Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 11-11-2019, 10:30 PM   #1
Racur96
Senior Member
 
Racur96's Avatar
 
Join Date: Jul 2011
Location: lawrenceburg, tn
Posts: 117
Default Gear ratio

Hey everyone, Iíve been thinking of upgrading my rear gear ratio to be a little more highway friendly. Stock engine . Just curious if anyone had done this and what ratio you chose?
Racur96 is offline   Reply With Quote
Old 11-12-2019, 02:33 AM   #2
J Franklin
Senior Member
 
J Franklin's Avatar
 
Join Date: May 2010
Location: oregon
Posts: 3,968
Default Re: Gear ratio

Lots of people have done it but you need a ratio that conforms to the weight of your car and the hilliness of the terrain you most drive in.
J Franklin is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 11-12-2019, 10:43 AM   #3
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Location: Wisconsin
Posts: 1,606
Default Re: Gear ratio

I had my truck changed from 4.11 to 3.54. Am satisfied, but I drive lower speeds 45 mph is usually max. Motor is rebuilt, Standard head, but not balanced or built for touring. It will do 55-60, but is in the 2200 - 2400 rpm range maxed out, which personally I do not think is good for a standard motor, especially for more than a few minutes.


Most people who want to run higher speeds 55-60 use a high compression head, touring built motor, brakes and suspension/front end in tip top shape, radial tires, and a Mitchell overdrive with I believe 3.78 rear end (not 100% sure of 3.78). Quite a few also add an oil filter.


If you get the wrong component mix you may have OK speed/RPM, but be lacking in ability to take on hills without shifting way down (lack of torque). This is additional info on J Franklin's Post.


If going to a 3.24 rear end without a Mitchell, consider a high compression head, which also means the motor should be fairly fresh with good compression and Babbitt or Insert bearings to handle the extra load of higher compression and lower RPMs/loads.
30 Closed Cab PU is offline   Reply With Quote
Old 11-12-2019, 11:39 AM   #4
Jim Brierley
Senior Member
 
Join Date: Jun 2010
Location: Temecula, CA
Posts: 2,938
Default Re: Gear ratio

3.54:1 will help, 3.27:1 may be too much for a stock engine?
Jim Brierley is offline   Reply With Quote
Old 11-12-2019, 11:50 AM   #5
wmws
Senior Member
 
wmws's Avatar
 
Join Date: Feb 2013
Location: Coatesville, Pa
Posts: 554
Default Re: Gear ratio

All good advice above. Just to give you some figures.
A standard 3.78 rear at 2000 RPM = 46 MPH
A 3.78 rear with a 26% Mitchell OD at 2000 RPM = 58 MPH
A 3.54 with no OD at 2000 RPM = 49 MPH
A 3.24 with no OD at 2000 RPM = 53 MPH
I have the Mitchell and am happy with it. A little spendy but relatively easy to install.
wmws is offline   Reply With Quote
Old 11-12-2019, 11:51 AM   #6
Mike Peters
Senior Member
 
Mike Peters's Avatar
 
Join Date: Aug 2012
Location: South East Wisconsin
Posts: 643
Default Re: Gear ratio

I installed a Mitchel 26% overdrive last summer in our Tudor and am very happy. Best of both worlds. Overdrive for country driving and standard drive around town. 3.78 rear end ratio. Stock engine with stock head handles it very well. When installing the Mitchel, I replaced an old Borg Warner 33% overdrive in the same car, same engine. Honestly, the Borg pulled too hard for that engine. Any hill or headwind was too much, and always had to shift back to standard.
Mike Peters is offline   Reply With Quote
Old 11-12-2019, 12:00 PM   #7
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Location: Wisconsin
Posts: 1,606
Default Re: Gear ratio

Quote:
Originally Posted by wmws View Post
All good advice above. Just to give you some figures.
A standard 3.78 rear at 2000 RPM = 46 MPH
A 3.78 rear with a 26% Mitchell OD at 2000 RPM = 58 MPH
A 3.54 with no OD at 2000 RPM = 49 MPH
A 3.24 with no OD at 2000 RPM = 53 MPH
I have the Mitchell and am happy with it. A little spendy but relatively easy to install.
wmws - That's great info. Thanks for posting it. Perhaps I missed this info before, but do not remember seeing this comparison when researching 2 years ago when figuring out what to do. With the 4.11 I could not comfortably keep up with my club at 40 mph.
30 Closed Cab PU is offline   Reply With Quote
Old 11-12-2019, 12:06 PM   #8
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Location: Wisconsin
Posts: 1,606
Default Re: Gear ratio

Quote:
Originally Posted by Jim Brierley View Post
3.54:1 will help, 3.27:1 may be too much for a stock engine?


I believe it depends on your model car (Fordor vs. Pickup/coupe), what shape the motor is in, and what grades you are going to pull. For occasional hills it I've heard it will be OK with Stock, but in foot hills, mountains, steeper grades, and longer grades you may be needing a high compression head, especially if you do not have a Mitchell.


