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post #1 of 20 (permalink) Old 11-18-2006, 09:17 PM Thread Starter
 
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Question 7.5 posi

Hey im kinda new but i got a question. I want to put a posi in my stock 3.8 96 thunderbird and it has a 7.5 rear. I just want to get a one that would be relatively easy to put in and replacing the least amount of the rearend. I need a little advice on what to get. Thanks
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post #2 of 20 (permalink) Old 11-18-2006, 09:21 PM
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Get an 8.8 rear end from any V8 MN12/FN10 and then get a trac-lok unit and put it all together.

That is what I did.

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post #3 of 20 (permalink) Old 11-19-2006, 12:13 AM
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Quote:
Originally Posted by Nativedetroiter
Get an 8.8 rear end from any V8 MN12/FN10 and then get a trac-lok unit and put it all together.

That is what I did.


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post #4 of 20 (permalink) Old 11-19-2006, 07:36 AM
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I agree. Even if you just upgrade the 7.5 you still have to pull the whole pumpkin. You might as well upgrade to 8.8 for a few more $$$ and the same amount of work... it is a direct swap.
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post #5 of 20 (permalink) Old 11-19-2006, 05:38 PM
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The Turbo coupes before 1987 has trac lok 7.5's
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post #6 of 20 (permalink) Old 11-19-2006, 07:31 PM Thread Starter
 
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if i swap a 8.8 pumpkin for the 7.5 can i reuse my axles?

Last edited by lxthunderman; 11-19-2006 at 07:39 PM.
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post #7 of 20 (permalink) Old 11-19-2006, 07:37 PM
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You could always find an 8.8 that is already a trac-loc. Then its a direct swap (provided its the same ratio) Its still a direct swap even if you change ratios, you just have to change the speedo gear to. And as yours is a 96 I'd bet that you have a 3.27.


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post #8 of 20 (permalink) Old 11-19-2006, 09:45 PM
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Quote:
Originally Posted by lxthunderman
if i swap a 8.8 pumpkin for the 7.5 can i reuse my axles?
yes they will work, but why not ugrade to at least v8 axles while you have it apart , you have to pull them from the knuckle anyhow

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post #9 of 20 (permalink) Old 11-20-2006, 09:46 AM
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Daily driver?

~~Hello

If this is your daily driver than a 7.5 will hold up. Find a super coupe in the parts yards. The super coupe should have a traction lok. Either axle's will work. The smart way is to purchase the whole rear K. Generally is would be cheaper because they have less work & you get all parts together. look for the L in the gear ratio tag.(like 3L55 8.8)

I run a 7.5 in my oval track car with 4.10 open(rule) gears. I have used both V6 & V8 axles. Remember I race from a rolling start. If you will be drag racing Even a little go with the 8.8 & V8 axles for sure. If you will be drag racing hard go with aftermarket axles.

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post #10 of 20 (permalink) Old 11-20-2006, 06:01 PM Thread Starter
 
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yea this is just my daily driver with the v6 in it so which cars have the 7.5 posi in it with the gear ratio of 3.27 in it also the 8.8 posi. Thanks for the relies.
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post #11 of 20 (permalink) Old 11-20-2006, 07:13 PM
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lets face facts s well, the chances of findign a used 7.5 trac lock is rare , i can count on one hand how many i have seen, 2 ! the 8.8 has much more availablity, ie cheaper !

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post #12 of 20 (permalink) Old 11-20-2006, 10:51 PM
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when you get one out of a Mark, its even aluminum, so its a little lighter. Then you can get the half-shafts at the same time!

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post #13 of 20 (permalink) Old 11-27-2006, 03:39 PM Thread Starter
 
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what are half-shafts? Will any 8.8 work even if its off a car that doesnt have independent suspension.
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post #14 of 20 (permalink) Old 11-27-2006, 04:35 PM
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Half-shafts are our "axles" coming out of the differential.

You can use the 8.8 pumpkin out of a non independent suspension (IRS) car but the rear end's side gears will have to be machined. There is an article about the machining instructions somewhere. . . . .I can't find it right this instant. . .sorry.

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post #15 of 20 (permalink) Old 11-27-2006, 05:46 PM
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Quote:
Originally Posted by wether
Half-shafts are our "axles" coming out of the differential.

You can use the 8.8 pumpkin out of a non independent suspension (IRS) car but the rear end's side gears will have to be machined. There is an article about the machining instructions somewhere. . . . .I can't find it right this instant. . .sorry.
you need to be clearer on this! hes not talking the whole axle assembly just the actual differential inside ie the carrier,

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post #16 of 20 (permalink) Old 11-27-2006, 06:05 PM
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I'd just go for the 8.8 over the 7.5 - have a better rear end for down the road - maybe you'll need it

Quote:
Originally Posted by jk89cat
lets face facts s well, the chances of findign a used 7.5 trac lock is rare , i can count on one hand how many i have seen, 2 ! the 8.8 has much more availablity, ie cheaper !
Just for the record, my 91 used to have a 7.5 rear end and fairly sure it had TL. I'm looking for the pic of the rear end tag.

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post #17 of 20 (permalink) Old 11-28-2006, 03:52 PM Thread Starter
 
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isnt the 8.8 rear a widder punkin so i would need shorter axles? also would the mark rear work in the rear without the half shafts without any machinging required?

Last edited by lxthunderman; 11-28-2006 at 03:57 PM.
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post #18 of 20 (permalink) Old 11-28-2006, 05:15 PM
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Ahh, nope. Same set-up, same lengths. Ford kept it simple for budget reasons, the car fits around all of it.

As for the Halfshafts, I wouldn't cut corners, even thought the V6 halfs can fit, once you see the difference between the two, you will want to go with the V8 ones.

Just don't cut corners. If you are upgrading your rear end, do it all the way.

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post #19 of 20 (permalink) Old 11-28-2006, 06:47 PM
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But if u can’t upgrade to an 8.8, the 7.5 is plenty strong for a daily driven v-6 car. That’s why Ford put it there.

I know of a few people with v-8 ford rangers with the stock 7.5 rear end and they are still together. But they haven’t put drag slicks or huge off-road tires on them yet so the tires spinning is sort of a shock buffer. There not as weak as people make them out to be and are perfectly fine behind a v-6, but it shouldn’t be behind a V-8.

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post #20 of 20 (permalink) Old 11-30-2006, 08:02 PM
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7.5 traction lok pumpkins are avilable, but 8.8 traction lok are a lot easier to find. I can go out to the local wrecking yards any day of the week and find about a dozen MN12s with 8.8 traction loks, but I only see the 7.5s about 2-3 times a year. Whichever you were to choose would cost about the same as the other to purchase or rebuild. The 8.8 would bolt right in to your car and is a stronger piece.
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