So Im gonna get the TH-350 rebuilt to go behind the 454. I want it to perform on the street as well as the strip. I have a 2500 stall for it. Now what else shuld I have done to it? I.E shift kit, valve body, gearing, exct. I know esentually nothing about trasnmisions other than they go behind the engine in most cases and when you pull on the shifter it makes your car move. Thanks for any help Sam
I run one behind my 468 powered race car and have had no issues, even with a transbrake. As long as you use good parts on the rebuild you should have no problems. It is REALLY important to replace the stock direct drum & sprag with a aftermarket hardened direct drum & 36 element sprag. (about $300 I think) This is the weak point of the TH-350 & it will be exposed on a high torque big block application.
buy one done from a ****** building company, built to your engine specs, and your final drive ratio , and you will money and time ahead plus a warranty to go with it, so many friends had their trans rebuilt , and seems there was allways something,they did not understand how a stall drives, or , the best was a guy that had metal clutch packs and needed to use a fiber based ****** fluid , took it in to have all the oil changed at a place and the kid dumped all the fiber fluid,, 1 mile later the ****** went to hell, they told him his fluid was full of **** and needed to be changed, they put in regular dexron for the price you will pay to get all the parts and getting it together ,i dont have any problem wit ha ****** shop building one, but to say you have a 2500 stall already ,? what do you know about your engine performance the rear end ratio, to live with a stall convertor ? do some more reading on them and g ofrom there , iwould do reverse vlave body and bigger pan, more fluid the better, have a big high flow pump, and all the hardened drums, and they even make deepr ones for more clutch discs, more surface to hook up, more disc area, tight frim shifts are the best for any ****** slippage is heat, , make sure you have torrington bearing, not any thrust washers, one peice pump drive, no tangs to twist off, ,
I put the stall in it so I could actually stay stoped at a stop sign. and the cam is supposed to work from 3000 to 7500 rpms w/ a 750Dbl pmpr and a Holley Strip dominator intake. stock heads for now but I plan a Brodix set up in a few years. I would like to build a ****** that will withstand some torque.
Rather than buying every trick part in the book, would a Th400 be better? Like you I'm not that trans savy. But the 400's are suposed to be stronger, I believe.
1st I would personally use a th400 behind a BB a shift kit basically increases fluid pressure in the trans and is acheived by changing springs and drilling larger holes in the valve body, you can make changes to the valve body your self for free that will give it a little more grab and bump. I would actually find a performance oriented trans shop so they can help you build something that really matches your application. to find your stall speed fully depress the brakes, and give the car gas, as soon as it reaches an rpm where it starts to over come the brakes this is your stall speed I may be wrong if someone has more experiance then me and would like to chime in go for it
a 400 can be built up to a 475 they make a 425 used in bigger gm cars they 475 is more clutch discs bigger fluid flow, and better valve body design, all doable, just have to do more reading on them, i had one of my old dealerships tech build me a 475 in a 400 case, nothing magic ,i am sure you could get a 700 r4 built ,so many more ratios avialbel to build a great driving ****** plus overdrive, and have your drag racing ****** all in one, ,couple of places build them and they live up to any use you can put them through, i would google " how a stall convertor works" and see what it really does doesnt have a thing to do with you staying stopped at a stop sign
stall speed will have big effect on how the car behaves at a stop sign with a lumpy cam and fast idle....2500 would be what you want as a minimum. And with that cam you'll probably feel the cam "come on" when you get to 3000-3500 rpm, which means you need more stall if you want to go fast, but you'll also need sticky tires, etc or the power will all go up in tire smoke. I'd run a 400 trans, because a mostly stock rebuild will hold together just fine. Like luckydevil said, the intermediate sprag causes trouble on the 350 in high hp use. Maybe talk to some of the ****** shops and see who has built some 350s that are still working behind a big motor....or ask their customers The 350 does have some advantages as far as weight and power loss compared to a 400, but you pay for it with having to throw extra money at it.
