Gear swap done

Stever89 · May 28, 2011

I got a used set of 3.73 gears from a guy on ebay. Jacked the car up and got started. I've never done a gear swap so you can imagine my surprise when I pulled the 2.73 pinon and set it next to the 3.73.

All went well, all specs were good, no issues, no clunks no whine or roar. Backlash was .012". Gear pattern was perfect, just a little to the toe on the drive side of the ring gear. I did manage to pinch the hell out of my finger while putting the ring and trac-lok unit back in I also chunked the dogbone.
Took it for a ride afterward, no issues. I'm very happy with the outcome. I don't know if I'd try to do this again without a lift. I'm not a kid anymore and I'm not as flexible as I used to be

I love the awesome 2nd I can grab now.

jrichker · May 28, 2011

The dog bone as it is called, is a vibration dampener. With the driveshaft spinning faster with 3.73 gears, it and a perfectly balanced drive shaft play a big part in having a driveline that doesn't shake itself apart.

281pony · May 28, 2011

nice dude, thats awesome. i refuse to touch gears in any of my cars. i needed a new gear ratio so i bought a whole new rear end

1991notchbackLX · May 28, 2011

Nice job man. That's a big job to tackle for a first timer. I wouldn't attempt it myself without help so you're a better man than me. You can pretty much wave goodbye to first gear now, it's pretty much useless after a swap to 3:73s. I always started right from second in my mustangs with gear swaps.

NIKwoaC · May 28, 2011

Make sure you properly break in the gears!!!!! Even though they are used, I would still give them a break in period before you start thrashing them. But congrats on the successful install! It's night and day difference, isn't it?

jrichker said:
The dog bone as it is called, is a vibration dampener. With the driveshaft spinning faster with 3.73 gears, it and a perfectly balanced drive shaft play a big part in having a driveline that doesn't shake itself apart.

I pitched mine a long time ago, too, and never had any significant problems. Like anything else, it's just an attempt on Ford's part to reduce NVH. It's a Fox Mustang, not a Lexus, hahaha. These cars are kings of NVH.

Stever89 · May 28, 2011

NikwoaC said:
Make sure you properly break in the gears!!!!! Even though they are used, I would still give them a break in period before you start thrashing them. But congrats on the successful install! It's night and day difference, isn't it?

Too late I drove it easy for about 5 miles So far so good I will have to get used to these gears. I kept reaching for another gear in 5th!

And an extra surprise, the speedo is now accurate. It was always 15-20 mph too fast and unusable. I put my GPS in and they're lined up almost perfectly now. The guy that built the car must have put this speedo gear in preparation for a gear swap he never got around to.

NikwoaC said:
I pitched mine a long time ago, too, and never had any significant problems. Like anything else, it's just an attempt on Ford's part to reduce NVH. It's a Fox Mustang, not a Lexus, hahaha. These cars are kings of NVH.

Unless something changes, I'm not putting that heavy pos back on. From what I've read (and I could be wrong) it's for the original setup. I'll keep it on hand for a while, but I have a feeling it's going in the scrap heap.

Stever89 · May 28, 2011

281pony said:
nice dude, thats awesome. i refuse to touch gears in any of my cars. i needed a new gear ratio so i bought a whole new rear end

Thanks! If you can rebuild an engine, you can do this. A lift would be a great way to go. I used jackstands, had the whole car up, front tires about 6" off the ground, same with the rear with the diff hanging down. Patience, preparation, the right tools and good weather all help a lot.

Stever89 · May 28, 2011

1991notchbackLX said:
Nice job man. That's a big job to tackle for a first timer. I wouldn't attempt it myself without help so you're a better man than me. You can pretty much wave goodbye to first gear now, it's pretty much useless after a swap to 3:73s. I always started right from second in my mustangs with gear swaps.

I use 1st to get it moving, then on to 2nd. Those Nittos on the rear won't be good for long!

ratio411 · May 29, 2011

Stever89 said:
View attachment 187818

I saw the other day where FMS sells these things for 160!
Have no idea why someone would buy one?

Stever89 · May 30, 2011

ratio411 said:
I saw the other day where FMS sells these things for 160!
Have no idea why someone would buy one?

I'll bead blast it and sell mine for a low, low price of only $100.00

Mintsick · May 30, 2011

Congrats, sounds like the swap went pretty smoothly! I just picked up a complete 3.55 rear last week as it ended up costing me less than it would have to get a set of 3.55's installed.

hsean · May 30, 2011

Mintsick said:
Congrats, sounds like the swap went pretty smoothly! I just picked up a complete 3.55 rear last week as it ended up costing me less than it would have to get a set of 3.55's installed.

it is definately cheaper when you find a rear end complete with it already installed.alittle over a year ago i had bought a 96 gt rear end with with what i thought was a 3.27 gear [thats what the guy told me it had in it].i opened it up a couple of months ago only to find out that it only had a 2.73shortly after picking up this rear end i decided to get rid of a a 3.55 with trac lok complete and like new and very low miles for 27 bucks and an 8.8 rear end sandblasted and epoxy primered for 80 bucks.this same guy is now selling the 3.55 for 90 bucks on local forum so i contact him and he agrees to sell the 3.55 with trac lok back to me for 50.i am still waiting on this guy to send me his address so that i can pick it up which was supposed to be this morning.the moral of the story i will never sell another part that i think i don't need until i finish my project.

Mintsick · May 31, 2011

^ That is a great deal if it goes through. The rear I got had been gone through about 10+ years ago and the guy claims it has an auburn pro diff in it with about 10k miles total on the unit. I haven't popped the cover yet (I will be to install the 5 lug axles) to verify but he sent me a picture of the old 2.73 ring gear in the 3.55 gear box and the #'s checked out.

Flavadave4 · May 31, 2011

Congrats on the install, thats the kind of job I take to the shop to have done! I still say gears are the most effective mod you can do in these cars.

Stever89 · May 31, 2011

Flavadave4 said:
Congrats on the install, thats the kind of job I take to the shop to have done! I still say gears are the most effective mod you can do in these cars.

Thanks Now I can say I've done it, but unless I have a lift, I won't do it again. I'll pay someone else to do it

ratio411 · Jun 2, 2011

hsean said:
...rear end with with what I thought was a 3.27 gear. [That's what the guy told me it had in it]. I opened it up a couple of months ago only to find out that it had a 2.73.

I just recently bought a rear that the seller told me was a 2.73, and I found a 3.27 when opening it up.

Goes to show you need to be very careful when buying a complete rear.
Always count the rotation and know what you are buying. Remove the cover and look at it if you can.

hsean · Jun 2, 2011

ratio411 said:
I just recently bought a rear that the seller told me was a 2.73, and I found a 3.27 when opening it up.

Goes to show you need to be very careful when buying a complete rear.
Always count the rotation and know what you are buying. Remove the cover and look at it if you can.

i only paid 120 for the complete rear end and made it easy for my 5 lug swap i finally got back that 3.55 with trak lok from the guy that i sold it to yesterday.i didn't think the guy was going to come through everytime i called it was i will call you back later.50 bucks now hopefully i can get it installed for a reasonable price.

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