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Topic: 7.5 vs 8.8 (Read 50601 times) previous topic - next topic

7.5 vs 8.8

Ok after reading the 8.8 issues or non-issues for people, I was wondering what all the advantages are of the 8.8.  Yeah it's bigger and has a locker???  But how about if I want to take my "one wheel wonder" and turn it into a posi?  With my absolute lack of knowledge of cars (please ask bike questions) I wonder if a posi out of a 7.5 ranger or bronco II will work in my '88 5.0 T-Bird... I think both units are 28 spline.  I plan on autocrossing this puppy... and be able to drive it home!:confused:
:headbang: '88 T-Bird 5.0 LX

7.5 vs 8.8

Reply #1 –
The guts from those rear ends should work fine in yours.

The main reason most people change to 8.8" is because of thier ability to handle more power.  My 7.5" broke behind a stock 302 with 140 horses.  If weight is a big concern, though, you might want to stick with the 7.5".  Changing to an 8.8 will pack about 80 lbs onto your car.

7.5 vs 8.8

Reply #3 –
When it comes to cars I'm mechanically reclined.  The following thread is a little intimidating: http://www.foxtbirdcougarforums.com/showthread.php?t=3664
Also, mentioned two up, 80lbs in weight???  No thanks.  I add enough weight when I sit in it:D
:headbang: '88 T-Bird 5.0 LX

7.5 vs 8.8

Reply #4 –
Well, just leave the 7.5 in until you get more power. Then when it goes you will be more modivated on which to keep.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

7.5 vs 8.8

Reply #5 –
I figured if you were doing Auto-X you wanted a light car.  You can easily obtain a numerically higher gearset for the 7.5 and a Traction-Lok (posi) unit for it.

7.5 vs 8.8

Reply #6 –
I'm in the process of having my 7.5 posi w/4.10's removed to have put in an 8.8 posi. Not sure what it is worth, but it was original to my car when it had a V-6, before I had it changed to posi w/4.10 about 25-30,000 miles ago. I interested in just the rear without the gear, that's cool too. Car is in Owensboro, KY right now.

7.5 vs 8.8

Reply #7 –
Quote from: Big_D
Also, mentioned two up, 80lbs in weight???  No thanks.  I add enough weight when I sit in it:D


That's one of those myths that is never going to die... Yea the 8.8 is heavier, but 80lbs??? NO WAY...

Quote from: yellow86coogr
I'm in the process of having my 7.5 posi w/4.10's removed to have put in an 8.8 posi. Not sure what it is worth, but it was original to my car when it had a V-6, before I had it changed to posi w/4.10 about 25-30,000 miles ago. I interested in just the rear without the gear, that's cool too. Car is in Owensboro, KY right now.


Maybe you could weigh the rears so we'd know the weights??? Say with just the axles installed, no brakes..

7.5 vs 8.8

Reply #8 –
There was a thread about the weight difference a while back. I'm doing a search but nothing is coming up. I DO remember that it was marginal at best. Like, 10 lbs or something.
2005 Subaru WRX STi|daily driver

7.5 vs 8.8

Reply #9 –
That myth will die when I swap my TC rear in, I'm gonna have both rears side by side and weigh 'em both on bathroom scales. I can't see 80 pounds either - maybe if the 7.5 were aluminum you'd see a difference like that, but not iron - hell, the only parts on the rears that are really different are the center sections (the tubes, axle shafts, etc should be pretty much identical)
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

7.5 vs 8.8

Reply #12 –
Nice find. I deem it stickyworthy :D
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

7.5 vs 8.8

Reply #14 –
If you wanted True Posi just weld up the spider gears in your 7.5... that way you don't have to take a chance on getting the backlash perfect because you can weld it up with the axle still in one piece.  I could never put in a carrier assembly without it later ripping to shreads.  I tried carbon paper and lip stick to make sure the tolerances were correct but no matter what the 5 times i changed the gears they all went to !
84 TC 302 -5.0L/t5/7.5 locking rear and a 3.45 gear, Edelbrock Intake, Aluminum Heads, Edlebrock 65mm Throttlebody, Edlebrock Cam, 24lb injectors & MAS Air Sensor calibrated via chip,  BBK headers, Catback H pipe, Magnaflow lers :evilgrin:
:pics-stfu:

 Project Thread with pics