Maybe I know more than I thought. The reason I dont want a TH400 is exactly what Squrrel said, weight and pwr loss it takes an extra 50hp just to turn a TH400. i would google " how a stall convertor works" and see what it really does doesnt have a thing to do with you staying stopped at a stop sign A stall converter most certinly helps at a stop sign That why it is called a "stall" converter because it dosen't let the trans fully kick in untill 2500 or what ever the partucular converter is rated for. It also helps w/ va***e problems that come along w/ big lumpy cams. W/o a stall in a big cam app. you have to turn the idle way up just to keep it running when in drive and stoped then its like you are pwr braking it all the time and you will eventually tear out your trans and never have really put it through its paces. Also never heard of any TH425s or 475s lets hear more about that.
Maybe some of us should read this. These are just two of many that are found w/ " GOOGLE" <TABLE width=400><TBODY><TR><TD width=400> </TD></TR><TR><TD width=400>Torque converters are way up there on the list of Dark and Mysterious Things. Because there are so many factors involved in choosing the right converter, many people end up getting the wrong one for their application, resulting in poor vehicle performance. But it doesn't have to be this way. You too can learn how to choose the right torque converter, and this little primer will help you get started. You'll learn about things like stall speed, matching a converter to cam size and rear axle ratio, special considerations for nitrous and blowers, and more. What a Converter Does Simply put, a torque converter is a hydraulic coupler between the engine and the transmission. It changes mechanical torque (engine torque) into hydraulic pressure before sending it back to the transmission. The converter also multiplies the torque at low speed or during periods of high engine load. The insides of a converter consist of an impeller, a stator, and a turbine, all surrounded by transmission fluid. The impeller rotates at engine crank speed, acting as a fluid pump. The turbine is the output device hooked to the transmission input shaft. The stator sits between the two, acting as a torque multiplier when impeller speed exceeds turbine speed. When the converter reaches its stall, or lockup speed, the stator stops multiplying torque and the converter essentially acts as a fluid coupling. When the vehicle is coasting (no load), the converter directs torque back towards the engine, acting as a brake. What is Stall Speed, Anyway? The most misunderstood aspect of torque converters is stall speed. Many people think if a converter is rated at 2,500 rpm, their car will rev up to that rpm and then take off. That's not how it works. Stall speed is a function of engine rpm. The more torque an engine makes, the higher the rpm the converter will stall, or lock up at, and transfer that torque to the transmission. There are two types of stall speed-foot brake stall and flash stall. Foot brake stall (or true stall) is the maximum rpm that can be achieved with the transmission in gear, the brakes locked, and the engine at full throttle. The rpm reached before the vehicle moves is the true stall speed of the converter. The problem with foot brake stall is that you will end up overpowering the brakes and suspension before you reach the converter's stall speed. The only way to really measure true stall is by using a trans-brake. This will keep the vehicle from moving, allowing the converter to absorb 100 percent of the engine's torque. Race cl***es that do not allow trans-brakes are often called foot-brake cl***es. In this type of racing, the rpm obtained when the brakes are applied and the vehicle is not moving is considered to be foot brake stall. When the brakes are released, the engine goes to full throttle and “flashes" the converter. This brings us to flash stall. It is the maximum engine rpm reached when you launch a vehicle from a dead stop at full throttle, no brakes applied. Flash stall is always lower than foot (true) stall because there is less load on the converter. Changing the load on the converter can change the flash stall rating. Additional engine torque, a higher(numerically lower) rear axle gear, or adding vehicle weight will increase flash stall. Less torque, a lower (numerically higher) gear, and less weight will decrease flash stall. Another factor that gets confusing is converter slip. Slip is basically a measure of converter efficiency. Due to the difference in rotating speeds between the impeller and the turbine, there is usually a five to 10 percent efficiency loss at cruising speeds for non-lockup converters. Because a converter gradually slips, or creeps up, to full stall/lockup rpm, the higher the stall speed, the more slippage you get. On a street-driven vehicle, that can lead to poor idle and low end performance, worse gas mileage, and most importantly, greater heat buildup-the number one killer of converters and transmissions. If you do run a high stall converter, a good transmission cooler is a must. What Kind of Engine Are You Building? Before you even crack open a torque converter catalog, you need to