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Discussion Topic:
Speedway (Getz) 3.25 Gear Set?
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deluxe40 |
06-26-2010 @ 10:10 AM
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Member
Posts: 413
Joined: Oct 2009
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Has anyone installed a Speedway 3.25 gear set in a '40 Ford? The current 3.78 just isn't tall enough for the L.A. freeways. I was thinking of a Mitch*ll overdrive in my Sedan Delivery until I measured the floor pan and discovered there is only 12 inches of clearance between the rear flange on the torque tube and the step down in the floor (for the fuel tank). Any advice would be appreciated.
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supereal |
06-26-2010 @ 10:35 AM
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Senior
Posts: 6819
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I have a Ryan OD in my '47, and although the clearance to the floor pan is closer than 12 inches, it has never been a problem. My unit is a 3 to 1 (33%) bolted to a 3-78 axle. The OD is fine on the highway, above 45 mph, but lugs down considerably at lower speeds, such as in-town traffic. I can run on the hiway at the usual 60-75 mph, but don't do it often, given the rather primitive braking and handling of my '47. I do use it when cruising on the two lanes, unless it is in very hilly country. I believe you would find that with a 3-25, you will have an objectionable loss of power off the hiway. The Mitch*ll is well recommended, and I would go that way. 12 inches of clearance is more than enough.
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danliveshere |
06-26-2010 @ 3:13 PM
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Posts: 31
Joined: Jun 2010
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Do you think a 35 with fresh rebuild would handle a 3:78 with 30% Mitch*ll overdrive? I've had a 35 roadster for 24 years but it ran a merc and 3:78, never actually driven a 85 horse 21 stud motor to know the best ratio?
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37RAGTOPMAN |
06-26-2010 @ 4:20 PM
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Senior
Posts: 1965
Joined: Oct 2009
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I have a 354-1 from the V8 SHOP in BALLSTON SPA NY, and am happy the way it works, seems to get better milage and can cruise a 60 or better, but like staying in the speed limit, KEEP ON TRUCKIN 37RAGTOPMAN
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supereal |
06-27-2010 @ 10:36 AM
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Senior
Posts: 6819
Joined: Oct 2009
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You will find some difference between the 21 and 24 stud engines. My convertible is a heavy car, and has plenty of low end power in traffic with the 3-78, but can't get out of its own way if I forget to lock out the OD. With the 85, I'd be cautious about lowering the rear ratio. The difference between a 3-78 and a 3-54 is only about seven percent, not much for the cost and trouble. Most OD units provide 25-30 percent. The idea is to keep the engine in the best power band, around 2,000-2,500 rpm. You hit that around 50 with the 3-78. With a 30% OD, you will running about 65 at that rpm.
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Pauls39 |
06-27-2010 @ 1:42 PM
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Posts: 81
Joined: Oct 2009
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We just got back from Charlotte with a 40 pickup running a Mitch*ll OD. It ran well even in the mountains of Virginia and West Virginia. The OD slowed the motor enough to allow it to run cool and we had the option of going back to the 3.78 if we needed the power. The OD replaced the torque tube with no clearance problems. The installation is simple. It took longer to decide the route for the shifter cable than it did to install the rest of the unit.
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deluxe40 |
06-28-2010 @ 10:45 AM
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Member
Posts: 413
Joined: Oct 2009
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I was all set to order a Mitch*ll Overdrive for my '41 Ford Sedan Delivery (on a '40 Tudor frame). Then I noticed that there is only 12 inches between the rear flange of the torque tube and the point at which the floor pan drops down to accommodate the fuel tank (originally behind the seat). As shown in the photo below, there is 9" of clearance between the torque tube and the rear floor for only the first 12 inches (from the rear). Then the floor drops down 5 inches leaving only 4 inches of clearance for the next 3 inches. At 15 inches the top of the torque tube is level with the flat part of the floor. Looking at the photo in the V8 Times I don't believe there would be enough room to install the overdrive unit. I just sent a note to Mitch*ll to verify, but I'll be surprised if the unit will fit without modifying the floor. My second choice was the 3.25 gear set. I just bought a '46 Sedan Coupe that the previous owner said has a 3.25. It drives just fine (for me). So much so that I'm a little suspicious that the gear might be a 3.54 rather than a 3.25. i counted the teeth on the ring gear and got 39. That would indicate 3.54 (with a stock 11 tooth pinion.). However, it might also indicate 3.25, if the pinion has 12 teeth. Does anyone know how many teeth are on the ring and pinion of the 3.25 gear set from Specialty? Also, are there any special issues with installing the gear sets from Specialty? If I don't get this settled soon I'll have trouble keeping up with the trucks in the slow lane on my way to St. George.
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supereal |
06-28-2010 @ 11:26 AM
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Senior
Posts: 6819
Joined: Oct 2009
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The clearance isn't a problem. The only objection I had to my OD was the lever control. We made a bracket at the OD end, and installed a truck PTO cable with the knob just befow the dash on the left side. I'm not familiar with the Getz gear set, but we have put together a number of the old style rear ends. It is a big job, requiring considerable assembly and disassembly of the axle to get the lash and mesh correct. Installing the pinion and bearing assembly is also tricky. Simply swapping torque tubes is considerably less work.
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Pauls39 |
06-28-2010 @ 7:15 PM
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Member
Posts: 81
Joined: Oct 2009
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The Mitch*ll OD is available with a Cable shifter or a solid rod your choice when ordering. The 3.25 sounds a bit steep, but that would depend on your motor's HP. I like the versatility of the OD.
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Texas40 |
06-29-2010 @ 7:04 AM
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Posts: 66
Joined: Oct 2009
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I have a speedway 3.25 gear, it has a 12 tooth pinion which gives it a 3.25 ratio with the 39 ring. I have not found the power loss everyone else seems to believe. I live in Texas so its probably not for West Virginia driving but LA or Texas flat roads its fine. I find its perfect. I rarely going up a very steep grade so you might have to use second occasionally but its been so long ago that I experienced that I can't even remember it. Performance and cooling advantages at highway speed make it perfect for me.
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