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Username Post: 4 speed to automatic?        (Topic#357346)
MikeH 
Senior Member
Posts: 102
MikeH
Loc: Abington, MA
Reg: 09-24-02
07-23-19 12:28 PM - Post#2771382    

So after many years with a Muncie M21 and 3:08 rear in our 57 Bel Air we have decided to look into converting to an automatic transmission. Except for the American Racing TT wheels and stick on the floor the car looks original and the plan has always been to keep it this way. I did put in a crate 350/390HP a few years back. I would like members thoughts on what tranny (on a budget) would be the simplest way to convert. My steering column still has the setup for a shifter in the tree, but I would not rule out a floor mount shifter. In all honesty our previous 57 was all stock with 283ci and Powerglide and we were very happy with it. Am I unrealistic to think I could match a Powerglide to the 350 without a lot of modifications?
Thanks ahead for your thoughts.
MikeH



 


Bad56Sedan 
"13th Year" Gold Supporting Member
Posts: 1145
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
07-23-19 02:15 PM - Post#2771389    
    In response to MikeH

Simplest on a budget;
Turbo 350/converter/ dip stick & tube,
External Trans cooler an option
After market floor shift,
Rear trans mount/ brackets,
Drive shaft to trans yok, unless yours fits the new trans,
New u joint if you swap yok,
Verify drive shaft length is ok,
(Consider side mounting block, unless it already is or,
Consider using rear block/trans brackets to frame horn mounts,
sold at one of the after market boutiques, or chain down front driver side of block to frame)
(I' m guessing a turbo 350 is the cheapest)
My thoughts, it's what I did



VC56S 2 door Sedan, 39 Years



Edited by Bad56Sedan on 07-23-19 02:16 PM. Reason for edit: No reason given.

 
acardon 
Ultra Senior Member
Posts: 11298
acardon
Loc: DFW TEXAS
Reg: 03-25-05
07-23-19 04:15 PM - Post#2771395    
    In response to MikeH

I wouldn't even think about using a 2 speed powerglide. Since your changing, go with a 4 speed overdrive, a 700R4 or 2004R. Not any more trouble than a powerglide or th350 and the cost is well worth it for years to come. Cruising down the freeway at 1800 RPM is sure nice.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
4dr 57 
Valued Contributor
Posts: 4624

Loc: Texas Hill Country
Reg: 11-10-04
07-24-19 02:11 AM - Post#2771415    
    In response to acardon

Wouldn't a 350 trans with the lock-up/lock-out feature be equally as beneficial? I converted from a 350 to a TH400 trans in hope of gaining better MPG - that didn't happen - 1 mpg improvement under ideal driving conditions. I wish I had never bothered with it, it's all hype. The 350 with the lock-out feature is the same as OD and it is cheaper to buy/rebuild. My $.02
Stan



It's all good. mostly




 
5Larry7 
"16th Year" Gold Supporting Member
Posts: 1974
5Larry7
Loc: Dallas, TX
Reg: 05-17-04
07-24-19 05:06 AM - Post#2771427    
    In response to acardon

  • acardon Said:
I wouldn't even think about using a 2 speed powerglide. Since your changing, go with a 4 speed overdrive, a 700R4 or 2004R. Not any more trouble than a powerglide or th350 and the cost is well worth it for years to come. Cruising down the freeway at 1800 RPM is sure nice.



X2. I did this swap several years ago replacing a manual with a 700R4 and I am happy with my decision.

'57 210, 327 cid, Holley MPFI, 700R4, A/C & more.
'51 Studebaker Starlite coupe, 350, TH400, GV OD.
'96 Replica of a 1950's Teardrop Trailer.


 
Shepherd 
Frequent Contributor
Posts: 1864

Loc: Lake George, NY
Reg: 11-11-15
07-24-19 06:42 AM - Post#2771435    
    In response to MikeH

3.08 rear with an od trans is not a good combo, we recommend 3.55 or even 3.73 in my shop.



 
acardon 
Ultra Senior Member
Posts: 11298
acardon
Loc: DFW TEXAS
Reg: 03-25-05
07-24-19 07:36 AM - Post#2771443    
    In response to Shepherd

The 700R4 has a pretty low 1st gear so getting it moving with a 3.08 shouldn't be a problem, with 390 HP. I had a 3.08 in my 57 with 350 HP and it did fine, excerpt it was noisy. I replaced it with a 3.36 only because it was free.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
557B2100 
Poster
Posts: 55
557B2100
Reg: 06-02-13
07-24-19 06:35 PM - Post#2771489    
    In response to acardon

  • acardon Said:
The 700R4 has a pretty low 1st gear so getting it moving with a 3.08 shouldn't be a problem, with 390 HP. I had a 3.08 in my 57 with 350 HP and it did fine, excerpt it was noisy. I replaced it with a 3.36 only because it was free.



