3.27 Gear without an Overdrive

[Model A Ron]

I would like to hear from people who are running a 3.27 rear end without an overdrive. Would you get a 3.27 if you had to do it again?

I have a fresh engine that will be getting a HC head and I would like to build this one without an OD.

[Bruce of MN]

My coupe with 3.78 gears and 6:1 head does pretty good on a long grade in high, but I don’t think it would do so well with 3.27s. Getting up to speed from a stop would be even more leisurely, also.

[Ruth]

What body style Model A? A Heavier car like a Town Sedan or a lighter car like a Roadster? It does make a difference. Is it the Phaeton in your Avatar?

[Model A Ron]

Originally Posted by Ruth

What body style Model A? A Heavier car like a Town Sedan or Roadster. It does make a difference. Is it the Phaeton in your Avatar?

I have a 29 Phaeton but the care I am considering the 3.27 for is my 31 Victoria project.

[Oldgearz]

I have a 30 Coupe with a 3.27 rear. My car has a B zenith Carb (the only difference from an A Zenith carb is the presence of a power jet), a B camshaft, modern upper distributor plate, a Snyder's 5.5 head, and a V8 clutch set-up. No overdrive. The car has excellent acceleration and hill pulling power. I love it. Would never think of any other rear end ratio. I can start out in 2nd, but don't do so to reduce clutch plate wear. However, I still turn a lot of RPM's (don't really know how many) at 50mph and am uncomfortable at 55 mph. I am going to put a Mitchell OD in it, and have been waiting 4 months on a waiting list to get one. Car should be really sweet then with a 26% reduction in rpm's engine will be doing 45 mph and car will be doing 55-60 mph. I have no fears that the engine can't handle the OD with the 3.27 differential.

[Model A Ron]

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Originally Posted by Oldgearz

I have a 30 Coupe with a 3.27 rear. My car has a B zenith Carb (the only difference from an A Zenith carb is the presence of a power jet), a B camshaft, modern upper distributor plate, a Snyder's 5.5 head, and a V8 clutch set-up. No overdrive. The car has excellent acceleration and hill pulling power. I love it. Would never think of any other rear end ratio. I can start out in 2nd, but don't do so to reduce clutch plate wear. However, I still turn a lot of RPM's (don't really know how many) at 50mph and am uncomfortable at 55 mph. I am going to put a Mitchell OD in it, and have been waiting 4 months on a waiting list to get one. Car should be really sweet then with a 26% reduction in rpm's engine will be doing 45 mph and car will be doing 55-60 mph. I have no fears that the engine can't handle the OD with the 3.27 differential.

Good to know you have no issues with the 3.27. If I have my math right the 3.27 is a 15.5% overdrive from the standard 3.78.

[johnneilson]

I run a 3.27 gear in my BVille car, right about 165 mph at the 2 mile mark....

John

[old ugly]

Originally Posted by johnneilson

I run a 3.27 gear in my BVille car, right about 165 mph at the 2 mile mark....

John

its a good thing there aren't many hills.

[Model A Ron]

I took my 29 out today for ride in Mitchel high and that was a bit to much being a 26% overdrive or a 3.00 to one ratio. the 3.27 would give the same effect as 15.5% full time overdrive when compared to the standard 3.78. With a high compression head and a strong engine that is doable. Sure she will be a little slow off the line but very happy at 40 to 50 mph.

[nkaminar]

Model A Ron, I would advise against 3.27 in North Carolina unless you stay in the flats. It also depends on how you drive your car. Do you spend more time going on back roads or the interstate? Do you drive it into town or on long road trips? Ford put the 4.11 gears in cars that were shipped to mountain areas. I still think an overdrive is a better solution.

[jwmckenzie]

I didn't think the 3.27 was available any more, so took a look as Snyder's, they now offer a 3.25.

[DJ S]

I would not recommend 3.27s to anyone with a Victoria in a hilly area. My Victoria with a healthy stock motor and 3.78s has a tough time with some of the bigger hills around here. A fellow club member experiences the same issue with his Victoria and has installed a Mitchell in one of them. I have a Mitchell on order and can’t wait for it to come in.

