How easy is it to install 3.73 gears?
 

I have to replace my pinion seal, and I figured while I'm in there, I might as well replace the gear and pinion if it's easy enough. Is it easy enough? Or do I need several specialized tools and 5 hours? LOL

(warning! nonstandard methods below!)

IF and only if you get an FMS gearset, it's fairly easy. The ford gearsets are supposedly all machined to have the same depth. What I did was pop the back cover, take the retaining pin out. Then I put the car back on the ground and I used the resistence of the car and parking brake to hold it in place while I loosened the ring gear bolts. You have to lift the back end and rotate the wheels a few times to get them all. Then you pop the driveshaft and using a huge ( 1 1/16?) socket, go after the pinion bolt and remove it with the car providing resistence again. Then lift, pop the c clips and pull the axles. Pull the differential out and save the shims and remember where everything came from! With FMS gearsets, you can simply reuse everything (unless it's worn). Get a dead blow mallet and WHACK the pinion. It'll take a bunch of pounding to get it to come out. Have a shop transfer the bearing to your new gearset using the existing shims on the pinion and pound it back into the axle. Everyone will tell you to replace the crush sleeve but you need herculean strength to get the new one to crush. I reused the crush sleeve as well. Pound the ring gear off the differential and use the oven bake trick to get the new ring gear on. Loc tight it and replace it, push the axles back and reinstall everything so the car can hold the ipnion for you. Get your pinion nut and tighten it till you have elimanated the wobbling effect and get ready for a hernia. Tighten it until it feels solid and gives a light resistence when you try to spin it. This will take at minimum a breaker bar. Reattach the driveshaft and take it for a careful spin! Problems will show up on deceleration. The only variable here is the pinion nut. If it howls, tighten the pinion nut till it goes away. See? No tools necessary. I used this method to go from 3.08 to 3.73 and have been driving around since last september on them with no noise whatsoever.

BSBSBS


FMS gears are crap.. and i'm just waiting for a flame on this but go ahead and ask me to back up my statement!!!!

Well, I should hear both sides of the coin... :D

That's true, there are ways of doing it yourself, I recommend getting it installed proffesionally just to be sure of the backlash and shims and all are done right. It's better to have it done right the first time than to have fun doing it twice.

Yeah, I've heard that more than once myself. So far, I think I'm gonna stick to replacing my pinion seal...

:D

STFU you bastard, I've got FMS gears:) They're fine unless your making mucho power and beating the hell out of them (ie, TimeBomb)

Brad put my gears in using the method of reusing the old pinion shims. It worked pretty good.

Just make sure to stick the pinion gear in the freezer for a few days first.

-Josh, aka the tireburner

u had it mostly right except for checking the backlash and wear pattern which is the most critical part. yes the original shims for fms gears should work(they did on mine), but make sure they work before you drive it! And just a word of advice for you crazypete, not replacing your crush sleeve was a BIG no no! You'll see the difference in the long run when your gears bust within a few years.

Now the crush sleeve just creates some backward pressure on the pinion while the pinion nut creates forward pressure, right? So if I get the pinion nut to the exact same tightness as it originally was, the crush sleeve should be doing it's job. Here was my mentality: if I do it wrong, I drop the rear end and have someone fix it. By the way, I dont own any air tools, so I have to work with mallets and breaker bars and crushing a crush sleeve sounded like it was out of the arm power range of this lowly programmer =P. But it worked (i.e., I got lucky). Even on engine braking at highway speeds, the gear doesnt make a peep. The driveshaft is ready to shatter and fly out of the car but thats a different issue. Hey if it all blows up.......4.30's!!!

Yeah...or a driveshaft sticking through your back seat floorboard. :)

--nathan

if my driveshaft breaks....

POLEVAULT!!!

It'll be fun, I've never flipped a car before =P

Good thing I dont have any bumpers to throw off the center of gravity. If one day I suddenly stop posting then you'll all know pete went went down with the ship!

Yeah, a driveshaft loop is cheap and well worth it

No, it's the stock driveshaft. They cant handle gearswaps and end up vibrating because the driveshaft now has to spin 3.73/2.73 = 36% percent faster at the same speeds. You could produce the same DS vibration by driving a stock 2.73 equipped mustang 75/.64 = 116 mph! Even then, the vibration damper thingy hanging off the pumpkin will probably help.

i've installed a lot of gears in my time.. FMS are the worst one's as far as problems i've had.. i've had 3 sent to me that were missing teeth from the factory.. and one sent to me that the ring gear wasnt tapped GREAT QUALITY HUH???????????? is that all????????? NO i've busted 2 sets of FMS gears in a million pieces.. no precision gears yet.. and precision has never sent me a busted up gear or one that wasnt tapped for bolts..

That crush sleeve is a PITA. I replaced mine with a solid spacer from Ratech. I reused a crush sleeve once (because I had no other choice) and it loosened up.

Andy

crush sleeve??
 

ok what the heck is a crush sleeve?
i have a set of 3:73's in my car but i didnt put them in. so there for i have never done a gear swap
so plez bare with me i am new to the gear swaping issues!

just thought i'd ask cuz i was wounding
thanks

I would just that done at a shop its not thate expensive and I got mine done at a local shop and also while you have the rear end apart its a good time to look at the wheel bearings and axles to see if they need to be replaced which was the case on mine and I got it done in one shot I also wish I would of gotten the after market pumpkin cover, just my .02

exactly. somebody back me up if im right but the crush sleeve(a new one) serves 2 purposes connected to each other.

1.) Maintain proper torque with the pinion nut.
2.) Hold pinion gear back so it does not move back and forth

Re: crush sleeve??
 

the crush sleeve goes between the pinion nut and the pinion gear. check the pic out

Re: Re: crush sleeve??
 

!@#$, did that pic even work?

Re: Re: crush sleeve??
 

Thats pretty much right. It goes in between the front bearing and a step that is machined in to the gear. When tightened correctly, the crush sleeve can give you proper preload, and torque on the pinion nut.

Andy

No offense to you bud, but if the words wear pattern and backlash don't meen much to you i would let a shop swap your gears. It is a pretty exact trial and requires special tools also like a dial indicator. And it is also a PITA if you are trying to do it lying on your bcak under a car on stands. If you do decide to go ahead anyway you might as well rebuild your t-lock while you are at it. A rebuild kit can be had for $30 and it comes with some extra shims to use in on the carrier when you are putting the 3rd mamber back together. Good luck. Don't hesitatem to ask how to check wear pattern of back lash if you need to. There is a apecific number to try and achieve with the lasha nd shims a variety of shims will be your best friends. Light Em Up!!!:)

After reading this thread, I've decided that I'm not going to mess with it. All in all, I'm pretty happy with it. If it was just simple "pop-the-gears-out-than-in" I'd do it, but too much to risk and investment involved at this point.

Maybe I'll give it a shot over the winter when she's put away for a few months, but I just wanna drive my 5.0!

Thank you for the comments!