| thirtysixford | -- 05-16-2012 @ 6:38 PM |
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I have the rear axle out of my '36 while I'm rebuilding the trans clutch etc. While cleaning the axle housing to paint it, I noticed these numbers stamped into the web on the underside of the diff. heading to the pinion. Looks to me like a 9 underlined and then 40. That would divide out to a 4.44 ratio. The axle is a '37 or later as the radius arms mount right next to the brake backing plates. I see this ratio in the books, but not that tooth count. If its 4.44 no wonder it seemed like it was going to blow up at 60.
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| 34billct | -- 05-16-2012 @ 7:06 PM |
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For a 60 hp pass. 9/40 = 4.44 pn. 74-4209
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| thirtysixford | -- 05-16-2012 @ 7:17 PM |
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Thanks 34billct Who would have guessed a v8-60 axle!
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| ford38v8 | -- 05-16-2012 @ 8:10 PM |
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Back in the day, the 60 hp Fords went to the junkyards first, and thus were sooner available for transplant parts. I found the same differential ratio in my '38 Convertible Coupe, and later changed it out for a 3.78 gear set. With the 4.44, I was able only to attain 65 on the freeway, that speed being all the engine could do before the points would float, maxing out the RPM. Alan
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| thirtysixford | -- 05-16-2012 @ 9:15 PM |
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Thanks Alan! Can't wait to get a 3.73 in her.
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| Stroker | -- 05-17-2012 @ 8:04 AM |
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Actually, it will be a 3.78.
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| 40 Coupe | -- 05-19-2012 @ 4:38 AM |
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It would be bad to buy new gears and when installing, find the same gear ratio already installed. Over the years it is impossible to know from stampings on the differential what actual ratio is now installed. You know the ratio is high but how high? There is a test to estimate gear ratio without taking it apart. Mark the pinion or the drive shaft, turn the LH wheel or axle two complete turns count the rotations of the pinion or the drive shaft for example just over 4 turns 4:11 ratio, about 4 1/2 turns= 4:44, just less than 4 turns =3.78 etc. If your going to buy another assembled differential to replace yours, this test will help confirm that you are getting what you want.
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| Stroker | -- 05-19-2012 @ 6:37 AM |
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40: Prolly want to re-think that advice to accommodate the spider gears.
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| thirtysixford | -- 05-19-2012 @ 3:02 PM |
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I tried 40Coupe's method and with the right side drum on the driveway so it would not turn, the pinion rotated aprox. 4 1/2 times when I turned the left drum 2 turns. Looks like 4.44 Stroker is this not an accurate way to tell the ratio? Thanks Mike
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| Stroker | -- 05-19-2012 @ 3:55 PM |
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thirtysix&40: I stand corrected. You are both correct! I can only plead slovenly-sloppiness by not reading 40's TWO revolutions of the wheel that 40 specified. This of course accounts for the spider gears. Methinks I need to start READING before I start typing. 40's method is a valid way to approximate the ratio. My apologies to 40. Having said that, it wasn't just 60 hp Fords that were delivered with 4:11's. If the car was sold in the Mountain West, you could specify "Rocky Mountain gears" when you ordered the car with the 221 V8. My dad's 38 Ford "big V8" SW came with 4:11's, and that was because he ordered a Columbia 2-speed axle, and we lived in a mountainous area in the West. This gave him the option of tailoring the axle ratio to terrain encountered, and the 4:11's were perfect for the 6%+ grades.
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| thirtysixford | -- 05-19-2012 @ 4:33 PM |
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stroker Thanks for your candid reply... I've hit the "send" button more than once only to find a mistake. No big deal. This puppy has 4.44 not 4.11. Engine noise above 40MPH is LOUD. Mike
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| Stroker | -- 05-19-2012 @ 4:48 PM |
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thirtysixford: My new reading glasses are on order. If you like "loud", I have a set of 4:56's you are welcome to if you are willing to trade a set of 3:54's. Dan
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| thirtysixford | -- 05-19-2012 @ 5:05 PM |
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Thanks for the offer, but I don't think so Dan. Any one want to trade 4.44 for 3.78 or 3.54?? Didn't think so.
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