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Author
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Topic: Ford Posi and non-Posi rears
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Fight2Conquer
Gearhead Posts: 112
From: Vernon, NJ
Registered: Sep 2004
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posted 06-25-2005 11:40 PM
   
I want to switch my non-posi rear (2.79) to a posi rear end. Dont know too much about rears other than if I were lucky enough to find a trac-lok parts car to pick it up and rob the rear. But they are expensive so Im not sure what to do. Do I have to buy a whole complete rear that was already posi or can I go on eBay or something and buy all the parts I need and build it with the one I have? I go to swap meets all the time and at the local junkyards they have many rears, I just dont know how to distiguish one from another and if they are posi or not and Im not about to believe someones "guess" or what they think is posi for $200 cash no return. Any help is appreciated!!------------------
David
68 Coupe
302 with edelbrock performer intake work in progress partsandcars.8m.com
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68 Coop
Gearhead Posts: 2911
From: Mesquite, NV. 89027 M&M# 4256
Registered: Oct 2004
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posted 06-26-2005 12:11 AM
David, this should answer ALL the questions that you have about 9" rear ends, and 8's too. Hope it helps.
http://www.kevinstang.com/Ninecase.htm------------------
William
68 Coupe
289
Edelbrock 600
Performer Intake
Headers/X-pipe/ Flowmaster 30's
C4
8"rear/2:79gears
"Restomod in Progress"
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Fight2Conquer
Gearhead Posts: 112
From: Vernon, NJ
Registered: Sep 2004
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posted 06-26-2005 12:23 AM
Okay, after reading all that I know how to spot a 9" from an 8". Are all 9" rears posi? I will probably go to the next swap meet I can and see if I can pick one up. That oage helped a lot! Thanks!------------------
David
68 Coupe
302 with edelbrock performer intake work in progress partsandcars.8m.com
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68 Coop
Gearhead Posts: 2911
From: Mesquite, NV. 89027 M&M# 4256
Registered: Oct 2004
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posted 06-26-2005 12:37 AM
I could be wrong, but I don't think so. I think they came with different gears and set-ups for different applications, just like the 8" do. I do know one thing for sure tho, you will get an answer on this, soon. Sorry, I thought that page pretty much covered everything.------------------
William
68 Coupe
289
Edelbrock 600
Performer Intake
Headers/X-pipe/ Flowmaster 30's
C4
8"rear/2:79gears
"Restomod in Progress"
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68mustang351w
Gearhead Posts: 357
From: San Diego, Ca
Registered: Sep 2004
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posted 06-26-2005 03:48 AM
Knowledge is this is pretty limited, but from what i remember, if you turn one of the wheels on an open rear one way, the opposite tire turns the opposite way. So in a locking diff, both would turn the same way, get it ? Hope that helps... David F.
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ejbrez
Journeyman Posts: 33
From: Bellevue, NE, USA
Registered: May 2005
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posted 06-26-2005 09:09 PM
"Okay, after reading all that I know how to spot a 9" from an 8". Are all 9" rears posi?"David...no, not all 9" rears were posi's. Some 9" rears were open, some were posi-traction, or traction-lok, which is the same thing. A locker, or Detroit Locker as they are known, has both output splines, or tires spinning constantly at the same ratio no matter what (these are the ones that experience a lot of wheel hop especially around corners). A traction-lok senses wheel spin and as soon as it spins will lock the other tire/spline. Check out this web-site: http://www.enjoythedrive.com/content/default.asp?id=7024 ------------------
72 Mustang Mach1 351CJ/C6/3.50 Open
99 F150 5.4/3.73 K&N/FLOWMASTER/HYPERTECH
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SteveLaRiviere
Administrator Posts: 44954
From: Saco, Maine
Registered: May 99
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posted 09-04-2005 08:27 PM
Positraction is the name of GM's limited slip axle. Fords do not have posi, you're showing your green when you call a Traction Lock a Posi.------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'05 Mercury Sable LS 3.0L DOHC 24V Duratech V6
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68F100
Gearhead Posts: 2610
From: Burlington, Iowa
Registered: Oct 99
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posted 09-04-2005 08:38 PM
Picky, picky...  I admit, I've called it posi too. Most of the time I call it limited slip, but I'm usually talking about old Ford trucks. Is it the same term for cars and trucks, 8.8's, 9 inchers, etc. ? Is it Traction Lock across the board?
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SteveLaRiviere
Administrator Posts: 44954
From: Saco, Maine
Registered: May 99
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posted 09-04-2005 08:49 PM
Yes.Fords use limited slips called Traction Locks {aka Trac Loks} and locking rears such as the Detroit Locker and the older Equa-Loks. GM uses Positraction, Mopar uses Sure Grips I think and AMC used No-Spins or something like that. When I hear someone say 'Ford posi' I cringe. Read a book!  ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'05 Mercury Sable LS 3.0L DOHC 24V Duratech V6 [This message has been edited by SteveLaRiviere (edited 09-04-2005).]
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427Fastback
Gearhead Posts: 261
From: N.Vancouver.B.C
Registered: Jan 2005
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posted 09-04-2005 10:29 PM
There is also the Ford Equa-lock which was used in the same years in 8&9 inch assy,it has slightly different clutch pack and can be mistaken for the the stronger Trac-loc.Just because you have a Ford clutch pack posi in your car does not mean you have a Trac-loc.------------------
68 Fastback 427MR 4 spd.Deluxe interior,8000 tach,140 speedo,am/fm,tilt.
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Fastback68
Gearhead Posts: 3721
From: Sucat, Paranaque, Philippines
Registered: Jul 99
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posted 09-04-2005 10:32 PM
Devil's advocate only here, Steve - don't get upset, huh? My sense is that for many folks positraction (let's spell it with a small "p" for this example) was and still is a brand name that has also become a generic term to cover the whole bunch, a la kleenex, hoover, pampers, etc.
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SteveLaRiviere
Administrator Posts: 44954
From: Saco, Maine
Registered: May 99
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posted 09-06-2005 06:37 PM
True, but it dilutes the brand, not to mention the many times each day kids probably buy true Positraction units on ebay and get an ugly surprise when it's time to try to bolt it in. Besides, we wouldn't want people starting to call 289s 'Mouse motors' would we? ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Hardtop 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'05 Mercury Sable LS 3.0L DOHC 24V Duratech V6
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sigtauenus
Gearhead Posts: 2982
From: Va Beach
Registered: Jun 2000
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posted 09-07-2005 09:46 AM
quote:
Originally posted by Fastback68:
was and still is a brand name that has also become a generic term to cover the whole bunch, a la kleenex, hoover, pampers, etc.
Yeah, I'll buy that. Same thing as when you ask somebody if they want a coke, when you are really asking if they want a soft drink. I do know from hanging out here for some time now that it seems to be one of Steve's pet-peeves, so I'll humor him, since it is his wepsite and all. 
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