TH-700R4 in place of a T-400

[C9]

Ejenjo stopped by a few days back and we had an interesting conversation.
One of things we talked about was the TH-700R4 transmission.
I didn't realize these OD transmissions did not require a computer to operate them . . . some of them do perhaps, but it looks like an easy transmission to set up.

Aside from that, I'm wondering if the TH-700R4 is a direct bolt-up to the 455 Buick?

I think I have the physical room for the trans with the only problem being the trans mount would probably need to be moved.

The present trans mount - set up for the T-400 - is on the bottom 1 x 2" x .120 wall crossmember and it has a bolt-in trans dropout as part of its construction.
The short run of 1 x 2"  between the rear mounted angled 1 x 2" braces that blocks the view is for the driveshaft loop.

[Charlie Chops 1940]

Jay,

I believe there are two versions, maybe three: Chevrolet, BOP and maybe a fits-all. Tony will probably tell us. A little web searching should find a site that shows the lengths of all the GM automatics. Also look at Sumners site.

I replaced a 350 with a 700R4 in my '40 Chevy and since my trans mount was a bolt in I just made a new one. I did have to take a bit more out of the k-member leg on the passenger side though.

I did a lot of changes at once 2 years ago on the '40, a ZZ4 crate motor, 700R4 trans, 3.55 posi gears, 2.5" exhaust , and a/c, but I gotta say the most marked improvement came from the driveline changes. The old 350/350 combo with a 3.08 gear strugggled for 17mpg ( a little tired but when fresh it was always about the same) and the new turns in  19/20 on a crappy day, 23/24 regularlr and has hit a best of 25.7.

I'm sold on it.

[C9]

Thanks Charlie.

I think I have sufficient width where the trans passes through the crossmember area the way the frame is now.
Height shouldn't be too bad either.
The pic makes it look shallower/shorter than it really is.

One reason for the change is that we're driving lots more highway miles here in Arizona than we were in California.
The 32's RPM with T-400, 3.70 diff and 30" tall tires settles out at 3000 rpm at 75 mph - which is the speed limit on the nearby freeway.

Better gas mileage wouldn't hurt my feelings either.
In town, the 462" Buick with 750 cfm Carter - jetted lean for the altitude - and mild cam nets 10-12 mpg.
Highway it runs about 13-16 mpg depending on whether I've been a good boy or not.
(Freeway on-ramps are hard to resist, gotta get up to traffic speed ya know?)

The 700 trans in the 31 would be an especially good deal.
Rear tires on it are 28" tall and I'm looking at a 3.25 or 3.50 diff for it although am leaning toward the 3.25 right now.
The 3.25 would be a good compromise between performance and mileage if I run the T-400.

The mileage increase would help the car's range as well.
It can be a long way between gas stations out here in the Dez.
The Barstow to Needles run at approx 207 miles can be a tough one to finish with a 13-16 mpg car with 12-13 gallon fuel cell capacity.*
Although running strictly on the highway should net the higher end of the highway mileage figures.

You can top off about 20-25 miles out of Barstow, but things would still be close.
There is a gas station/rest stop/convenience store/restaurant about 2/3 of the way down, but with gas at $3.22 per gallon there, I'd like to avoid that if I could.

The other part to this whole mileage thing is that the 31 roadster will be running a dual quad setup - pair of 500 cfm Carters (jetted for altitude, I live at 3300') along with a bigger cam than the 32 runs.
A touch more compression and that will be the main difference between the two engines.


*The fuel cell in the 32 is a 16 gallon model and measuring it agrees with the manufacturers capacity rating, but most times all the fuel it will take is 12 gallons and one time it took 13 gallons.
Apparently the fuel cell's foam takes up quite a bit of room.
Fwiw - I can see the fuel level getting seriously low by noting the low and sometimes swinging needle in the fuel pressure gauge.
The capacitance fuel level sender in the fuel has become somewhat useless so I use the resettable odometer to gauge time to fuel up.
One hundred miles is a fairly safe figure in the 32.

[DRD57]

It'll take a pretty trick 700R4 to live behind the torque of that big Buick. I know several people who have scattered stock and mildly built 700R4 trannys with lesser engines.

I was under the impression that all 700R4's were Chevrolet bell housing cases which would require a BOP to Chevrolet adapter.

I would recommend a Gear Vendors overdrive.

[C9]

Thanks Don.
I hadn't thought about that end of it because I thought the 700 was a T-400 with the OD added on.

Once the dust settles, it looks like the 700 build-up and install would cost about the same as a home-built 400 with GV OD.


So the next question is; what are the present day GM pickups running for a trans?

[Scrap Fe]

Thanks Don.
I hadn't thought about that end of it because I thought the 700 was a T-400 with the OD added on.

Once the dust settles, it looks like the 700 build-up and install would cost about the same as a home-built 400 with GV OD.


