I know the 700r4 has the bad 3-4 clutch failure, but what makes the thm 350 and 400 better?

with all the money im pouring into my enigne I'd hate to have my trans bite it/fail all the time so which of the 3 is best for 320+HP?

(and for who know about the caprice, Will the thm 350 or 400 bolt to my new 350? would I need a new driveshaft?)

The TH400, for brute strength, wins here. However, they soak more power than the TH350 or 700R4 does - more rotating mass. The TH350 is not quite as strong as the TH400 is, but has less rotating weight and therefore soaks less power. Either of these is good if you're not into economy, my personal pick is a TH350 because I like the way it shifts.

The TH700R4 prior to 1986 is weak in the 3-4 clutch area, later ones are better but could be made better still. Best thing is to repack the 3-4 clutch to use 8 plates instead of 6 - this requires a replacement clutch piston which is thinner to provide clearance for the additional two plates.

The TH350 and 700R4 are pretty comparable, as far as torque handling capability is concerned. They can both be built to withstand far more torque than factory. The 700R4 also has a LOW 1st gear (3.06:1) vs. 2.52:1 (TH350) or 2.48:1 (TH400). This will certainly motivate a larger car such as a Caprice from a stop, but racers tend not to favor that too much due to the separation of gears. There is a replacement planetary set available for the 700R4 which makes 1st gear taller. Blue Bowtie has the lowdown on that.

Is the THM 350 only a 3 speed?

Is the THM 350 only a 3 speed?

Yes, so is the 400. Basically in the newer GM nomenclature using car weight,

TH350 = 3L60
700R4 = 4L60
TH400 = 3L80

I was looking at some on Jegs and Summit, and I can score a thm 350 for about 800$ that can handle 400hp. Which isnt a bad deal considering the work my trans needs.

But none of them have Lock up for the Torque converter. Is this something I should consider? what does lock up do? Idk if they have overdrive or not, neither site says anything bout it. Im assuming no cause its a older trans.

About my driveshaft to, Is the THM 350 the same length as my 700R4? Im probably gonna have to find a dif lenght driveshaft to fit right?

The 700R4 is somewhere in the middle, size-wise, of a TH400 and a TH350 w/ medium output housing. You will have to get the proper driveshaft, but they are out there. The Caprice was available from '77 -'86 with a TH200/C or TH350/C - a driveshaft from these will fit yours with a TH350.

Lockup takes the torque converter slip out of the equation. Basically, if you're accelerating, the output shaft of the transmission will be slower than the engine RPM when in 3rd or direct - this speed is up to the stall speed of the converter. Therefore, if the converter has a performance stall speed of say, 2200RPM, then on a non-lockup converter, your engine could be turning 2200RPM higher than the direct-drive output of the transmission! Locking the torque converter, so the impeller and turbine run at the same speed, remove this slip and allow the engine to run at the same RPM as the transmission output shaft in direct. This does two things - it reduces wear on the engine and also saves fuel!

Lockup on the 3-speed transmissions, TH200C or TH350C (the C denotes lockup), is optional and is generally for CAFE requirements. On the overdrive transmissions, such as the 2004R or 700R4, lockup is mandatory. TCC failure is the leading cause of 3-4 failure on the TH700R4.

yeah old turbo350s hold up pretty good even when stock. my buddy had an 86 silverado with a 454 that had all the goodies, such as a racing cam, installed. he could be cruising along at 30 mph and just stomp it and loosen up the rear tires. he used a stock th350 in that sucker and it never gave him any trouble.

as for the th400... i had one in my truck before i dismantled it for restoration and it seemed to work very well. one time this stupid chick i was hanging out with (a blonde by the way lol) decided to throw the floorshifter up into reverse randomly to see what would happen. mind you i was going about 35 or 40 in the forward direction when she did this, and the tranny actually did shift into reverse and started spinning my rear tires backwards and everything, at least until i let off the gas a moment later and it killed the motor lol. didnt seem to really mess it up at all though and i was really surprised.

They will all bolt to your new SBC 350, old 350, old 305, 283, 327, 400 SB, and even the 262 V-6. However, the rear trans mount is in a different location, so you'll have to deal with that on EITHER the 350 or 400. The rear mount on the 350 is closer than the 400, unless the car had a TH200-4R. The splines at the tailshaft may not match either, so plan on adjusting the driveshaft length with a TH350 and the yoke either way. And depending upon what was in the vehicle, you may have a modulator, TV cable, and/or kickdown cable to consider.

