The Stovebolt Site Forums The Shop Area Driveline 200-4r, 3.07 rear, 350 carbed

I have a rebuilt 200-4r from a project I gave up on. I'm considering putting it in my '56. Do you think my rear end is too high geared for such an application?

Yes

I take you are talking about when it goes into OD which is D. Is your car a highway driver (lower rpm torque) or high performance? You can use a formula to see rpms at a certain speed.

https://www.ringpinion.com/calculators/Calc_RPM.aspx

1:1 in 3rd gear - normally will not go into lockup

I think .7 in OD.

If you have lockup it will reduce about 200 rpm more at cruising speed - no acceleration.

If you do not want OD put shifter in 3rd. 1 to 1

Trans will run coolest in Lockup, but trans heat may not be a problem, with a trans cooler and how you drive the 56.

I had a 3:08 rear end with a 700 R4 trans in my 70 stepside. with a basic 350 Goodwrench engine. It was a pleasure to drive. It would pull long hills on the interstate in o-drive w/AC on with no problem. If I did have a long hard pull with a load I could lock it in direct drive & still run as fast as I wanted.
I kick myself every day for selling that truck.

It is a highway cruiser with a stock Goodwrench engine. Using the calculator above I would be at 1900 rpm at 70 mph. But that is for a .70 OD and the 200-4r is a .67 OD. George, do you remember what size tires you were running? Mine are 225/60R16.

Yes. They were 235/75/15. They measured just shy of 29 in.
George

Thanks. Mine measure just over 26". I think I'd be right on the borderline.

Use an on/off switch for the lockup and you may be happy with it.

3.07 rear, .67 OD, 26" tires, 70 MPH.
=1,861 RPM.
At 100 MPH, you would be at 2,658 RPM.

Yeah, it is a little too high geared for it. I have an appointment to get the leak fixed on the TH400 Monday.

I recently finished putting together a '49 3100 with a TH400 with and 3.08 rear end and 30" tires. 2,415 RPM at 70 MPH. It performs very nicely.
With your 26" tires you would be doing 2,786 RPM at 70 MPH.

Yes. it is spinning pretty good at 70-75. That is why I was considering the OD.

I think you will be better off staying with the Th400. They are tough. They stood up to motors as big as the 500 Cadillac. And 2800 used to be considered a fast idle. It won't hurt it a bit and it really won't use much more gas. I'm afraid an OD would constantly be shifting back and forth.

Going with taller tires will get you right where you want to be at 70 MPH. You won't be doing any burnouts or pulling stumps, but your highway cruising will be stress-free.

Another option would be a trans that was used pretty frequently ahead of a 3.08 rear axle, the TH 350C. It has a locking clutch in the torque converter that gives approximately a 10% RPM reduction at light throttle cruise by eliminating the built-in slippage in the converter. That one uses a 3-switch series of controls, a vacuum switch that senses engine load, a brake switch that disengages converter lockup anytime the brake is used, and a governor pressure switch in the valve body that sets the minimum lockup speed. All three switches must be closed to send power to the solenoid valve that locks in the converter clutch, but no computer is needed for the system to function.

BTW, converter locking clutches are nothing new- - - -the 1949 Studebaker automatic had one, and also the 55-57 Packard Ultramatic. No electrical controls were used on either one of them, however.
Jerry

But the kick is he has a good 200r4 in hand for a sbc. From what he said a stock 350 crate which should have good low end. Especially with a 3600 lb truck. Just to have the option of OD at 45/up if in D is compelling. The option of driving in 1 to 1, OD with no lockup, and OD with lockup is compelling. Driveshaft should fit.


Maybe he has a better plan for the 200r4.

A boat anchor is a better plan for the 2004R. Maybe he can sell or trade it to someone who doesn't know any better.
Jerry

i put a 700R4 behind a goodwrench 350 driving a 3.08 posi in my 75 Camaro. that car is right around 3600 lbs. its a good set-up, but my tires are only 24" so its geared a bit lower than the truck would be. the 200R4 is weaker but it suggests the ratios would be OK with the V8. i really like the OD/lockup.