So the next question is; what are the present day GM pickups running for a trans?

Jay, I agree with Don's advice on the Gear Vendors OD.  Had I not decided on a T-56 manual 6-speed for my '39, I was going to use a T-400 with a Gear Vendors.  You can hammer on that combination all day long with a blown big block and not hurt it.

[Charlie Chops 1940]

Jack (Phat Rat) has a H.O. BBC crate motor in his '41 ford coupe with a 700 behind it. It's living just fine and he doeasn't baby it at all. He will probably have something to say. As for the 400 with a gear vendors behind it; certainly a bullet proof combination. I have a friend with that combo behind a 434 aluminum small block in a '55 two door and it works great. I have a 400 with an American Overdrive on it that I bought some years ago for the now gone '55 Nomad project...guess it needs a home one of these days...maybe in a shop truck of some sort.

No lack of possibilities,

Charlie

[1FATGMC]

Thanks Don.
I hadn't thought about that end of it because I thought the 700 was a T-400 with the OD added on.

Once the dust settles, it looks like the 700 build-up and install would cost about the same as a home-built 400 with GV OD.


So the next question is; what are the present day GM pickups running for a trans?

Just to throw a couple things at you.

One there are quite a few guys on the chevy talk board running Bowtie overdrives and they swear by them.  They are running in the 11's and 12's with them and I think that is with the one that is about $1200.  They make them in different builds.  From what they said I would trust one of those behind your motor.

Two it won't bolt up to you motor, but Enjenjo (just left here) said you were aware of that and were looking at an adapter to take care of that.

There is a 400 based overdrive and that is the 80LE, but it is a lot more and does require a computer to control the shifts like the latter model 700's.

The GV is attractive, but don't forget it is only a 20% overdrive and the 700 is a 30% overdrive.

I'm running 28" tires and a 3.50 rear with my 700 and really like that combintaion.  75 mph is about 2400.  I would go to a 3.43, but probably not below that with my 350.  With your larger motor you could proabably go to the taller rear gear with no problems if you wanted.

The bigest thing with the 700 is you have to get the linkage correctly installed for the TV cable.  This is critical, not that hard to do, but you have to do it if you want the 700 to live behind any motor.  I have that information on my site and it is on other sites and has been it a number of mag. lately.

What ever you do, put that thing in cruise and come up a visit now that you aren't that far away.

c ya,  Sum

[phat rat]

As Charley said I've got one behind an HO 454 in a 3700 lb cpe. and it's not babied. I'm running a 3.42 gear with 255/65x15's and have pulled a high of 19mpg. When I first put the car together I was running a .090 over 396 backed with a T-350 and the very best I ever did with that combo was 14mpg. So I'm happy as can be with the 700R. RPM's went from 3000 at 70mph down to 2100

[Crosley.In.AZ]

I guess I can comment on this...

large CID engines break 700 trannys if there is much traction.  Torque is the guy that gets the job done.

Pick your part..... input shaft , input drum shell, output shaft

[1FATGMC]

I guess I can comment on this...

large CID engines break 700 trannys if there is much traction.  Torque is the guy that gets the job done.

Pick your part..... input shaft , input drum shell, output shaft

Tony I'm just wondering how much HP/Torque did that car/cars have and what kind of tires and under what conditions did they do that?

From what you are saying a good 700 with a big motor and poor traction on the tires could probably live?  Is that right?

Thanks, Sum

[Crosley.In.AZ]

I'll give a couple of examples.... late model SUV or trucks.

LS1 motors with whipple or similar super charger with a 4L65E tranny. These are  a 6 liter motor, with AWD.

the owners wound the trannys early, last caddy SUV had 1200 miles on it with burned tranny.  GM tells them "sorry no warranty"

Some times the trannys come back blown to bits as the above photos show, usually only once .  LOL  

BTW , we do not warranty the GM hard parts in a super charged application, only the parts we install.

All of the above tranny parts were broken by NOS or super charged engines.

[Inprimer]

I don't mean to hyjack this post, while on the subject,  though.... I will be getting a 78 Caddy Coupe d'ville it's pristine to say the least, well taken care of it has 33k on it, no winters stored indoors on jacks etc .also started every two weeks for 15 min running time, dont ask, long story will explain someday.We are going to move to Lake Havavsu AZ in about 3 yrs,. By the way its a 425 w/400 turbo.What is your opinion on trannys for mileage , is it worth using a Gearvendors over/under unit? I was told the better way is a universal FI sys. The car will not be used for towing etc just for criuzing. As you all well know you have to drive at least 75 mi to get anything Shopping etc that's why Im aking the best approach to mileage, thanks.  PS George I hope you are doing better, I just found and read your e mail only about 7 wks late sorry.Serge PPS see y'all at cobo hall in afew Inprimer