think about the type of engine you have or are building. For the street, you need to match low and midrange engine torque to the converter's stall speed. For example, if you are building a street small block that makes most of its torque around 2,500 to 3,000 rpm, don't get a converter that stalls at 4,000. Not only will the car be hard to drive, the converter will constantly slip and will eventually be destroyed due to overheating. If you build a big block that makes its torque at 4,500 rpm, don't expect it to be much fun on the street because of the high stall converter and big rear axle gear required to lock up the converter. Camshaft selection is also critical to torque converter selection. On the street, many people will choose a cam that will put an engine's rpm range 1,500 to 2,000 rpm higher than stock. Not only does that reduce bottom end torque, a higher stall converter will be required to match the new torque peak. Many people will get the recommended converter, but neglect to upgrade the rear axle gear to compliment the higher stall speed (more on gear ratios and tire sizes in a minute). Say you built a small block V8 with a 235 degree (at .050)/.488 inch lift cam and added a converter rated at 3,000 to 3,500 rpm. To make the combination work properly with a minimum of converter slippage, you will need a 4.10 or higher rear axle gear with 26 to 27 inch tall tires. Illustration One shows you approximate stall speeds based on engine type, cam duration, and rear axle gear ratio. Nitrous oxide and superchargers also affect converter selection. An engine with a power adder produces more torque than it would if it was normally aspirated. That means a nitrous or blown engine needs a converter with a lower stall speed range. Otherwise, the converter will stall too high, causing it to slip and eventually self-destruct due to the extra heat. The Final Ratio Rear axle gear ratio and tire diameter are very important to proper converter selection. You need to have a final cruise rpm (rpm generated based on tire diameter and rear axle gear ratio) that allows the converter to function at full lockup at cruising speeds. If you don't, the converter will constantly slip. Illustration Two shows you the rpm generated at 60 miles per hour with various gear ratios and tire diameters. This will help you determine where your converter should stall. You can see how close your vehicle's actual cruise rpm is to the chart by reading the tach at a steady 60 mph, find your gear ratio and tire diameter in the chart, then compare your rpm reading to the chart's suggested rpm. Size Does Matter Torque converter size can also be confusing. Converters can range from 11 and 12 inches in diameter all the way down to 7 inches. Basically, the smaller the converter, the less fluid has to be pumped through it. Less fluid means less drag on the converter internals, which allows it to stall at higher speeds. That's why you see 8, 9, and 10 inch converters listed for racing applications. In general, you want to avoid small converters on a typical street car due to the much higher stall speeds (usually 3,000 rpm and up). If you are adding a lot of nitrous (over 200 horsepower), running high blower pressure (over 12 psi), or use a trans-brake, you will need a converter built to handle the extra stress. The extra torque generated can cause a converter to “balloon", or expand in diameter. Look for a converter with a high quality stator ***embly and an anti-ballooning plate to keep it from expanding. The Fitting Room A common complaint about aftermarket torque converters is fitment. Often, a new converter will not fit the transmission's input shaft because it is built to closer tolerances than OEM converters, so the hub-to-input shaft fit is tighter. Just because the new converter will not slip onto the input shaft doesn't mean the converter is defective-just use a little extra effort. A good way to check if a new converter will fit properly is to compare it to the stock converter you are taking out. Illustration Three shows the three critical dimensions: overall length (from engine mounting face to end of hub), hub slot depth, and hub slot inside diameter. Before you remove the old converter, check the dimension from the bellhousing to the front. This will help you position the new converter properly. Other Considerations A higher stall converter will place extra stress where it mates to the engine, so make sure you use quality converter bolts (like those made by ARP) and an SFI approved flexplate. Flexplates for Chevys are usually double drilled for small and large bolt patterns, eliminating the need to guess which bolt pattern you have. Aftermarket torque converters are neutral balanced, designed for internally balanced engines. Most externally balanced engines have the balance weight on the flexplate, so this is no big deal. But on externally balanced Chryslers-340 and 360 small block and 440 big block-the factory put the balance weight on the torque converter. If you have one of these engines, make sure to get the appropriate flexplate counterweighted to match the engine balance. Most SFI approved Chrysler flexplates have this counterweight. Don't consider this to