Mark VIII rear end on a Thunderbird? - TCCoA Forums
 
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post #1 of 10 (permalink) Old 07-09-2009, 01:54 PM Thread Starter
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Mark VIII rear end on a Thunderbird?

There has been some threads about this subject, but stuff isn't adding up. While poking around SCP, it shows drive shafts that cross reference a Thunderbird AND a Mark VIII. It also looks like haf-shafts are the same as well, based on part numbers. The rear differential pinion brace is also listed for both applications.

I am looking to put 3.73s in my Thunderbird. I was wondering if I can get a whole axle and swap it out. I was also looking for confirmation that there are indeed 3.73s in there.

On another thread, someone said..

Quote:
-- It's not a drop in unit for a IRS rear end, there is no grove in the end gears to lock in the CV axles.
and..

Quote:
he Gears for the axles need a groove machined in for the spring clip on our (IRS) axles; the Straight axles use a circlip and a flat washer...no groove...

Our axles aren't able to come out, due to the suspension design, so there is no need for a solid lock at the end of the axle.

Get whoever is doing the mark parts swap to machine it for you.
Has anyone taken a good look to see if this is do-able? There are also weight savings swapping the axles and of course, I want to take advantage of that.

What do you guys think?

-=James
1995 Ford Thunderbird V8
SCT Tuned by Amercian Motorsport, Mustang PBR, FRPP 3.73 gears, Modified Trak-Lok, Steeda UDP, K&N Panel, 1990 SC Seats, 2.5" Single Exhaust/Magnaflow Hi-Flow Cats, Michelin Pilot Sport A/S +, Windstar wheels, RichardM Intake, Kenwood KDC-HD552U HD Radio, 2800 stall DirtyDog Marauder TC, J-MOD, 2002 Grand Marquis transmission, DynoTech Driveshaft, AeroForce Interceptor Scan Gauge, Griffin Super High Capacity Radiator, 180* Thermostat, Cobra steering wheel, 6000K HID, Clear Corners Getting a makeover Spring 2015


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post #2 of 10 (permalink) Old 07-09-2009, 01:59 PM
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Yes, they should work for both Tbirds and Mark's . I used a pumpkin from a 99 Cobra they too have a IRS .

1997 Ford Thunderbird 4.6 Sport .

60'...... 2.06
1/8th .. 9.194
mph .... 77.13

mods*
PI heads *PI intake*Mark VIII torque converter*Cobra T-loc w\4.10's * Jmod*tranny fluid cooler*P&P stock T/B & plenum*UD pulleys* Dynotech 4in ds*80mm Lightning maf*Xcal2*02 GT intake tube.
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post #3 of 10 (permalink) Old 07-09-2009, 02:47 PM
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I'm not entirely sure about what you're asking, but... Between Mark VIIIs and Thunderbirds/Cougars the entire housing (center section) with gears, diff., etc. inside will interchange with no modifications necessary.

Step 1: Remove center section from Mark VIII
Step 2: Remove center section from Bird/Coug
Step 3: Do nothing to your fancy aluminum Mark differential/gear/housing assembly (assuming you're keeping the lame stock gears), do nothing to your Bird/Coug
Step 4: Bolt Mark center section into Bird/Coug

The side gear questions you have are in reference to the difference between the side gears in a solid axle differential and an irs differential. This will only come into play if you acquire a solid axle differential out of a mustang, etc. A good route to go is to acquire a used Mark differential housing (they're all aluminum), get a trac-lok differential (preferably an irs one, but I run a solid axle one with no issues), get some gears, and assemble and install them in your car. I'm not sure how much weight I shaved off, nothing to get excited about though.

lowered, koni sport adjustables, 4.30 tl in aluminum housing, mark 8 trans, j-mod, 93 mark viii ds, antenna hole=gone, kooks headers 1.75" primaries, 2.5" catless duals, midmount magnaflow, 96-97 sport wheels with 255/50/16 sumitomo HTR Zs, optima in the trunk, new motor...94 mark 6/6/08
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post #4 of 10 (permalink) Old 07-09-2009, 05:51 PM Thread Starter
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I am just trying to see if we can take a Mark VIII axle and put it into the Bird. My whole goal is to put 3.73s in. We are thinking it would be a short cut if the Mark came with them, plus the extra bonus of having the weight savings.

