TH400 The real answer
- Thread starter charliep
- Start date
Even with dual feeding, if you calculate available piston area in the 200-4R and compare it to the 400, you'll see why the high clutch setup in the 200-4R is marginal in high HP applications.
When I was playing with the 200C I threw every trick in the book at it. Dual feeding, generous apply passages, different syncronizations for band release/high pack apply, additional oil cooling to the plates, different line pressures, numerous clutch plate types and grooving strategies,and a redesigned TV boost hydraulic circuit. Granted, the 200C clutch pack would only allow me to install 8 friction plates in it, the experience showed me how marginal the high clutch pack was at only an 800 HP level.
For those that don't know what the 200C is, it is a three speed version of the 200-4R. A very basic design and very similar to the 200-4R which came out later.
Basically, the 200-4R is a 200C with an OD section added to the front of it, along with more hydraulic circuitry for better control of the friction elements and a different, variable volume pump design for better gas mileage. The high clutch drums in both units are very similar dimension wise, except that the clutch pack pressure plate snap ring location is lower in the 200C and thereby limits the amount of extra frictions that can be added to the drum. Even so, I was able to get 8 friction plates into the drum and it wasn't enough.
Another thing that aggravates the high clutch drum situation with both units is that you must thin out the frictions and steels to get additional capacity in the drum. When a shift occurs energy in the form of torque is transferred to these plates as they are applying. This torque energy is changed to heat energy. The higher the torque that is being transferred to the clutch pack, the more heat. This heat must be dissipated to prevent the plates from glazing or worse, burning. The friction plates hold a certain amount of fluid (ATF) in the lining and the steel plates act as heat sinks. When a clutch pack applys, the ATF in the lining and the steel plates absorb this converted heat energy and draw it away from the applying surfaces between the steel plates and the frictions. The thinner the plates, the less fluid and heat sink capacity available to absorb this heat energy. The applying surfaces overheat and glazing occurs or worse, burning. Once glazing has occurred, it's over. Torque load capability of the clutch pack is drastically reduced so that the next application of that clutch pack will not take hold as fast and will generate even more heat energy. It turns into a snow ball affect until the clutches burn and a slipping begins to be felt by the driver.
If you don't mind racing with equipment on the mechanical edge, then keep using the 200-4R.
When I was playing with the 200C I threw every trick in the book at it. Dual feeding, generous apply passages, different syncronizations for band release/high pack apply, additional oil cooling to the plates, different line pressures, numerous clutch plate types and grooving strategies,and a redesigned TV boost hydraulic circuit. Granted, the 200C clutch pack would only allow me to install 8 friction plates in it, the experience showed me how marginal the high clutch pack was at only an 800 HP level.
For those that don't know what the 200C is, it is a three speed version of the 200-4R. A very basic design and very similar to the 200-4R which came out later.
Basically, the 200-4R is a 200C with an OD section added to the front of it, along with more hydraulic circuitry for better control of the friction elements and a different, variable volume pump design for better gas mileage. The high clutch drums in both units are very similar dimension wise, except that the clutch pack pressure plate snap ring location is lower in the 200C and thereby limits the amount of extra frictions that can be added to the drum. Even so, I was able to get 8 friction plates into the drum and it wasn't enough.
Another thing that aggravates the high clutch drum situation with both units is that you must thin out the frictions and steels to get additional capacity in the drum. When a shift occurs energy in the form of torque is transferred to these plates as they are applying. This torque energy is changed to heat energy. The higher the torque that is being transferred to the clutch pack, the more heat. This heat must be dissipated to prevent the plates from glazing or worse, burning. The friction plates hold a certain amount of fluid (ATF) in the lining and the steel plates act as heat sinks. When a clutch pack applys, the ATF in the lining and the steel plates absorb this converted heat energy and draw it away from the applying surfaces between the steel plates and the frictions. The thinner the plates, the less fluid and heat sink capacity available to absorb this heat energy. The applying surfaces overheat and glazing occurs or worse, burning. Once glazing has occurred, it's over. Torque load capability of the clutch pack is drastically reduced so that the next application of that clutch pack will not take hold as fast and will generate even more heat energy. It turns into a snow ball affect until the clutches burn and a slipping begins to be felt by the driver.