be the end-all and be-all on torque converters. The best way to get the perfect converter for your application is to talk with the tech guys at Summit or directly with the companies that build the converters. Hopefully, this guide will help you ask the right questions-and understand the answers. </TD></TR></TBODY></TABLE> <TABLE cellSpacing=0 cellPadding=0 width="100%" bgColor=#ffffff border=0><TBODY><TR><TD vAlign=top width=526 height=57><TABLE cellSpacing=0 cellPadding=12 width="100%" bgColor=#e5e5e5 border=0><TBODY><TR><TD vAlign=bottom width=502 bgColor=#ffffff height=57>[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=+2]Banks Talks Tech[/SIZE][/FONT] </TD></TR></TBODY></TABLE></TD><TD vAlign=top width=226><TABLE cellSpacing=0 cellPadding=12 width="100%" border=0><!--DWLayoutTable--><TBODY><TR><TD vAlign=top width=284 height=52> </TD></TR></TBODY></TABLE></TD><TD width=3></TD><TD vAlign=top width=1 bgColor=#000000 rowSpan=3></TD></TR><TR><TD vAlign=top colSpan=3><TABLE cellSpacing=0 cellPadding=12 width="85%" align=center border=0><!--DWLayoutTable--><TBODY><TR><TD vAlign=top width=618>[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1] Understanding Stall Speed By Aaron Gold[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]With the introduction of the Banks Billet Torque Converter, you'll hear a lot of talk about stall speed. What exactly is stall speed, and how does it affect your vehicle?[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]This article ***umes you have a basic knowledge of how torque converters work. If you'd like more in-depth detail, see "Understanding Torque Converters" elsewhere on this site.[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]Let's start by illustrating how the stall speed works. Even under light loads, a vehicle with an automatic transmission will start moving as soon as you take your foot off the brake. The stall speed comes into play under all load conditions. When we talk about stall speed, we're referring to engine RPM. If the vehicle isn't moving by the time the impeller reaches the stall speed, either it will start to move, or the engine RPM will no longer increase. In other words, stall speed is the engine RPM at which the torque converter transfers the power of the engine to the transmission.[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]In the real world, the torque converter's stall speed roughly equates to the clutch engagement point on a manual transmission. Let's say you're driving your stick-shift car around town. Normally, you'd give the car a little gas and ease off the clutch pedal gently enough to get a smooth start. Likewise, under most driving conditions the torque converter will start delivering power to the transmission at relatively low engine RPM.[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]Now, let's say you need lots of power, either to make a fast getaway or to start with a heavy load. You'd rev the engine up to a point where it delivers more power before letting up on the clutch pedal. It's under those same cir***stances that the stall speed becomes important. The torque converter will allow the engine to build RPM without turning the output shaft (the turbine) until the stall speed is reached. [/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]Unlike gas engines, diesels develop m***ive amounts of torque (pulling power) at low RPM – enough that it's possible (and, in fact, desirable) to get a heavily-loaded diesel truck rolling by simply easing off the clutch without touching the accelerator. Banks' dynamometer tests show that Ford's 7.3 liter Power Stroke hits peak torque at 1,600 RPM and begins to drop off at around 1,850 RPM, while the Dodge's 5.9L ***mins engine peaks at 1,400 RPM and drops off at 1,800 RPM. As RPM continues to rise, torque decreases even further.[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]How would you translate this to a torque converter? With a low stall speed. But both the Ford and Dodge torque converters stall between 2,000 and 2,500 RPM – so with a heavy load, the torque converter won’t start turning the rear wheels until well beyond the engine's torque peak. In this case, the stall speed is too high - it is literally impossible to get the engine's full power to the rear wheels! In order to access all of the engine's potential power, the stall speed must be lowered.[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]Lowering the stall speed has another advantage: It reduces the transmission's temperature. Let's go inside a high-stall torque converter under heavy load. The impeller (input side) of the torque converter is spinning quickly, while the turbine (output side) is spinning slowly or not at all. The motion energy of the impeller is being converted into heat energy, most of which is p***ed on to the transmission fluid. The higher the stall speed, the more heat will be generated. Heat is the enemy of a transmission. You want to keep the fluid temperature as low as possible. With a lower stall speed, less time elapses before the motion energy of the impeller is converted to motion energy to drive the turbine, so the transmission runs cooler and lives longer.