This might help:

http://www.maliburacing.com/auto_tranny_id.htm

So really all I need to do is find the right driveshaft for my THm 350 (just called a junkyard there looking for one) and a way to hook up the kickdown cable?

whats this about the rear trans mount?(is confused)

I forgot to mention it, Blue Bowtie caught it - the TH200C/TH350 has a different mounting location than either the TH700R4 (about an inch) or the TH400/TH2004R (about 5 inches or so). You will want to make sure that you have the proper crossmember for your application. I found out the hard way that the TH350 and TH700R4 are off about an inch - when I swapped my TH2004R for a 700R4/4L60, I grabbed a crossmember for a TH350 thinking it would fit - well, it didn't, and so I had to modify it.

The proper crossmember for any of the aforementioned transmissions exist for the '77-'96 B-body, you just need to snag the right one.

I forgot to mention it, Blue Bowtie caught it - the TH200C/TH350 has a different mounting location than either the TH700R4 (about an inch) or the TH400/TH2004R (about 5 inches or so). You will want to make sure that you have the proper crossmember for your application. I found out the hard way that the TH350 and TH700R4 are off about an inch - when I swapped my TH2004R for a 700R4/4L60, I grabbed a crossmember for a TH350 thinking it would fit - well, it didn't, and so I had to modify it.

The proper crossmember for any of the aforementioned transmissions exist for the '77-'96 B-body, you just need to snag the right one.

Whew, thanks, I thought I had to make some special holes in my frame :P

The stock drivesgaft that came with the thm 350. How much power can those take before twisting?

my goal is 330-350HP and 380-400lbs torque.

if its not too late to change your mind, you should go with the 700 trans.
i have the th350 and its a real gas guzzler on the highway due to only having 3 gears and no overdrive. top speed is redlined at around 85-90.
you would be much better off with getting a 700 and rebuilding it with more clutches.
thats just my opinion tho.

Iwant to keep my 700r4 I still can I havent bought thje 350 yet.

But I havent been able to find a smaller piston for my 3-4, I did find the TCI beast sun shell silicon mentioned before on eBay.

Anyone know of were I can buy a smaller 3-4 piston ?

try summit racing or jegs. those kind of places will probly have what you need. if you do a search, someone did a very in depth explanation of this exact procedure in the caprice forum a while ago.
try looking there for info.

Tried both places(summit/jegs), no luck on the 3-4 piston.

anyone know were I could find one?

Try GM, or B&M, or any transmission supply company. You should be able to get one of those from Cottman Transmission, they have a lot of that stuff and they'll sell you just the part. Make sure you get the piston for an 8-stack clutch pack. I think the 2002-up 4L65E has an 8-stack 3-4 clutch pack, you can use the piston from that. In fact, you can use a lot of 4L65E parts in your 700R4 - things like the 5-pinion planetary sets, the reaction sun shell (these are revised and are about as strong as a Beast and probably cheaper), larger 2-4 servo piston set, Kevlar 2-4 band, etc.

Try GM, or B&M, or any transmission supply company. You should be able to get one of those from Cottman Transmission, they have a lot of that stuff and they'll sell you just the part. Make sure you get the piston for an 8-stack clutch pack. I think the 2002-up 4L65E has an 8-stack 3-4 clutch pack, you can use the piston from that. In fact, you can use a lot of 4L65E parts in your 700R4 - things like the 5-pinion planetary sets, the reaction sun shell (these are revised and are about as strong as a Beast and probably cheaper), larger 2-4 servo piston set, Kevlar 2-4 band, etc.
Can I just call like a dealership, and ask for a kevlar 2-4 band, 2-4 servo piston set, reaction sun shell, 5 pinion planetary set, piston for a 8 stack 3-4 clutch pack? Do I have to say larger 2-4 servo. or is the 4L65 large aleready?

what cars had a 4L65E in them, theyll probably ask. or so I know when i call them.

is it really that easy as just calling them? lol wish i knew that :( any more parts I should get to make my 700R4 bulletproof?