Agree 100% with Don...The 3.06 first gear of TH700-R4 is a good match for a 3.08 rear end.




 
wagonman100 
Super Senior Member
Posts: 14321
wagonman100
Loc: Baltimore, MD
Reg: 11-27-04
07-24-19 07:36 PM - Post#2771493    
    In response to 557B2100

The lock up on a TH350 is not the same as overdrive. You lose some of the converter slippage but you don’t get the gear reduction of overdrive. The 700-R4 does have a low first gear, but remember it has a pretty wide gap for second gear. The 3.08 gears will do fine, but may not feel the peppiest off the line. I have a 700-R4 with 3.50:1 gears and a 25” tall tire in my El Camino and it is pretty quick off the line and cruises at around 2,000 RPM at 70 MPH.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
GreatNorthWoods 
"5th Year" Silver Supporting Member
Posts: 1048
GreatNorthWoods
Age: 77
Loc: Littleton, New Hampshire,...
Reg: 03-31-02
07-25-19 03:11 AM - Post#2771508    
    In response to MikeH

IMHO, I would go with the 700-R4. I'm running one in my '53 Sport Coupe with an 8.2 inch 3.08 rear end from a '70 Nova. A lower ratio would be better than a 3.08 with the OD transmission but I'm using what I have for now. I may go to a 3:55 posi at some point. That said, if your Powerglide is in good shape and you are happy with it, I would not hesitate to keep it. It should be pretty much a bolt-in to the 350. Just remember that you will get better gas mileage and performance from the 700-R4 than the Powerglide but if those are not your goals then keep the Powerglide. If the Powerglide needs a rebuild or has very high mileage on it, I would definitely not use it.

Vern

1953 Chevy Belair Sport Coupe - 355 Blueprint Engine, 700-R4, Vintage Air, EZ Wire, Ididit column, Cruise/Tilt, 59 Vette Steering Wheel, 4-Wheel Disc Brakes, Posies Springs, Coker Radials, Nova 10-bolt, Mustang II front, Continental Kit


 
acardon 
Ultra Senior Member
Posts: 11298
acardon
Loc: DFW TEXAS
Reg: 03-25-05
07-25-19 05:36 AM - Post#2771519    
    In response to GreatNorthWoods

  • Quote:
I did put in a crate 350/390HP a few years back.



Is you engine a later model with a one piece crank seal?
Isn't the power glide flex plate unique to cast iron power glide only, and won't bolt to the one piece seal crank?

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
Bad56Sedan 
"13th Year" Gold Supporting Member
Posts: 1145
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
07-25-19 06:56 AM - Post#2771524    
    In response to MikeH

Original poster posted,
(On a budget)
From one of the big parts places,
A turbo 350 is just under $1000,
A 700R4 is around $1500,
I must have misunderstood "on a budget" as meaning cheapest



VC56S 2 door Sedan, 39 Years



 
57tim 
Valued Contributor
Posts: 3058
57tim
Loc: Cameron, Wi, USA
Reg: 11-09-01
07-25-19 02:52 PM - Post#2771562    
    In response to Bad56Sedan

IMHO you are wasting your money going to a turbo 350. I would never go with a Powerglide either. Save up some more and get an OD trans.

57 Bel Air 2dr Ht
327 700r4
http://www.picturetrail.com/tmneid


 
Bad56Sedan 
"13th Year" Gold Supporting Member
Posts: 1145
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
07-25-19 03:31 PM - Post#2771568    
    In response to MikeH

Well mike,
The consensus is it can't be done on a budget,


VC56S 2 door Sedan, 39 Years



 
4dr 57 
Valued Contributor
Posts: 4624

Loc: Texas Hill Country
Reg: 11-10-04
07-26-19 06:36 AM - Post#2771644    
    In response to MikeH


After reading all the comments I just have to ask the OP if the car is indeed 'Stock' or simply looks like it.
These cars were engineered to travel at 60 - 65mph maximin.
Running down a highway at 70 with stock brakes or front disc conversion that has a lot of pedal travel . . . well, that's up to the driver. To me it seems more than just a bit careless/risky.

That said, most cars in general get the best mpg at 60mph, that's a fact. Older cars in stock form may be a bit lower - 55mph.
This leads to your engine and where it's torque band is. This is where performance and efficiency meet. I would suggest you put a pencil to it and figure out where the engine wants to be at a normal cruising speed and gear accordingly.

