Rear End
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Trailering
Joined: Aug 2022
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Rear End
Okay so I'm looking to get rid of the rear end on my truck. I have a 351w and a C6 3at. I want to replace it with something that won't cause my truck to scream at 5krpm while running 70mph. I do not want to lose the LSD when switching it out. I am going to be replacing the C6 transmission with the A4LD transmission. Anyone know a good rear end that's capable of allowing me to have the LSD and be able to hop on the highway without it screaming at high rpms?
Hotshot
Joined: Jun 2015
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You want to replace the axle to bring the rpms down but also mention changing the transmission. You’re all over the place. What is the current axle ratio? The C6 is why the engine rpms are so high. I drove my ‘87 Bronco (302/C6/3.55 gears) as a daily driver for years. It got 14mpg in city/hwy driving. The engine didn’t care about doing 3K rpm on the highway. I put almost 300K on it.
No, you aren’t bolting an A4LD to that 351W. That transmission was only available in the Ranger, Aerostar, Bronco II/ Explorer trucks.
No, you aren’t bolting an A4LD to that 351W. That transmission was only available in the Ranger, Aerostar, Bronco II/ Explorer trucks.
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Trailering
Joined: Aug 2022
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i am sorry for being all over the place... um, according to my father I should have a 3:55 or a 4:10 gear in the rear end. He wants to put a 2:89 highway gear in it. I'm still a little new to RWDs. I am sorry
Hotshot
Joined: Jun 2015
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Don’t guess. What is the axle code on the driver side door jamb sticker? Is the tag still on the axle? Jack up the rear end, rotate a tire one revolution and count the number of times the driveshaft goes around.
I wouldn’t change the rear axle ratio to anything higher. I actually went from 3.55 to 4.10 in my F-150.
I wouldn’t change the rear axle ratio to anything higher. I actually went from 3.55 to 4.10 in my F-150.
Hotshot
Joined: Jun 2015
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Safer than driving something like a Smart car. You can also see better being higher up.
You will find yourself pushing harder on the gas pedal with “highway” gears. They aren’t exactly the most aerodynamic vehicles.
You will find yourself pushing harder on the gas pedal with “highway” gears. They aren’t exactly the most aerodynamic vehicles.
i ain't rite
Joined: Mar 2005
Posts: 65,425
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From: Marlboro Mental Hospital.
there is no 2.89 ratio.
i would be 2.73, or 3.08.
and those ratios would kill gas mileage.
minimum ratio i would run is 3.55
i would be 2.73, or 3.08.
and those ratios would kill gas mileage.
minimum ratio i would run is 3.55
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Trailering
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Logistics Pro
Joined: Aug 2010
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From: Chillicothe
There is a sticker in the door jam that will have a code for what rearend the truck has. If you post that we can better help you
Hotshot
Joined: Sep 2001
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I'd leave the rear end alone and just swap in an overdrive transmission, but the A4LD is a light duty transmission used in 4 cyl fox body and Ranger. A good AOD should make things better.
Do you have a tach. I don't see how it could be turning 5k rpm at 70. Figure out what the actual rear gearing is. If it is 3.55 that is a great gear. I would never put anything numerically lower but higher ratio in a truck, talk about gutless wonder.
Do you have a tach. I don't see how it could be turning 5k rpm at 70. Figure out what the actual rear gearing is. If it is 3.55 that is a great gear. I would never put anything numerically lower but higher ratio in a truck, talk about gutless wonder.
Hotshot
Joined: Sep 2001
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I used to daily drive an 85 with a C6 and 3.55 and it was perfectly happy at 70 mph. Would have been nice if it had another gear though, but still no big deal. Years ago they worked just fine, so why wouldn't they now? I don't know why your parents are worried about it, especially if it is a stock configuration.
FTE Legend
Joined: Nov 2015
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From: Angier, NC
I used to daily drive an 85 with a C6 and 3.55 and it was perfectly happy at 70 mph. Would have been nice if it had another gear though, but still no big deal. Years ago they worked just fine, so why wouldn't they now? I don't know why your parents are worried about it, especially if it is a stock configuration.
As said this was normal for back in the day and no one ever said before OD how high the motor is twisting.
You know we dont know what the OP has as he did not say other than 351 and C6 auto.
What is the year and is it a 150 / 250 / 350, F or E truck?
What will the truck be used for mostly?
Driving to from school / work and never towing or have a heavy load in the bed.
Or mostly the bed full of bricks and pulling a trailer with a skid steer on it?
Who will be doing the work to make this happen?
How much are you looking to spend to get the RPM lower?
Just know what ever you do will not be cheap, be it add on over drive to the C6 or a AOD transmission.
Dave ----
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Trailering
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Okay after reading all of your guys' replies here is some answers.
I have a 1989 Ford F-150 XLT Lariat. I do not go over 75, my parents watch me like a hawk on life 360. I mostly use it to get back and forth to school, but I am buying another car here soon and it will be used to tow it to C&O in Kennesaw, GA. For reference I live down in McDonough, GA. The truck has been used here recently to clean up tornado damage. But with an empty bed, It hovers around 5k at 70mph. And yeah I will get the ratio off of the door jam sticker if it is on there. And yeah, I don't know why my parents are so worried either.
Thanks everyone. I will get everything to the thread here shortly
I have a 1989 Ford F-150 XLT Lariat. I do not go over 75, my parents watch me like a hawk on life 360. I mostly use it to get back and forth to school, but I am buying another car here soon and it will be used to tow it to C&O in Kennesaw, GA. For reference I live down in McDonough, GA. The truck has been used here recently to clean up tornado damage. But with an empty bed, It hovers around 5k at 70mph. And yeah I will get the ratio off of the door jam sticker if it is on there. And yeah, I don't know why my parents are so worried either.
Thanks everyone. I will get everything to the thread here shortly