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post #1 of 20 (permalink) Old 10-19-2007, 12:43 AM Thread Starter
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Mark VIII Differentials

I originally thought I read that Mark VIII's had alluminum trac lock diff's. But recently I think I have read that they have open rears due to the traction control. So which is correct? Do any Mark VIII's have trac lock? And are they all alluminum? Thanks

C.Hill

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post #2 of 20 (permalink) Old 10-19-2007, 01:07 AM
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they are alluminum open diffs only, most are 3.08's, lsc's are 3.27's

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post #3 of 20 (permalink) Old 10-21-2007, 09:42 PM Thread Starter
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I was reading on one of the forums here that 93 Mark VIII's had trac lock? Is this not true? If it is, were they aluminum? thanks

C.Hill

'97 Laser Red T-bird w/ Option 66S - 125,000 miles, stock except for 3.73s Best ET 15.6 @ 88.3
'94 Electric Red T-bird LX V-8- 212,000 miles- SOLD
2005 Ebony Black Excursion Limited 6.0 Diesel STUDDED

"Thinking is the hardest work there is, which is the probable reason so few engage in it."
- Henry Ford

"Opportunity is missed by most people because it is dressed in overalls and looks like work."
- Thomas A. Edison

http://www.tailofthedragon.com <---- A test of driving ability and nerves.

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post #4 of 20 (permalink) Old 10-21-2007, 09:46 PM
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not that i know of, but they are all aluminum

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post #5 of 20 (permalink) Old 10-21-2007, 09:55 PM Thread Starter
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I was thinking i read they were out of a 1997 LSC but I don't konw for sure.

C.Hill

'97 Laser Red T-bird w/ Option 66S - 125,000 miles, stock except for 3.73s Best ET 15.6 @ 88.3
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post #6 of 20 (permalink) Old 10-21-2007, 09:59 PM
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lsc's got 3.27's instead of 3.08's, thats the only real difference

-Matt
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post #7 of 20 (permalink) Old 10-21-2007, 10:03 PM
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just check the diff tag when your pulling it, it will tell you if its open

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post #8 of 20 (permalink) Old 10-21-2007, 10:37 PM
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I shoulda looked at the diff in the car I pulled the driveshaft from. I'm curious now.
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post #9 of 20 (permalink) Old 10-22-2007, 12:07 AM
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I've never heard of a Mark having a factory installed trac-loc. This is due (as stated earlier) to the traction control that is standard on lincolns. They do all have alulminum cases however. If you can get a lincoln case, and trac-loc innards, you'll have yourself a Cobra pumpkin.

Edit: speaking of which, does this seem like a crazy price for this thing to anyone else but me?

http://cgi.ebay.com/ebaymotors/ws/eB...NA:MOTORS:1123


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post #10 of 20 (permalink) Old 10-22-2007, 12:50 AM
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Quote:
Originally Posted by Traveler View Post
I've never heard of a Mark having a factory installed trac-loc. This is due (as stated earlier) to the traction control that is standard on lincolns. They do all have alulminum cases however. If you can get a lincoln case, and trac-loc innards, you'll have yourself a Cobra pumpkin.

Edit: speaking of which, does this seem like a crazy price for this thing to anyone else but me?

http://cgi.ebay.com/ebaymotors/ws/eB...NA:MOTORS:1123
sucker born every second....only thing whizbang about the Cobra pumpkin is the Carbon Fiber trac lok clutches.




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post #11 of 20 (permalink) Old 10-22-2007, 01:00 AM
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LOL Wish that sucker would buy some stuff from me!!


1997 Thunderbird Sport
Low Miles
Wifes Car
destined to remain stock

1997 T-Bird GT 4.6
80 MM Mustang GT MAF - P&P'd Mustang GT TB and Intake Plenum - PI Intake manifold - PI Heads
Mark VIII Torque Converter - J-Modded 4R70W transmission - Mark VIII Aluminum Driveshaft - 3.73 gears
PBR Brake Calipers - Eibach Springs - KYB Shocks
'89 SuperCoupe front and rear sway bars
SCT Chip programmed by Lonnie Doll
255/50/16 Falken Ziex ZE-512's
True Dual exhaust with Magnaflow DI/DO muffler
<<< SOLD >>>
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post #12 of 20 (permalink) Old 10-22-2007, 01:13 AM Thread Starter
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Quote:
Originally Posted by The Great Obucina View Post
sucker born every second....only thing whizbang about the Cobra pumpkin is the Carbon Fiber trac lok clutches.
And correct me if I am wrong, but can't you put in the Carbon Fiber clutches for about $100 anyway?

C.Hill

'97 Laser Red T-bird w/ Option 66S - 125,000 miles, stock except for 3.73s Best ET 15.6 @ 88.3
'94 Electric Red T-bird LX V-8- 212,000 miles- SOLD
2005 Ebony Black Excursion Limited 6.0 Diesel STUDDED

"Thinking is the hardest work there is, which is the probable reason so few engage in it."
- Henry Ford

"Opportunity is missed by most people because it is dressed in overalls and looks like work."
- Thomas A. Edison

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post #13 of 20 (permalink) Old 10-22-2007, 01:22 AM
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Quote:
Originally Posted by stangboy7 View Post
And correct me if I am wrong, but can't you put in the Carbon Fiber clutches for about $100 anyway?

C.Hill

well, whatever the price on the OEM Trac Lok Carbon Fiber clutch kit is, yes...




