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Is there any other differences, besides the weight, when picking between an 8.8 pumpkin with posi?

I am wanting to convert my open iron 8.8 pumpkin to posi and I have found an 8.8 out of an manual Super Coupe that I am considering purchasing

or

Should I keep on looking for an aluminum unit instead?

Suggestions?

Thanks,

Doug
 

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doug said:
Is there any other differences, besides the weight, when picking between an 8.8 pumpkin with posi?

I am wanting to convert my open iron 8.8 pumpkin to posi and I have found an 8.8 out of an manual Super Coupe that I am considering purchasing

or

Should I keep on looking for an aluminum unit instead?

Suggestions?

Thanks,

Doug
The only real difference is weight and even that is slight. If you already have a cast iron pumpkin and you are going to have a limited slip differential put in then that's just fine. The iron pumpkin still has an aluminum cover.

There are a lot of threads about this topic. You may want to do a search and see some of the specifics.

BTW, Ford uses the name of "Trac Lock" and GM uses "Posi-trac" for their respective limited slip differentials.
 

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I'd prefer an aluminum, but I wouldn't turn down a good deal on an iron one. You can always have it painted or powdercoated if the rust really bothers you.
 

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The weight difference is actually closer to 15 pounds. Probably not a noticeable difference. I don't think you'd want a pumpkin out of a manual SC unless you're just using it as a core for a rebuild and gear swap. they only came with 2.72s or 3.08s if you're lucky.
 

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but if you plan on upgrading the gears anyway, getting a supercoupe unit with the trac-lock from the factory would be easier than buying one and the gears.

wether the weight difference is 6 or 15 it's still weight lost. It's all part of the weigh losing project Im undergoing. Every little thing adds up very quickly. Aluminum pumpkin, aluminum control arms, aluminum driveshaft, skinny front tires, etc.

I have the iron and the aluminum sitting in my garage, I think I'll go weigh them and report back :)

-Thomas
 

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k weighed them both just a few minutes ago.

Cast Iron 3.08 open differential - 81lbs
Aluminum 3.08 open differential - 62lbs

So it weighed in at just under 20lbs lighter than the cast iron. I can lift the aluminum with a little effort, but I had to drag that damn cast iron POS across the floor.

-Thomas
 

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Thomas said:
Cast Iron 3.08 open differential - 81lbs

...but I had to drag that damn cast iron POS across the floor.
Time to hit the gym.
 

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yeah no kiddin. At the first of the year I weighed 220lbs and now Im down to 185lbs I dont know what happened but hey, more weight loss for the car I guess :)
 

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I used to be hard on the trail for one of those aluminum ones. Then I started seeing the way that the cover flexes and thought...I would be willing to bet if you have 400 hp and sticky tires that you will crack the aluminum one. Now, I will be happy with the cast one and make the cover brace.

Chris
 

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the aluminum case should really have no reason to crack, the cover would be the only problem, which can be solved with the conver brace and poly mount bushings. I also invested in the poly bushings, cover brace, and the reinforced rear mount, along with the pinion brace, which all combined, should make the differential virtually indestructible.
 

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When I weighed my FRPP 3.73 rearend it came in at around 80 lbs.

Trac-lok adds to weight possibly?

r
 

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Thomas said:
the aluminum case should really have no reason to crack, the cover would be the only problem, which can be solved with the conver brace and poly mount bushings. I also invested in the poly bushings, cover brace, and the reinforced rear mount, along with the pinion brace, which all combined, should make the differential virtually indestructible.
I agree with that. When I broke the cover on my FRPP centersection (aluminum case, 3.73's, and T-Loc), no damage at all occured to the case. The chances of breaking the case itself are pretty slim, the cover and halfshafts are usually the weak links.


RichardM said:
When I weighed my FRPP 3.73 rearend it came in at around 80 lbs.

Trac-lok adds to weight possibly?
Definitely. Thomas, were both of the diffs that you weighed equipped (or not equipped) with a Trac-Loc?

-Rod
 

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racecougar said:
I agree with that. When I broke the cover on my FRPP centersection (aluminum case, 3.73's, and T-Loc), no damage at all occured to the case. The chances of breaking the case itself are pretty slim, the cover and halfshafts are usually the weak links.




Definitely. Thomas, were both of the diffs that you weighed equipped (or not equipped) with a Trac-Loc?

-Rod

Both are open diffs. well at least I was told...by you :) Remember the 8.8 you sold me? You told your dad it was an open 3.08, so Id assume thats what it is. Cast iron is naturally much heavier than aluminum, so 20lbs seems about right for the same internals.
 

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Rude said:
Go to a junk yard and get the pumpkin out of a Lincoln Mark VIII. It's aluminum and limited slip. But I put a Auburn Pro in mine.


Rude
All Mark VIIIs have traction control, which means none of them have limited slip. Still a good pumpkin though...if you put a TL in it yourself.
 

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Decy said:
The weight difference is actually closer to 15 pounds. Probably not a noticeable difference. I don't think you'd want a pumpkin out of a manual SC unless you're just using it as a core for a rebuild and gear swap. they only came with 2.72s or 3.08s if you're lucky.
Not necessarily true. I purchased a Trac-Loc pumpkin out of a SuperCoupe and it has 3.27 gears, which is what I wanted.

I would love to have an aluminum case, but don't want to pay anyone to swap internals from my cast Iron case. And its a little higher on the mechanics scale of difficulty than I am currently at right now. :D
 
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