Do the gears have to be removed to install the LS? If so, then I run the chance of developing a "hum" like you would when swaping out gears?

 

I believe the LS is the housing for the gears
In other words yes. Basically the ring gear slips over it, the axles go through it, and the spyder gears are in it


Not F150 but a bronco you get the idea though

 

hmm I see... interesting... thanks!

 

Yes the carrier must be exchanged to install a limited slip. YOu only risk a hum if the gears are not setup properly.

 

yeah I know, this just means I WILL be upgrading to 4.10 gears when I have the LS installed... the stock 3.55 I have SUCK! Man I'm going to be poor....

 

Another question.. since I will most likely have the dealer install the LS (probably the stock one... but they are pretty mod friendly so they may allow me to have them put in a detroit trutrac..) if I do end up using the stock one, does it come with gears already set inside? Aka... like I HAVE to buy gears with the stock LS because they come pre installed?

 

When I visited the dealer, their labor price was what I paid to get the whole job done. Have you shopped around on this job? Just checkin

As far as your question, Im not sure if I follow.

What setup do you have now? 3.55 and Open differential or 3.55 and Limited Slip?

What exactly are you looking at doing?

I can answer your question, im just not sure where we are.

 

that carrier should come with everything bundled together. all you (or the shop) would have to do is pull the carrier out, pull the ring gear off and put it onto the LS unit and put it back in. I have one sittin in the shop that i've yet to install.

they make an additive you have to run when using a LS. it's not just regular gear oil.

 

Sadly I have a 3.55 OPEN rear end WITH the stock 20's... talk bout a slug (however I was previously driving a 4.6 expy so this truck feels way faster). I was looking to order an 08 reg cab fx2 w/ 5.4, but went with an 07 supercab fx2 w/5.4 because I walked out with a 33k stickered truck for 25k. Ideally, I shall have the dealer put in my LS because they will cover it under my trucks warrenty.

I REALLY want to avoid any hum in the rear end, because my old expy developed it around 120k miles and I couldn't stand it. I was just going to get the LS added to my 3.55 rear end, but since it seems as though the gears will be removed anyways, I might as well upgrade to a 4.10 while I'm at it

 

Now I understand! lol

Ok as far as LS units, do you offroad the truck at all? If no, then the Ford LS is fine. A trutrac would be ideal, but you dont absolutely need it. If you just swap carriers, Open to LS, they only need to set the ring gear, not the pinion (which is a ton of the work). Labor will be cheaper if you just swap carriers, But, since they have the rear end apart, if you want to do 4.10's nows the time to do it.

I would check out ebay to see if you can find some 4.10's. Shouldnt be a problem.

sorry it took so long for me to understand.

 

No offroading for me... just lovely 8+ inches of snow like every weekend this winter. So if I just swap to an LS I don't have to mess with the gearing then?

EDIT: hmm... ring gear... now I see from the pictures above. Where does the pinion go in the rear end?

 

While your in there, and wanting 4.10s, you might as well just put them in.

However, to put in an LS, all you have to do is take out the case w/ ring gear on it, no messing with the pinion gear. Stick the ring gear on the new case, play with some shims, and your done, as opposed to redoing the whole rear end if you would put 4.10s in it

 

Yeah but how much of an increase would it be to install just an LS to LS + 4.10?

 

Here is the cheapest place I know of for a truetrac

http://www.drivetrainspecialists.com...ruetrac-1.html

Here is the gears

http://nationaldrivetrain.com/shopsi.../ford_975.html

Figure roughly 7 bills in parts plus labor for gears and a truetrac