The Ford Barn

Model A Ron · 12-20-2022, 10:56 PM

Anyone running a 3.54 or a 3.25 ring and pinion over the stock 3.78? If so what are your thoughts?

jeepguy1948 · 12-20-2022, 11:57 PM

A friend of mine installed a 354 and had to take his overdrive out it was just too much.

Benson · 12-21-2022, 12:19 AM

....

Dodge · 12-21-2022, 12:32 AM

3.78 with overdrive, 3.54 with a high compression head and touring cam no overdrive.
3.25 same as 3.54 but on flat ground no hills.

My 2 cents

Model A Ron · 12-21-2022, 06:11 AM

The Mitchell 26% OD takes the 3.78 down to 2.8. With a 3.54 its 2.62.

Model A Ron · 12-21-2022, 06:14 AM

Sponsored Links (Register now to hide all advertisements)

The Mitchell 26% OD takes the 3.78 down to 2.8. With a 3.54 its 2.62. If you ran an OD with the 3.25 it would be 2.4

springerpete · 12-21-2022, 07:16 AM

When I got my roadster the ring gear was bad. Replaced it with 3.54 set. 9000 miles later I am still satisfied with the performance. Lots of local trips, 20,30 miles. Some over 100. Good performance and 17-18 mpg. This is a 35-45 mph car. Bill

old31 · 12-21-2022, 07:51 AM

Quote:

Originally Posted by Model A Ron

The Mitchell 26% OD takes the 3.78 down to 2.8. With a 3.54 its 2.62. If you ran an OD with the 3.25 it would be 2.4

Curious, how is the math done on this to get to the end number?

Mike Peters · 12-21-2022, 10:39 AM

3.78 times .26=.983. 3.78-.983=2.787, or 2.8. .26 is the same as 26%.
Same calculation for other ratios.

Mike Peters · 12-21-2022, 10:42 AM

3.78-.983=2.797. even closer to 2.8

Mike Peters · 12-21-2022, 10:46 AM

I agree with others above that the 3.25 rear end ratio with a stock engine will be too much. Your car will die on hills and headwinds.
Been there, done that with a stock 35 Ford, and put a 3.78 back in the car. A Model A will be similar.

Seth Swoboda · 12-21-2022, 11:07 AM

I run a 3.54 in a '47 Tudor. Flathead powered, all stock engine. It's perfect for cruising. I know it's not Model A but I like the 3.54 in the V8's.

MrBruce · 12-21-2022, 11:28 AM

Hey Ron, I've run 3:54 in our 31 S/W Town Sedan with a B motor for 45 years, it's run great but will be putting in a Mitchell and probably go back to 3:78 gears.

Benson · 12-21-2022, 12:00 PM

Update: 12-30-22

Engine is and was Fresh rebuild Model B with 5.2 Police Head (Head with the LARGE B)

I removed 3.54 and put 3.78s in.

Installed Mitchell with 15% 1st / 15% 2nd. With 26% Mitchell over drive.

Still too high in OD LOW range for driving on "real back road" mountain roads.

Plan is to put the 4.11 rear-end back in and use the 26% Mitchell to drive above 50 MPH.

Jim Brierley · 12-21-2022, 12:05 PM

As Benson and others have stated above, it depends on many other things. I ran a 3.27
:1 R&P in my speedster for awhile, it is a light car and I live in mostly flat country. It was fine on the highway but not so good from the stop light. I switched to a quick-change so I can run the highway or on hill climbs, as-needed. My widebed has 4.11's and a 26% Colombia, I love it!

Benson · 12-21-2022, 12:50 PM

deleted

Joe K · 12-21-2022, 02:37 PM

Newly rebuilt upgraded (HC head, Model B intake manifold, right cam) and a "lighter" vehicle (i.e. pickups, roadster, coupe, possibly Tudor) I would go with the 3.27.

Reasonable engine in good shape, not upgraded, light or medium vehicle loaded with family and used regularly nearing 55mph do the 3.54.

Worn engine not upgraded, little need to go above 55 do the 3.78.

I have the 3.54 in my 29CC pickup. On the trip moving the vehicle to New Hampshire, I had my Dad follow behind me in the family wagon - a "just in case."

We traveled Route 110 from Central Massachusetts all the way up into SE NH, traveling through every small town along way. The rationale being to stay off of a major highway namely Route 495 in case there was an issue with 55mph. (The then state speed limit, although most went faster.)

I did not have the proper gears to make the speedometer "correct." So my actual speed appearing to me was a conjecture.