[denis4x4]

This A powered hot rod weighs 1700 pounds and pulled 60HP at the rear wheels on a dyno. I tried a 3:27 and found it wanting, even with a '39 transmission and lightened flywheel. I live at 6700' and there are plenty of hills around here. Went back to 3:54 and pleased with the performance. The '29 CCPU in my avatar has a B engine with a CRAGAR head and a T-5 transmission that is the answer from my perspective.

[Model A Ron]

Originally Posted by nkaminar

Model A Ron, I would advise against 3.27 in North Carolina unless you stay in the flats. It also depends on how you drive your car. Do you spend more time going on back roads or the interstate? Do you drive it into town or on long road trips? Ford put the 4.11 gears in cars that were shipped to mountain areas. I still think an overdrive is a better solution.

Most of my driving is between 40 and 55 on country roads. I am about 50 miles from the foot hills so for the most part the roads are flat with the occasional small to medium sized hill. I am looking to put a 3.27 into my new project a 1931 Victoria as an alternative to an OD.

The Mitchel OD at 26% with 3.78 gears is wonderful......I have one in my 29 Phaeton and love it. Top end in overdrive is well over 60 but you could drive all day long at 55 to 60 without issue. That said I do not want to go much over 50 with most of my driving. The car will do it but you need to think about the limitations of a car designed for use 90 years back. That said the 3.27 is the equivalent to a 15.5% full time overdrive with 3.78 gears.

Starting off in Mitchel high with the equivalent of 3.00 to one gearing is to much and too slow to get up to speed. The 3.27 should be a slow start but doable and happy between 35 and 50 in my opinion.

[DJ S]

Originally Posted by Model A Ron

Most of my driving is between 40 and 55 on country roads. I am about 50 miles from the foot hills so for the most part the roads are flat with the occasional small to medium sized hill. I am looking to put a 3.27 into my new project a 1931 Victoria as an alternative to an OD.

The Mitchel OD at 26% with 3.78 gears is wonderful......I have one in my 29 Phaeton and love it. Top end in overdrive is well over 60 but you could drive all day long at 55 to 60 without issue. That said I do not want to go much over 50 with most of my driving. The car will do it but you need to think about the limitations of a car designed for use 90 years back. That said the 3.27 is the equivalent to a 15.5% full time overdrive with 3.78 gears.

Starting off in Mitchel high with the equivalent of 3.00 to one gearing is to much and too slow to get up to speed. The 3.27 should be a slow start but doable and happy between 35 and 50 in my opinion.

If most of your driving is between 40-55 then 3.54’s will be more than adequate...

[ThosD]

Originally Posted by Model A Ron

Good to know you have no issues with the 3.27. If I have my math right the 3.27 is a 15.5% overdrive from the standard 3.78.

This may be a trivial observation. Typically, percent change is calculated from the starting value. The difference of 0.51 between the two ratios would be divided by 3.78; yielding a 13.5% change. What really matters is the way your car performs.

I am curious if there is a change when accelerating from a stop. Faster or slower? With enough torque a light car maybe faster. Having a 3.78 with OD is an expensive way to have it both ways.

[BRENT in 10-uh-C]

Originally Posted by Model A Ron

I would like to hear from people who are running a 3.27 rear end without an overdrive. Would you get a 3.27 if you had to do it again?

I have a fresh engine that will be getting a HC head and I would like to build this one without an OD.

FWIW, I actually DO have multiple firsthand experiences running a 3.27 ratio in many different bodystyles and terrains, ...and yes I have one in my own vehicle.

Going further, I actually have a 3.25 ratio in a couple of my Model-Ts, and one with a 3.0 ratio and all of my cars have many miles on them from touring all over this country. What I always find sad (-not just here but in other forums & social media formats too) is there will be ones that give their opinion on what won't work well or why it wont work well however when truth is known, in reality they have never actually had any firsthand experience with the advice they are giving to someone else. It's like the person asking the question must decide the correct answer to his question first by needing to determine whether the advice he is given is actually factual or just fiction. There was a time in my life when I remember it wasn't that way.

[Hitman]

...

