutch disc surface area are the players here.
As far as Brakes, I exclusivly use Hipster for 400 and Griner for Torqueflite. But I have also known both these guys for almost 20 years.
I had one 400 with 300 psi line pressure eat a thrust bearing once. (It also broke the int lugs , but same story different chapter) I have had NO 2004r's eat one.
That does not mean it cannot happen? no , just my experiance.
I will say that everytime you thin steels to add clutch area you are actually headed the wrong way as the KEY is in the steel. Don't believe me? Ask any of the clutch manufactures as they are discovering this too. More heat you can "suck" out of a clutch plate before and after apply, the longer that clutch will live. Thats why the 9 pack in the direct 2004r is a bad way to go.
But that is a whole nother debate we can have at another time.
My take anyway....
Bruce
WE4
Wrong. Ten psi on a 1 square inch piston is ten psi. Ten psi on a 10 square inch piston is still ten psi. However, ten psi on a 1 square inch piston will exert a force capable of moving 10 pounds, and ten psi on a 10 square inch piston will exert a force capable of moving 100 pounds. It is the area of the piston multiplying the force of the pressure. With a given pressure, increasing the area of the piston will increase the force exerted by the piston, but increasing the length of the cylinder will not. This is because the pressure remains the same throughout the cylinder whether it is 2" long or 2' long. In other words, if you have a 1" diameter piston and 100 psi of pressure, it will exert 100 pounds of force, no matter how long the cylinder is, because no matter how long the cylinder is, the pressure remains the same, and so does the surface area of the piston.
The piston only sees the pressure exerted against it because pressure in the vessel (in this case a drum) is equal at all points. Therefore, pressure applied by the piston is equal to the area of the piston that fluid pressure is applied to, times the amount of pressure applied. If you have 300 psi in a drum, then you have 300 psi, regardless of the volume of the drum. Adding clearance to the clutchpack and thereby increasing the volume of fluid in the drum does not increase the pressure, nor does it increase the area of the piston, so therefore it does not increase the force exerted on the clutchpack by the piston. It's really quite simple.
Regarding the number of clutches in a clutchpack, like anything else, you can reach the point of diminishing returns. At some point, adding clutch discs will not add significant capacity for torque, and making the discs thinner will reduce the structural integrity and the ability to dissipate heat. When that happens, the instant slippage occurs for any reason, the ability of the clutchpack to dissipate heat is exceeded, and structural integrity rapidly decreases. At that point, it becomes a vicious cycle.
The reason some people cause thrust bearing failures and others don't is their approach to their work. There are those who simply go to jacking pressure up to prevent slippage while not considering the fact that it may not be a lack of pressure that is causing slippage, but rather pressure leakage in a certain area, or some other problem. Then there are those who look for the real reason for failure, rather than just jacking up pressure looking for a band aid solution.
In all honesty, Griner's brakes for three speeds are the best available, even the people who make their own will admit that if they can be honest.
The piston only sees the pressure exerted against it because pressure in the vessel (in this case a drum) is equal at all points. Therefore, pressure applied by the piston is equal to the area of the piston that fluid pressure is applied to, times the amount of pressure applied. If you have 300 psi in a drum, then you have 300 psi, regardless of the volume of the drum. Adding clearance to the clutchpack and thereby increasing the volume of fluid in the drum does not increase the pressure, nor does it increase the area of the piston, so therefore it does not increase the force exerted on the clutchpack by the piston. It's really quite simple.
Regarding the number of clutches in a clutchpack, like anything else, you can reach the point of diminishing returns. At some point, adding clutch discs will not add significant capacity for torque, and making the discs thinner will reduce the structural integrity and the ability to dissipate heat. When that happens, the instant slippage occurs for any reason, the ability of the clutchpack to dissipate heat is exceeded, and structural integrity rapidly decreases. At that point, it becomes a vicious cycle.
The reason some people cause thrust bearing failures and others don't is their approach to their work. There are those who simply go to jacking pressure up to prevent slippage while not considering the fact that it may not be a lack of pressure that is causing slippage, but rather pressure leakage in a certain area, or some other problem. Then there are those who look for the real reason for failure, rather than just jacking up pressure looking for a band aid solution.
In all honesty, Griner's brakes for three speeds are the best available, even the people who make their own will admit that if they can be honest.
When you build anything that works off of hydraulic cylinders, you quickly learn that longer cylinders do not give your device more power, but larger diameter cylinders do. Because it is piston diameter and not cylinder length that multiplies force. Go look at hydraulic cylinders anywhere, the larger the diameter of the piston, the higher the force rating of the cylinder (more power it has to move an object). I learned this long ago, both in agricultural work and later in industrial work. College engineering courses weren't entirely wasted either, but the chick two rows over was a major distraction, and was almost my wife.
Chris,
You mentioned the reason everyone dual feeds.
Not only does it have the capability to apply quicker but it DOES increase the presure applied to the clutches,
not because of a greater volume of fluid behind the piston but because it exposes a greater area of the piston to fluid pressure.
Since we're talking 400's here I'll use it as an example.
There are several ways to dual feed one, the two I know, and have used are one (the po' boy way), to leave the center seal out of the direct drum and block the reverse passage.
This allows direct apply fluid to get behind all of the piston instead of just the direct portion. It gets behind the direct portion and the reverse portion. Greater apply area. There is also a greater volume but only because it is filling a portion of the drum it wouldn;t be in stock form, the greater clamping is provided by the larger area.
Then a TransGo Reprogramming kit does the same thing but allows you to leave the center seal in to retain circuit integrity.
Gonna have to break out the digital camera and go get a drum....
This is how I understand it anyway,
I do agree that the clutches don't need to be overly tight, and also agree with Bruce about the thicker steels transfering heat better.
Lots of good info may come out of this thread.
You mentioned the reason everyone dual feeds.
Not only does it have the capability to apply quicker but it DOES increase the presure applied to the clutches,
not because of a greater volume of fluid behind the piston but because it exposes a greater area of the piston to fluid pressure.
Since we're talking 400's here I'll use it as an example.
There are several ways to dual feed one, the two I know, and have used are one (the po' boy way), to leave the center seal out of the direct drum and block the reverse passage.
This allows direct apply fluid to get behind all of the piston instead of just the direct portion. It gets behind the direct portion and the reverse portion. Greater apply area. There is also a greater volume but only because it is filling a portion of the drum it wouldn;t be in stock form, the greater clamping is provided by the larger area.
Then a TransGo Reprogramming kit does the same thing but allows you to leave the center seal in to retain circuit integrity.
Gonna have to break out the digital camera and go get a drum....
This is how I understand it anyway,
I do agree that the clutches don't need to be overly tight, and also agree with Bruce about the thicker steels transfering heat better.
Lots of good info may come out of this thread.
