3.54 vs 3.25
- Thread starter flathead 39
- Start date
drolston
Well-known member
I changed the 3.78 for 3.25 gears in my '41 coupe with a 284 inch motor and Schneider 248f cam and Offy 425 heads. I love the quieter and more economical cruise and with the torque of that 4.125" stroke engine, no problem getting rolling, even on a steep incline. I bought a transmission case to build a 15/29 for lower gears, but I think that transmission case will stay under the work bench.
alanwoodieman
Well-known member
I run 3:25 in my 41 truck with a 51 merc engine, only problem is starting off on a big hill, need to ride the clutch to get going which is tough on the clutch but do like the gear on a road trip-
tubman
Well-known member
I have 3.55's in my '51 with a "warmed over" 255 ci Mercury. I find the car absolutely fine while driving around town, but I find myself trying to "grab another gear" on the highway. I plan on solving that by installing an overdrive transmission. I don't know their exact diameter, but I am running 2.25/75R15 rear tires. I believe that my '51 is about 300 lbs. heavier than a pre-war Ford.
flathead 39
Member
Thanks. Wow, Practically a perfect match! I'll definitely go with the 3.25.
thanks for the info!
flathead 39
Member
john in illinois
Well-known member
I am very happy with 3.25s in my lighter roadster. I do have the low first and second. It has plenty of torque in 3rd ,which surprised me.Schneider 248F cam.
It sounds like your car would pull just fine .
John
It sounds like your car would pull just fine .
John
flathead 39
Member
Thanks, from the specs I got from the prev. owner, my cam is the Schneider P-3/8.
blucar
Well-known member
I have to second, well almost, the above suggestion. A built 2004R would work better with the 3.78 ratio. The 2004R is basically the same size as a TH350.
An overdrive, be it a Columbia or an AOD, or a 5 spd T-5 is the better way to go.. My '36 has a well built 59AB with a 47-48 Columbia w/3.78 gears. the car runs very well on the street and/or highway. In my younger years I use to street race the car on a regular basis, very seldom got beat even against the stock tri-five Chevy's in the '50's.
I have 3.26 gears in my '39, however the engine is a 330 hp 350 w/700R4, the car is a rocket ship. Apples and banana's...
flathead 39
Member
Actually, changing gear ratios is my only option. I want to keep it simple and keep the stock rear end and xmission. Have pretty much decided on the 3.54 as most of my driving is on back roads and surface streets (except for some interstate driving to get off this mountain).
blucar
Well-known member
To recap what I said earlier about installing an OD in lieu of trying to find a gear ratio that works under multiple conditions.
A late model Columbia, 46-48 will bolt right up to your stock 3.78 center section. The 46-48 Columbia's have electric over vacuum shifting which is very user friendly.
The 46-48 Columbia's are very strong compared to the 36-41 units, they do need a few modifications and are a little spendy, but when you take into consider the benefits of not having to modify the car and the flexibility of the multiple gears, the benefits are huge.
I have driven my '36 over 94k in the 68 years I have owned the car, never had any problems with the Columbia, blew out several transmissions street racing, due to missed speed shifting.
A late model Columbia, 46-48 will bolt right up to your stock 3.78 center section. The 46-48 Columbia's have electric over vacuum shifting which is very user friendly.
The 46-48 Columbia's are very strong compared to the 36-41 units, they do need a few modifications and are a little spendy, but when you take into consider the benefits of not having to modify the car and the flexibility of the multiple gears, the benefits are huge.
I have driven my '36 over 94k in the 68 years I have owned the car, never had any problems with the Columbia, blew out several transmissions street racing, due to missed speed shifting.
19Fordy
Well-known member
As a side note, it's intersting to note that:
"The maximum speed was 35 MPH until 1940 and was 50 MPH from 1941 until 1958 (excepting the national 35 MPH limit of World War 2). In California [Chartrain 2005], the maximum speed was 45 MPH from 1931 until 1941. In 1941 it was raised to 55 MPH."
"The maximum speed was 35 MPH until 1940 and was 50 MPH from 1941 until 1958 (excepting the national 35 MPH limit of World War 2). In California [Chartrain 2005], the maximum speed was 45 MPH from 1931 until 1941. In 1941 it was raised to 55 MPH."
flathead 39
Member
Yes and that's what my car was designed for.. the 1939 suspension, steering, etc is most comfortable at speeds under 55 mph, and so am I (in this car). The 3 speed & stock rear end is all I want. I bought the car more for nostalgia than anything else. My first car was a 40 Merc (1958-60) and this one takes me back there every time I drive it. But thanks for the comments & advice.
JSeery
Member Emeritus
Man, that is a different world than I was around! Kansas didn't even have a speed limit until the 50s I think. It was what ever you felt was prudent under the conditions. It may have been earlier, I can't find a reference.
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Old Redneck
Well-known member
My friend has a 40 Ford 2 door sdn. and he put 325 in it and they are super great. We live in hilly country and no problem. I wish I had put them in my 35 Ford pickup. No problem taking off. I was surprise how nice they are.
Ford Freak
Well-known member
What is your 40 Ford friend running for an engine? If modified, how much?
I was thinking of putting 3.50's in my '37 w/stock 85 hp., 24 stud engine,
w/27" tall tires. Now, I am thinking that 3.25's might be better. Hmm........
flathead 39
Member
OK, so now you got me looking at the 3.25 again.. I've been bouncing between that & the 3.54.. Maybe by the time I'm ready (any time now) I'll be able to make up my mind. Going over the rpm/mph chart for both, I think 3.25 would be just right. Thanks.