Hopefully others can chime in who live in hilly/mountainous areas that have 1st hand experience.
30 Closed Cab PU is offline   Reply With Quote
Old 11-12-2019, 12:07 PM   #9
Purdy Swoft
Senior Member
 
Purdy Swoft's Avatar
 
Join Date: May 2010
Location: Alabama
Posts: 7,464
Default Re: Gear ratio

I prefer the 3.78 gear ratio . Henry thought that the 3.78 ratio was best for the model A . Low and mid range power is more important than actual top speed for me . For the most part , fifty MPH is fast enough for the model A .


My original mechanical brakes are as good as most hydraulic brakes . I feel that a person would be lucky if they survived a wreck at 55-60 MPH in a model A .
Purdy Swoft is offline   Reply With Quote
Old 11-12-2019, 12:10 PM   #10
GPierce
Senior Member
 
GPierce's Avatar
 
Join Date: Dec 2014
Location: Germantown,TN
Posts: 195
Default Re: Gear ratio

Quote:
Originally Posted by wmws View Post
I have the Mitchell and am happy with it. A little spendy but relatively easy to install.
What rear end do you have?
GPierce is offline   Reply With Quote
Old 11-12-2019, 12:21 PM   #11
Joe K
Senior Member
 
Joe K's Avatar
 
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 3,397
Default Re: Gear ratio

I converted my 29 CC pickup to 3.54. Driving it from my parents house in mid-Massachusetts to my new house in Seacoast NH I was followed on the way by my father with "tools, spare parts" and his somewhat familiarity with the car - and a tow cable.

The engine was newly replaced and still on the initial trials - hence the insecurity on my part. (what if we did something wrong?)

We followed the back-roads rather than the more time effective and then quite new Route 495. Route 110 figured heavily in my navigation which is a road which passes through the center of EVERY small town on the way - my rationale being I'd rather coast into a local garage for service by someone who MAY know cars, or leave myself to a "towing service" of unknown destination and probably not trivial cost.

On our trip, I attempted to maintain the speed limits, whatever it was. There are sections of Route 110 which are posted (then) 55mph, and a lesser 40mph as one approaches towns dropping to even 25 within the town limits.

Meanwhile, my speedometer was at best "approximate" and somewhat "in and out." Some issue then and suddenly with the cable ends and pot metal gears?

On our arrival in NH with no problems and having made good time my father had commentary for me. "You drive too fast - you were up to 68 mph at times in a car which you shouldn't be driving half that fast because of your brakes."

I really had no sense of going that fast. The car took it well albeit the soft top on that CC pickup can really get to "fluttering." above 60.

Since then I have resolved both of the speedo issues (broken cable and the cable would "catch" and do a couple of dozen turns and then "disengage", plus the gear ratio correction.)

Joe K
__________________
Shudda kept the horse.
Joe K is offline   Reply With Quote
Old 11-12-2019, 12:29 PM   #12
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Location: Wisconsin
Posts: 1,606
Default Re: Gear ratio

Joe - Was that with Stock compression Head and stock components? With or without a Mitchell?. I just do not understand, my late 30 comes no where close to that.
30 Closed Cab PU is offline   Reply With Quote
Old 11-12-2019, 12:37 PM   #13
31Tudor
Senior Member
 
31Tudor's Avatar
 
Join Date: May 2010
Location: North Carolina
Posts: 427
Default Re: Gear ratio

With a stock engine in a 28 pickup, with a 3:54 rear end, I can run 50-55 all day. Going up into the NC mountains, with that set up, on club touring events, I see no difference in shifts points compared to anyone else. I do think a 3:54 on a 4 door in a hilly area, you may see a difference.
31Tudor is offline   Reply With Quote
Old 11-12-2019, 12:43 PM   #14
wmws
Senior Member
 
wmws's Avatar
 
Join Date: Feb 2013
Location: Coatesville, Pa
Posts: 554
Default Re: Gear ratio

Originally Posted by wmws View Post
I have the Mitchell and am happy with it. A little spendy but relatively easy to install.

I have the 3.78 rear. The nice thing about the Mitchell is if on a hill you can go from 3rd OD to 3rd standard to 2nd OD and even to 2nd standard although I have not found a hill yet that I can't make in 2nd OD.
wmws is offline   Reply With Quote
Old 11-12-2019, 12:56 PM   #15
31Abone
Senior Member
 
31Abone's Avatar
 
Join Date: Apr 2013
Location: Big pine Ca 93513
Posts: 705
Default Re: Gear ratio

Have 32 "B" PU ..had 4:11 had Tom Endy put 3:54 works good about 55 mph..no cigar but about right for 4 cyl...but a 21 stud v8 32 needs 3:27 for sure for 55 -60 mph range...these old rigs don't feel good above 60..not safe
31Abone is offline   Reply With Quote
Old 11-12-2019, 01:30 PM   #16
Joe K
Senior Member
 
Joe K's Avatar
 
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 3,397
Default Re: Gear ratio

Quote:
Originally Posted by 30 Closed Cab PU View Post
Joe - Was that with Stock compression Head and stock components? With or without a Mitchell?. I just do not understand, my late 30 comes no where close to that.
Stock everything except for the Tillotson X.