[J Franklin]

My only experience with ratio changes was when I was a kid and didn't know anything and installed a 4.11 rear axle. I didn't even go around the block before I removed it for a 3.78. It was like 3rd gear was 2nd. I have thought of a 3.54 but the difference I experienced back then keeps me from changing things. My car cruises at 50 easy enough as it is.

[Benson]

Brent,

My experience with 3.54 with a Fresh B engine with unknown reground cam by Mike Reichter is low end torque is lacking and as such pulling hills or mountain roads is not what I remember from 1962 to 1975 (40,000 miles) with a worn out Model A engine with a worn A camshaft.

I have no idea what cam Mike was using in 1989 (except that it was a regrind) and he since died.

Do the 3.25 cars that you mention have reground camshafts or Stipe IB330 or IB340 cams?

I wonder if reground cams raise torque curve too high to work with the lower RPMs of a 3.54 / 3.25?

I removed the 3.54 7 years ago and used a 3.78 which is in car now ... it works much better than 3.54.

This Coupe is run from 6000 to 11,000 feet.

Thank you

[Ruth]

I'm curious, does anyone have a 36% Mitchell O/D? How does it compare to the 26% O/D. I have the 26% and like I have said before, I use it more like an underdrive, keeping the Mitchell in O/D most of the time and downshifting the Mitchell as needed for hills.

[updraught]

Maybe fit a tachometer and work out what range the engine pulls in to start with. I think this is what Ford would have done.

[Model A Ron]

Originally Posted by Ruth

I'm curious, does anyone have a 36% Mitchell O/D? How does it compare to the 26% O/D. I have the 26% and like I have said before, I use it more like an underdrive, keeping the Mitchell in O/D most of the time and downshifting the Mitchell as needed for hills.

Mitchel will tell you the 36% was made for the 4.11 gears.

4.11 with a 36% OD is the same 3.00 to 1 that you get with the 3.78 and 26% OD

[Model A Ron]

Originally Posted by Ruth

I'm curious, does anyone have a 36% Mitchell O/D? How does it compare to the 26% O/D. I have the 26% and like I have said before, I use it more like an underdrive, keeping the Mitchell in O/D most of the time and downshifting the Mitchell as needed for hills.

Ruth
How do you drive your Mitchel?

I start in first, second, Second high, third, and then third high. Are you doing the same?

[BRENT in 10-uh-C]

Originally Posted by Benson

Do the 3.25 cars that you mention have reground camshafts or Stipe IB330 or IB340 cams?

I wonder if reground cams raise torque curve too high to work with the lower RPMs of a 3.54 / 3.25?

Yes, I pretty much use IB330 camshafts exclusively.

Many reground cams back in that timeframe were refurbished with masters of unknown origin. Additionally, the centerline of each lobe can be all over the place in relation to the other 3 lobes as they were one cheaply.

With regard to taking away power, when the heal of the camshaft is ground to allow the nose to gain more lift, the grinder must generally must remove material from the area 90° from the heal, and 90° from the tip of the nose which decreases duration. This is a bad thing. Just because the lift is the same number, a smaller degree of duration does not allow for volumetric efficiency to get the air/fuel into the cylinder. A Model-A/B engine was originally designed as a torque engine. It was never intended to be an engine that needed to be revved to make power. Many of these so-called "touring camshafts" are pitiful when it comes to improving on what Ford had designed originally.

I would venture a guess on your engine, that a cam change to an IB330 would totally change the driving characteristics of your vehicle. Also knowing what carburetor you are using might tell us more too.

[Ruth]

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Originally Posted by Model A Ron

Ruth
How do you drive your Mitchel?

I start in first, second, Second high, third, and then third high. Are you doing the same?

No, I start in 1st high, to 2nd high, to 3rd high. I leave it in overdrive most of the time. I shift out of O/D only when I have to on a hill that I can not pull in 3rd over.

I have shifted your way but find just leaving it in O/D works best, for me.

[Model A Ron]

Originally Posted by Ruth

No, I start in 1st high, to 2nd high, to 3rd high. I leave it in overdrive most of the time. I shift out of O/D only when I have to on a hill that I can not pull in 3rd over.

I have shifted your way but find just leaving it in O/D works best, for me.

Ruth
I do appreciate the feedback. A local member of my club drives this way as well and by starting off in Mitchel High (if your running 3.78 gears) is the same as having 3.00 to 1 gearing.