Just keep in mind when reading replies that modern engines are very torquey at low rpms (1800 rpm) while older engines actually are more efficient at a bit higher rpm. my $.02

I know there are probably other reasons for your wanting to change to an A/T other than HP, efficiency, etc.
Is opting for a 336 rear gear and keeping the 4 way in the cards? You will only be adding 250 rpm's to the cruising speed rpm, which may actually be beneficial to the engine at highway speed.

It's all good. mostly




 
Shepherd 
Frequent Contributor
Posts: 1864

Loc: Lake George, NY
Reg: 11-11-15
07-26-19 06:48 AM - Post#2771646    
    In response to 4dr 57

Agreed on the gearing issue. In o/d with 3.08 gears, the final ratio is about 2.30, not a good set up.






 
Bad56Sedan 
"13th Year" Gold Supporting Member
Posts: 1145
Bad56Sedan
Loc: Pasadena, Texas
Reg: 04-29-04
07-26-19 08:30 AM - Post#2771656    
    In response to MikeH

Well Mike,
Sounds like you'll need to pull the rear axle

VC56S 2 door Sedan, 39 Years



 
MikeH 
Senior Member
Posts: 102
MikeH
Loc: Abington, MA
Reg: 09-24-02
07-29-19 04:27 PM - Post#2771954    
    In response to Bad56Sedan

Thanks to all for your ideas. All will be considered before I start this project.
I did notice a misprint I made in my original post...I have a 350ci/290 hp, not 390 hp.
MikeH



 
WagonCrazy 
"14th Year" Platinum Supporting Member
Posts: 3187
WagonCrazy
Loc: So Cal
Reg: 06-07-05
07-29-19 05:16 PM - Post#2771958    
    In response to MikeH

Mike,
I did a 3 speed manual (column shift trans) to 200-4r (4 speed automatic-column shift) install on my 4 door wagon several years ago. Did it all myself, and it was a domino effect, but it was well worth it. Helped fuel mileage and general enjoyment when freeway driving.
The wagon had a stock 290 hp 350 ci engine and a 3:55 ratio rear end.
It ran at about 1800 rpm when at 70mph.

Documented it in these posts.
Enjoy...

3sp manual to 200-4r auto

200-4r conversion update

57 Nomad -LS1 with C4 suspension
59 Apache Fleetside Shortbed BigWindow



 
acardon 
Ultra Senior Member
Posts: 11298
acardon
Loc: DFW TEXAS
Reg: 03-25-05
07-30-19 05:46 AM - Post#2771990    
    In response to WagonCrazy

  • Quote:
It ran at about 1800 rpm when at 70mph.



Either your tach is wrong or you have 32" rear tires. Put the numbers in. DO the math.
https://www.randysworldwide.com/calculators/rpm/


Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
bowtie56jw 
Poster
Posts: 17

Reg: 03-02-09
08-01-19 02:28 PM - Post#2772188    
    In response to acardon

i run 1800 at 70 in my 57 with a th200 4r and 3:36 gear but im also running 275 60 15's



 
4dr 57 
Valued Contributor
Posts: 4624

Loc: Texas Hill Country
Reg: 11-10-04
08-03-19 08:17 AM - Post#2772300    
    In response to bowtie56jw

  • bowtie56jw Said:
i run 1800 at 70 in my 57 with a th200 4r and 3:36 gear but im also running 275 60 15's





That sounds just about what I run at 70 in my 57 with a 4L60e 4dr and 323 ('64 pumpkin) but I'm also running 205 14's.

The engine is an 97 LT1. That's why I said that I suspect the OP new engine may like to run a bit higher rpm in order to get into the torque range the motor likes, but what that rpm is will be up to the OP and must include rear gears and tire sizing once he finds out where the engine wants to be.
My LT1 torque starts at 1800 and I am at 1950 at 70. So I drive 60 and get the best mpg.
Stan


It's all good. mostly




 
5/7HEAVEN 
Old as Dirt Member
Posts: 5661
5/7HEAVEN
Loc: In a quandry
Reg: 05-27-01
08-10-19 07:25 AM - Post#2772879    
    In response to MikeH

  • MikeH Said:
Thanks to all for your ideas. All will be considered before I start this project.
I did notice a misprint I made in my original post...I have a 350ci/290 hp, not 390 hp.
MikeH


Lol,I was thinking that's a very powerful crate motor.


'57 BELAIR sport coupe/383/4-speed


 


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