TH400: How To Recipe for 800-1000HP

good afternoon shawn here from mountains garage i received several viewer requests uh asking for the recipe on how to build a th400 to withstand 800 to 1000 horsepower that's the range i typically build them for uh you can go a lot higher uh they haven't yet found the limit of the turbo 400 if you replace enough parts i mean in pro mod it's one of only a few choices for a transmission and they're making 3 500 horsepower who knows how much power they're making running mid threes and low fives in the quarter mile it's an incredible transmission amazingly in reach for the average guy with a couple hundred dollar core and some parts don't be fooled into thinking that this is a pro mod transmission but at the power level we're talking about today it's very comfortable probably much higher there's many cases where a stock case turbo 400 is running low fours in the eighth mile so they're very capable before aftermarket shafts and parts and gear sets became available this is what there was to use and the reason all the parts became available is because the common parts that break on a regular basis they were improved by the aftermarket another very popular question is powerglide or turbo 400 you're going to see today the turbo 400 needs very little to withstand 800 to 1000 horsepower a powerglide pretty much needs everything you're better off starting from scratch in most cases by the time you buy an aftermarket case tail housing and gear set or a minimum gear set and an input shaft and a hub for a power glide you'd be well on your way to making this thing withstand 2 000 i spent a few years racing top sportsmen i ran a lanco all but seven passes of that so i didn't experience a lot of transmission failure but typically after one qualifying session or one round half the field has their power glides out for fixing them i actually know a guy that did a same-day comparison at a test session he had his car set up for powerglide swapped everything out to our turbo 400 did not go any faster with the powerglide and his exact quote to me was why bother with the powerglide when the 400 doesn't break and the powerglide does and i hate to come off sounding negative on powerglides because i actually like them they're nice and compact and what they're asked to do they do a really good job and it kind of taught us a little bit about not needing so much starting line ratio as a power glide only has a 176 or 180 first gear where a turbo 400 has a 248 and a 148 second gear stock it made the converter work harder and that people have learned in the last 20 years isn't such a bad thing with small tire drag racing and street car type drag racing taken off in the last 20 years where the cars are slightly heavier and the tires are smaller it made the turbo 400 even more popular because the aftermarket pots makers can fit different ratios in a 400 more so than powerglide the powerglide you kind of restrict it on space with a 400 they can make so far about any conceivable ratio you can imagine but we don't need that today we're talking a transmission capable of 800 to 1000 horsepower handling out on a regular basis without any trouble which coincidentally kind of lines up with your junkyard ls turbo setup 800 to 1000 it's probably uh livable before you have to spend a lot of money on aftermarket pots the turbo 400 is no different at about that threshold and that threshold changes all the time you know it's right around this maybe a little more you'll find out you'll be the guy behind the wheel but after a certain level not much beyond what we're talking about today you need to spend a lot of money to make it compatible with more horsepower than that last spring and summer when i shot my other turbo 400 videos and there's a whole series if you don't mind going back to watching them liking and subscribing and all that stuff i had not joined or didn't even know it existed the diy turbo 400 page on facebook on that page are all your industry giants if you will the owners of all the american-made aftermarket turbo 400 pots manufacturers are on their answer and tech questions pretty much daily uh do them a favor and you use a search function and don't ask the same simple question like what's the best filter you know 400 times if you google a search on this not google but if you search on the facebook page your answer your question will probably answer if you have something beyond that lots of people regular people like me and also the people that really know what they're doing will answer your question it's an awesome page i'm glad i'm part of it i wish i had been a part of it all along let's start with the case they will all work for what we're going to do there's some hd ones that have some thicker areas the oldsmobile pontiac buick cadillac ones are sometimes stronger and most always have eight bolts sometimes only seven the number of pump bolts is only important of course if you want to run an aftermarket belt housing if you're gonna run the stock bell housing on the case for instance this gray transmission is an eight bolt case it came with a six bolt pump the pump itself isn't gonna jump out of there because it only has six bolts the only reason you want the eight is to bolt on your aftermarket bell housing after you cut the old one off down inside the case in the very back we see those six small dots that's where the thrust washer and the three tanged washer set on the back of the lower gear unit you want to replace that with a roller baron and some shims to take up the end play it's nothing but a turbo 350 pump bearing that's the gm pot number that's what it looks like it goes in black side down and the shims one shim kit will probably do you a half dozen bearings because it only takes a couple shims to come up with the correct thickness i typically measure the original shim and spacer and subtract excuse me add about another five in my shim so i'm taking about five thousandths out of it and i'll start checking right there for my rear end play if you go online like on ebay you can buy a kit with the rear thrust bearing and the shim pack 25 or 30 dollars you can buy them independently