8.8 to 9.75 swap

[DRJ]

So I need to replace my rear end, I called a few yards and came upon this 9.75 rear end with the factory limited slip geared @ 3.73. I was told by them that it should bolt right on.. Now I have a couple questions..

1)Will it bolt in
2)is $1600 worth it

my truck is a 2005 XL with the 8.8 geared @ 3.31 ..
alrighty thanks in advance

[kingfish51]

Just remember, if you change to a 3.73 in the rear, you are also going to have to do the front also.

[DRJ]

but it's 2wd so no worries there, also.. it's the 4.2L so will that motor be ok @ least for the time being?

[Patman03SprCrw]

Yes it will bolt in if it is off of a 2004-2008 F150 (exterior shock mounts)
No it will not bolt up if its 2003 and earlier (inboard shock mounts)

No it is worth no where near 1600

You will also need to either have ford reprogram your PCM for the different gear ratio, or have an aftermarket tuner. Unless you already have 3.73s

What does your door jam sticker say under "axle code' square?

[DRJ]

I'm almost certain it's got 3.31's now I'll have to post the axle code later tonight when I get home.

[Patman03SprCrw]

Just for ****s and giggles.....

Motive 3.73 with install kit $250 shipped

8.8" LS with carbon fiber clutches $260 shipped

so $510 bucks for all new parts. Unless your axle is damaged some how, no need to replace absolutely everything.

[Code]

Are they asking 1600 bucks for a 9.75??!!

Worth it..HELL NO!

What's wrong with your 8.8?

[minimonster17]

I wouldn't pay half that for a 9.75, however, it is an excellent axle, much better than the 8.8.

[Bindernut]

I agree...1600 is too much for a complete axle.

I would think your 8.8 would survive just fine behind a 4.2 and you could get the same ratio setup for 1/3 the price by just installing new gears/limited-slip like Patman posted.

[DRJ]

gotcha, now I see how $1600 is pricey, but basically my housing was damaged when my (mind that I am in an unfamiliar realm here so bare with me) connecting part that held the spider gears together basically got loose and tore through the differential cover. I'm not 100% on the extent of the damage so I've been shopping around. My dad is the DIYer and is set on doing this @ home, but I'm like let's take it to a shop dude.. So I'm trying to get the picture on what the best road is.

BTW under my axle tag it reads 27

[_cashel]

Originally Posted by Patman03SprCrw

Yes it will bolt in if it is off of a 2004-2008 F150 (exterior shock mounts)
No it will not bolt up if its 2003 and earlier (inboard shock mounts)

No it is worth no where near 1600

You will also need to either have ford reprogram your PCM for the different gear ratio, or have an aftermarket tuner. Unless you already have 3.73s

What does your door jam sticker say under "axle code' square?

the programming isn't mandatory, but your speedo will be off by a good bit if you don't. Mine reads 10mph faster than I'm going, but I'm going to get custom tunes later this year.

[Patman03SprCrw]

Originally Posted by _cashel

the programming isn't mandatory

Actually on 2wd it is necessary because it can mess with your wheel speed sensors, and thus mess with your ABS. The computer will think the back is going alot faster then the front. And then it will take the rear reading and disregard the front readings....

Unless you do something like smaller or bigger tires all the way around, and the change is equal for all the sensors, i would recommend programing

[Hillbilly_Delux]

Umm, I'm gonna back Cashel on this one. The ABS tone ring is mounted to the ring gear, and the ring gear always turns the same RPM as the rear wheels. So........no matter what gear ratio you have, the tone-ring speed stays the same. It doesn't matter if you've got 2.73's or 5.13's, it's all the same to the ABS.

[DRJ]

I love EBAY! What do you guys think?

LINK TO EBAY

[Bindernut]

Sounds like a much better pricetag than $1600. Should be what ya need.

I would still have your speedo recalibrated to the new ratio when ya get it though too. Otherwise your transmission shift points will be affected.