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Discussion Starter · #1 ·
Hi everyone. The 700R4 trans. didn't work out for me. I'm very happy that several members are enjoying their overdrive transmissions, but I'm not going to try another one. I have to move on from my futile, costly experience. So, I'm looking at either the TH350 or TH400. I'm hoping someone can give me some direction as to which one would work better for me. My '56 gasser has a "W" engine putting out about 425 hp or so. The cam is an Isky hydraulic and is one level above stock. Sorry, I don't have the numbers. The rear is a stock 3.70 posi. My purpose of the car is some red light action, occassionally a run at the drag strip and to cruise mostly. By cruise I mean a longer ride going maybe 45-50 mph. I will run the car hard on occassion, but I'm not going to constantly beat it. I have the drive shaft and cross member leftover fron the 700R4 and would like to use them if possible with the new transmission, although it's not a given. So, which one would select and why??? Thank you very much, Carmine.
 

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Hi everyone. The 700R4 trans. didn't work out for me. I'm very happy that several members are enjoying their overdrive transmissions, but I'm not going to try another one. I have to move on from my futile, costly experience. So, I'm looking at either the TH350 or TH400. I'm hoping someone can give me some direction as to which one would work better for me. My '56 gasser has a "W" engine putting out about 425 hp or so. The cam is an Isky hydraulic and is one level above stock. Sorry, I don't have the numbers. The rear is a stock 3.70 posi. My purpose of the car is some red light action, occassionally a run at the drag strip and to cruise mostly. By cruise I mean a longer ride going maybe 45-50 mph. I will run the car hard on occassion, but I'm not going to constantly beat it. I have the drive shaft and cross member leftover fron the 700R4 and would like to use them if possible with the new transmission, although it's not a given. So, which one would select and why??? Thank you very much, Carmine.
Go with the TH400. It hold up much better.
 

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The TH400 is a much stronger trans, Go with that if possible. Your drive shaft is going to be about 3 inches too short and the yoke is smaller than the TH400 yoke so that won't work either. The cross member is going to be the same but you will have to relocate the brackets on the frame to mount it. What happened to the new 700 trans, I thought it only had 50 or so miles on it.
 

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Discussion Starter · #5 ·
The TH400 is a much stronger trans, Go with that if possible. Your drive shaft is going to be about 3 inches too short and the yoke is smaller than the TH400 yoke so that won't work either. The cross member is going to be the same but you will have to relocate the brackets on the frame to mount it. What happened to the new 700 trans, I thought it only had 50 or so miles on it.

Yes Bruce, I was told it only had about 50 miles on it and I still have no reason to doubt it. I honestly don't know what went wrong. I read everthing I could about properly adjusting the tv cable. I read all the threads on this site dating back to 2007, read magazine articles and watched several videos on YouTube until I got a serious headache. I couldn't have been more informed when I made this adjustment. Installed the trans. on Tues. and went for a ride on Thurs. It shifted soft from 1st gear-2nd gear-3rd and then seem confused about the OD. Someone used the word "hunting" and that would be a good description. It hunted back and forth it seemed forever. I stopped and got gas and started down the road again. When it shifted into 3rd it seemed to go from soft to like slipping. I then smelled a burnt disc odor similar to a burnt mechanical clutch smell. I don't recall exactly how the trans. was acting at this point. I was too busy praying to get home with this car. I did make it home and put it in the garage. I let it cool down and checked the tv cable adj. again. Seemed to be fine. Yesterday, Friday, decided to go for another ride. Kind of assess the damage. First smelled the trans. fluid on the dip stick and it wreak of being burnt. It was very strong. Started down the road. First and second gear worked fine. It went to shift into 3rd, nothing. Might as well been in neutral. I turned around and came home in 2nd gear. At 12N, I started taking the trans. out. At 1:10P, it was on the jack and outside. Have to say that this fluid really stunk.
If this was my fault, so be it. Still don't know how. I went about 12 miles with this trans. before it took a crap. I don't want another OD trans. because I wouldn't do anything different on the hook up. I really wouldn't know what to do differently to avoid burning it up. I have limited ability, talent and expertise. When I step beyond those borders, I get into trouble. So, I have to cut my losses and move on. That's why I'm looking at either the TH350 or 400. I put a TH400 in my blown '57 and it worked really well. So, that's my story; an expensive one at that, Carmine.
 

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My opinion, I don't think you can burn up a 700-R4 with bad TV cable adjustment in 12 miles, even if you don't hook it up. Exception would be if you made 48 quarter mile passes. So there was something wrong internally.

With 425 hp, I would put a TH350 in it. But it still has to be assembled correctly.

So think hard about who builds this thing.

No warranty on the 700-R4?
 