On our successful arrival in New Hampshire, Dad says to me "Yunno, at times you were going faster than 65mph on those back roads - maybe you should hold it down being the brakes are as they are (i.e. not real good) on your truck?"

So maybe the highway would have been a safer option?

Joe K

Bruce of MN · 12-21-2022, 03:39 PM

The correct math is 3.78 / 1.26 = 3.00. No subtraction with gear ratios.

rfitzpatrick · 12-21-2022, 04:12 PM

When my 3:78 went bad - upgraded to 3:54. PicUp is entirely stock - I have no idea if gas milage improved -- don't care either. An excellent purchase for South Florida

Terry, NJ · 12-21-2022, 04:46 PM

When my rear went bad in my coupe, I went to the 3.54 and I've never looked back! I love it! It climbs hills much better. It gets better mileage! The engine runs slower. I live in this rock pile in Northern Bucks , Pa. It does better on the hills than before. I am running a"Head", ratio unknown,"B' manifold and Carb (estimate 45 to 50 HP) and that's it! Much improved!
Terry

12-20-2022, 10:56 PM	#1
Model A Ron Senior Member Join Date: Feb 2021 Location: Troutman, NC Posts: 717	Ring and Pinion 3.78, 3.54 or 3.25 Anyone running a 3.54 or a 3.25 ring and pinion over the stock 3.78? If so what are your thoughts?

12-20-2022, 11:57 PM	#2
jeepguy1948 Senior Member Join Date: Jan 2022 Posts: 721	Re: Ring and Pinion 3.78, 3.54 or 3.25 A friend of mine installed a 354 and had to take his overdrive out it was just too much.

12-21-2022, 12:19 AM	#3
Benson Senior Member Join Date: May 2010 Posts: 2,599	Re: Ring and Pinion 3.78, 3.54 or 3.25 .... Last edited by Benson; 12-21-2022 at 12:00 PM.

12-21-2022, 12:32 AM	#4
Dodge Senior Member Join Date: Nov 2011 Location: Sonoma, CA. Posts: 1,497	Re: Ring and Pinion 3.78, 3.54 or 3.25 3.78 with overdrive, 3.54 with a high compression head and touring cam no overdrive. 3.25 same as 3.54 but on flat ground no hills. My 2 cents

12-21-2022, 06:11 AM	#5
Model A Ron Senior Member Join Date: Feb 2021 Location: Troutman, NC Posts: 717	Re: Ring and Pinion 3.78, 3.54 or 3.25 The Mitchell 26% OD takes the 3.78 down to 2.8. With a 3.54 its 2.62.

12-21-2022, 06:14 AM	#6
Model A Ron Senior Member Join Date: Feb 2021 Location: Troutman, NC Posts: 717	Re: Ring and Pinion 3.78, 3.54 or 3.25 Sponsored Links (Register now to hide all advertisements) The Mitchell 26% OD takes the 3.78 down to 2.8. With a 3.54 its 2.62. If you ran an OD with the 3.25 it would be 2.4

12-21-2022, 07:16 AM	#7
springerpete Senior Member Join Date: Jul 2012 Location: Central Maine Posts: 644	Re: Ring and Pinion 3.78, 3.54 or 3.25 When I got my roadster the ring gear was bad. Replaced it with 3.54 set. 9000 miles later I am still satisfied with the performance. Lots of local trips, 20,30 miles. Some over 100. Good performance and 17-18 mpg. This is a 35-45 mph car. Bill

12-21-2022, 10:39 AM	#9
Mike Peters Senior Member Join Date: Aug 2012 Location: South East Wisconsin Posts: 1,279	Re: Ring and Pinion 3.78, 3.54 or 3.25 3.78 times .26=.983. 3.78-.983=2.787, or 2.8. .26 is the same as 26%. Same calculation for other ratios.

12-21-2022, 10:42 AM	#10
Mike Peters Senior Member Join Date: Aug 2012 Location: South East Wisconsin Posts: 1,279	Re: Ring and Pinion 3.78, 3.54 or 3.25 3.78-.983=2.797. even closer to 2.8

12-21-2022, 10:46 AM	#11
Mike Peters Senior Member Join Date: Aug 2012 Location: South East Wisconsin Posts: 1,279	Re: Ring and Pinion 3.78, 3.54 or 3.25 I agree with others above that the 3.25 rear end ratio with a stock engine will be too much. Your car will die on hills and headwinds. Been there, done that with a stock 35 Ford, and put a 3.78 back in the car. A Model A will be similar.