the barons 10 or 15 and a pack of shims probably gonna cost about the same but it'll give you enough shims if you buy more bearings to do more transmissions it depends how many you want to do if you're doing one buy the little kit moving ahead your second gear or intermediate clutch pack lugs into the case on the very outside edge of the snap ring right there the center support lugs in back here no problem there because it bolts up through the case but second gear only has a flimsy snap ring around these lugs and there's a giant void right there with no lugs at minimum you need a thick snap ring i would never reuse the even pretty much in a stock transmission the stock intermediate snap ring it's prone to failure even in a stock case this is a spiral lock this is actually two spiral locks in a package this is an awesome piece it spirals into the case the extra thick snap ring works well also combined with a case saver which bolts into the void i just showed you and supports the snap ring portion that's not supported originally this is a must it's the only weak link in the turbo 400 case that fails on a regular basis is the second gear intermediate snap ring lugs it will spit them out like chiclets it's also possible to lock up the rear tires when this happens it's unlikely but it's possible and that'd be a scary situation so both these pieces here maybe 75 excellent insurance so other than normal case prep i've mentioned before i drill and tap the vent fitting i trim off the ears give it a good deburring and i flat file i use a stone on the valve body surface other than that the case is race ready i don't have a lower gear unit to show you but i've gone over it several times if you go back to the old videos but i do on the output shaft i machine off the o-ring groove so the yoke can slide all the way in without being restricted if you're gonna run a roll a tail housing instead of a bushing they make a bearing you have to have a hardened yoke not required for what we're doing i'm just mentioning it because we're here you're all set with the stock bushing and the regular style yoke straight cut planetarius or helical cut the straight cuts are not that hard to find no tests exist that i'm aware of that make them actually better i know general motors spent money on them and only put them in the heavy duty trucks leading you to believe they're better but the helical planetary lower unit lasts at twice the horsepower level we're talking today probably more it's not a weak link it's an awesome unit there's very little issue there not a concern for what we're doing so whatever you have you have straight cuts that's great the noisy they claim this one has it i can't wait to try it it's been a long time since i uh drove a motor home with a turbo 400 but or school bus it's probably what it's going to sound like if you can hear it over the engine but the helical stuff the the ones you're going to find 95 of the time just bolt it in don't worry about it you're good to go the rear band if you have one in nice shape that's oem use it it's gold you'll see it'll wear first on the opening on the inside if you don't have that and short of that buy a kevlar one good to go if you run a case saver you won't be using the forward band you won't have engine braking in second gear a small price to pay for not blowing the case up most all your aftermarket valve bodies there are a few that will retain the front band so you can have engine braking in second gear but i don't know what they do with you know protecting the case i'm not sure what horsepower level that's made for moving on pistons i like aluminum because i can machine them and i can set my clutch clearance that way and they actually have a wider area to push on the first steel once again no tests exist and i'm aware of that they're better in any other way if you can if you build a transmission with steel pistons it'll last just fine i don't think it'll be a problem my opinions go both ways i buy these only because i can machine them easily but they're readily available three pistons is probably going to cost you 150 the direct drum and sprag finding a factory chevy round back drum that'll accept a 34 element sprag they're getting harder to find the go to is a 97 and up 480e drum they're all over the internet for about a hundred dollars refurbished comes with steels the pressure plate snap ring a great deal important to remember start your burnout in second and shift to high don't go one two in the water box and this will last a good long time i mentioned in my other videos this area here is actually slightly wider on the ade drum because the four ledee has four intermediate clutches and steels not required at our horsepower level we're talking today you can see dash six machines the aluminum piston now when you buy the ade drum it's going to come with a molded piston you got to chuck that and put a turbo 400 piston in here the molded one is not going to work with your aftermarket valve body because it's going to come with heavier springs that's why this isn't in yet when i buy a valve body i have to put the return springs in here that are super heavy duty you need a piston that'll accept that the molded one will not but a stock turbo 400 average has five forward clutches in the forward five in the direct three in the intermediate that'll far exceed our horsepower level we're talking about today you don't need extra clutches if you want them i've showed you videos how to do that i'm telling you again now you can machine the aluminum drum and add more you're gonna need a rebuild kit and in that kit there'll be different choices of clutches you can have smooth you can have waffle the kit's going to come with two different thicknesses because forward and direct while they will share the same clutch and steal the different thicknesses from the factory you can jumble them around to make up your clearances as i've said in the past the kit may not come with enough parts to accomplish what you want to do if you want to add clutches but if you're running five five and three your kit should handle that your actual choice of clutch material manual argue is