Tranny Question???
Thread Starter
|
8th Gear
Joined: Sep 2005
Posts: 8
Likes: 0
Tranny Question???
I have an 87 f-150 with 4.9 and 4spd manual at Highway speeds (70-75) in overdrive the engine is pushing a lot of RPM. I am wondering if the 5spd out of a latter model would drop the RPM since the Interstate speed limit rose by 15mph a few years latter. Or are teh final drive ratio the same on both the 4spd and 5spd. Thanks
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
What is your rear end ratio? You'll have to tell us because there were lots of different ones available. Look for a tag hanging off a diff cover bolt, and/or the axle code on the door.
Thread Starter
|
8th Gear
Joined: Sep 2005
Posts: 8
Likes: 0
In 87 they offered a 3spd auto and 4spd auto and a 3spd plus overdrive manual tranny the manual is what I have. The rear end ratio is a 3.73 but I dont need nor do I want to change the rear end. I am just wondering about the final drive ratio in the 5spd OD manual Vs. the 4spd OD manual.
Thread Starter
|
8th Gear
Joined: Sep 2005
Posts: 8
Likes: 0
I was hoping that since the 55mph Speed limit law was repealed in 87 and was reset to 65mph that ford changed the final drive ratio in the 5spd in 1988 so that they could keep better fuel economy. Which is what I'm looking for.
Senior User
Joined: Feb 2005
Posts: 242
Likes: 1
From: Pittstown NJ
you could change the rearend ratio if you really want to lower your rpms and get better fuel miliage
Trending Topics
Thread Starter
|
8th Gear
Joined: Sep 2005
Posts: 8
Likes: 0
I still need that bottom end power and I have access to a 5spd that is cheap. And the tranny is fairly easy to swap out. Hauling is its main purpose in life but I do occasionally take it on a long trip in it.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
When you say "a lot of rpms" what number is that? With stock tires on your truck I'm guessing you would be turning 3000rpm at 70mph if your tranny is actually just a 1:1 final drive ratio. I had an 83 ranger with a 4sp that did not have a real overdrive and it reved a lot on the highway. Switching to a 5speed that actually has a 0.78 overdrive would drop engine speeds about 500rpm.
Thread
Thread Starter
Forum
Replies
Last Post
sfford
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
2
Jul 23, 1999 09:52 AM