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post #1 of 34 (permalink) Old 01-01-2015, 11:47 PM Thread Starter
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open diff?

The tag on my rear diff says that I have a 3.08 open diff but if you get on it from a stop it leaves two tire marks. I guess its possible someone put in a limited slip before I got it but doubtful. I have rear disc brakes, dont know if that makes a difference as far as option packages?
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post #2 of 34 (permalink) Old 01-02-2015, 05:15 AM
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Have you checked your drivers side door jamb sticker?

Under the "AX" on the door jam sticker:

Gears and Axles

Most likely you have an open rear end..Even with an open rear end if you (power brake) it on a flat dry surface you can get both tires to lay tracks..

One way to check to see if you have an open rear end is to lift up the rear of the car..Then spin one of the rear wheels by hand..

The other rear wheel will spin in the opposite direction if you have an open rear end..

Of course if you do have a Trac-Lok, and it is really worn out this test may not work..I've seen that happen before too..

In that case..Just to be 100% sure of what you got in the rear end the differential cover has to come off..





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post #3 of 34 (permalink) Old 01-02-2015, 12:09 PM
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You can leave parallel skid marks with an open diff. Did it a couple times in my old 3.8 Cougar... no brakes involved.

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post #4 of 34 (permalink) Old 01-02-2015, 02:25 PM
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I was able to spin both wheels all the time when I had an open diff, really the trac-lok shows its value more on wet inclines or when you need to countersteer. LSDs weren't engineered to just make burnouts cooler

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post #5 of 34 (permalink) Old 01-02-2015, 03:13 PM
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I used to be able to spin both tires on an open diff also, when the tires were worn out.
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post #6 of 34 (permalink) Old 01-02-2015, 06:31 PM Thread Starter
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Every other car I had that had an open diff only did the one wheel peel. So seeing an open diff leaving two marks had me wondering.
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post #7 of 34 (permalink) Old 01-02-2015, 08:31 PM
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Pretty sure from what you all describe is an open, that what's in mine. But with 2.73's wheel spin from a dead stop is not an issue. However, mainly due to the surface I'm on, I get 1 or both breaking loose, just never really know which is going to happen.
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post #8 of 34 (permalink) Old 01-02-2015, 08:36 PM
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If you get really curious, pop the diff cover and have a look. The "S" spring is an immediate giveaway.

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post #9 of 34 (permalink) Old 01-02-2015, 09:41 PM
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How strong is a properly functioning 8.8 trac loc? I'm putting one in soon and curious how different driving the car will be. I have never have driven a Ford with one before. I have driven a few trucks with lockers and they come on quick and hit hard.
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post #10 of 34 (permalink) Old 01-02-2015, 09:54 PM
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Since the Cougar has always had a TracLok in it, I can't say for sure - but really, with my driving, I can't tell much difference on dry ground as with the open diff in the Dakota pickup.

Slick streets, OTOH ... *grins* Rather have the Cougar diff.

(Which is why I'm saving up for a Dana LSD for the Dakota.)

RwP

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post #11 of 34 (permalink) Old 01-03-2015, 12:49 PM
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They drive completely differently.

A one-leg rear will hold a line thru a corner better at wot; a locker will drift.

Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
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post #12 of 34 (permalink) Old 01-03-2015, 01:43 PM
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There seems to be some confusion between a limited-slip (like a Traction-Lok) and a locker (Detroit Locker, ARB, etc.) . They behave quite differently.

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post #13 of 34 (permalink) Old 01-03-2015, 03:13 PM
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Disclaimer: I've never driven a "Real" geared type locker rear end.

Lazarus is easy to "fine steer" with the throttle in curves, as most of my older 'locker' Fords were.

The one side drive doesn't lose the line in a curve as easy with increasing throttle; that's the biggest difference I notice.

It's much easier to do donuts with the trac-lok, lol.

I just don't do a lot of wot action from a stop...

Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
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post #14 of 34 (permalink) Old 01-03-2015, 03:18 PM
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LSD > than all in the real world. Lockers have their place but not on a IRS IMO, or on the street.

IMO Geared LSDs are the best.

If all else fails get a bigger hammer!

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post #15 of 34 (permalink) Old 01-03-2015, 04:44 PM
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It seems like the Trak-loc makes a tire skip occasionally, and imho, that makes it "driftier".

Whoever has the least load 'barks' a bit in a sharp corner, kinda, to give up the bind.

(We have curvies here so sharp you can see both bumpers at the same time; ymmv. )

Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
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post #16 of 34 (permalink) Old 01-03-2015, 05:16 PM
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Quote:
Originally Posted by Grog6 View Post
They drive completely differently.

A one-leg rear will hold a line thru a corner better at wot; a locker will drift.
I agree,
The open on my 95, I could take an aggressive turn and stomp on the gas I might get a little loss of traction. Then, if I PB I could eventually get both tires roasting leaving 2 marks one darker then the other. My 96, had a aftermarket trac-loc installed before I bought it. Now if I do the same driving with this I get drifting out of corners and both tires start to spin at once not just one then the other.

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post #17 of 34 (permalink) Old 01-04-2015, 06:45 PM
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I saw this post in an older thread:

Quote:
Originally Posted by David Neibert View Post
... I'm still using the stock size S spring and standard friction/steel stack in my 91 SC. They were replaced at around 85K miles when installing gears, but no upgrades over stock. My 93 SC has an Auburn Pro and the only difference you can feel when driving is when the tires spin. On the 91 SC with stock trac loc it kicks sideways, when the 93 SC spins with the Auburn Pro it tracks dead straight.
...
David
I'll assume this is what I'm missing with only Trac-lok experience to go by.