really not that important what is important is proper hydraulics and this transmission will have an aftermarket valve body at this horsepower level 800 to a thousand we have an aftermarket valve body and in that valve body kit whoever made it has gone through the research and is going to come with a pressure regulator spring for the pump like the springs i just mentioned in the direct drum it's a kit it's been thought out well thought out and they work well and then increase in hydraulic pressure is pretty much going to make any clutch live that in proper assembly i can almost guarantee you the instructions that come with your aftermarket valve body whether it's a manual valve body or a trans brake valve body will instruct you on dual feeding the direct popular subject you're gonna leave out the middle seal behind the piston and while you're at it go ahead and leave the one out of the forward don't need the middle one let the whole piston fill up faster i covered this in other videos but to make this longevity wise make the clutches last regardless of materials you want to have a lot of clamping force and the valve body itself probably has the dual feed mod down on that end so you're leaving a seal off the center support you're leaving a seal out of the center of this drum and you're blocking it in the valve body whether the valve body separated plate did that or they have you drive a plug in it'll be in the instructions i'm sure unless you buy the chinese valve body then you're on your own buy an american-made one they'll probably walk you right through it or you can talk to the guys that made it that's just a fact with the increased pressure from the spring you installed in the pump i go ahead and do the engine thrust protection mod it's in my other videos it's all over the internet to try to protect the engine this isn't something that's going to make the transmission last longer but it'll push on the thrust bearing of the engine less by doing a simple mod to the back side of the pump this transmission has a billet internal solenoid trans brake valve body uh it's a very popular one it's sold by a whole bunch of people it's also the last one i'm going to install since joining the diy turbo 400 site on facebook i can now see that there's an american-made choice be it the jake's performance or the atd automatic transmission design and others in the same price range and if i need help it's available no problem if you have a problem with this valve body you're on your own but to be fair i've installed probably 10 of them and i've had zero issues once i figured out the poor instruction sheet the forward hub this is a stock turbo 400 this is a 4l80 they look slightly different but the easiest way to tell the difference is to ring it ring it like a bell this will be pretty dull this will have a much higher pitch if i had an aftermarket one it also has an even higher pitch than this one when you ring it like a bell it's very hard very strong 480e forward hub is an excellent upgrade direct image change and at our horsepower level today it's a good choice even if you buy an aftermarket one and they're about a hundred dollars probably somewhere around 1200 horsepower and up you can stop worrying about the input shaft the intermediate shaft and eventually the output shaft and you need a book blueprint transmission as far as clearances correct bushing clearance build yourself a sound transmission that's a very important factor in making it last at any horsepower level but especially the higher you go the more risk for damage when you're shopping for a rebuild kit make sure you have bushings in there well buy them separately the whole bushing gets like 20 bucks excellent insurance kind of hard to change you have to use a seasoned transmission builder can look at a bush and measure it compare it to the specs in here and sometimes he may choose to replace he or she may choose to replace the whole pipe that has a good bushing in it or he may go ahead and change it he she so to recap we rollerize the output shaft we put a heavy duty snap ring and a case saver on the intermediate clutches we put a heavy duty sprag that also has a spiral lock i like to use a good sound rebuild kit with good quality clutches and an aftermarket valve body kit that's going to come with increased hydraulic pressure spring and a few upgrades they're going to recommend you do and that's it this thing is ready to whale all the normal things like a deep pan a nice cool lines are not gonna burst because you've increased the hydraulic pressure i run and fittings or steel no rubber in hose clamps that's a fire waiting to happen a nice cooler that has a mechanical connection not hose clamps all the normal things you do a lock and dip stick way to go that's a requirement by the rules so you don't spit fluid over the track more importantly under your rear tires and spread you all over the track a shield over the center of the transmission be it a blanket or aluminum shield or an aftermarket case a flywheel shield or an aftermarket bell housing that's what an aftermarket belt housing does for you if you bell housing is cracked obviously it fixes that problem but more importantly you don't have to run a shield that bolts around the via the bell housing you can just bolt the bell housing on the engine and you're done you put an aftermarket case combined with an aftermarket belt housing you don't have to run any other safety shields it fits in the stock hole that a turbo 400 did the shields are kind of cumbersome sometimes depending on the body they're going in and that and lots of other reasons strength wise the aftermarket case is a great deal they're kind of hard to come by right now but they're coming back to market so that's it find yourself a good core that's not full of water buy a good quality rebuild kit with everything you need an aftermarket valve body and a few other trinkets and build yourself a reliable transmission or have your local guy do it for you

Channel: Mountains Garage

Views: 70,988

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Id: 8qaRTmEvAI4

Length: 20min 38sec (1238 seconds)

Published: Thu Jan 07 2021