How easy is it to install 3.73 gears?

Beanhead · 10-08-2003, 08:45 AM

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

crazypete · 10-08-2003, 09:24 AM

(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.

b055 · 10-08-2003, 09:41 AM

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!!!!

Beanhead · 10-08-2003, 10:05 AM

Quote:

Originally posted by b055
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...

USMC302 · 10-08-2003, 10:24 AM

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.

Beanhead · 10-08-2003, 10:35 AM

Quote:

Originally posted by USMC302
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...

tireburner163 · 10-08-2003, 11:03 AM

Quote:

Originally posted by b055
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!!!!

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

stang_racer20 · 10-08-2003, 11:07 AM

Quote:

Originally posted by crazypete
(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.

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.

crazypete · 10-08-2003, 01:07 PM

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!!!

silver_pilate · 10-08-2003, 03:12 PM

Quote:

Hey if it all blows up.......4.30's!!!

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

--nathan

crazypete · 10-08-2003, 03:24 PM

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!

USMC302 · 10-08-2003, 03:24 PM

Yeah, a driveshaft loop is cheap and well worth it

crazypete · 10-08-2003, 03:29 PM

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.

b055 · 10-08-2003, 06:19 PM

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..

andy669 · 10-08-2003, 09:19 PM

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

pedley · 10-08-2003, 11:26 PM

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

Scrapla · 10-09-2003, 12:47 AM

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

stang_racer20 · 10-09-2003, 02:03 AM

Quote:

Originally posted by andy669
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

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

stang_racer20 · 10-09-2003, 02:10 AM

Quote:

Originally posted by pedley
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

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

stang_racer20 · 10-09-2003, 02:13 AM

Quote:

Originally posted by stang_racer20
the crush sleeve goes between the pinion nut and the pinion gear. check the pic out

!@#$, did that pic even work?

10-08-2003, 08:45 AM	#1
Beanhead Registered Member Join Date: Oct 2002 Location: Near Boston, MA Posts: 51	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 __________________ '94 Cobra '95 V6

10-08-2003, 09:24 AM	#2
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	(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. __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

10-08-2003, 09:41 AM	#3
b055 Registered Member Join Date: Mar 2003 Location: philadelphia ms Posts: 180	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!!!! __________________ i got mustangs. do u?

10-08-2003, 10:24 AM	#5
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	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. __________________

10-08-2003, 01:07 PM	#9
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	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!!! __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

10-08-2003, 03:24 PM	#11
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	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! __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

10-08-2003, 03:29 PM	#13
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	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. __________________ 91 GT Carb conversion, holley 600 double pumper, edelbrock performer intake, FMS "C" drop springs, march 1000 underdrive pullies, crane 1.7 roller rockers, GT-40P headers, bassani x pipe, american thunder catback, FMS 4.56's, msd aL6, trunkmount battery, A/C eliminator kit, 3000 stall tci streetfighter, AOD with transgo kit, A+ servo, 300M hardened lockup shaft, kevlar bands and 28,000 gvw trans cooler, 3 core radiator, 300 lbs stripped with a full interior

10-08-2003, 06:19 PM	#14
b055 Registered Member Join Date: Mar 2003 Location: philadelphia ms Posts: 180	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.. __________________ i got mustangs. do u?

10-08-2003, 09:19 PM	#15
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	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 __________________ 88 coupe 91 LX NMRA Pure Street 5120

10-08-2003, 11:26 PM	#16
pedley Registered Member Join Date: Jul 2003 Location: canada Posts: 74	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

10-09-2003, 12:47 AM	#17
Scrapla Registered Member Join Date: Apr 2002 Location: Florida Posts: 532	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 __________________ 90gt 347 and some bolt ons :-) RICE HATERS MEMBER #73

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