I have no positive verification of the speed so part of this may be my Dad's parental exaggeration.

But I drove the same 3.54 rear end with a VERY worn out painted red Allstate engine at 55 on the Mid-Cape Highway at Rush Hour - and have told my tale about losing a connecting rod nut - and tenderly driving it home a couple of miles off the Mid-Cape.

With the 3.54 most any engine/car should do 55mph - easily and no sense of imminent dissolution.

Joe K
__________________
Shudda kept the horse.

Last edited by Joe K; 11-12-2019 at 01:51 PM.
Joe K is offline   Reply With Quote
Old 11-12-2019, 02:24 PM   #17
Kurt in NJ
Senior Member
 
Kurt in NJ's Avatar
 
Join Date: May 2010
Location: on the Littlefield
Posts: 4,863
Default Re: Gear ratio

At work many of the customers know about my A, they would tell stories of the A they had in college, driving several hundred miles home and to girl friends places, they all said they drove over 55, but that there were stops for oil, that they got the used oil most times, they never worried about driving "too fast", but that it always got them there, and would have been faster if they didn't have to stop for oil so often
I have stock rear ratio, don't worry about driving over 55, have driven all day at 65+
Kurt in NJ is offline   Reply With Quote
Old 11-12-2019, 02:49 PM   #18
J Franklin
Senior Member
 
J Franklin's Avatar
 
Join Date: May 2010
Location: oregon
Posts: 3,968
Default Re: Gear ratio

Quote:
Originally Posted by Kurt in NJ View Post
At work many of the customers know about my A,----
I have stock rear ratio, don't worry about driving over 55, have driven all day at 65+
I don't think your story is too useful to most new model A owners.They should drive more conservatively and keep the engines going longer.
J Franklin is offline   Reply With Quote
Old 11-12-2019, 03:15 PM   #19
Tom Endy
Senior Member
 
Tom Endy's Avatar
 
Join Date: May 2010
Location: Southern California
Posts: 2,482
Default Re: Gear ratio

Quote:
Originally Posted by wmws View Post
Originally Posted by wmws View Post
I have the Mitchell and am happy with it. A little spendy but relatively easy to install.

I have the 3.78 rear. The nice thing about the Mitchell is if on a hill you can go from 3rd OD to 3rd standard to 2nd OD and even to 2nd standard although I have not found a hill yet that I can't make in 2nd OD.

My recommendation is to install a Mitchell 26% overdrive. This will give you many advantages. High gear overdrive for going above 45 mph comfortably and second gear overdrive for going up and down steep grades. The cost is about $2500, about twice the cost of changing out the ring & pinion. However, it is a good investment as it adds to the value of the car and it can be removed without leaving alteration to the car and they are easily sold.

Tom Endy
Tom Endy is online now   Reply With Quote
Old 11-12-2019, 04:02 PM   #20
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 4,509
Default Re: Gear ratio

Quote:
Originally Posted by wmws View Post
Originally Posted by wmws View Post
I have the Mitchell and am happy with it. A little spendy but relatively easy to install.

I have the 3.78 rear. The nice thing about the Mitchell is if on a hill you can go from 3rd OD to 3rd standard to 2nd OD and even to 2nd standard although I have not found a hill yet that I can't make in 2nd OD.
The motor in my Phaeton is very good but even then, there are hills I have to climb out of my place even before I get to the main road that require a bit of skill to get up even in standard 1st gear when I'm towing my camper. It weighs about a tonne and I have to zig zag my way up the hill to get there. Once out in the open, I am very happy with the 3.78 rear end and 26% Mitvhell O/D. We travel at 50 mph all day, every day (our longest single trip so far has been 14,000 miles)
At the other end of the scale, I have a 1928 Tudor with a B motor. The motor is fitted with a 5.5 head and Stromberg downdraught carburettor. The rear end is 3.54 and there is another 26% Mitchell in front of that. I find that to be too much. Fuel economy is terrible, it almost stops if a hill even comes into view, it is hard work driving it and it hates a head wind. The tyres were getting low so I recently put a set of 19" wheels on it hoping that the slightly smaller diameter would help. It did not. I see a 3.78 set of gears going into the rear end of that car pretty soon - once I save up o buy them.
__________________
Pulsing like a beacon through the days and nights, one's birthplace sends out its invisible waves of recollection. It always has and it always will, until even the last of us come home. : Clive James
Synchro909 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 02:19 AM.