I'm building a 454 bbc and i dont know what transmission to put in it. The 454 is hot nothing in it is stock only the pistons and crank. I would like to put a 700r4 due to the over drive. But alot of people are tellin me that i am going to do a big mistake if I put a 700r4 they say that I should go with the th400.But I know the 1990 to 1993 454 ss trucks came with a 700r4 4l60/4l80 and they do take the punishment. The guy at the transmission shop says it will work with a shift kit. I also told him to put a corvette servo. and i'm going to use two oil coolers. But what else do you guys think I should do

I'm building a 454 bbc and i dont know what transmission to put in it. The 454 is hot nothing in it is stock only the pistons and crank. I would like to put a 700r4 due to the over drive. But alot of people are tellin me that i am going to do a big mistake if I put a 700r4 they say that I should go with the th400.But I know the 1990 to 1993 454 ss trucks came with a 700r4 4l60/4l80 and they do take the punishment. The guy at the transmission shop says it will work with a shift kit. I also told him to put a corvette servo. and i'm going to use two oil coolers. But what else do you guys think I should do

You're going to want a 4L80E - a TH700R4/4L60 can't handle that for long, at least in stock form. Two things to look at - the reaction sun shell and the input shaft/drum.

The problem is that my truck is a 1978 and is not electronic

The problem is that my truck is a 1978 and is not electronic

They make stand-alone control modules to allow use in any vehicle. There's even one company that modifies it to pure hydraulic control.

They make stand-alone control modules to allow use in any vehicle. There's even one company that modifies it to pure hydraulic control.


Yes I found them, The hydraulic goes for 69.99 but I have to take apart the trans.there is one module on ebay that gose for 14.99 and it says that you only need one hot wire.B&M sells a lock up madule but it goes for about 150-160$ and I dont want to spend $$$ on some thing that might not work. I need one that could take about 450 hp and 500 tq.

The 4L80E is your only choice if you want overdrive. I'm not talking about the TCC when I say module, I am talking about the transmission control module - the computer. I've not seen one of these go for less than $500.

The 4L80E is your only choice if you want overdrive. I'm not talking about the TCC when I say module, I am talking about the transmission control module - the computer. I've not seen one of these go for less than $500.

Where can i get that madule. and what is the price on a 4l80 and i need it to take 450 hp and 500 tq

This is what I found on ebay:You are bidding on a new billet aluminum Lokar indicator control module. Part # INC-1736.
For use with TH-350, TH-400, 700R4, TH-200, 200-R4, 4L60, 4L60E, and 4L80E transmissions.
Features:

Solid state circuit boards and state-of-the-art sensors
Long life LED
Displays only engaged gear
Compatible with most 12 volt LED indicatorsDo you think this will work?

The advantage with the 700r4 is you have overdrive,same as the 4l80e.Only way you can get overdrive for the THM 400 and 350 is put on an overdrive unit.There is one company that does that and I cannot remember the name of that company

The advantage with the 700r4 is you have overdrive,same as the 4l80e.Only way you can get overdrive for the THM 400 and 350 is put on an overdrive unit.There is one company that does that and I cannot remember the name of that company

are you talking about the gearvendor that is one of the only copanies thet make overdrive units for the 350 and 400 but for alot of $$$$ 2500.00
That is a lot of money

So really all I need is a Trans go Shift Kit JR, a 4L65e sun reaction shell and a corvette 2-4 servo?

Would I really need a smaller piston for my 3-4? I found a Kevlar band for a 700r4 made by Hughes for 31$ off summit, ill be getting that to when I get my trans done.

isnt the later 700R4 stronger? mines is a 1987 idk if its one of the better ones

Instead of a factory 4l65E sun shell, go with the "Beast" shell. The factory made the hub more radiused and a bit stronger in the 4L65E, but they STILL BREAK (Look at the 2004 model year GM TSB regarding breakage and the units covered).

You may need a thinner 3-4 apply piston if you go with the eight-stack clutches at original thicknesses. You also have the option of going with a higher plate count clutch array with thinner steels and friction plates so they use the stock apply piston. Look at TCI.com, transtarindustries.com, transmissioncenter.net, or Makco.com to view the options. You might want to get a 2002-later 4L60 five pinion input planetary set, or you can get aftermarket in the same configuration.

The 1987-later TH700-R4s have some enhancements, like the auxuliary valve body and 10-vane pump, but still have their weaknesses behind higher torque engines Tou can get an aftermarket ("Torque Drive" package) which includes all the hard parts you'll need to make a 700-R4 survive constant 400 ft/lb or more. You'll twist driveshafts and axles before damaging a well-built 700-R4.

Instead of a factory 4l65E sun shell, go with the "Beast" shell. The factory made the hub more radiused and a bit stronger in the 4L65E, but they STILL BREAK (Look at the 2004 model year GM TSB regarding breakage and the units covered).

You may need a thinner 3-4 apply piston if you go with the eight-stack clutches at original thicknesses. You also have the option of going with a higher plate count clutch array with thinner steels and friction plates so they use the stock apply piston. Look at TCI.com, transtarindustries.com, transmissioncenter.net, or Makco.com to view the options. You might want to get a 2002-later 4L60 five pinion input planetary set, or you can get aftermarket in the same configuration.

