3.54 vs 3.25

[flathead 39]

Currently constantly looking for another gear when driving my 3.78. I'm sure I have enough power for the 3.25, but will have to use 1st & 2nd gear a bit more.?? Any advice appreciated.

[Mart]

What size rear tires are you running?

[VeryTangled]

What top speed are you wanting?

4:11 in my '36 Phaeton, the engine screamed at me over 55. Switch to 3:78 and the same configuration is ok to 70.

So where is the 3:78 letting you down?

[V8COOPMAN]

Originally Posted by VeryTangled

What top speed are you wanting?

I can't answer that for him, but his speedo does go to 140 mph! DD

[flathead 39]

Originally Posted by Mart

What size rear tires are you running?

28" 235/70-15s. I seldom go over 55 on the freeway and figure that's 2495rpm.. ok, not bad but a taller gear would save some gas, run quieter stop me from looking for another gear.?

[flathead 39]

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Originally Posted by V8COOPMAN

I can't answer that for him, but his speedo does go to 140 mph! DD

I know! It's ridiculous but that's all they sell now.. even so called vintage gauges.

[flathead 39]

Originally Posted by VeryTangled

What top speed are you wanting?

4:11 in my '36 Phaeton, the engine screamed at me over 55. Switch to 3:78 and the same configuration is ok to 70.

So where is the 3:78 letting you down?

Gas mileage, noise, & the feeling that there needs to be another gear. I drive her a lot.

[40cpe]

The 3.25 will lower your RPMs at 55mph to 2145. I think it will take it to make a significant difference. Then you might have difficulty getting rolling. That can be helped with pick-up transmission gearing. One thing leads to another.

[flathead 39]

I shoul have made it more clear. I don't like the 378. Some have gone to the 354 and are quite happy. I'm wondering what' wrong with the 325.?

[flatford8]

JM35Sedan posts about his car with 3.54’s. He does a lot of long trips. I don’t know what he runs for tires. Maybe try a PM. Real good guy and if he has info to help, I’m sure he’ll share it....... Mark

[Mart]

I run 3.54s with 7.50:16s on my roadster. I think with the 235-70-15s you'd be ok with the 3.25s.
If you found it difficult to pull away you could always pair the 3.25s with a 15/29 gearset to lower the first gear.

Edit: You could try some taller tyres. I ran L78s on my 40 with 3.78s and it was ok.

[flathead 39]

Originally Posted by 40cpe

The 3.25 will lower your RPMs at 55mph to 2145. I think it will take it to make a significant difference. Then you might have difficulty getting rolling. That can be helped with pick-up transmission gearing. One thing leads to another.

I shouldn't have any trouble getting rolling in 1st gear, It's almost worthless now.. with the 378 it' like a very close ratio xmission. I like using the gear shift & will like it even more when I get more proficient at double clutching.

[Ggmac]

How much motor do you have and any towing or major hills to deal with ? Ive got a 41 tudor with 378 and have been working on a 354 dif this week . I too have been thinking about changing . 378s down here in Florida are decent but always looking for more also .

[HDowse]

Here's a link to a calculator that I used a lot to figure out my gearing/speed/rpm. You'll need your tire diameter as one of the factors. My 40 Fordor came with a 4.11, talk about screaming at 55, that lead me to buy a Mitchell OD, ends up an equivalent of a 3.10 +/-
I don’t think the 3.54 would make enough difference for you but the 3.25 would. Others with a 3.25 will know.
http://www.advanced-ev.com/Calculators/TireSize/

[flathead 39]

Originally Posted by Ggmac

How much motor do you have and any towing or major hills to deal with ? Ive got a 41 tudor with 378 and have been working on a 354 dif this week . I too have been thinking about changing . 378s down here in Florida are decent but always looking for more also .

Got enough motor, built 8ba, 284 cu in, cam, 2 94s properly tuned, offy heads.etc. I do live in the mountains & the 3.78s Has no problem pulling 6% grades with little effort, so the 3.54s would be fine. might have to downshift occasionally with a 3.25.

[flathead 39]

Originally Posted by HDowse

Here's a link to a calculator that I used a lot to figure out my gearing/speed/rpm. You'll need your tire diameter as one of the factors. My 40 Fordor came with a 4.11, talk about screaming at 55, that lead me to buy a Mitchell OD, ends up an equivalent of a 3.10 +/-
I don’t think the 3.54 would make enough difference for you but the 3.25 would. Others with a 3.25 will know.
http://www.advanced-ev.com/Calculators/TireSize/

Thanks, I used that & charted all 3 ratios from 25mph to 70mph. Yea I was hoping to hear from a 3.25 user two.

[Ggmac]

Definitely more than my stock motor , you should be fine with the 325.

