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Discussion Starter · #1 · (Edited)
So I need to buy some gears, I'm going with 3.73's so i can drive on the highway in decent RPM's while have decent acceleration.

I was wondering if I could just take out the current ring and pinion and replace it with a 3.73 ring and pinion. Add some lube yada yada and go on?

Is it necessary to buy the whole $450 kit form summit or the $300 from jegs?

What else would i have to do once I get the 3.73 gears?

Thx!
 

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You should replace the seals but inspect everything. Most people just purchase the basic installation kit which comes with the seals and **** so you don't have to worry about opening it back up later.

Only other thing you'll need is to find out how far off your speedo is from being correct again. To correct this or get it close enough to deal with is to change the "speedo gear" which is bolted into the side of your trans and connected to the speedo cable that runs up into your dash. It's a simply five minute job and like two bolts I believe or one can't remember off hand but it's simple but you'll have to buy the correct one. They range from different sizes (amount of teeth) just google for the chart to find the correct one.
 

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Ryan, I would replace the seals but what kind of install kit?
Ford Racing 8.8 Ring and Pinion Installation Kit

And I wasn't very detailed on the post above because it's late a **** here and I have to be up in four hours but real quick read through this install writeup listed below and a few post down and you'll know exactly what has to be done for the install because it's a great writeup. Good luck

How to install your own gears!!! - Mustang Forums at StangNet

also, if your car has a t5 from an 89 or below you have a 7 tooth drive gear so you'll need a 21 tooth speedo gear for the 3.73's.

late
 

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when i did mine i got new bearings seals and everything. didnt want bearing failure 1000miles after the whole rebuild. then i also put new bearings in the outsides too. just easy things you should do when you rebuild your rear end.
 

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Just a suggestion. If it's no issue, ignore this. When I had my 87 mustang's rear end switched to 3.73's, we rebuilt the differential with kevlar clutches. Consider rebuilding the differential especially if it hasn't been done yet. My internals were pretty worn. I had the 1 wheel spin blues and that's why I did it. Now it grabs like crazy, catching 2nd and 3rd easily. While you have things apart...... Just consider it.

I replaced the bearings also, for the reason 88 saleen noted. The guy that rebuilt it had the shims and seals, so he included that in his install price, but I did run across the street to carquest and got the bearings he told me I needed. He is a service manager at a ford garage that drags mustangs, so he knew his stuff.

You will LOVE the 3.73's !! mine was a t-5 with 3.08's originally. At 70 on the highway, I spin about 2500 instead of 2000, but who cares about the higher rpms, It's a lot more fun to drive now.:yes
 

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Discussion Starter · #9 ·
yeah, I found out this weekend I have a POSI rear end!

I think its an 8.8 posi. Both wheels spin the same way when manually rotated and both spin during a burn out sooo....???

CHRISBMX: I might have to consider that. can you do that to a posi? I can't wait until the 3.73!!!
 

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If your not familiar with the rear end at all, please leave it to a professional to install the gears who knows that they are doing. It is very precise back there...best to leave it to a professional with the right equipment.


good luck with your gears--- you will enjoy them!
 

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yeah, I found out this weekend I have a POSI rear end!

I think its an 8.8 posi. Both wheels spin the same way when manually rotated and both spin during a burn out sooo....???

CHRISBMX: I might have to consider that. can you do that to a posi? I can't wait until the 3.73!!!

Well, you shouldn't have posi, since it's a chevy brand name. For Ford, it's Tracktion-Lok, both are rebuildable clutch type limited slip diffs. You don't call it Miller, if you have Budweiser, do you? ;)
 
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