If you don't mind racing with equipment on the mechanical edge, then keep using the 200-4R.
I have built 350s that went through some punishment and left me impressed with the unit. Still, in my opinion, if you've made the decision to upgrade, go with the 400 and be done with worrying about your transmission.
Or, if your the stubborn type, you can spend your money and try to prove me wrong about the 200-4R. These days, there are plenty of 200-4R experts that are making a good living repairing them. In some cases, over and over again.
Or, if your the stubborn type, you can spend your money and try to prove me wrong about the 200-4R. These days, there are plenty of 200-4R experts that are making a good living repairing them. In some cases, over and over again.
i am talking about 6 stock thickness frictions and 6 stock thickness steels and dual feed.the pistons are very close in size.also design practices dictate that the weight of the direct drum is an important factor in the way the direct clutch size and apply pressure must be calculated.the main point of load on the frictions is the split second during a gear change when the engine power is on one side of the clutch pack and the weight of the vehicle is on the other.once the clutch pack is applied and it recieves a steady uninterrupted feed of oil the clutch pack is not in danger. also note that while the 400 is run in competition sucessfully at 2000 horsepower with 175 psi line the 2004r as we set it up uses 215.this means that clamping force in the drum applied to the frictions is almost identical to that of the 400.now the difference becomes the friction surface area but we still have a lighter drum.a good example of this is the c4.it is univerally accepted that the c4 direct clutch with a heavier direct drum than the 2004r,with smaller frictions and less apply area can handle 1000 hp.the rest of the trans may fall apart but the direct clutch is still alive.i know that the direct clutch in the 2004r can handle 800 horsepower based on testing and the canculations that can be accurately made with sae design practices of automatic transmission literature and handbook math being used as a reference.its the rest of the transmission that needs attention above 550 horsepower.the oil volume of the variable displacement oil pump at an engine rpm capable of producing high horsepower,the use of a band instead of a multiple disc clutch pack for 2nd gear reduction,the planetary gear sets ratios,and the physical dimensions of the internal components are among the causes of failures at high horsepower levels.even with billet guts i draw the line at 650 hp and 800 foot pounds .this is where the ravigneaux drive aod comes in 
Chris, we're pretty close in agreeing that the limit is around 800HP for the 200-4R. Actually, my number is 750HP with a short life expectancy. 1 to 2 years with moderate race time. By far the usual failure being the 3rd clutch, even with higher line pressures than you prescribe. 215 psi, to me, seems very tame. Next time your at the shop, pull out a direct clutch piston for the 200-4R and the 400 and get the ruler out. I think it may surprise you. It surprised me when I finally broke down and did it. Do the calculation to determine available apply area in square inches. Again, you will be surprised.
Eight 200-4R friction plates has about 23 percent less friction area than six turbo 400 plates. This on top of the fact that the apply piston size of the 200 is smaller too. I don't even care to know how six 200 plates would compare to six 400 plates. To me it would be a waste of time to calculate.
The simple fact is there are three main ways to increase a clutches torque capacity:
Increase pressure to the apply piston.
Increase the size of the apply piston.
Increase the size of the friction element(s).
Simple hydraulic principles.
It works the same way as your brakes or standard transmission clutch. If you want more stopping power, you go to:
Larger diameter brake rotors or flywheels.
Larger brake pads or clutch discs.
Larger wheel cylinders or clutch pressure plates with more clamping pressure.
Eight 200-4R friction plates has about 23 percent less friction area than six turbo 400 plates. This on top of the fact that the apply piston size of the 200 is smaller too. I don't even care to know how six 200 plates would compare to six 400 plates. To me it would be a waste of time to calculate.
The simple fact is there are three main ways to increase a clutches torque capacity:
Increase pressure to the apply piston.
Increase the size of the apply piston.
Increase the size of the friction element(s).
Simple hydraulic principles.