-=James
1995 Ford Thunderbird V8
SCT Tuned by Amercian Motorsport, Mustang PBR, FRPP 3.73 gears, Modified Trak-Lok, Steeda UDP, K&N Panel, 1990 SC Seats, 2.5" Single Exhaust/Magnaflow Hi-Flow Cats, Michelin Pilot Sport A/S +, Windstar wheels, RichardM Intake, Kenwood KDC-HD552U HD Radio, 2800 stall DirtyDog Marauder TC, J-MOD, 2002 Grand Marquis transmission, DynoTech Driveshaft, AeroForce Interceptor Scan Gauge, Griffin Super High Capacity Radiator, 180* Thermostat, Cobra steering wheel, 6000K HID, Clear Corners Getting a makeover Spring 2015


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post #5 of 10 (permalink) Old 07-09-2009, 06:16 PM
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Our cars do not have a 'proper' axle. In the middle there is a differential housing, sticking out from that on each side is an axle shaft. These axle shafts pass through wheel bearings on each side pressed into the spindle. The 'axle tube' on our cars is a cylinder of air surrounding the axle shafts.

Marks did not come with 3.73 gears. Their diff housing is Al opposed to our Fe housing. This is where the weight savings comes in. I don't know the precise difference in weight, I did not put mine on a scale. This info is on this site however.

lowered, koni sport adjustables, 4.30 tl in aluminum housing, mark 8 trans, j-mod, 93 mark viii ds, antenna hole=gone, kooks headers 1.75" primaries, 2.5" catless duals, midmount magnaflow, 96-97 sport wheels with 255/50/16 sumitomo HTR Zs, optima in the trunk, new motor...94 mark 6/6/08
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post #6 of 10 (permalink) Old 07-09-2009, 06:37 PM
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I think the M8 diff housing weighs about 2/3 of the T'bird/Cougar one. You could rebuild the M8 with 3.73 and trac-loc out of the vehicle and when you got ready, you could just pop it in. You can use the solid axle side gears, BUT, you will have HELL getting the 1/2 shaft stubs out unless you remove the diff cover and remove the c clip from the stub. I think 95badbird just left the clips off and just stuck them in and let it ride.
Quote:
Originally Posted by _95badbird View Post
thats how I run mine.....mustang diff, no clips.

Last edited by rayner601; 07-09-2009 at 06:46 PM. Reason: can't get anyting straight today
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post #7 of 10 (permalink) Old 07-11-2009, 10:55 PM Thread Starter
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Thanks for the posts. I think I am just going to get the 3.73s installed and call it a day. I found a place to do it for me.

-=James
1995 Ford Thunderbird V8
SCT Tuned by Amercian Motorsport, Mustang PBR, FRPP 3.73 gears, Modified Trak-Lok, Steeda UDP, K&N Panel, 1990 SC Seats, 2.5" Single Exhaust/Magnaflow Hi-Flow Cats, Michelin Pilot Sport A/S +, Windstar wheels, RichardM Intake, Kenwood KDC-HD552U HD Radio, 2800 stall DirtyDog Marauder TC, J-MOD, 2002 Grand Marquis transmission, DynoTech Driveshaft, AeroForce Interceptor Scan Gauge, Griffin Super High Capacity Radiator, 180* Thermostat, Cobra steering wheel, 6000K HID, Clear Corners Getting a makeover Spring 2015


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post #8 of 10 (permalink) Old 07-11-2009, 11:49 PM
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I modify those side gears often.
Alan

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post #9 of 10 (permalink) Old 07-13-2009, 02:17 AM
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I'm doing this week exactly what you said you wanted to do. I bought a worn out Supercoupe center section with a 3.27 trac-loc in it. Then I bought a set of 3.73 gears, and then found a Mark VIII aluminum Case. Took those to a builder along with the kits for rebuilding the trac-loc and the rear end. When its done I'll just swap it into the car.. (hopefully this weekend)


1997 Thunderbird Sport
Low Miles
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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
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post #10 of 10 (permalink) Old 07-13-2009, 11:26 AM Thread Starter
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Good luck with that! Let us know how it goes. I came pretty close to buying your 3.55s but after doing some research and asking around, it looked like 3.73s was the right way for me to go.

-=James
1995 Ford Thunderbird V8
SCT Tuned by Amercian Motorsport, Mustang PBR, FRPP 3.73 gears, Modified Trak-Lok, Steeda UDP, K&N Panel, 1990 SC Seats, 2.5" Single Exhaust/Magnaflow Hi-Flow Cats, Michelin Pilot Sport A/S +, Windstar wheels, RichardM Intake, Kenwood KDC-HD552U HD Radio, 2800 stall DirtyDog Marauder TC, J-MOD, 2002 Grand Marquis transmission, DynoTech Driveshaft, AeroForce Interceptor Scan Gauge, Griffin Super High Capacity Radiator, 180* Thermostat, Cobra steering wheel, 6000K HID, Clear Corners Getting a makeover Spring 2015


http://www.fordthunderbird.net - For Pics and more!
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