Goodbye 700R4

[SanitysBane]

Well I finally came to my scences and said screw it with trying to run a 700R4 behind a built big block, so now I am going to put in a turbo400. What all is going to need to done/modified to do this to my truck? Its an 83 long box 1/2 ton that originally had a 700R4 in it. I am thinking about going down to the local wrecking yard and looking for a 2 piece driveshaft for it, does anyone have any pictures of the carier bearing and were that mounts to the frame? My truck had a 1 piece drive shaft origally but I think I should be able to just mount the carier bearing up there with out adding a cross member, or am I incorect? Sorry for the long post and thanks for any help.

[John39671]

I have a really built 396 in my 84 SWB with a 700 and have had no problems with it YET.

[SanitysBane]

I have been threw more 700R4's than I can count on my hands and feet.

[Russell]

There ya go David, finally came to your senses Get yourself a TH400 with a Gear Vendor's unit, and never have to replace a tranny again!

[1FaastC10]

Originally Posted by Russell

There ya go David, finally came to your senses Get yourself a TH400 with a Gear Vendor's unit, and never have to replace a tranny again!

i was just thinking something along those same lines. however, with a truly built big block, and auto trans is going to be tough to find that will stand up the the abuse forever unless the trans is REALLY built too. TH400 will stand up much better than a 700 though.

[pedrofixlater]

you should only have to change the nose of the drive shaft (Slip Yoke) the turbo 400 is larger in that respect. the 700 should be working as long as the TV cable is set right.

[MylilBowTie]

I would look for a two piece driveshaft out of a 3/4 ton that had a th400. Problem that I ran into was I couldn't really find anyone that would take the crossmember and carrier bearing support for the driveshaft out. It could have been I didn't find the right people at the time but nobody wanted to mess with it at all. The crossmember supports the rear of the cab with two cab mounts, its factory riveted into the frame, has the metal gas lines running across it, and something else. This is the way I wanted it to get done but it didn't. I got lucky and found a driveshaft that had a longer slip yoke for a th400. It works, but its not (ideally) what I wanted and it does vibrate a little bit most the time not very noticeable. It could be worse than what it is but I do drive it with it and its been in there about a year and six months.

I had to move my crossmember back some for the transmission mount on the th400. I used a black polyurethane from energy suspension and also installed a double hump transmission crossmember. Your stock transmission crossmember should work it should only need move back just like my double hump one. I got three bolt holes to line up on mine and needed to drill one hole (d/s front).

Driveshaft universal joints if you get a 3/4 ton one, you will probably need a conversion universal joint I'm thinking 1350 / 1410 is the size difference. That will depend on what you end up with for a driveshaft and if you are leaving the stock 10/12 bolt differential in place.

As for mine its seems the more I want to do to it and have done to it I should of bought a 3/4 ton.

I also made a really cheap (10.00) kick down switch. I installed a transgo shift kit and adjustable transmission modulator valve. The transgo shift kit from Summit was like 75.00 it came with everything and a video to do the install.

I can email you any pictures you want to see about my setup or anyone else that wants to see them. Most of them are to big to load here or host.

[86k10]

Are you having them built by someone who knows what they are doing?

[SanitysBane]

Quote:
Are you having them built by someone who knows what they are doing?

Yes I am, next question.

[86k10]

Well you don't have to be so snippy about it, it's just a logical question. There must be something amiss, there are many around here that have just as many or more horse ponys as you have and not a problem at all. So what exactly is failing on them.

[Russell]

He probally is not using a built tranny. With upgraded servos, a bigger sungear and so on, a 700r4 will last up to 700 horse, but that gets expensive real quick.

90% of the time, you break the sungear in the tranny, and often that occurs because of a badly adjusted TV cable, or simply too much horsepower for a stock tranny built for a 200 horse engine.

[SanitysBane]

Me and dad have been rebuilding the transmissions, here are the problems:
1st-used cheap clutches and fried the transmission in a manner of 6 months.
2nd-Worked great, but the bell housing busted on it.
3rd-shifted to high with on valve body on it, shifted to low with another one, probally a problem in the case, didn't feel like messing with it, also lost 3rd gear.
4th-improper spring used in the TV kickdown and got the valve stuck on the idle setting and burned out 3rd gear and the 2-4 band.
5th-valve body gasket got damaged, and their are alot of metal slivers in the oil.

I have never had a problem with the sun gear at all, I don't have enough money to go and get a transmission from anywere, so I have to do all the work. With as much money and time as it is costing from the 700R4's from going out, and we have a a turbo400 in the back that needs clutches and thats it, why not go with the transmissoin GM ment to be behind a BBC?

