Looking to install a top loader
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Looking to install a top loader
I have a 75 F-100 currently with a 360 and a 3 speed. I would like to install a toploader 4 speed. Truck is lowered a little. I am planning to go on the Hot Rod power tour with it. I want to try to do what I can to improve gas mileage. What all do I need to look for in a top loader. I tried the forum search and did not find much Any help would be great
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Joined: Dec 2010
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From: Chino Hills
A top loader will not improve mpg's unless you really drive alot of city. Both your 3 speed and the 4 speed toploader have a 1-1 top gear.
I would add a fanclutch or electric fan, advance the timing, and dual exhaust or a single 3" one. Also if you do not have a 400+ treadware tire I would get some.
Beyond these few things you would need to go to a sub 3.0 gearing which hurts performance or an expensive overdrive transmission unless you can junkyard a T5 out of a 5.0 Mustang and S10. Then you add the S10 tail section to the Mustang T5 to get the shifter in the right area.
A wide ratio Top-loader and sub 3.0 gears would be cool if you can source a cheap top-loader, but the T5 combo plate would be a bit cheaper to do. Although relibility would be a bit lower due to the strength of the T5, but if just drive it wouldn't be a problem.
I would add a fanclutch or electric fan, advance the timing, and dual exhaust or a single 3" one. Also if you do not have a 400+ treadware tire I would get some.
Beyond these few things you would need to go to a sub 3.0 gearing which hurts performance or an expensive overdrive transmission unless you can junkyard a T5 out of a 5.0 Mustang and S10. Then you add the S10 tail section to the Mustang T5 to get the shifter in the right area.
A wide ratio Top-loader and sub 3.0 gears would be cool if you can source a cheap top-loader, but the T5 combo plate would be a bit cheaper to do. Although relibility would be a bit lower due to the strength of the T5, but if just drive it wouldn't be a problem.
Laughing Gas
Joined: Aug 2009
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From: Georgia
I don't know how to do this either, but I want to do the same swap one day. I've got the exact same combo engine/trans as you do. The toploader 4-speed is very similiar to the 3-speed toploader. The 4-speed has 3 shift arms versus the 3-speed's 2 shift arms. The 3-speed has a 9 bolt top cover versus the 4-speed's 10 bolt cover. I'm thinking that it couldn't be too hard to do this swap since they are very similar. Keep us posted if you find out exactly how to do this swap.
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Joined: Aug 2001
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The hardest part is figuring out the shifter, the rest is gravy.
Also, you'll need a small-block toploader with the truck bellhousing, or use a car bellhousing with an FE bigblock toploader.
Josh
Also, you'll need a small-block toploader with the truck bellhousing, or use a car bellhousing with an FE bigblock toploader.
Josh
Laughing Gas
Joined: Aug 2009
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From: Georgia
That's good you mentioned that, I've read that somewhere but forgot how exactly it went. This is because the input shaft is longer right? If you do it like this, can you use your same driveshaft?
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Thanks for the input. I think I have changed my mind. I do not have the time to chase parts and a 4 speed is a want and not a need. I think I will get a floor shifter and stick with the original tranny to save time and money
Elder User
Joined: Jan 2009
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From: Western N.C.
You also want to find a toploader that has the short output shaft and tailshaft housing. They are easy to spot because the tailshaft housing is VERY short and is cast iron. Others will have a long aluminum tailshaft housing. I am pretty sure that most of the car versions of this trans had a long tailshaft. Then again, you may not have a choice...if you have to use a small block toploader, most if not all of them will have the long aluminum housing.
My '69 RAT-H truck 3 speed has a wide ratio, and it gets pretty decent mileage...much better than the old C6 slush pump that was in it. As Ziegelsteinfaust said, top gear in both the three and four speeds is 1:1...no overdrive...so absolutely no difference on the highway, which is where you will do most of your driving, I would assume.
If you have a high numerical gearing in your diff (again, as Ziegelsteinfaust said), it would probably be easier and more effective to swap out your ring and pinion for a little lower numerical ratio. I have a diff ratio of 3.00 in my nine inch, and my truck has no problem pulling hills or getting up and going. With 235/75R15s on it, it only turns about 2300 RPM at 65mph, so it'll cruise on down the highway, too. No overdrive necessary. I don't think I'd go below a 3.00 ratio with a three speed, though. You might find yourself gassing it more just to lug it down the road. A 3.50 diff ratio is going to net you 2650 RPM at 65. A 4.10 will put you up to 3100 RPM at the same speed.
Here's the calculator I used: RPM Calculator
Your biggest fuel economy issues with highway or interstate driving have to be that:
1.) these things have the aerodynamic properties of a cinderblock.
2.) the 360 is a pretty thirsty engine in the first place, and
3.) at times it can be hard to keep your foot out of it.
When you combine all of these factors together, you find that you really can't do much about mileage except keep RPMs down and have a light foot. These motors make pretty good torque, so you shouldn't have any issues with keeping it up to speed while still feathering the gas.
Besides, I think the old 3 speed manual screams hot rod. Well, old school hot rod, at least.
My '69 RAT-H truck 3 speed has a wide ratio, and it gets pretty decent mileage...much better than the old C6 slush pump that was in it. As Ziegelsteinfaust said, top gear in both the three and four speeds is 1:1...no overdrive...so absolutely no difference on the highway, which is where you will do most of your driving, I would assume.
If you have a high numerical gearing in your diff (again, as Ziegelsteinfaust said), it would probably be easier and more effective to swap out your ring and pinion for a little lower numerical ratio. I have a diff ratio of 3.00 in my nine inch, and my truck has no problem pulling hills or getting up and going. With 235/75R15s on it, it only turns about 2300 RPM at 65mph, so it'll cruise on down the highway, too. No overdrive necessary. I don't think I'd go below a 3.00 ratio with a three speed, though. You might find yourself gassing it more just to lug it down the road. A 3.50 diff ratio is going to net you 2650 RPM at 65. A 4.10 will put you up to 3100 RPM at the same speed.
Here's the calculator I used: RPM Calculator
Your biggest fuel economy issues with highway or interstate driving have to be that:
1.) these things have the aerodynamic properties of a cinderblock.
2.) the 360 is a pretty thirsty engine in the first place, and
3.) at times it can be hard to keep your foot out of it.
When you combine all of these factors together, you find that you really can't do much about mileage except keep RPMs down and have a light foot. These motors make pretty good torque, so you shouldn't have any issues with keeping it up to speed while still feathering the gas.
Besides, I think the old 3 speed manual screams hot rod. Well, old school hot rod, at least.
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