7.5 Rear end question?

Dec 5, 2018
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Buffalo
#1
I would like to keep my 7.5 rear end in my car and not convert to an 8.8 rear end what is the cheapest way to make it posi. I would also like to add 373 gears or 355 gears, approximately pushing 300HP with new build what gears should I go with?
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
#2
Why? The cost to build a 7.5 would be the same and have half the strength as an 8.8
 

90sickfox

I didn't really have an issue with the stink...
SN Certified Technician
Mar 2, 2015
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#9
All the mustang 5.0s from 86 to 93 have limited slip posi traction 4 lug 8.8 rears. The clutch packs aren't hard to rebuild. They wear out causing a bunch of cats to one wheel peel.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
9,753
3,077
193
polk county florida
#10
An old school method of helping the clutch packs last is to change the oil every 40-50 thousand miles and then drive in a tight figure eight slowly for 5 or 6 rounds, kinda cleans the clutch faces.
 
Dec 23, 2003
366
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foxchassis.com
#11
Also, 7.5 in 1982 through 1985 Capris and Mustang are already Traction-Lok from the factory (they are not "posi" so please stop calling it that) so there is no need to "convert" to T-L. And 3.55 is a 8.8" gear. It is not available for 7.5. The close equivalent for a 7.5 is 3.45.
 
Sep 1, 2010
2,092
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124
Kearney, NE
#16
When the 8.8 was new in Mustangs and available in the Ford Performance catalog, I found it a lot less expensive to put the Eaton style (clutch plate) actual Ford Limited slip in the stock 7.5” rear end.
Now, a salvage 8.8” rear is easier to find that should bolt in. I’d start with a good 8.8” core and go through it with new bearings, seals, and possibly clutches.
 
Feb 19, 2018
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#17
You can buy 7.5 in traction locks in Ranger trucks and early foxes and aftermarket. I have a 2.73 stock one in my 79 and a Ford Racing one with a 4.10 gears in my 82. And there are four and five lug axles for them. My 4.10 has been 7.90 in the eighth with 1.80 sixty foots. So far so good. Its a lot lighter than an 8.8. No worries, I have several 8.8s waiting in the wings.
 

CarMichael Angelo

I don't like your attitude, let me fix that.
SN Certified Technician
Nov 29, 1999
10,391
10,848
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Birmingham, al
#18
What?.
Also, 7.5 in 1982 through 1985 Capris and Mustang are already Traction-Lok from the factory (they are not "posi" so please stop calling it that) so there is no need to "convert" to T-L. And 3.55 is a 8.8" gear. It is not available for 7.5. The close equivalent for a 7.5 is 3.45.
What??? I’m not the one that has a problem with people using GM terminology for their Ford parts??

Say it ain’t so.
 
Sep 1, 2010
2,092
266
124
Kearney, NE
#19
All of the Fox 5.0 Mustangs (except the 93 Cobra and maybe the turbo coupe super edition I am blanking out on) came with 8.8 rear ends and a LSD WITH 4 lug axles. Your wheels will not have to be changed, nor the front end parts. A wiki search will tell you for sure, but it seems like 85 was the first year the GT got the 8.8”.

There are many 8.8 traction lock rears with 4lug axles
 
Last edited:
Sep 1, 2010
2,092
266
124
Kearney, NE
#20
You can buy 7.5 in traction locks in Ranger trucks and early foxes and aftermarket. I have a 2.73 stock one in my 79 and a Ford Racing one with a 4.10 gears in my 82. And there are four and five lug axles for them. My 4.10 has been 7.90 in the eighth with 1.80 sixty foots. So far so good. Its a lot lighter than an 8.8. No worries, I have several 8.8s waiting in the wings.
@Rcdgl any idea on HP and torque without me using a drag calculator? How many passes, how much other driving and what transmission are you using with the 7.5”?
I wish my Ranger had come with a LSD rear end.
 

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