TH400 to 700r4 Conversion

[gchemist]

One of my local builders can survive. Follow the links above to the MegaRaptor series. As long as you don't tow with it, a stout 700R4 can run in the dually. Your best option is a NV4500. 5 speed OD and towin capabilities all in one.

[veinbar]

Okay... I need 700r4 build recommendations. Not too extreme.

I am having a 700r4 built to replace my TH400. It will be going in my '79 1/2 Ton 2WD SWB Chevy. I will be using this truck as a daily driver (99%), road tripper, and occasional moderate towing. (Moderate towing = 3k lbs or less)

What are the "must have" upgrades?
What items should I get to save me headaches through this process?
Once installed, are there any break-in tips you can share?
Or maintenance schedules that will keep it alive?

[Jonboy]

I would run a Corvette servo, or an aftermarket equivalent. Sounds like your usage will be about the factory application, so it shouldn't need anything too exotic. A good auxillary trans cooler will help, too.

[veinbar]

Originally Posted by Jonboy

I would run a Corvette servo, or an aftermarket equivalent. Sounds like your usage will be about the factory application, so it shouldn't need anything too exotic. A good auxillary trans cooler will help, too.

My core has many upgrades already. Monster shell, corvette or better servo, and other items. Not sure, it was rebuilt long ago. I am going to rebuild it because the fluid was darker and smelled like bbq. Can the shell and servo be reused?

Thank you.

[Jonboy]

All of the hard parts can be reused. A general rebuild will replace the clutches and steels, and most seals.

[veinbar]

Originally Posted by Jonboy

All of the hard parts can be reused. A general rebuild will replace the clutches and steels, and most seals.

Assuming that all I need is a straight forward rebuild / install, and all of my internal upgrades can be reused, what am I going to pay for this? Estimate of course... My game plan has to be written out and budgeted otherwise it won't get done.

[Jonboy]

Locally you can get one done for $500-600. Not sure about Austin.

[406 Q-ship]

Replace the "shell" with a Beast Shell (can't remember who makes them). The GM and standard shells are almost always cracked. TCI makes a full pressure valve body so that the TV cable adjustment is not critical for line pressure, no more burned up 700R4's from a misadjusted TV. Get the Corvette servo cover at least, there are better ones from the aftermarket (more surface area). Put a trans cooler on it too if you plan any towing.

I would not even consider using a 700R4 in a 454 Dually unless it is a show truck that gets used as a car. GM never put the 700R4 or the 350TH in 1 ton trucks for a good reason. I would use a 4L80E or a 400TH w/gear venders OD in a dually that was to be used like a truck.

[DetroitDan]

well that answers that question. I recently missed out on a smokin deal on a built 700r4, since then I have been considering a stock one, but I dont want to do all that work and have my 454 eat it. It's all stock right now but I am pretty hard on stuff. Guess I'm stuck with the th400 that I HATE since I cant afford a gear vendor.

[DetroitDan]

re-reading this, maybe its time to reconsider a 4l80e. I beat the snot out of one in my diesel dually for years without a wimper, and it was all stock except for a shift kit.


Craigslist here I come

[D.FENS]

Originally Posted by DetroitDan

re-reading this, maybe its time to reconsider a 4l80e. I beat the snot out of one in my diesel dually for years without a wimper, and it was all stock except for a shift kit.


Craigslist here I come

Kind of came to the same conclusion myself.

[veinbar]

The 3.73 Posi is getting installed!!! Next is to complete this conversion. I have the 700r4 core, all I'm missing is a driveshaft... Are there any driveshafts out there that will just fit without having to cut and balance it? If so, what year, make and model of truck or van would I be targeting?

[DetroitDan]

I can't convince myself the 700r4 will be strong enough for what I want. I can't figure out if a 4l80e will work with my 82 np205. It looks like my t-case should be a 10 spline, not a 32 spline like some newer ones had. I want to keep my t-case if at all possible. I am getting so frustrated by this. I started looking at putting an NV4500 5 speed in it, but that isn't a simple or inexpensive proposition either. There are adaptors available to do what I want to do, but they don't seem to be complete or they are ridiculous money. I'm not used to having to work on an old Chevy where everything isn't an easy swap.

I know it isn't going to be free, but I refuse to spend more than I have invested in the whole truck just to get overdrive. Gear Vendors are nice but they cost more than twice what I paid for the truck.

[Jonboy]

Originally Posted by veinbar

The 3.73 Posi is getting installed!!! Next is to complete this conversion. I have the 700r4 core, all I'm missing is a driveshaft... Are there any driveshafts out there that will just fit without having to cut and balance it? If so, what year, make and model of truck or van would I be targeting?

The original driveshaft from my '74 fit perfectly. It originally had a long tailshaft TH350 in it.

[veinbar]

Originally Posted by Jonboy

The original driveshaft from my '74 fit perfectly. It originally had a long tailshaft TH350 in it.

If you're able, could you measure length of your driveshaft? It would be a huge help. That way I can drop this thing off to get cut and balanced already. I'm really dragging my feet on the transmission install because of the driveshaft.