I tried this and found it to be a very slow once I got into 3rd. I spoke to the man in my club doing this last night and he told me to ride out 2nd a bit longer and I should be fine.......I think both you and this man are correct. At what speed do you shift from 2nd high to 3rd high? I plan on taking a second run with my Mitchel in High later on today.

Like I said above this method is like driving 3.00 to 1 gearing and is a 26% overdrive from standard gearing. In my 31 Victoria Project I think I should be fine running 3.27 gearing that would offer 15.5% full time overdrive over standard gearing.

Using a 3.27 gives you about 60% of the benefit of a 26% Mitchel with the 3.78. The only down side I see is you do not have Mitchel 3rd low to drop down into on hills if needed

[Ruth]

Originally Posted by Model A Ron

Ruth
I do appreciate the feedback. A local member of my club drives this way as well and by starting off in Mitchel High (if your running 3.78 gears) is the same as having 3.00 to 1 gearing.

I tried this and found it to be a very slow once I got into 3rd. I spoke to the man in my club doing this last night and he told me to ride out 2nd a bit longer and I should be fine.......I think both you and this man are correct. At what speed do you shift from 2nd high to 3rd high? I plan on taking a second run with my Mitchel in High later on today.

Ron, I would like to answer that question but unfortunately my speedometer reads quite low (after being rebuilt by a well known rebuilder on here). Next time I'm out I can check my GPS for you, but that is not going to do you any good right now.

When I am accelerating I shift at ~2100 rpm but normally don't like to rev it that high.

My car is a heavy '30 Town Sedan so I imagine your Vicky will do quite well with the 3.27's. The beauty of having the Mitchell in the mix is the synchromesh for the down shift.

A friend has a Mitchell O/D and a Mitchell synchro trans. What a nice combo, but a little too spicy for me. Maybe I should start collecting beer bottles from the side of the road??

[Ruth]

Duplicate.

[Model A Ron]

Originally Posted by Ruth

My car is a heavy '30 Town Sedan so I imagine your Vicky will do quite well with the 3.27's. The beauty of having the Mitchell in the mix is the synchromesh for the down shift.

Ruth
I love the Mitchel in my 29 and if I had an unlimited budget the Victoria would get one as well. My problem is the Victoria has 4.11 gearing so my cost would be $2400 for the Mitchel plus the cost of 3.78 gear. By dropping to the 3.27 gear I get 60% of the overdrive Benefit and get to use that money on the restoration.

Whenever you get a chance to get a GPS speed when shifting from 2nd high to 3rd high just let us know......this is all good information so thank you.

[J Franklin]

4.11 and overdrive is the best of both worlds.

[Model A Ron]

Originally Posted by J Franklin

4.11 and overdrive is the best of both worlds.

With a 4.11 you would have to drive your car in Mitchel High. I have a 4.11 in the Victoria and that's just tp low for me.

[Keith True]

I have a 31 coupe with 3.54's and a 26%Mitchell OD.Works great.The only known for sure mod to the engine is a BF head.The previous owner had put the 3.54's in and the head on,I put the Mitchell in.Most of the time I forget the OD is in high and just drive it.I've had two BW OD 33%setups,they were just a bit too much.I have a 30 RPU with just 3.54's,B cam,BF head,B carb,i can climb mountains with that.I am thinking about putting some 3.27's in it.

[Model A Ron]

Originally Posted by Keith True

I have a 31 coupe with 3.54's and a 26%Mitchell OD.Works great.The only known for sure mod to the engine is a BF head.The previous owner had put the 3.54's in and the head on,I put the Mitchell in.Most of the time I forget the OD is in high and just drive it.I've had two BW OD 33%setups,they were just a bit too much.I have a 30 RPU with just 3.54's,B cam,BF head,B carb,i can climb mountains with that.I am thinking about putting some 3.27's in it.

If you put a 3.27 in with a 26% Mitchel that's the equivalent of 41.5% overdrive with the standard 3.78. Are you sure you do not have a V8 in that thing

[J Franklin]

Originally Posted by Model A Ron

With a 4.11 you would have to drive your car in Mitchel High. I have a 4.11 in the Victoria and that's just tp low for me.