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T 400

With your stated intention to make some drag strip passes I would buy a built trans with a 34 element sprag. and a stall converter. there are also 2 different diameters of output yoke for the 400. If you get the large diameter one I have a drive shaft in the basement as my car had a T400 when I bought it. Now has a 700R4. Do you have a stock rear in stock location?
 

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A TH400 if properly built is practially indestructable, I have also had decent luck with properly built TH350. I have both and given a choice I will use the TH400.
 

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I'll add that if you don't want any trouble with a T V cable then go with the 400, it doesn't have one. You have to hook up a switch that closes at full throttle instead. And if you find a switch kit for under $50 let me know, I still don't have one hooked up. I manually downshift to 2nd or 1st when I feel the need for speed. (or would that be the need for torque?)
 

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Friend just had his 700r4 transmission with Constant Pressure Valve Body drop 1 gear today.
 

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Discussion Starter · #11 ·
My opinion, I don't think you can burn up a 700-R4 with bad TV cable adjustment in 12 miles, even if you don't hook it up. Exception would be if you made 48 quarter mile passes. So there was something wrong internally.

With 425 hp, I would put a TH350 in it. But it still has to be assembled correctly.

So think hard about who builds this thing.

No warranty on the 700-R4?
No warranty Rick. Handshake and a wink. I don't mind spending money on something I need. I just totally hate wasting money. Very expensive mistake for me.
 

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Discussion Starter · #12 ·
With your stated intention to make some drag strip passes I would buy a built trans with a 34 element sprag. and a stall converter. there are also 2 different diameters of output yoke for the 400. If you get the large diameter one I have a drive shaft in the basement as my car had a T400 when I bought it. Now has a 700R4. Do you have a stock rear in stock location?
Yes, stock 3.70 posi rear in stock location. I did have to move my "W" engine forward about 1.5 inches. Thanx.
 

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With your stated intention to make some drag strip passes I would buy a built trans with a 34 element sprag. and a stall converter. there are also 2 different diameters of output yoke for the 400. If you get the large diameter one I have a drive shaft in the basement as my car had a T400 when I bought it. Now has a 700R4. Do you have a stock rear in stock location?
The small diameter yoke you speak of is actually a TH375, Not a TH400 and is not as heavy duty as a TH400 is. The TH375's are few & far between but are still out there.
 

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Honestly, I drive like a throttle hammering a-hole quite a bit. my el Camino has a 700r4 in it . it cost me $1250.00 10 years ago. it has all the good stuff in it . I have a healthy 406 small block in the car and have many (70k+) trouble free miles on it. It sounds to me like you got a bad/poorly/cheaply rebuilt stock unit to begin with. Since you have the trans already I would take it to a really good shop, be very frank about what you have for a motor and how you drive. be prepared to spend a few bucks(1000-1200). in the end it will work great and you will be happy especially on those 45-50 mile trips.
 

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Worth a true professional look.

It sounds to me like you got a bad/poorly/cheaply rebuilt stock unit to begin with. Since you have the trans already I would take it to a really good shop, be very frank about what you have for a motor and how you drive. be prepared to spend a few bucks(1000-1200). in the end it will work great and you will be happy especially on those 45-50 mile trips.
X2.

You are calling the shots, but I am so impressed with the service I have had from TurboHydramatic overdrives, I suggest first to never return to that transmission shop again. Locate a shop that has expertise on TH trannies, drop it off, and have it straightened out. No more fabbing and you can bolt it right back in. With a working trans, you'll be happy.

JMO :anim_25:
 

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x3
If you get it built right and get the shop to adjust everything and test drive it you should be safe. Mine has been great for over five years now,cruising at 60 mph @2400rpm,towing a camper trailer and running 11s on the track. I know a built th400 is tough but you still have to buy one and spend money on it.
You already have the 700 that may only need clutches etc and get set up right by a good shop.
Cheers
 

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The small diameter yoke you speak of is actually a TH375, Not a TH400 and is not as heavy duty as a TH400 is. The TH375's are few & far between but are still out there.
Wow, I had forgot about those things, in the early 80s I was in the salvage business and we bought a dozen mid 70s Checker Cabs with 250 CI inline six cyl equiped with these things. I have not seen a Th-375 since.
 

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I recently had a 400 short shaft trans built for my 56 build. The reason i chose a 400 is because i have ran them before and i know they can take the punishment if built right as opposed to a 350 turbo. I really dont need an overdrive trans for the type of driving i plan to do with this 56 nor do i waunt to deal with a lock type converter. I set it up with a 12 bolt posi and a fairly decent road gear rear end. Besides fuel economy is not a concern as the engine is a stroker with two 500 cfm 4 barrel carbs and a fairly heathy cam.
 
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