[Jonboy]

If I can get around to putting it up in the air, no problem. I have been slammed with Honey-do stuff lately, and it's much cooler in the house.

[68C1087GTA]

Sorry for the thread bump, but I believe it is better to rely on existing threads for info rather than starting new ones.

Originally Posted by veinbar

I have a TH400 currently that needs to be rebuilt. With the suggestion of a few members I am now considering a 700r4 conversion. I drive a '79 SWB 1/2 2-wheel drive Bonanza. I know that the 700r4 will bolt up to the motor and cross member w/ no issues. The questions I do have:

I am starting on the same thing....400 to 700R4 swap but am I understanding correctly that the 400 crossmember can be used on a 700R4? Do it need to be moved (forwards/backwards) or will the 700R4 bolt right up to the crossmember in it original location?

Originally Posted by veinbar

[LIST=1][*]My '400 has a 2-piece drive shaft. I will need a 1-piece for the 700r4. Does anyone know the exact length of a driveshaft on a '73-'80 truck w/ a 700r4?

I am dropping in a 1984 305TPI/700R4 combo out of a 1984 Camaro Z28. Did you ever find out what donor vehicle would be a good candidate for a direct swap driveshaft, or will just have to get a 1-piece driveshaft shortened to fit?

[Skunksmash]

I had heard that the 4l60e was just a 700r4 made a little bit more modern.

[INSIDIOUS '86]

Transmissioncenter.net
Posted via Mobile Device

[68C1087GTA]

Originally Posted by Skunksmash

I had heard that the 4l60e was just a 700r4 made a little bit more modern.

Yes. The 4L60 was barely more than a name change for the 700R4 (with only mild internal changes). The 4L60E was an electronic controlled version of the 4L60.

[cal30_sniper]

Originally Posted by 68C1087GTA

Sorry for the thread bump, but I believe it is better to rely on existing threads for info rather than starting new ones.


I am starting on the same thing....400 to 700R4 swap but am I understanding correctly that the 400 crossmember can be used on a 700R4? Do it need to be moved (forwards/backwards) or will the 700R4 bolt right up to the crossmember in it original location?


I am dropping in a 1984 305TPI/700R4 combo out of a 1984 Camaro Z28. Did you ever find out what donor vehicle would be a good candidate for a direct swap driveshaft, or will just have to get a 1-piece driveshaft shortened to fit?

The TH400 and TH700 crossmember are identical. You will need to move it, but the bolt holes should already be in the frame to do so.

Depending on the wheelbase, you should be able to use a complete TH700 driveshaft from a compatible squarebody truck. If yours is a 2-piece driveshaft already, you're in luck. most half-ton 2WD suburbans used a 2-piece driveshaft setup with a TH700 transmission. Pull the bearing and forward half of the driveshaft, and slip it onto the rear portion of the 2-piece driveshaft already on your truck. That's what I did when I went from TH400 to TH700 in my Suburban. Worked like a charm. You may need to get the entire shaft rebalanced when you're done though. I have a slight vibration from 70-75mph that goes away everywhere else. I still need to get that taken care of.

-cal30sniper

[68C1087GTA]

Originally Posted by cal30_sniper

The TH400 and TH700 crossmember are identical. You will need to move it, but the bolt holes should already be in the frame to do so.

Depending on the wheelbase, you should be able to use a complete TH700 driveshaft from a compatible squarebody truck. If yours is a 2-piece driveshaft already, you're in luck. most half-ton 2WD suburbans used a 2-piece driveshaft setup with a TH700 transmission. Pull the bearing and forward half of the driveshaft, and slip it onto the rear portion of the 2-piece driveshaft already on your truck. That's what I did when I went from TH400 to TH700 in my Suburban. Worked like a charm. You may need to get the entire shaft rebalanced when you're done though. I have a slight vibration from 70-75mph that goes away everywhere else. I still need to get that taken care of.

-cal30sniper

Thanks. It is a 2-pice driveshaft & I wanted to convert it to a 1-piece. Why? I dunno. I guess just because I'm used to 1-piece driveshafts. Since the '68 SB wheelbase is only 115", I kinda figured there would be very few compatible driveshafts that would just drop right in.

[Desert1957]

Originally Posted by 68C1087GTA

Thanks. It is a 2-pice driveshaft & I wanted to convert it to a 1-piece. Why? I dunno. I guess just because I'm used to 1-piece driveshafts. Since the '68 SB wheelbase is only 115", I kinda figured there would be very few compatible driveshafts that would just drop right in.

FYI , Some 2 piece drive-shafts have a bolt on yoke at the transmission. This yoke is not designed to slip in and out like a 1 piece shaft. I would check what set up you have.

Desert

[cal30_sniper]

Desert,

The only bolt in yokes I've seen came on TH400 trucks. As long as he grabs a yoke along with the front half of the TH700 driveshaft, he'll be good to go.

[68C1087GTA]

It had a 400 in it but it is a 2-pice ds with a slip yoke.