12-21-2022, 11:07 AM	#12
Seth Swoboda Senior Member Join Date: May 2010 Location: Southern Illinois Posts: 3,795	Re: Ring and Pinion 3.78, 3.54 or 3.25 I run a 3.54 in a '47 Tudor. Flathead powered, all stock engine. It's perfect for cruising. I know it's not Model A but I like the 3.54 in the V8's.

12-21-2022, 11:28 AM	#13
MrBruce Senior Member Join Date: Oct 2014 Location: Charlotte, NC Posts: 310	Re: Ring and Pinion 3.78, 3.54 or 3.25 Hey Ron, I've run 3:54 in our 31 S/W Town Sedan with a B motor for 45 years, it's run great but will be putting in a Mitchell and probably go back to 3:78 gears.

12-21-2022, 12:00 PM	#14
Benson Senior Member Join Date: May 2010 Posts: 2,599	Re: Ring and Pinion 3.78, 3.54 or 3.25 Update: 12-30-22 Engine is and was Fresh rebuild Model B with 5.2 Police Head (Head with the LARGE B) I removed 3.54 and put 3.78s in. Installed Mitchell with 15% 1st / 15% 2nd. With 26% Mitchell over drive. Still too high in OD LOW range for driving on "real back road" mountain roads. Plan is to put the 4.11 rear-end back in and use the 26% Mitchell to drive above 50 MPH. Last edited by Benson; 12-30-2022 at 12:11 PM.

12-21-2022, 12:05 PM	#15
Jim Brierley Senior Member Join Date: Jun 2010 Location: Temecula, CA Posts: 4,089	Re: Ring and Pinion 3.78, 3.54 or 3.25 As Benson and others have stated above, it depends on many other things. I ran a 3.27 :1 R&P in my speedster for awhile, it is a light car and I live in mostly flat country. It was fine on the highway but not so good from the stop light. I switched to a quick-change so I can run the highway or on hill climbs, as-needed. My widebed has 4.11's and a 26% Colombia, I love it!

12-21-2022, 12:50 PM	#16
Benson Senior Member Join Date: May 2010 Posts: 2,599	Re: Ring and Pinion 3.78, 3.54 or 3.25 deleted Last edited by Benson; 12-24-2022 at 08:29 AM. Reason: Spelling and grammer

12-21-2022, 02:37 PM	#17
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Ring and Pinion 3.78, 3.54 or 3.25 Newly rebuilt upgraded (HC head, Model B intake manifold, right cam) and a "lighter" vehicle (i.e. pickups, roadster, coupe, possibly Tudor) I would go with the 3.27. Reasonable engine in good shape, not upgraded, light or medium vehicle loaded with family and used regularly nearing 55mph do the 3.54. Worn engine not upgraded, little need to go above 55 do the 3.78. I have the 3.54 in my 29CC pickup. On the trip moving the vehicle to New Hampshire, I had my Dad follow behind me in the family wagon - a "just in case." We traveled Route 110 from Central Massachusetts all the way up into SE NH, traveling through every small town along way. The rationale being to stay off of a major highway namely Route 495 in case there was an issue with 55mph. (The then state speed limit, although most went faster.) I did not have the proper gears to make the speedometer "correct." So my actual speed appearing to me was a conjecture. On our successful arrival in New Hampshire, Dad says to me "Yunno, at times you were going faster than 65mph on those back roads - maybe you should hold it down being the brakes are as they are (i.e. not real good) on your truck?" So maybe the highway would have been a safer option? Joe K __________________ Shudda kept the horse.

12-21-2022, 03:39 PM	#18
Bruce of MN Senior Member Join Date: May 2010 Location: VA Posts: 1,410	Re: Ring and Pinion 3.78, 3.54 or 3.25 The correct math is 3.78 / 1.26 = 3.00. No subtraction with gear ratios.

12-21-2022, 04:12 PM	#19
rfitzpatrick Senior Member Join Date: May 2018 Location: Coral Springs, Florida Posts: 552	Re: Ring and Pinion 3.78, 3.54 or 3.25 When my 3:78 went bad - upgraded to 3:54. PicUp is entirely stock - I have no idea if gas milage improved -- don't care either. An excellent purchase for South Florida

12-21-2022, 04:46 PM	#20
Terry, NJ Senior Member Join Date: May 2010 Location: Bucks Co, Pa Posts: 3,740	Re: Ring and Pinion 3.78, 3.54 or 3.25 When my rear went bad in my coupe, I went to the 3.54 and I've never looked back! I love it! It climbs hills much better. It gets better mileage! The engine runs slower. I live in this rock pile in Northern Bucks , Pa. It does better on the hills than before. I am running a"Head", ratio unknown,"B' manifold and Carb (estimate 45 to 50 HP) and that's it! Much improved! Terry