10 Tooth Pinion and 4:1 Rear End Gear Ratio Review

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Model T Ford Forum: Forum 2017: 10 Tooth Pinion and 4:1 Rear End Gear Ratio Review
Top of pagePrevious messageNext messageBottom of page Link to this message  By Cameron Whitaker, Oklahoma City on Monday, October 23, 2017 - 09:57 am:

I've been wanting to put a 10 tooth pinion in my '24 Touring for a while. It's pretty hilly here in Oklahoma, and windy too! Lizzie has to struggle to climb hills in a headwind. Plus, we sometimes carry passengers. I figured that the 4:1 differential ratio would help out, short of getting a Ruckstell or Warford or something. A lot of people say the 4:1 is great when coupled with an auxiliary transmission, especially in speedsters, so I figured I'd give a review of how it performs in a stock T with just the stock transmission.

I picked up an almost new 10 tooth pinion and a very nice used ring gear at Chickasha, but didn't get around installing them until my rear end went BANG!, and I decided that another differential teardown was in order (diff was fine, problem was in the passenger brake drum). That was a good time to swap out my gears!

First off, for those who aren't familiar with the 10 tooth pinion and 4:1 rear end gear ratio, it was a Ford factory option. Ford had designed a 10 tooth pinion with specially-shaped teeth so it could mate to a standard 40 tooth ring gear. This option was mostly reserved for heavier closed cars and cars in hilly areas. In theory, you'll lose about 10 percent of your top speed, but gain hill climbing ability.

Here's what I've noticed after driving the car around for a little while. First off, she definitely has more pulling power and climbs hills much better. There is a marked improvement in acceleration, and the stock transmission brake works better as well. I did notice that you have to shift out of low much sooner, but I find that you can now run around parking lots in high gear with the engine almost idling, which I couldn't do before.

I've never been interested in what difference there was in top speed. I never want to go that fast anyway! I really wanted to know what difference there would be in normal cruising speed. To be honest, any real difference is barely noticeable. The motor just turns a little faster. But it's much easier to maintain speed going up a hill.

Overall, I'm very happy with the change! It just seems to me that the 4:1 offers a lot of benefits, only at the cost of a little speed. Personally, I'd rather have the torque than the speed any day!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Monday, October 23, 2017 - 10:48 am:

Thanks for the testimonial! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Monday, October 23, 2017 - 10:56 am:

Hi Cameron,

I, too, am thankful for your report of the comparison of the two (stock and 4/1) ratios. I find your evaluation all the more relevant as it conducted on the same car with NO changes other than the gears. Thank you for sharing. Bill


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nevada Bob Middleton on Monday, October 23, 2017 - 10:10 pm:

Can loose a tad at the top end but not enough to mention


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Tuesday, October 24, 2017 - 02:33 am:

Did you notice much difference in the gas mileage?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Cameron Whitaker, Oklahoma City on Tuesday, October 24, 2017 - 09:37 am:

I'm glad you all appreciate my post. As I was making a decision in switching to 4:1, I discovered that there was a total lack of before-and-after reviews on an otherwise unchanged T, so I figured I'd help fix that!

Roger,

I haven't driven the car enough yet with the new gears to see if there's any difference in gas mileage. I really don't expect it to see any noticeable change, though. I'll comment as I keep driving!


Top of pagePrevious messageNext messageBottom of page Link to this message  By george house . . .caldwell county, TX on Tuesday, October 24, 2017 - 11:30 am:

Yes, I too appreciate your testimonial about the differential ratio change. A few years ago a notable Montana 500 participant/sometimes winner said I could expect more top end speed in my '26 Tudor by combining 4:1 ring/pinion with my cast iron original Warford overdrive. I currently run the stock 3.63/1.....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Mikeska, Denver CO on Tuesday, October 24, 2017 - 11:39 am:

I live in Denver and there are a few hills around here. My 26 Coupe has a 4 to 1 rear end...and a KC Warford. I like the combination. Plenty of power when you need it and when you slip it into overdrive you can still out run cars with standard gearing. YMMV


Top of pagePrevious messageNext messageBottom of page Link to this message  By george house . . .caldwell county, TX on Tuesday, October 24, 2017 - 12:19 pm:

Howdy Paul, Did you ever put a SCAT crank in your '14 touring? I had one installed in my '14 runabout and love it !! No more white knuckles on the steering wheel waiting for a crank to break..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Mikeska, Denver CO on Tuesday, October 24, 2017 - 12:47 pm:

George,

I am in the middle of restoring a 30 Model A Coupe and have not touched the 14 yet. I don't want 2 cars torn apart at the same time. You never know what will happen when those parts intermingle...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, October 24, 2017 - 01:02 pm:

I guess it depends on whether most of your driving is around town or on tours. You will find that most tour drivers go about 35-40 mph and at that speed you might be reving the engine a bit. That ratio would be very good in a fordor or a center door or in a pickup which is used for actually carrying loads. But in a touring the standard gearing works very well. I personally use standard gearing and Ruckstell in mine.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Tuesday, October 24, 2017 - 11:47 pm:

My 27 Tudor is running a 10 tooth and a KC Warford. Great combo. I'm turning 1680 rpm at 45 mph. It's great in the hills and mountains.


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