This exactly describes my experience with the T-L diff.

I'm going to have to look into this further.

Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
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post #18 of 34 (permalink) Old 01-05-2015, 10:44 AM
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Quote:
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IMO Geared LSDs are the best.
A Torsen gear driven LSD sucks, at least on a high powered turbo car. On a big turbo (laggy) setup, when the boost hits, the back end kicks out hard at 55-60 MPH! That can be very dangerous. After switching to a clutch type LSD, the Toyota tracks straight.

And for the record, every open diff car I have ever has only spun one wheel on a dry surface. The only exception was when turning on slick surfaces, both would spin enough to kick the back end out or do donuts.

Al

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post #19 of 34 (permalink) Old 02-03-2015, 04:35 PM
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I ran a Torsen T2 on my Bird for 10 years and was very happy with it. It was especially helpful when I was still daily driving in Michigan winters. Also did pretty well at the drag strip with 375 rear wheel hp, although I did have to preload the right rear tire to get it to launch straight. When I did the rear end upgrade two years ago, I switched to a Detroit TruTrac for improved strength.

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post #20 of 34 (permalink) Old 05-16-2015, 02:44 PM
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Question : On my trip to the boneyard today, I checked the the door sticker and rear axles on the Birds & Cougars there. Only 1, a '94, has rear discs and a Z code axle. Is that rear axle assembly a direct fit in place of a '91 rear axle assembly??
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post #21 of 34 (permalink) Old 05-16-2015, 04:03 PM
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Quote:
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Question : On my trip to the boneyard today, I checked the the door sticker and rear axles on the Birds & Cougars there. Only 1, a '94, has rear discs and a Z code axle. Is that rear axle assembly a direct fit in place of a '91 rear axle assembly??
If you mean the pumpkin(differential)..Then yes your 91 pumpkin will swap right out for the 94 pumpkin..

You would have to change your speedo gear for your speedometer to read correctly..


If you mean swapping the whole rear disc assembly onto your car that currently has rear drums..

You would need to transfer over the disc brake lines as well as the left and right rear parking brake cables..

All That is covered here-->>Rear Drum to Disc Brake Conversion






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post #22 of 34 (permalink) Old 05-16-2015, 04:35 PM
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Awesome!! And Thanks again!!
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post #23 of 34 (permalink) Old 05-18-2015, 12:59 PM
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post #24 of 34 (permalink) Old 06-20-2015, 06:49 PM
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OK. Was back at the boneyard again today, and they are starting to squish some stuff. The Bird I got my cluster from was gone. The '94 with the Z code axle and disks is still there, Dude told me for them to pull the whole assembly and set it in the back of my Dodge would set me back $300. Sounds good to me, but is that a fair price??
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post #25 of 34 (permalink) Old 06-20-2015, 08:25 PM
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Yep.

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post #26 of 34 (permalink) Old 06-20-2015, 08:30 PM
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Originally Posted by xquzzme View Post
OK. Was back at the boneyard again today, and they are starting to squish some stuff. The Bird I got my cluster from was gone. The '94 with the Z code axle and disks is still there, Dude told me for them to pull the whole assembly and set it in the back of my Dodge would set me back $300. Sounds good to me, but is that a fair price??
That's not a bad price..Especially if they are pulling it for you..They go for around $250 over here in Ohio..

Just make sure if they do cut it out instead of unbolting it..That they don't cut off parts you will need..

Like the frame itself.. As well as the parking brake cables/coil springs/sway bar..etc,etc..







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post #27 of 34 (permalink) Old 06-20-2015, 10:11 PM
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Would the springs and bar be any stouter that the base 5.0 that are in my '91? If not, I won't need them. Figured on new bake lines anyway. Read about the E cables, so need them. The '94 has been sitting in the dirt with no wheels for a while, so a lot will need redone before I try the swap. Just can't let that stuff get squished. Hard to find in this part of the world.
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post #28 of 34 (permalink) Old 06-20-2015, 10:41 PM
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Would the springs and bar be any stouter that the base 5.0 that are in my '91? If not, I won't need them. Figured on new bake lines anyway. Read about the E cables, so need them. The '94 has been sitting in the dirt with no wheels for a while, so a lot will need redone before I try the swap. Just can't let that stuff get squished. Hard to find in this part of the world.
Unless it's a 94 SC..Then just use your 91 (V8) base coil springs (provided they are in good condition)..

You don't want to install NA (V6) coil springs on a (V8) car..

Your 91 base may, or may not have a bigger rear sway bar than what's on that 94 rear end..You would just have to measure both, and use the bigger of the two..

My thinking was..If you're going to pay for a complete rear end..Then get as much of the rear end as possible..

Because even if you don't use all the parts..You could always sell them to try, and recoup some of the money you paid for the rear end..

It never hurts to have a few spare parts either..






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post #29 of 34 (permalink) Old 06-21-2015, 03:00 AM
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Quote:
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You don't want to install NA (V6) coil springs on a (V8) car..
Pretty sure rear springs are the same.

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post #30 of 34 (permalink) Old 06-21-2015, 02:33 PM
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I don't want to discount the fact that it's a possibility that his 91 has has Sport Springs on it..

In which case he would find a green "JVC" tag on the front springs..Then the rears would have a green "NUD" tag on the springs..

If you don't find the "JVC" tag on the front springs, and "NUD" tag on the rear springs..Then they are just regular old NA V6/V8 springs..

So yeah..The rear coil springs might be the same..It doesn't hurt to look though..

I've amended the original Coil Spring chart found here to make it accurate..







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