[Charlie ny]

39,
When you mentioned 1st gear for you is almost worthless made me wonder if you already had the 15/29 first gear in the trans now. Obviously third is still one to one
so high gear on the road won't change. The motors in my '32 and '41 pickups are near
what you are running and first gear for me is very worth while ,both trans have the 16/28 gear set.
The cam in my '32 makes power above 3000 rpm and the drivability went to hell when I changed to 3:78's from 4:11. Something to keep in mind as the rear gets taller.
I do have a Columbia with 3:78's in the '41 and in OD I think the ratio drops to 3:22
or somewhere close. The Max 1 cam has no problem motivating in OD.
Charlie ny

[flathead 39]

Originally Posted by Charlie ny

39,
When you mentioned 1st gear for you is almost worthless made me wonder if you already had the 15/29 first gear in the trans now. Obviously third is still one to one
so high gear on the road won't change. The motors in my '32 and '41 pickups are near
what you are running and first gear for me is very worth while ,both trans have the 16/28 gear set.
The cam in my '32 makes power above 3000 rpm and the drivability went to hell when I changed to 3:78's from 4:11. Something to keep in mind as the rear gets taller.
I do have a Columbia with 3:78's in the '41 and in OD I think the ratio drops to 3:22
or somewhere close. The Max 1 cam has no problem motivating in OD.
Charlie ny

I have a Schneider cam but don't know the #. It seems to have lots torque from very low rpm until I shut it down, probably around 3000 rpm (abt 70 mph). I'm pretty sure my trans will be ok with a 3.25.

[Kurt in NJ]

This chart may help

[Bill OH]

I am running a Max 1 cam in a 221 driving a 3.54 with 6.00 x 16 tires and the sweet spot is at 65mph. I am running in flat county and the acceleration is good.

[drolston]

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]

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]

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.

[Tinker]

I'd just setup to a 3:54 and see how it goes. Worked for years stock.

[flathead 39]

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Originally Posted by drolston

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.

Thanks. Wow, Practically a perfect match! I'll definitely go with the 3.25.

thanks for the info!

[flathead 39]

Thanks to all for your responses, I was going back and forth but have decided on the 3.25. This forum is amazing!

[john in illinois]

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

[flathead 39]

Originally Posted by john in illinois

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

Thanks, from the specs I got from the prev. owner, my cam is the Schneider P-3/8.

[gfriedr]

Put an overdrive in it like a 700r

[blucar]

Originally Posted by gfriedr

Put an overdrive in it like a 700r

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]

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]

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.

[19Fordy]

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."

[flathead 39]

Originally Posted by 19Fordy

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."

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]

Originally Posted by 19Fordy

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."

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.

[Old Redneck]

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]

Originally Posted by Old Redneck

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.

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]

Originally Posted by Old Redneck

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.

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.

[35fordtn]

I have the 3.25 and the 15/29 transmission gears in my 36 and so far I LOVE it..

[40 Deluxe]

Originally Posted by flathead 39

I shouldn't have any trouble getting rolling in 1st gear, It's almost worthless now.. with the 378 it' like a very close ratio xmission. I like using the gear shift & will like it even more when I get more proficient at double clutching.

If you have to double clutch going into 2nd or 3rd, you need new synchros. As far as 1st gear goes, you should rarely, if ever, need to shift to 1st while moving. Just wait to shift into 1st until you come to a complete stop.

[38 coupe]

Originally Posted by 35fordtn

I have the 3.25 and the 15/29 transmission gears in my 36 and so far I LOVE it..

A friend of mine put 3.25 gears in his 47 sedan years ago. It ran fine on the road, but wasn't much fun around town. The problem was 30 to 35 mph is where most in town drivers seemed to drive. 30 mph was as slow as third gear wanted, and 35 was getting wound out in second. Also, 30 in third was discharging the battery with the headlights on.

[drolston]

Originally Posted by 40 Deluxe

If you have to double clutch going into 2nd or 3rd, you need new synchros. As far as 1st gear goes, you should rarely, if ever, need to shift to 1st while moving. Just wait to shift into 1st until you come to a complete stop.

I am probably not the only one who likes to shift to low gear when turning into the driveway. I have pretty well mastered the double clutch down to first gear without crashing the gears. By "mastered", I mean I get it right about half the time.

[flathead 39]

I double clutch when I downshift in any gear. Still working on 2nd to 1st.. It's the heel & toe (gas & brake) that take practice. Was easy when I was kid..

[Fred A]

Testimonials like we have been getting here, although useful miss some of the finer points that effect the choice of final gear. I don't have to go beyond the guys in the clubs who may be large believers in their gear own choices but may fail to consider the rest of the engineering picture. Strong in the elements show up where trans ratio (popular Zephyr sets?), over cammed engines, light flywheels, vehicle weight, and even tire size. Judgements like "I love it!" or " 3.54 is great". How about 4.11 with overdrive? I might like that one. Finer points? Don't need no stinkkin finer points! We hear 4.11 is for pulling stumps. 3.54 is cruising gear. Blah, Blah, Blah! Like Fauchi says, "Go with the science" Good Luck: Fred A

[Old Redneck]

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My 32 Ford I know the gears in the rear are not 411 maybe 378. It drives nice and at 45 MPH. My 35 Pickup has 354 and runs nice at 50 no juice brakes. My 40 Ford has 354 and I wish it had 325 to run quiet as my Buddy 40 2 door sdn. He had 411 in it and I talk him in putting 325 in it. He came in to take me a ride in it with the 325. He so happy with them and in his 40 stock engine they work super nice. Now maybe in my 35 they might be to tall. You got to ride in a car 40 or newer with 325 to know how they preform. I wish I had 325 in my 40 Ford Conv. Now Model A's yes 354. My 39 Conv. has a Columbia with 378 and My buddy'40 is a lot nicer on the open road. Now we live in steep hills and Mountains his 40 no problem going up them. He stays in high gear unless he has to slow up for traffic. Until you try them you have no idea about 325 gears preform.