[/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]What many people don't know is that the torque converter is a tunable device. Stall speed is determined by several factors, including the distance between the impeller and the turbine and the design of the stator. By properly modifying the converter's internal components, it's possible to alter the stall speed and create a torque converter that is tuned for a particular engine. [/SIZE][/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]Enter the Banks Billet Torque Converter. Our new torque converter is designed to stall at a speed to match Banks Power systems – precisely the point where the applicable truck or SUV diesel engine puts out maximum pulling power. And because the Banks Billet Torque Converters "hook up" sooner, they run cooler, even under high loads. You don't need a dynamometer to see the results – with a Banks Billet Torque Converter, the truck will accelerate faster. Fuel economy goes up, transmission temperature goes down, and your transmission will live longer. It's a match made in heaven! (Or is it Azusa?)[/SIZE][/FONT] </TD></TR><TR></TR></TBODY></TABLE></TD></TR><TR><TD> </TD></TR></TBODY></TABLE>
Another thing to look at when deciding on a transmission is the gear ratios for each gear. I dont remember what the gear ratio differences are between the th350 and the th400. If I recall correctly they are significant in first gear (think wide ratio vs close ratio). Back to the original question, what else to do, put the biggest cooler you can find inline with the cooler in the radiator and mount it in front of the radiator. Use a deep sump cast aluminum pan it will help stabilize the case as well as allowing for more fluid and cooling. Use a high quality input shaft. I prefer to use Kevlar friction materials. In my opinion Redline makes the best trans fluid with Mobil 1 being second, follow the recommendation of the friction material supplier. Install a trans temperature guage with the sender installed in the pan. The main things to remember is that heat kills automatic transmissions. High stall convertors generate ALOT of heat. You need to do everything you can to monitor and dissipate the heat.
I hear people quote this mysterious "50 hp" figure to turn a TH400...and I don't get it....heck, I can turn a TH400 at idle, with hardly any power at all! you have to realize that every transmission takes power to turn...but the loss is best expressed as a percentage, NOT a horsepower number. I don't know what the percentage loss is for a TH400, but I'll bet you don't know what it is for a TH350 either. And I doubt it is very much different. Gear ratios are not too far different either, I think the 350 has 2.52 vs the 400 2.48 first gear ratio. Weight and rotating inertia are definitely higher with the 400, the geartrain is much stronger....and it has a real center support...and second gear is much stronger...but both suffer from center supports loosening over time with high hp, and both have a relatively (compared to the newer trans like the 700) inefficient pump design. Bottom line, you can make either trans live, and you can go fast with either trans, which you choose has more to do with other considerations, such as cost, availability, vehicle size/weight, etc.
I have a test somewhere where they put all the transmissions through their paces. I think the difference between teh TH350 and TH400 was about 20hp at the rear wheels on a 450hp setup. The ford C4 and Mopar 904 were the most efficent 3 speeds. They were just behind the PG.
thanks for the info Rick.... if you can make a TH350 live behind a 600+ hp (at the flywheel) engine, you're doing good! go for it.
Thanks for all the input on this matter. Its very helpfull to have so many respond and not just get one or two opinions. No I dont know what the percentage loss on a TH350 is cause noone ever told me that wifestale. 50 hp is what ive always heard on a 400. I just ***uMEd that it was correct since so many say it is so.
As crazy as it sounds, just ask your trans man. He's going to have certain things he is, and isn't, comfortable with. His everyday vendor probably sells the few things a th350 needs. And if you supply parts or tell them what to do, typically the warranty goes out the window. As far as gear ratio, work the math with your tire diameter and desired highway cruise RPM answer that question. I'm guessing 3.08-3.42 if you're trying to keep it under 3000rpm on the interstate. Then make sure your stall is less than cruise RPM or you risk heat build up and mushy throttle response. The average converter rebuild shop can build a stock converter to what most call "corvette" specs and stall around 2200-2300, and your trans shop will be comfortable offering a warranty. good luck
If a 400 requires so much extra power to operate, how come they put them behind a 4.3 V6? I'd think moving something as unareodynamic as a van down the road, they couldn't afford to loose anything "extra" in the power department, especially if it was fully loaded.
i'd opt for something that i can't kill... unless there's just not room or i need the last little bit of power, 400 turbo all the way..
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