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post #14 of 20 (permalink) Old 10-23-2007, 01:57 PM Thread Starter
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I have found a Mark VIII open with a 3.07. Can I still use this for my 3.73 upgrade? I had never heard of that gear ratio so I was a little leary. thanks

C.Hill

'97 Laser Red T-bird w/ Option 66S - 125,000 miles, stock except for 3.73s Best ET 15.6 @ 88.3
'94 Electric Red T-bird LX V-8- 212,000 miles- SOLD
2005 Ebony Black Excursion Limited 6.0 Diesel STUDDED

"Thinking is the hardest work there is, which is the probable reason so few engage in it."
- Henry Ford

"Opportunity is missed by most people because it is dressed in overalls and looks like work."
- Thomas A. Edison

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post #15 of 20 (permalink) Old 10-23-2007, 02:00 PM
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I've never head of a 3.07 either. I'm betting its a 3.08. And yes, if its a Mark VIII case you can use it for your 3.73 internals. Just install the 3.73 trac-loc into it like you would into the iron case T-bird rear end.


1997 Thunderbird Sport
Low Miles
Wifes Car
destined to remain stock

1997 T-Bird GT 4.6
80 MM Mustang GT MAF - P&P'd Mustang GT TB and Intake Plenum - PI Intake manifold - PI Heads
Mark VIII Torque Converter - J-Modded 4R70W transmission - Mark VIII Aluminum Driveshaft - 3.73 gears
PBR Brake Calipers - Eibach Springs - KYB Shocks
'89 SuperCoupe front and rear sway bars
SCT Chip programmed by Lonnie Doll
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True Dual exhaust with Magnaflow DI/DO muffler
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post #16 of 20 (permalink) Old 10-23-2007, 02:14 PM
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I've read a number of places that the actual Mark VIII gear ratios are 3.07 for the base model or 3.27 for the LSC.

But I really never looked into any more because I have the 3.27's.

But to get back on topic: To my knowledge: All Mark VIII's are aluminum housing with an open 8.8, 28 spline differential.

IMHO, the only benefit between to them is the weight savings. Anyone know what the weight difference is?

Just my .02.

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post #17 of 20 (permalink) Old 10-23-2007, 04:47 PM Thread Starter
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Well I just want to put the trac lock unit in it, I wasn't going to use it as-is. I just wanted it because it was lighter than my iron casing. I was just wondering if I could use it since it was an unusual gearing (3.07). I called and double checked today, and they confirmed it was a 3.07. I pick it up thursday so I will konw for sure.

C.Hill

'97 Laser Red T-bird w/ Option 66S - 125,000 miles, stock except for 3.73s Best ET 15.6 @ 88.3
'94 Electric Red T-bird LX V-8- 212,000 miles- SOLD
2005 Ebony Black Excursion Limited 6.0 Diesel STUDDED

"Thinking is the hardest work there is, which is the probable reason so few engage in it."
- Henry Ford

"Opportunity is missed by most people because it is dressed in overalls and looks like work."
- Thomas A. Edison

http://www.tailofthedragon.com <---- A test of driving ability and nerves.
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post #18 of 20 (permalink) Old 10-23-2007, 08:14 PM
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Originally Posted by stangboy7 View Post
Well I just want to put the trac lock unit in it, I wasn't going to use it as-is. I just wanted it because it was lighter than my iron casing. I was just wondering if I could use it since it was an unusual gearing (3.07). I called and double checked today, and they confirmed it was a 3.07. I pick it up thursday so I will konw for sure.C.Hill
The MKVIII diffs are a 3.07 ratio. That's what mine had when I picked it up: 43 ring gear teeth and 14 pinion teeth as I remember. The tag coding (on the diff) is different from the Ford coding as well. Took the rear cover off, and thought I really had something when I saw all those teeth on the ring gear. The 3.08 ratio has 37 ring gear teeth and 12 pinion teeth. No Marks had traction-lok from the factory.

As for the weight savings, I believe it was in the neighborhood of 50 lbs total after swapping the LCAs AND differential from a MKVIII. Can't seem to locate the exact figures - weighed everything from both sets when I swapped them out. Should I find the exact numbers, I'll post them. There was a thread started a year or two ago about weights of MKVIII aluminum vs. T'Bird iron/steel parts... can't find that either!

Best of Luck!
That is all...

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post #19 of 20 (permalink) Old 10-23-2007, 08:21 PM Thread Starter
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But i still would be able to swap the 3.07 to the 3.73 with no problem? THat is really all i want to know?

C.Hill

'97 Laser Red T-bird w/ Option 66S - 125,000 miles, stock except for 3.73s Best ET 15.6 @ 88.3
'94 Electric Red T-bird LX V-8- 212,000 miles- SOLD
2005 Ebony Black Excursion Limited 6.0 Diesel STUDDED

"Thinking is the hardest work there is, which is the probable reason so few engage in it."
- Henry Ford

"Opportunity is missed by most people because it is dressed in overalls and looks like work."
- Thomas A. Edison

http://www.tailofthedragon.com <---- A test of driving ability and nerves.
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post #20 of 20 (permalink) Old 10-23-2007, 08:50 PM
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But i still would be able to swap the 3.07 to the 3.73 with no problem? THat is really all i want to know?

C.Hill
Yes, the gears (8.8" ring gear 1.625" pinion) will fit. Might have a bit of a time getting the original carrier out of the case is all.

That is all...

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