The 1987-later TH700-R4s have some enhancements, like the auxuliary valve body and 10-vane pump, but still have their weaknesses behind higher torque engines Tou can get an aftermarket ("Torque Drive" package) which includes all the hard parts you'll need to make a 700-R4 survive constant 400 ft/lb or more. You'll twist driveshafts and axles before damaging a well-built 700-R4.

Is these torque drive kits availble from summit or jegs?

Thanks to silicon anf BB for their info on this :) I started out knowing my trans was only a 4 speed with OD. lol.

In my opinion, I would keep the 700r4. Your have 2 advantages -- overdrive, and lockup. In the past, they may not have been the most reliable, but with the right parts, they can be made pretty bulletproof. The other overdrive options are too costly or too much trouble.

i rebuilt my 700r4 last spring in my basement -- not as hard as you would think. I bought a rebuild manual and most of the parts I needed here:
http://www.transmissioncenter.net/highperf700r4.htm#Parts

I got the rebuild kit there, a 9 clutch power pack for the 3-4 clutches (actually not the best option, but cheap). I also checked ebay and got a corvette servo, kevlar 2-4 band. I already had a shift kit before the rebuild -- I would go with a transgo, and you'll need a filter and fluid.

I spent about $300 in parts for mine, including a new stock torque converter.

If I were to do it again here's what I would do for the best rebuild to stand up to all the power-- start with an 87 or newer 700r4, get the beast sunshell and whatever other updated hard parts I could get, all alto red eagle clutches, and the 8 clutch 3-4 pack.

For the lockup, all you need is a switch wired up with 12v to the lockup solenoid in the pan, with the other end grounded to the transmission case. You can get elaborate with wiring through brake switches and vacuum switches if you want, but not necessary.

Mine has about 5,000mi on it now, and 15 or so passes down the track, behind a 400 small block in an 85 caprice wagon. No problems other than a valve sticking in the valve body causing my lockup to not always function correctly. Squeels the tires at full throttle on the 1-2 shift, and recently added a 2400rpm stall converter. Make sure you have plenty of cooling for the trans -- heat is what kills most trannys.

One thing I need to add about the thin steels that Blue Bowtie mentioned - they're NOT forgiving in a high-performance application - they do not dissipate the heat well, leading to warpage and resulting failure. You're better off with the thinner piston and stock thickness steels for high-torque applications.

I've also done research on the five pinion planetary sets for a unit I have here on the back porch - stick with the GM ones. The aftermarket ones might be cheaper, but many transmission builders claim that the factory 4-pinion sets are stronger.

I need to learn how to build trannys cant trust no machanic. I have alot of parts for the 700r4 but I dont trust any one working on it they might not use my parts and just say they did.

One thing I need to add about the thin steels that Blue Bowtie mentioned - they're NOT forgiving in a high-performance application - they do not dissipate the heat well, leading to warpage and resulting failure. You're better off with the thinner piston and stock thickness steels for high-torque applications.

I've also done research on the five pinion planetary sets for a unit I have here on the back porch - stick with the GM ones. The aftermarket ones might be cheaper, but many transmission builders claim that the factory 4-pinion sets are stronger.
EDIT
I mean would I be really able to rebuild my own trans? that site sells a ultiamte rebuild which comes with everything I could ever stuff into my 700R4 900$ >_< but if im stuffing close to that in a awesome engine its worth it.

I know next to nothing on trans in general, i can adjust my TV cable, and change my fluid/filter. Is it really that hard to rebuild? (ive seen DVD's and walkthrough books)

EDIT
I mean would I be really able to rebuild my own trans? that site sells a ultiamte rebuild which comes with everything I could ever stuff into my 700R4 900$ >_< but if im stuffing close to that in a awesome engine its worth it.

I know next to nothing on trans in general, i can adjust my TV cable, and change my fluid/filter. Is it really that hard to rebuild? (ive seen DVD's and walkthrough books)

There is a lot to a transmission, it's an involved piece of hardware, but it's not especially difficult to work on. Just make sure you get your roller/sprag clutches in the proper direction. One of the two TH700R4s that I've done, I didn't and as a result, in OD the trans didn't work - it suddenly felt as though I was climbing a 9% ascending grade in a Pinto, so I had to drive it in D.

