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Old 01-13-2021, 04:24 PM   #1
yohoc1
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Default Model A rearend conversion

Looking for information to convert a Model A rearend to accommodate a modern driveshaft yoke
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Old 01-13-2021, 04:50 PM   #2
Bob C
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Default Re: Model A rearend conversion

Here you go. https://valleymachineshop.com/model-a-parts.html
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Old 01-14-2021, 12:37 AM   #3
PotvinV8
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Default Re: Model A rearend conversion

I converted my Model A rearend to an open driveline using parts from Speedway Motors as part of the T5 swap.

You can read the whole story here: https://clampdowncomp.com/tech/insta...-model-a-ford/
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Old 01-14-2021, 09:26 AM   #4
old31
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Default Re: Model A rearend conversion

1: Potvin, at 60 what are your rpms?

2: What gear ratio is your your end?

3: Is it true that on a T5 first gear is too low, and you end up taking off from 2nd?
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Old 01-14-2021, 12:26 PM   #5
Charlie Stephens
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Default Re: Model A rearend conversion

Remember you will need to add brackets to keep the rear end from twisting. My advice would be a later, stronger, rear end if you are going to make the brackets.

Charlie Stephens

Last edited by Charlie Stephens; 01-14-2021 at 08:04 PM.
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Old 01-14-2021, 04:22 PM   #6
1930pu
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Default Re: Model A rearend conversion

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I used Valley Machine also, great guy....
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Old 01-14-2021, 07:42 PM   #7
Dan McEachern
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Default Re: Model A rearend conversion

Valley Machine Shop offers a brace for the rear end when converting to open drive line.
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Old 01-15-2021, 09:32 AM   #8
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Default Re: Model A rearend conversion

Thanks for the info!
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Old 01-16-2021, 07:06 PM   #9
Gene F
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Default Re: Model A rearend conversion

Some people I talk to say going to the S-10 5-speed doesn't pick up that much, and it's whole lotta work. So how much MPH do ya pick up?
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Old 01-16-2021, 07:41 PM   #10
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Default Re: Model A rearend conversion

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Some people I talk to say going to the S-10 5-speed doesn't pick up that much, and it's whole lotta work. So how much MPH do ya pick up?
Have had my T-5 for ten years and it has nothing to do with speed, engine modifications determine the increase in speed. I can run 75 MPH with a fifth gear overdrive without stressing the engine.
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Old 01-16-2021, 07:50 PM   #11
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Default Re: Model A rearend conversion

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Some people I talk to say going to the S-10 5-speed doesn't pick up that much, and it's whole lotta work. So how much MPH do ya pick up?
Have had my T-5 for ten years and it has nothing to do with speed, engine modifications determine the increase in speed. I can run 75 MPH with a fifth gear overdrive without stressing the engine.
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Old 01-17-2021, 02:33 AM   #12
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Default Re: Model A rearend conversion

It is a bit of work, but my Model A trans had bad bearings and I wasn't about to do all the work to fix it just to replace it with another A trans. For me, it was about the benefit of having a trans with syncros as much as it was the overdriven 5th gear. Being able to down shift and/or shift into first without stopping completely, as well as the closer gear spread, changed the nature of the car completely.

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Old 01-17-2021, 02:35 AM   #13
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Default Re: Model A rearend conversion

Quote:
1: Potvin, at 60 what are your rpms?
I don't have a tach in the car, but using an engine rpm calculator, about 2000 rpm, give or take.

Quote:
2: What gear ratio is your your end?
3.54:1

Quote:
3: Is it true that on a T5 first gear is too low, and you end up taking off from 2nd?
No, there are a number of different gear ratios that came in the T5 transmissions.
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Old 01-17-2021, 03:26 AM   #14
Charlie Stephens
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Default Re: Model A rearend conversion

What many of the people are overlooking is that the Model A is not a car you would like to run all day at 75 MPH. I have a '31 RDPU with 3.54 gears. It is happy at 55 MPH. It will do 75 but at that speed the front fenders act like airplane wings making it very light in the front and susceptible side winds. A good example would be the wind being pushed by a semi or a wind blowing down a canyon that crosses to road. I like it to be my decision when to change lanes. Mechanical brakes are not designed for 75 MPH. The steering and suspension are not designed for 75 MPH.

Charlie Stephens
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Old 01-18-2021, 02:18 PM   #15
PotvinV8
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Default Re: Model A rearend conversion

Quote:
Originally Posted by Charlie Stephens View Post
What many of the people are overlooking is that the Model A is not a car you would like to run all day at 75 MPH. I have a '31 RDPU with 3.54 gears. It is happy at 55 MPH. It will do 75 but at that speed the front fenders act like airplane wings making it very light in the front and susceptible side winds. A good example would be the wind being pushed by a semi or a wind blowing down a canyon that crosses to road. I like it to be my decision when to change lanes. Mechanical brakes are not designed for 75 MPH. The steering and suspension are not designed for 75 MPH.

Charlie Stephens
Agreed 100%!! I never drive my A at 75 mph for every reason and then some as you stated. I avoid the freeway 95% of the time, here in Southern California, mostly due to idiot drivers.

The takeaway, for me, on the T5 conversion was the syncros that allowed easier shifting around town and the closer ratio of gears between first and fourth. Around town, with the stock box, second seemed to get rung out a little farther than I preferred and third tended to be a little too tall. Splitting the difference with the T5's gearing seemed to helped a lot. Food for thought I guess...
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Old 01-18-2021, 02:41 PM   #16
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Default Re: Model A rearend conversion

Quote:
Originally Posted by Charlie Stephens View Post
What many of the people are overlooking is that the Model A is not a car you would like to run all day at 75 MPH. I have a '31 RDPU with 3.54 gears. It is happy at 55 MPH. It will do 75 but at that speed the front fenders act like airplane wings making it very light in the front and susceptible side winds. A good example would be the wind being pushed by a semi or a wind blowing down a canyon that crosses to road. I like it to be my decision when to change lanes. Mechanical brakes are not designed for 75 MPH. The steering and suspension are not designed for 75 MPH.

Charlie Stephens
I like that comment...laughed...and agree!
I have often said over 75mph feels like you have air suspension. With the full fenders, you do!
Good Day!
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Old 01-18-2021, 02:47 PM   #17
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Default Re: Model A rearend conversion

Our speedster will cruise effortlessly at 70mph with the F150 gearbox and the highest ratio 4th gear, but we only hold this speed on a motorway in light traffic and excellent road surface. Otherwise, it's most comfortable cruising speed is around 55 mph and it's brakes and suspension that dictate that.
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Old 01-19-2021, 11:11 AM   #18
denis4x4
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Default Re: Model A rearend conversion

Quote:
Originally Posted by Charlie Stephens View Post
What many of the people are overlooking is that the Model A is not a car you would like to run all day at 75 MPH. I have a '31 RDPU with 3.54 gears. It is happy at 55 MPH. It will do 75 but at that speed the front fenders act like airplane wings making it very light in the front and susceptible side winds. A good example would be the wind being pushed by a semi or a wind blowing down a canyon that crosses to road. I like it to be my decision when to change lanes. Mechanical brakes are not designed for 75 MPH. The steering and suspension are not designed for 75 MPH.

Charlie Stephens

Agreed....my point was simply that the engine determined top speed, not the transmission. I'm running a B engine with an original CRAGAR head, hydraulic brakes, F-100 steering box and a host of other go-fast goodies.
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