That is one good idea and think of the hills you could climb.

[Benson]

Originally Posted by BRENT in 10-uh-C

Yes, I pretty much use IB330 camshafts exclusively.

Many reground cams back in that timeframe were refurbished with masters of unknown origin. Additionally, the centerline of each lobe can be all over the place in relation to the other 3 lobes as they were one cheaply.

With regard to taking away power, when the heal of the camshaft is ground to allow the nose to gain more lift, the grinder must generally must remove material from the area 90° from the heal, and 90° from the tip of the nose which decreases duration. This is a bad thing. Just because the lift is the same number, a smaller degree of duration does not allow for volumetric efficiency to get the air/fuel into the cylinder. A Model-A/B engine was originally designed as a torque engine. It was never intended to be an engine that needed to be revved to make power. Many of these so-called "touring camshafts" are pitiful when it comes to improving on what Ford had designed originally.

I would venture a guess on your engine, that a cam change to an IB330 would totally change the driving characteristics of your vehicle. Also knowing what carburetor you are using might tell us more too.

Brent

Thanks for your thoughts on cams.


That answers my questions. I will replace my present regrind with IB330 I have and then reevaluate the 3.78 / 4.11 idea after I restore low end torque.

From your experience I might not have to change to 4.11s.

I have used 4 or 5 different Bert's Zenith rebuilds and they all work the same.

[Keith True]

The pickup that I want to put the 3.27's in doesn't have a Mitchell,just the 3.54's.I have a coupe with 3.54's and a Mitchell.

[Model A Ron]

Originally Posted by Keith True

The pickup that I want to put the 3.27's in doesn't have a Mitchell,just the 3.54's.I have a coupe with 3.54's and a Mitchell.

Do you think the pickup would be better with the 3.27? I would think that it pulls without any issues with 3.54's.

Have you ever driven the coupe with the Mitchel and 3.54's in high from a stand still to 40 or more?

[Keith True]

I really only use the pickup now if I am going somewhere for the day,and have to carry a bunch of stuff with me.Chairs,coolers,little grill,etc.I just like to keep my revs down on anything.I ran a 58 HD panhead with the tallest set of sprockets I could come up with for it.65 MPH was a high idle.Of course that had the brute low end torque to carry it off.I drive the coupe with the OD in high more than I do in low.I take off with it in low,and when I'm on a main road and shift it into high,then forget to take it out again.I will remember to take it out when I'm in a line at a drive up window.

[Hotrodfil]

Originally Posted by Model A Ron

I would like to hear from people who are running a 3.27 rear end without an overdrive. Would you get a 3.27 if you had to do it again?

Running one in my Coupe. Love it. Tempted to fit my close ratio gearbox too.

600 mile round trip to race at Pendine. Mainly country lanes up hill and down dale, with a few forays onto bigger roads, keeping pace with a friend in his 32 roadster. Running 50-65moh most of the time.

Averaged 25mpg (proper sized gallons too) and hit 74mph on the beach.

Spec on the engine. Ported diamond B block, modern stock sized valves, stock bottom end, Stipe 340 cam, Brierley head, Burns manifold and a single 97.

Stock height T Coupe on an A chassis, B front axle, '35 brakes, stock A transmission - and a 3.27 final drive...

Oversize tyres too. 4.50 x 19 Blockleys on the front and 6.00 x 19 Michelin DR on the rear.

Dunno if you can tell but - couldn't be happier with the set up.

[Terry, NJ]

Can you even get a 3.27 ? I've heard they are out of them and none are available. Oh well, Where I live in PA, there are a lot of hills. I was afraid I wouldn't get up the hills too well so I compromised and bought a 3.54. So far it's been great! I love that thing! It climbs hills better than before! It's a bored out block, .040 off the head , B carb. with a bored out A . manifold, turned top 55/6 LB flywheel. Nothing outrageous! Maybe 50 HP. But much better to keep up up with modern traffic with. But there are some who don't like it too. But, For me? Great!
Terry

[Model A Ron]

Mike's has it listed as a 3.27 but when you look at the teeth and divide them out it's a 3.25.

[J Franklin]

Snyder's lists 3.25 gearsets.