highway gears
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Junior User
Joined: Nov 2004
Posts: 62
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highway gears
Hello all,
I have a 71 f100, 360 with stock 2 barrel, manual 4 speed granny sport custom.
I'm looking to change the gear ratio in my truck so that I can get better gas mileage from it. I drive 40 miles round trip to work everyday on the highway and it is geared a bit low right now.
How do I even START something like this? I've looked on the site and got a lot of good information, but where would I go to find the gears I need? Also, what gears should I look for to get the best mileage on the highway? Are they hard to change?
I won't be towing much with this truck and use it for transportation daily.
thanks,
andrew
ps
rebuilding the carb was easier than I thought and it made the truck drive a whole lot better.
I have a 71 f100, 360 with stock 2 barrel, manual 4 speed granny sport custom.
I'm looking to change the gear ratio in my truck so that I can get better gas mileage from it. I drive 40 miles round trip to work everyday on the highway and it is geared a bit low right now.
How do I even START something like this? I've looked on the site and got a lot of good information, but where would I go to find the gears I need? Also, what gears should I look for to get the best mileage on the highway? Are they hard to change?
I won't be towing much with this truck and use it for transportation daily.
thanks,
andrew
ps
rebuilding the carb was easier than I thought and it made the truck drive a whole lot better.
Postmaster
Joined: Apr 2002
Posts: 3,613
Likes: 6
From: Coal country
First, we need to know what your current rear end is like. Most likely, you have a 9 inch rear. If your wheels are 5 lug, you have a 9 inch.
This rear is easy to re-gear. You can easily change out the center section, called a punkin, a chunk or a 3rd member. You can also have a shop change out the actual gears inside the chunk, but that takes special tools. Not a job for the novice.
The second piece of information we need to know is what your current rear end gear ratio is, in order to make a recommendation.
Under one of the nuts holding the punkin in place should be a metal tag. Look on the second line for the numbers.
Those numbers will tell your ratio. It probably is 3.50, and would look like this:
3 50
Post back and let us know.
This rear is easy to re-gear. You can easily change out the center section, called a punkin, a chunk or a 3rd member. You can also have a shop change out the actual gears inside the chunk, but that takes special tools. Not a job for the novice.
The second piece of information we need to know is what your current rear end gear ratio is, in order to make a recommendation.
Under one of the nuts holding the punkin in place should be a metal tag. Look on the second line for the numbers.
Those numbers will tell your ratio. It probably is 3.50, and would look like this:
3 50
Post back and let us know.
Senior User
Joined: Sep 2003
Posts: 131
Likes: 1
You can also get an overdrive unit that bolts to the back of the tranny, It will cost you around $2500 in all, but they are sweet. www.gearvendors.com makes them.
Postmaster
Joined: Apr 2002
Posts: 3,613
Likes: 6
From: Coal country
Very true! I have a Doug Nash unit in my '66 F-100, the predecessor to the GV or US Gear overdrive units.
However, it will be cheaper and easier to replace the punkin, at about $100 or so. Not to mention, the cost of altering the driveshaft.
However, it will be cheaper and easier to replace the punkin, at about $100 or so. Not to mention, the cost of altering the driveshaft.
Laughing Gas
Joined: Aug 2004
Posts: 964
Likes: 1
From: Roseburg, OR
An over drive is very sweet, but it is, as was mentioned, expensive. I got my 4.10s for about $130 on eBay. They were used, but only had a few hours on them. I took my 3rd member to a driveline and differential shop, and they put in new side gears, spiders, bearings, and set the whole thing up for less than $200.
You can set up your own (and really, it's a lot easier on the 9" than others), but by the time you buy some quality equipment to do it with, you could have had someone else set it up for you.
You can set up your own (and really, it's a lot easier on the 9" than others), but by the time you buy some quality equipment to do it with, you could have had someone else set it up for you.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
andrew, I run 3.00 rears behind my FE and am happy with it. I have run 2.75s in it, and if I never towed would run them now. With the manual tranny that you have the 2.75 might be a good candidiate for you. IMHO
John
John
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Trending Topics
Junior User
Joined: Sep 2005
Posts: 79
Likes: 0
From: Roy,WA
I run 3.25's in my truck, can acheive 14-15 mpg if you keep your foot out of it, and that's with the 390.
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Joined: Nov 2004
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From: Wayland, Iowa
Gear Ratio
I was thinking about swapping out a 410 for a 373. After tlking to a friend of mine he said to save my money and that the next time I get tires go to a tire that is about a half inch higher and that would make up the difference. Which makes alot of sense. I am running mine with the stock 16.5 rims and 875 tires so I should be pretty close to the 373 ratio. Correct me if I am wrong though. Thanks
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