It works the same way as your brakes or standard transmission clutch. If you want more stopping power, you go to:
Larger diameter brake rotors or flywheels.
Larger brake pads or clutch discs.
Larger wheel cylinders or clutch pressure plates with more clamping pressure.
I will second that! Rossler has the best th400 out there. When I switched to a th400 the car went quicker not slower like some would lead you to believe. The 200 trans is just a bomb ready to go off, you just don't know when. It's nice going to the track with a 400 knowing the trans is the least of your worries!
Sam Colalillo
low 9's w/ a 109
- Joined
- Jan 12, 2005
??? 4 Top Gun
I have always wondered if the th400 would slow a car down.
Top Gun you went faster with a TH400 very interesting. I have a question for you: At your power level do you run a 9" or a 10" converter?
I am thinking you went faster with the Th400 because you got all your power to the rear wheals instead of letting the clutch slippage in the trans eat some of that power up.
I have always wondered if the th400 would slow a car down.
Top Gun you went faster with a TH400 very interesting. I have a question for you: At your power level do you run a 9" or a 10" converter?
I am thinking you went faster with the Th400 because you got all your power to the rear wheals instead of letting the clutch slippage in the trans eat some of that power up.
I was running 10.50's tearing up 200's every 10 passes, switched to a 400 then ran 10.30's. I am running a 10 inch Neil Chance converter purchaced and from Dan @ DLS.
You are right on with the gain from the 400 was due to all of the power being put to the ground not slipping away like the 200 trans.
Refer to the above post, the car picked up e.t. and mph. More power to the ground with the TH400.
My car seems faster with the 400 but can not back it up with facts. I have a 400 with a 2.75 first gear, manual valve body, trans brake, 3400 converter,
gear venders overdrive, b&m rachet shifter, shiftnoid air shifter for up and down shifts. It sure is a lot more fun than my 200, but only because of the set-up.
gear venders overdrive, b&m rachet shifter, shiftnoid air shifter for up and down shifts. It sure is a lot more fun than my 200, but only because of the set-up.
What HP level you have in front of that 2.75 400?
I had the car on chasis dyno a few years ago and I think it was around 340hp and over 400lbs of torque at the rear wheels. It is a stock long block with a
thdp, dequick front mount, 009's, 52, tinman, remote oil filter, big aluminum radiator, dual fans, trans plus, hemco upper, internal intake plates. The car is an 87.
thdp, dequick front mount, 009's, 52, tinman, remote oil filter, big aluminum radiator, dual fans, trans plus, hemco upper, internal intake plates. The car is an 87.
Ok. Your in good shape.
im surprised to see anyones commercially purchased th400 2.75 gearsets last that long.the tci piece has the gear set pattern backwards between both planets usually resulting in immediate failure.john kilgore makes one that uses a bearing to stop the reverse thrusting,although i have never seen one.i use a planet with the same gear pitch / helix as the th400 resulting in optimum performance without negative gear set thrusting.also the rear carrier is bored out so we can use a thicker wall on the rear ring gear after we weld them together.this slightly reduces contact between the castles on the output shaft and rear carrier but has not shown itself to be a problem.too thin a ring gear would cause swell fractures similar to putting a rubber band over your fingers and stretching it outwards.i think the maximum power and weight ive used the gearset at is 3200 lbs and 650 ft lbs or 3800 lbs and 450 ft lbs.this was also with a vp converter and transbrake in the higher powered lighter vehicle combo.killa results
I can tell you this. I don't have any experience with the 2.75 in a high HP application. When I was putting my 400 together and researching the different parts available, while talking things over with a supplier I have gained alot of trust with, I mentioned the desire to use a 2.75 gearset in my anticipated 1,000 HP application. He quickly talked me out of it. Not strong enough. I went with a THM475 gearset.
As a race car's HP and torque level increases, the importance of having a low initial gear ratio decreases. Especially if the car is traction limited (10 inch slicks). Small turbo engine in a big car, it does help get that turbo spooled up a little quicker by getting the engine into its' optimum operating rpm band sooner. But then, that is why God gave us the juice.