I know this question has been answered and asked many times as I've read some threads about the topic. I'm still a little confused about it as to what to buy where to buy it as I have a buddy of mine that can do the labor free of charge. I have a 03 F-150 XLT 4x4 4.6 3.55ls and want to regear to 4.56 and have a Detroit true trac in the rear and maybe the front not sure yet.

Now my question is how do I know if I have a 8.8 or 8.8 reverse cut? The truck is stock all the way around when it was bought new off the lot. Also what gears front and rear to buy and install kits/ bearings. What sites can I find all that I need at?

If I'm missing anything please shed some light I want to do it the right way.

Thanks

 

Im pretty sure regular cut for rear axles. Reverse cut for front axles. Our gears are also 31 spline not 28


I would add more but i'm half asleep and don't wanna give the wrong info lol.

 

Ohh okay well that clears a lot up. How would I know if it's 31 and not 28 spline? Or did it change to 31 at a certain year?

 

The front 8.8 IFS has 28 spline axles and reverse cut gears. The rear 8.8 has 31 splines and standard gears. And the optional rear 9.75 has 34 spline axles w/ standard gears.

 

Are you lifting with bigger tires? You don't need 4.56's unless your going 35" or larger.

 

I have 35 on their now and want to regear within this month. It has a 3in body lift and a 6" fabtech in the box waiting to be put on. I just want to know what to get to change out everything.

 

Honestly EBay has been my source for the best deals on gears. I bought a front and rear set of 4.56's for my 9.75 & 8.8 with the install kits for less than $700(motive gears). If you go with front or rear LSD's, you can plan on spending around $500 ea. I would recommend only LSDing the rear unless your doing some serious 4wheeling. Then you'd be running lockers on both ends. Please don't bash me for eBay, I have to be frugal.

 

Hahaha Don't worry about bud I shop on eBay too. How would you know what axle the truck came with I'm pretty sure it 8.8 and what about 31-28 spline?

You think you could make up a list on what to get?

 

Yeah man, no prob.
First identify your rear axle precisely.
You can either look at the axle code on your drivers door sticker and cross reference it. Or, count the bolts on your rear cover. 10 bolts= an 8.8, 12 bolts= a 9.75.

The front axle is always a 28 spline reverse cut 8.8.

Next shop for a complete front/rear 4.56 ring and pinion set

You'll need:
(Front)
1 - 8.8 reverse cut 4.56 ring and pinion
1 - 8.8 master install set (includes all bearings races seals, shims, and crush collar)
---optional--- 8.8 28 spline Detroit truetrac or comparable differential

(Rear) if you do in fact have the 8.8
1 - 8.8 standard cut 4.56 ring and pinion
1 - 8.8 master install set
1 - 8.8 31 spline Detroit Truetrac or suitable locker/LSD.

Make sure you have a couple big breaker bars, impact wrench, etc for removing the pinion nut & ring gears. And a dial caliper for checking pinion backlash. You'll need access to a press to remove/install the carrier bearings.

Measure everything twice! The ring and pinion have to have a perfect mesh on the teeth or you'll grenade it in no time flat. You adjust it by adding/removing pinion shims of different thicknesses to obtain a good mesh. I found a couple good video's on YouTube to give you a visual idea of what to do.

Hope this helps!

 

Thanks a lot man, that was really helpful. yea the rear is 10 bolt 8.8 now I know what to get time to go pricing around. As for the install I'm not doing it a buddy of mine gonna do it at a shop he works at. But again thanks.