Areas to pay attention to are the 1-2 and 3-4 shift accumulators. Don't be tempted by some transmission kit to remove the springs and replace with spacers - accumulators are shock absorbers and prevent a sudden hydraulic apply action (in water pipes, a "water hammer") from breaking parts in the transmission. When you replace the springs with spacers, you are disabling the accumulators and while this does make the tires bark during shifts, it's also stressing the pump and breaking your reaction sun shell, among other things. You can firm up soft shifts by varying the compression rate of the accumulator springs (stiffer springs etc) so that you still have the shock absorber action of the accumulator. Believe me, there are springs which can make it shift hard!

Also, as myself and others have recommended, run a TCI (SPX/Filtran) Beast sun shell and many of your breakage problems will be history. The other main weakness on these transmissions is the input shaft/drum assembly - under high-torque stress, the shaft can snap at the drum, or strip the splines off the drum. There are aftermarket cures for this illness as well.

The process of actually doing the work is involved, but easy if you have some good mechanical skill. The most important thing, and I can't stress this enough, is a clean work environment - white glove clean, and don't use rags that produce lint. Don't take apart the valvebody unless you know you have a sticking valve. Dirt or lint can enter the valvebody and cause valves to stick and your transmission to smoke. There is a modification you can make to the MTV upshift valve - remove valve, remove spring, discard spring, replace valve without spring - that you can perform in order to knock out a 3-4 hunting problem (the thing hunts between 3rd and 4th on the highway, for example).

Get a good manual for that transmission - this is invaluable. I have the Haynes GM automatic transmission manual - this covers the TH2004R, TH350, TH400 and TH700R4 - I've used it to rebuild at least one of all 4 of these and I find it to be indispensable.

Thanks for the input Silicon. It doesnt <i>seem</i> that hard to rebuild a trans, with a complete kit most is just take out old and put new in.

I dont think im gonna risk doing my own trans, if I h ad a 2nd one I would most definently try.

Im trying to find a shop to install the rebuild Im getting. no luck.

I found this kit though http://www.700r4l60e.com/store/customer/product.php?productid=41&cat=19&page=1 supposed to be good up to 450hp and comes with most everything I need, Cept "the beast" it has the sealed power beast shell(sealed power is owned by federal mogul which works in my favor, federal mogul owns.) I might just buy the TCI one instead.

A lot of this is still in the air with my trans.

"Beast" is a trademark of SPX/Filtran Co., so there's a good bet that's who makes it and it's rebranded as Sealed Power. TCI does the same thing.

Pay attention to the thrust washers and Torrington bearings within the transmission when you do this, some of those plastic thrust washers are selective - meaning that they can be replaced with various thicknesses in order for the input shaft endplay to be within spec. If one of these is too thick, you can damage the transmission upon startup, and if too thin, the transmission will wear out faster. Whatever manual you decide to get will detail this.

Your kit seems like a decent one.

"Beast" is a trademark of SPX/Filtran Co., so there's a good bet that's who makes it and it's rebranded as Sealed Power. TCI does the same thing.

Pay attention to the thrust washers and Torrington bearings within the transmission when you do this, some of those plastic thrust washers are selective - meaning that they can be replaced with various thicknesses in order for the input shaft endplay to be within spec. If one of these is too thick, you can damage the transmission upon startup, and if too thin, the transmission will wear out faster. Whatever manual you decide to get will detail this.

Your kit seems like a decent one.

Yeah ive heard good things about that site. I occasionaly read thirdgen.org and while in the drivetrain section they were talking about dana and his site.

And everyone was giving good reports about him. and the kit doesnt seem bad it has a lot of the HD parts i need in my 700 to make it last behind my new engine. and its half the price of the raptor kit. I dont need my trans to be able to take up to 700 HP lol

when my dad is back in town ill ask if he can help me rebuild my trans. between the two of us we should be able to at least put it back together, lol.

I know the 700r4 has the bad 3-4 clutch failure, but what makes the thm 350 and 400 better?

with all the money im pouring into my enigne I'd hate to have my trans bite it/fail all the time so which of the 3 is best for 320+HP?

(and for who know about the caprice, Will the thm 350 or 400 bolt to my new 350? would I need a new driveshaft?)

I was just wondering if someone could answer something for me. Is it possible to bolt a 350 block up to a 450 big block. I think no, and someone tells me you can. Others agree with me...I was wondering if someone could tell me and explain why you can or can't. Also if you know one a website that proves it...I would really appretiate it.

Welcome to AF.
To get you started on the right foot.
This thread is very old and started by another person on his own problem.
To cut down on post hyjacking and hitting on old post.
It is best to start your own New thread or post and someone will help you.
MT