[CHEVYE]

i would go with the 400 too. alot of guys will tell you that you can get the 700 to hold up to alot of power...... which you can...... for alot of $$$. my buddy has $1600 in his 700r and hasn't had any problems out of it. he has a 480 horse SB. i have $150 in my junkyard 400 turbo and i dog the living $h!t out of it. i have a built 454 in front of mine and i've towed 5500 lb. loads for several hundred miles. bottom line "for the money" i'd leave the 700 alone.

[MylilBowTie]

I was also having transmission problems with th350's. Since the th400 was installed there hasn't been any transmission related problems of breaking hard parts anymore. I installed a transgo shiftkit, external transmission oil filter, and cooler. Its been pretty good ever since then. The th400 I got could use a rebuild (2nd gear clutch pack and probably some other misc stuff) but its lasted about 2 years so far. Yes its big heavy not as efficient (power loss / drivetrain loss) as other transmissions like the th350-700r4-200r4.. but they can hold there own when it comes to power. I will take a transmission that will get me home over one that will give me 2 mpg more and maybe get me home.

[SSC's76]

Cant beat a nice overdirve TH400 AKA 4L80E. Of course by the time you buy the trans, (controller) or (transgo full manual kit) you would be in the hole kinda deep.

[SanitysBane]

Yup, back to the original question, whats it going to take to put in a turbo400 in place of the 700R4? This truck came from the factory with a 700R4.

[8t5Silverado]

Originally Posted by SanitysBane

Yup, back to the original question, whats it going to take to put in a turbo400 in place of the 700R4? This truck came from the factory with a 700R4.

I'd like to know also.

[AirMale]

I love those stories about 700's built to handle 700hp.....please share

[79BIG10]

Just curious- What are you going to do with the 700r4 after you swap it out?

[MylilBowTie]

I would see about getting the 3/4 ton setup for a th400. Or you may want to look at fabing up a crossmember for the two piece driveshaft, use the same two piece 3/4 driveshaft setup and conversion joint for the rear diff. Other than that I would save all the 700r4 related stuff if you ever decide to sell or have a change of mind.

TH400 doesn't have a detent cable, or lockup torque convertor. You can make a 10.00 kick down switch, get all the factory stuff to make it stock looking if you can find the parts, get a lokar kickdown setup $$ but I much prefer it to the B&M kickdown setup they have.

Have any specs on the th400 you have or are you still locating one?

[87 Shortwide]

GM 4-speed automatics will never stack up to a 3-speed... END OF STORY

I had my 4L60E built to the hilt by a local shop with upgraded servos, valve body, converter, vaccume controlled OD and the works. it was a 1300 dollar buildup if I supplied the tranny and that didn't include the converter I bought.

After ALLLLL that, I was still skeptical about putting nitrous or boost to it, because I knew that I was playing a dangerous game.

[phantom dually]

Originally Posted by 87 Shortwide

GM 4-speed automatics will never stack up to a 3-speed... END OF STORY

I had my 4L60E built to the hilt by a local shop with upgraded servos, valve body, converter, vaccume controlled OD and the works. it was a 1300 dollar buildup if I supplied the tranny and that didn't include the converter I bought.

After ALLLLL that, I was still skeptical about putting nitrous or boost to it, because I knew that I was playing a dangerous game.

That is just a matter of opinion. The 4L80E willhold plenty of power when built correctly, just as a TH400 will. The only thing is most people dont want to spend the $$ to do it.

[MylilBowTie]

4L80 I have no bones about = modern day th400, the 4L60 on the other hand is another story when it comes to power in a heavy vehicle that gets abuse of any kind.

If its safe to fab up a crossmember for the carrier bearing it be really easy to do it the right way. Transmission crossmember gets moved back toward the rear, cooler lines still work unless its a th475 is has bigger cooler ports, dipstick will work but you should use the one that comes with the th400 unless its not correct for it, kickdown switch isn't really that much of a concern right away it will still work fine without it, you will need to add a metal vacuum line for the th400s modulator valve from the rear of the intake to the modulator, convertor bolts up just the same, you will also want to get all your shift linkage parts off the 700r4 to use on the th400.

The main thing is the carrier bearing crossmember and driveshaft. In the case of getting a th400 with a 4in tailshaft. If you go with a th400 and two piece driveshaft the other thing you would want to pay attention to is if its a bolt on yoke or slip yoke. You will want a bolt on yoke.

[SanitysBane]

THe 700R4 I have is going in my Dad's 468BBC Chevelle. What about the shifter? Wil it work with the 400? Just not be able to pull it all the way down into the 1spot on the column or what?

[79BIG10]

Originally Posted by SanitysBane

Wil it work with the 400? Just not be able to pull it all the way down into the 1spot on the column or what?

You can adjust the downshift rod connecting the column to the linkage to adjust for the 3 gears for the 4 gears.