Its a 1997 f150 4.6 4x4 automatic. What is the stock gear ratio? and,I know the rear axle is a 8.8,but Is the rear carrier a 28 or 31 spline and do they already come as a limited slip (posi)?

Please reply
Thanks
Lowflyingbird

 

Read the axle code off the door jamb sticker, then look it up. That will tell you what the ratio is and whether it's LS or not.

 

The 8.8 rear diff has 31 spline axles. If it has a front one it is 28 spline. the most common gear ratio is the 3.55.

JMC

 

it says in the owners manual...mine is the LS 3.55 8.8 Rear diff....recently replaced by ford bc i did a BREAK torque and blew it up. always check your rear diff fluid b4 u do a brake torque

 

I don't think the low fluid was the major contributing factor. The 8.8 is a fantastic differential. IN A MUSTANG! It a truck it is at its limits when you want to play. I blew up 2 of them in my 97 and 3 in my 00 before I wised up and swapped it for a 9.75.

JMC

 

well after i blew it up i stuck my finger as far in as i could and couldnt feel any fluid.....and i had done brake torques every day after school for like 6 months.....then when i went to do it for my buddys Cell Video they were just about to spin when CLANK and then under 30MPH it would clank in that same spot and the whole rear axle would jump up....limped 8 miles home doing like 35 so it wouldnt clank....then had AAA take it to ford..i looked in the junk yard for whole new rear axle but couldnt find one any were..one guy said that i was the 6th person that DAY to call about a 97 rear axle....hummm so why didnt ford beef up the rear axle for the 150's? whyd they put a mustang axle in there?? ever since ford redid my rear axle...ive only done one 3 min brake torque.

 

Why do you think that Ford puts the 9.75 behind the 5.4? As soon as you up the power on a 4.6 you are courting disaster. The Mustang weighs less than a truck so even if the car suddenly hooks it will shoot forward and that is it. Put a 4500+ lbs truck in the same situation and the diff will break. Maybe not on the first attempt but it is on its way....

JMC

 

Watch the video; http://www.youtube.com/watch?v=Lun_2alrz6k
The F-150 in it is mine. They come up to my truck holding a chunk of asphalt. It was part of a speed bump. I threw that chunk 5 ft in the air and 20 behind my truck. If I would have still had the 8.8 I would have been towed home.

 

i want what my buddy has in his bronco a sterling 10.25!!! that thing would never ever break!!!

 

how hard is it to put the 9.75 into a 97-03?

 

Look at the axle code in the door jam. If there is a letter in the front of the code, the truck was factory equiped with limited slip.